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MURRURUNDI, BLANDFORD
AND WILLOW TREE
FLOODPLAIN MANAGEMENT STUDY
APPENDIX A
FLOOD HYDROLOGY AND HYDRAULICS
Note: The Word version of the document was reformatted in December 2014 which has led
to minor differences in its structure when compared to the original report.
Job No: NX518
J:\NX518\docs\APPA.doc
Date: 03/06/98
Rev: 3.0 Author: SAB
Reviewer: BWL
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix A – Flood Hydrology and Hydraulics
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Lyall & Macoun
Consulting Engineers
TABLE OF CONTENTS
Page No.
A.1 INTRODUCTION ......................................................................................................... A-1
A.2 SCOPE OF INVESTIGATION ...................................................................................... A-1
A.3 STUDY APPROACH ................................................................................................... A-1
A.4 STUDY RESULTS ....................................................................................................... A-2
A4.1 Existing Conditions .............................................................................................. A-2
A4.2 Testing Flood Management Proposals ................................................................. A-3
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix A – Flood Hydrology and Hydraulics
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A.1 INTRODUCTION
LMCE prepared the Flood Study for the townships of Murrurundi, Blandford and Willow Tree,
which was submitted as a draft in February 1997.
The streams investigated in the study included the 12.5 km reach of the Pages River from
Murrurundi to Blandford, as well as the 4.5 km section of Borambil Creek in the vicinity of Willow
Tree.
The Pages River has its source near the eastern end of the Liverpool Range, from where it flows
in a south-easterly direction to join the Hunter River in its headwater region several kilometres
upstream of Aberdeen. Borambil Creek rises on the northern side of the Liverpool Range in the
Namoi River catchment and flows in a northern direction parallel with the New England Highway.
A short distance upstream of Willow Tree it is joined by Chilcotts Creek which drains the foothills
of the range to the east.
The study area has been subject to nine significant floods over the past 40 years since the record
flood of October 1949. Murrurundi is the most flood prone of the three townships with residential
development on both sides of the Pages River vulnerable to flooding. On two recent occasions,
in January and October 1996, flow surcharged the right bank and flowed down the New England
Highway (Mayne Street). Blandford and Willow Tree are flood prone but to a lesser degree than
Murrurundi.
A.2 SCOPE OF INVESTIGATION
Flood behaviour in the two streams was modelled in terms of flows, levels and flooding behaviour
for flood frequencies ranging between 5 and 100 years average recurrence interval (ARI), as well
as for the Probable Maximum Flood (PMF). A preliminary assessment of flood hazard has also
been made using velocity and depth results obtained from the investigation.
A.3 STUDY APPROACH
Flood behaviour was defined using computer based hydrologic models of the study catchments
and hydraulic models of the streams. The hydrologic models were based on the RORB runoff
routing program. The Pages River model was calibrated to recorded rainfall and streamflow data.
The records at the Blandford stream gauging station on the Pages River and pluviographic data
at Scone, Murrurundi, Blandford and Gowrie North were used for this purpose. Four floods were
used for model calibration. In the order of investigation they were: January 1996, February 1992,
January 1976 and October 1996.
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Murrurundi, Blandford and Willow Tree
Appendix A – Flood Hydrology and Hydraulics
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The January 1996 recorded flood peak of 1030 m3/s is close to the 50 year ARI in terms of peak
discharge at Blandford on the basis of the RORB model results. Further upstream at Murrurundi
the assessed flood peak was 450 m3/s, which is near the modelled 100 year ARI peak discharge.
The February 1992 and January 1976 floods were somewhat smaller, with recorded peak flows at
Blandford of 870 m3/s and 780 m
3/s respectively. They had an assessed frequency around the
20 year ARI magnitude. In October 1996, rainfall was most intense in the Pages River catchment
above Murrurundi, with lesser falls in downstream areas. At Murrurundi, the peak discharge of
380 m3/s approximated a 50 year ARI event, but at Blandford township just below the junction
with Warlands Creek, the peak discharge of 610 m3/s was less than the design 20 year ARI
discharge. For all of these events, there was a consistent set of RORB model parameters, which
gave reproduction of the recorded hydrographs.
There are no stream gauging stations on Borambil Creek. A formal calibration of the RORB
model was not therefore possible. Based on limited flood level data for the recent flood of
January 1996, an estimate of the peak discharge was made. This discharge was used to tune
the parameters of the RORB model. The October 1996 storm did not produce significant flood
flows on this catchment.
A fully dynamic network hydraulic model was adopted for the hydraulic analysis to account for the
time varying effects of flows from the tributary streams and the routing effects of the floodplain
storage. A one-dimensional link-node model, MIKE 11, was chosen which allowed for the
interaction of flows between the channel and the floodplain, flow through culverts and flow over
road embankments. Models were set up for both the Pages River and Borambil Creek. The
Pages River model extended from upstream of Murrurundi to a point about 1.8 km downstream of
Blandford and included Halls Creek, Unnamed Gully and Cohens Gully which join the Pages
River in the township, as well as Warlands Creek which joins just downstream of Blandford. The
Borambil Creek model commenced upstream of the Hams Bridge at Merriwa Road and extended
to a point downstream of the sporting fields. The two models were calibrated and tested using
recorded streamflow and flood level data, as available.
A.4 STUDY RESULTS
A.4.1 Existing Conditions
Design storms were then applied to the RORB models to generate discharge hydrographs within
the study area as described in Chapter 5. These hydrographs constituted the inputs to the
hydraulic model for the assessment of design flood behaviour.
The hydraulic model was then used to produce water surface profiles, flood contours and flow
and velocity distribution for the design events. Tabulated peak flood levels and the distribution of
flows and velocities for each model cross section were also presented.
Preliminary delineation of the floodplains into high and low hazard areas was undertaken using
the velocity - depth criteria set out in the draft Floodplain Management Manual (DLWC, 1995).
Hydraulic modelling was also undertaken to allow preliminary hydraulic categorisation of the
floodplain into floodway and flood storage areas.
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Appendix A – Flood Hydrology and Hydraulics
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The extent of flooding and the flood hazard delineation shown on the diagrams was approximate
only, particularly in the case of Blandford and Willow Tree. The best available contour mapping
at these two centres is at 1:25000 scale with 10 m contour spacing. Accurate delineation of
these lines would require more detailed survey. For Willow Tree any additional survey should
include the establishment of benchmarks to AHD. The cross sectional survey carried out for the
flood study adopted a local datum, as there are no reliable AHD survey marks in the township.
The local datum is about 100 m above AHD.
At Murrurundi, the survey situation is somewhat better as there is mapping at 1:1000 scale with
1 m contours. However, a flood fringe survey will need to be undertaken to confirm the extent of
flooding. This work could be carried out after the Designated Flood Event has been set.
Murrurundi is surrounded on its northern and southern sides by steeply rising hillsides, which are
drained by several gullies which have contributed to local flooding problems. Two local gullies,
Unnamed Gully and Cohens Gully drain the northern side. Halls Creek drains the southern
foothills. Flooding in these watercourses as well as overland flooding in the vicinity of Hall Street
in Willow Tree was also discussed in the Flood Study.
A4.2 Testing Flood Management Proposals
The models developed in the Flood Study were used in the Floodplain Management Study to
evaluate potential floodplain management strategies. The potential strategies modelled at
Murrurundi comprised levees along the right bank, channel improvements and enlargement of the
waterway area at Arnolds Bridge. Because the model is dynamic in nature, it was capable of
assessing the implications of each measure on downstream flood levels and flows as well as
upstream impacts. At Blandford, potential measures analysed included levees on Warlands
Creek both upstream of the Barsham Bridge, as well as enlargement of the bridge waterway area.
The results of hydraulic modelling are described in Chapter 4 of the Main Report.
Job No: NX518
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Date: 03/06/98
Rev: 3.0 Author: SAB
Reviewer: BWL
MURRURUNDI, BLANDFORD
AND WILLOW TREE
FLOODPLAIN MANAGEMENT STUDY
APPENDIX B
ASSESSMENT OF FLOOD DAMAGES
Note: The Word version of the document was reformatted in December 2014 which has led to minor
differences in its structure when compared to the original report. No hard copy version of this
Appendix was available at the time of compiling. As a result, the figures listed in this Appendix could
not be reproduced.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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TABLE OF CONTENTS
Page No.
SYNOPSIS ...................................................................................................................................S-1
B1. INTRODUCTION AND SCOPE ........................................................................................... B-1
B1.1 Introduction ...............................................................................................................B-1
B1.2 Scope of Investigation ..............................................................................................B-1
B2. DESCRIPTION OF APPROACH ......................................................................................... B-2
B3. SOURCES OF DATA ............................................................................................................. B-3
B4. RESIDENTIAL DAMAGES................................................................................................... B-5
B4.1 Direct Residential Damages ....................................................................................B-5 B4.1.1 Method .........................................................................................................B-5 B4.1.2 Damage Functions .......................................................................................B-5
B4.2 Indirect Residential Damages ..................................................................................B-6
B4.3 Total Residential Damages ......................................................................................B-7
B5. COMMERCIAL AND INDUSTRIAL DAMAGES ................................................................. B-9
B5.1 Direct Commercial and Industrial Damages ...........................................................B-9 B5.1.1 Method .........................................................................................................B-9 B5.1.2 Damage Functions .......................................................................................B-9
B5.2 Indirect Commercial and Industrial Damages ......................................................B-10
B5.3 Total Commercial and Industrial Damages ..........................................................B-10
B6. DAMAGES TO PUBLIC BUILDINGS ............................................................................... B-13
B6.1 Direct Damages - Public Buildings ........................................................................B-13
B6.2 Indirect Damages - Public Buildings .....................................................................B-13
B6.3 Total Damages - Public Buildings .........................................................................B-13
B7. DAMAGES TO INFRASTRUCTURE AND COMMUNITY ASSETS ............................... B-16
B7.1 Infrastructure ...........................................................................................................B-18 B7.1.1 Electricity ....................................................................................................B-18 B7.1.2 Telecom ......................................................................................................B-19 B7.1.3 Roads, Bridges and Railway .....................................................................B-19 B7.1.4 Sewerage Reticulation...............................................................................B-21 B7.1.5 Water Supply ..............................................................................................B-21 B7.1.6 Gas .......................................................................................................B-22
No gas supply is present in either of the three townships. ...............................................B-22
B7.2 Community Assets ..................................................................................................B-22
B8. SUMMARY OF TANGIBLE DAMAGES ............................................................................ B-25
B9. REFERENCES .................................................................................................................... B-28
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Appendix B - Assessment of Flood Damages
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FIGURES
B8.1 Total Damage - Frequency Curves Murrurundi
B8.2 Cumulative Average Annual Damages - Frequency Curves Murrurundi
B8.3 Total Damage - Frequency Curves Blandford
B8.4 Cumulative Average Annual Damages - Frequency Curves Blandford
B8.5 Total Damage - Frequency Curves Willow Tree
B8.6 Cumulative Average Annual Damages - Frequency Curves Willow Tree
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Appendix B - Assessment of Flood Damages
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SYNOPSIS
Estimation of flood damages has been carried out to permit a "broad brush" economic
assessment of various flood mitigation options and to provide information to assist Council in the
selection of the designated flood. Damages from floods ranging between the 5 year ARI and
PMF events were assessed.
Data for the flood damages model comprised a knowledge of the depth of inundation over the
floodplain, as well as information on the value of damages to residential, commercial and
industrial property.
The depth of inundation was determined from the results of the hydraulic modelling, described
previously in Appendix A, from available mapping and from site inspection. The type of structure
and potential for property damage were assessed from a drive-by survey of the town.
There are some data available on historic flood damages in the study area. Estimates of
damages to assets incurred in the January and October 1996 flood events were made by
Murrurundi Shire Council, as well as estimates to main roads in the Shire made by RTA. This
information was collated and compared with data on damages experienced during recen t flooding
in other centres in NSW. The data were transposed and used in the assessment for the
townships of Murrurundi, Blandford and Willow Tree. To that extent the computed values are
"potential" damages rather actually experienced. A reduction has been made to allow for
property evacuation, which would reduce, the damages actually experienced to values below the
potential damages.
The estimated damages, which could occur in the three townships for various floods, are
summarised in the table below.
TABLE S1
FLOOD DAMAGES IN MURRURUNDI, BLANDFORD AND WILLOW TREE ($x103)
Flood Event
ARI (years)
Residential Commercial Public Total
5
20
50
100
200
PMF
0
12
120
245
554
4,550
0
0
205
435
850
5,240
0
14
43
95
400
3,505
0
26
368
775
1,804
13,295
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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B1. INTRODUCTION AND SCOPE
B1.1 Introduction
Damages from flooding belong to two categories:
Tangible Damages
Intangible Damages
Tangible damages are defined as those to which monetary values may be assigned, and may
be subdivided into direct and indirect damages. Direct damages are those caused by physical
contact of floodwater with damageable property. They include damages to commercial and
residential building structures and contents as well as damages to infrastructure services such as
electricity and water supply. Indirect damages result from the interruption of community
activities, including traffic flows, trade, industrial production, costs to relief agencies, evacuation
of people and contents and clean up after the flood.
Generally, tangible damages are estimated in dollar values using survey procedures,
interpretation of data from actual floods and research of government files.
The various factors included in the intangible damage category may be significant. However,
these effects are difficult to quantify due to lack of data and the absence of an accepted method.
Such factors may include:
inconvenience
isolation
disruption of family and social activities
anxiety, pain and suffering, trauma
physical ill-health
psychological ill-health.
B1.2 Scope of Investigation
In the following sections, damages to residential, commercial and industrial properties as well as
public buildings have been estimated within the three townships. Damages to infrastructure and
community assets have also been assessed where data were available.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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B2. DESCRIPTION OF APPROACH
The potential damage caused by a flood to a particular property is largely a function of the depth
of flooding above floor level and the value of the property and its contents. A spreadsheet model
was used to estimate residential, commercial and public utility damages on a property by
property basis according to a probable damage category (high, medium or low value), the
location of the property and the depth of inundation.
Flood heights at locations defined by the hydraulic model results were imported to a contouring
program and the data were grided using the ‘Krigging’ method with matrix smoothing. The grided
data were then used to create flood contours through the town for each of the events of interest.
The location of each property in the flood liable area was digitised to the same reference grid
used for the hydraulic data. These locations were imported to the contouring program and a
flood height, for each event, was interpolated at each property.
The interpolated property flood levels were input to a spreadsheet model containing property
characteristics and stage-damage relationships. The depth of flooding was computed as the
difference between the interpolated flood level and the floor elevation at each property. Damage
was estimated by depth-damage curves entered as a series of points with the losses in each
property category indexed to a depth of inundation of 2 metres.
Included within the model is the ability to simulate the reduction in flood damages, which result
from flood awareness and flood warning. The reduced damages are denoted "actual" damages.
It should be understood that this approach is not intended to identify individual properties liable to
flood damages and individual values of damages, even though it appears to be capable of doing
so. The reason for this caveat lies in the various assumptions used in the procedure, the main
ones being:
assumption that computed water levels are accurate and without any error;
assumption that the water surfaces between hydraulic model sections are adequately
represented by the contouring program and are not subject to localised influences;
the use of "average" stage-damage relationships, rather than a relationship for each
property;
the uncertainty associated with assessing an accurate factor to convert potential to actual
flood damages for each property;
the accuracy of assessment of floor levels.
The consequence of these assumptions is that some individual properties may be inappropriately
classified as flood liable, while others may be excluded. Nevertheless, when applied over a broad
area these effects will tend to cancel, and the resulting estimates of overall damages, both potential
and actual, will be reasonably accurate. To minimise errors, floor levels were surveyed by a registered
surveyor for properties in the flood prone areas.
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Appendix B - Assessment of Flood Damages
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B3. SOURCES OF DATA
To estimate average annual flood damages for a specific area it is necessary to estimate the
damages for several floods of different magnitudes, ie of different frequencies, and then to
integrate the damages over the whole range of frequencies. To do this it is necessary to have
data on the damages sustained by all types of property over the likely range of inundation. There
are several ways of doing this:
The ideal way would be to conduct specific surveys in the aftermath of a range of floods,
preferably immediately after each. This has been done in a limited fashion for Murrurundi,
Blandford and Willow Tree, with the flood review studies undertaken following the 1992 and
January 1996 floods (Bush, 1991, 1996). A recent example approaching this ideal is the
case of Nyngan where surveys were conducted in May 1990 following the disastrous flood of
a month earlier (DWR, 1990).
The second best way is for experienced adjusters to conduct a survey to estimate likely
losses that would arise due to various depths of inundation. This approach is used from time
to time, but it can add significantly to the cost of a floodplain management study (LMJ, 1985).
It was not used for the three townships.
The third way is to adapt or transpose, data from another flood liable area. This was the
approach used for Murrurundi, Blandford and Willow Tree. It involved use of the bas ic data
collected for the Nyngan survey and making adjustments to account for changes in values
due to inflation, and to account for differences in the nature of developments between the
towns. Conducting a drive-by survey in flood liable areas of the townships assisted this.
The fourth way is to use generalised data such as that published by CRES (Centre for
Resource & Economic Studies, Canberra) and used in a recent Floodplain Management
Study for Forbes (SKM, 1994) This kind of data is considered to be suitable for generalised
studies, such as broad regional studies. It is not considered to be suitable for use in specific
areas, unless none of the other approaches can be satisfactorily applied.
As indicated above, an important source of data for this study was a drive-by inspection of
properties in the study area estimated to be affected by flooding events up to and including the
PMF event. The properties were divided into three categories: residential, commercial/industrial
and public buildings. The survey covered the main commercial area in the CBD, as well as
residential areas.
For residential properties, the data obtained in the drive-by survey included:
- the location/address of each property
- a description of the residence
- an estimate of the residence's value, age and size
- an assessment of the construction type and foundations
- a description of any external buildings/structures
- an estimation of the height of floor level above the road level.
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For commercial/industrial properties and public buildings, the drive-by survey obtained
information regarding:
the location of each property
the nature of each enterprise
an estimation of the floor area
an estimation the construction type and foundations of the property
an estimation of the height of floor level above the road level.
The property descriptions were used to classify the properties into categories (ie high, medium or
low value properties) which relate to the magnitude of probable flood damages.
For planning purposes it is useful to obtain an indication of the flood level at which the properties
become:
“affected” by floodwater on the land
“damaged” by floodwater above floor level.
For Murrurundi, Blandford and Willow Tree, all residential, commercial and public properties
likely to be affected by floods were surveyed to obtain an accurate floor level. The difference
between ground and floor level (assessed during the drive-by survey) was subtracted from the
floor level to obtain an estimate of the ground level adjacent to the building.
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Murrurundi, Blandford and Willow Tree
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B4. RESIDENTIAL DAMAGES
B4.1 Direct Residential Damages
B4.1.1 Method
Within the three townships damages were estimated for an area that extended approximately to
the extent of the PMF flood event.
B4.1.2 Damage Functions
A depth-damage curve relates flood damage to depth of flooding above floor level for different
property types. In this study, depth-damage curves were used to estimate:
Direct internal damages
Structural damages
External damages
Previous studies have shown that residential depth-damage curves, both actual and potential,
can be reduced to a generalised relationship of the following form (Water Studies, 1986):
D
DH H
2
20 06 1 42 0 61 . . . for H < 1 metre
and
D
DH
2
0 75 0 12 . . for H > 1 metre
Where D = potential damages ($)
H = depth of inundation above floor level (metres)
D2 = potential damages ($) at 2 metres inundation
These equations provide an estimate of the potential damage to a property if no action is taken
by the householder to reduce damage during a flood (such as removing valuable electronic
equipment or lifting furniture onto a table). The ability of a resident to effectively reduce damage
is closely related to the degree of flood awareness and the warning time available.
With high flood awareness and adequate warning time, residents can be expected to take actions
such as lifting and removing carpets, lifting some possessions to higher levels or evacuating
them from the house, removing garden furniture, mowers, boats and trailers, etc. A p revious
study (Water Studies 1992) for the township of Eugowra found that the ratio of potential to actual
damages for a historic flood could be reduced to as low as 0.3. However, this reduction was only
achieved because a large flood had already been experienced in the town that year. It is unlikely
that such a reduction would be achieved for future floods, because the flood awareness of the
residents will decrease.
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Appendix B - Assessment of Flood Damages
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A similar situation will probably occur in the Murrurundi area as memories of the 1996 floods
fade. Also, in the case of the study area, there is little warning time as floods are of a flash
flooding nature. It may be possible to quickly raise some items above flood level for shallow
inundation, but for deeper flooding there will be little opportunity for reducing damages.
Accordingly, the potential internal and external damages were multiplied by 0.9 for depths of
inundation above 200 mm to give estimates of actual internal and external damages. For shallow
inundation below 200 mm, the corresponding ratio adopted was 0.6.
No reduction was applied to potential structural damages when computing actual damage, as this
damage category is not sensitive to flood warning time or flood preparedness of residents.
Values of potential damage D2 are given below:
Internal External Structural
Low Value Property
Medium Value Property
High Value Property
$15,400
$18,200
$21,000
$900
$2,000
$2,000
$3,900
$6,000
$8,300
These values are based on the actual damages suffered in the 1990 flooding in Eugowra and
Forbes (Water Studies, 1992) and Nyngan (DWR, 1990), increased to allow for inflation.
The total potential damages for a high value property subject to 2 m of inundation amounts to
about $31,000. This value compares with estimated potential damages of $38,500 and $32,000
for brick and weatherboard properties respectively in Camden (in 1997 values). These damages
were estimated from an evaluation of flood liable properties undertaken by a loss adjustor (LMJ,
1985).
B4.2 Indirect Residential Damages
Indirect residential damages comprise the costs of evacuating people and contents, providing
temporary accommodation, cash grants to welfare and relief agencies, clean-up costs after the
flood and loss of wages.
Because of the lack of readily useable data on this subject, these costs are sometimes estimated
as a percentage of the direct damages. Typically, a value of 15% of actual direct damages is
adopted (LMJ, 1985, SKM, 1994).
In the Forbes Study the average indirect cost was $2,450 per flooded property. The cost of clean
up was $600 and the remaining financial cost amounted to 40% of the actual direct cost. This is
higher than often used, reflecting the low actual direct damages.
In the Nyngan study, the average indirect cost was $7,700 per flooded property. Of this amount
the cost of clean up was $2,400 and the remaining financial cost of $5,300 amounted to 28% of
the total actual direct cost to surveyed properties. The Nyngan residents were away from their
homes for a long period (21 - 28 days) and were accommodated at public expense. In other
situations, eg Georges River in 1986 where the ratio to direct damage was 5%, the flooded
individuals were away for a shorter duration, around 12 days, and found private accommodation.
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Appendix B - Assessment of Flood Damages
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For the present study clean up costs were estimated at $1,000 per dwelling, based on the Forbes
Study and adjusted for inflation. Additional welfare and disaster relief costs were assessed at
25% of actual direct damages, based on the Forbes and Nyngan Studies.
B4.3 Total Residential Damages
Tables B4.1 to B4.3 summarise residential damages for a range of floods within the study area.
The damage estimates were carried out for floods between the 5 year ARI flood level and the
PMF, which were modelled in the Flood Study.
The properties have been listed as being flood "damaged" and "affected." Flood affected
properties include those which only have water within the allotment, as well as those having
water above floor level, while damaged properties are defined as those for which flooding above
floor level occurs.
Murrurundi
Flood affectation within Murrurundi will commence for relatively minor events due to inundation of
the backyards of residential properties fronting the Pages River. Tables B4.1, which summarises
damages to residential properties within the township, does not note these properties as being
flood affected because the adopted ground level for each property was measured at the front of
the allotment adjacent to the roadway.
TABLE B4.1
RESIDENTIAL DAMAGES IN MURRURUNDI
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
2
21
36
60
127
0
0
14
24
41
121
0
0
75
160
350
2,190
0
0
30
65
130
670
0
0
105
225
480
2,860
Damages to residential properties commence at around the 50 yr ARI and are concentrated
within the CBD area of the township, on the right bank of the Pages River. Flooding within the
CBD area is caused by the surcharging of the right bank of the river at Adelaide Street. An
existing levee bank fronting Adelaide Street is overtopped and floodwaters flow down Mayne
Street before rejoining the Pages River downstream of Brooke Street.
Blandford
Table B4.2 summarises estimated damages to residential properties within the township.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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TABLE B4.2
RESIDENTIAL DAMAGES IN BLANDFORD
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
1
7
11
21
46
0
1
1
2
10
45
0
9
10
15
45
965
0
3
5
5
20
285
0
12
15
20
65
1,250
Damages to residential properties within Blandford are due mainly to the surcharging of the right
bank of Warlands Creek, with damages commencing around the 20 yr ARI event.
In the January 1996 event, Bush (1996) reported 2 residential buildings inundated with
floodwaters and numerous properties flood affected by water flowing along the roadways.
Willow Tree
Residential development within Willow Tree is located mainly to the east of the Great Northern
Railway on steadily rising ground. Floodwaters for events up to and including the 200 yr ARI are
confined to the west of the railway line and therefore damages to residential properties are
minimal for these events. In the event of a PMF flood the water will overtop the railway and flood
numerous properties along the New England Highway.
Table B4.3 summarises estimated damages to residential properties within the township.
TABLE B4.3
RESIDENTIAL DAMAGES IN WILLOW TREE
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
0
0
1
1
23
0
0
0
0
1
20
0
0
0
0
6
335
0
0
0
0
3
105
0
0
0
0
9
440
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Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
B5. COMMERCIAL AND INDUSTRIAL DAMAGES
B5.1 Direct Commercial and Industrial Damages
B5.1.1 Method
Direct damages up to the PMF event were estimated using the approach outlined in Section B2.
Floor levels were surveyed and the depth of inundation calculated as the difference between the
floor level and the flood surface at that location.
B5.1.2 Damage Functions
The method used to calculate damages requires each property to be categorised in terms of the
following:
- damage category
- grid location
- floor area
- ground level
- floor height above ground.
The damage category assigned to each enterprise was either "low", "medium" or "high",
depending on the nature of the enterprise and the likely effects of flooding. Damages were then
determined on the basis of floor area. The following damage functions were adopted for
potential internal damages for both commercial and industrial properties:
Low value enterprise $280/m2
Medium value enterprise $420/m2
High value enterprise $650/m2
These values were based on results presented in the Forbes/Eugowra Study (Water Studies,
1992) and the Nyngan Study (DWR, 1990) adjusted for inflation.
The above values are indexed to a depth of inundation of 2 metres. At floor level and 1.2 m
inundation, zero and 70% of these values respectively were assumed to occur. The resulting
depth-damage relationship is rather similar to that used in the ANUFLOOD computer model
(SKM, 1994).
The factor for converting potential to actual damages depends on a range of variables such as
the available warning time, flood awareness and the depth of inundation. Given sufficient
warning time a well prepared business will be able to temporarily lift property above floor level.
However, unless property is actually moved to flood free areas, floods which result in a large
depth of inundation, will cause considerable damage to stock and contents.
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Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
For the present study, the potential to actual damages was assessed by conversion factors
related to the depth of inundation. Potential damages were converted to actual damages using a
ratio of 0.9. This factor and the shape of the resulting relationship are related to the very short
warning time available.
External and structural damages were assessed as 4% and 10% of actual internal damages on
the basis of data derived from studies of flood losses in Forbes, Eugowra and Nyngan.
B5.2 Indirect Commercial and Industrial Damages
Indirect commercial and industrial damages comprise clean-up costs, costs of removal of goods
and storage, loss of trading profit and loss of business confidence.
Disruption to trade takes the following forms:
The loss through isolation at the time of the flood when water is in the business premises or
separating clients and customers. The total loss of trade is influenced by the opportunity for
trade to divert to an alternative source. There may be significant local loss but due to the
trade transfer this may be considerably reduced at the regional or state level.
In the case of major flooding, a downturn in business can occur within the flood affected
region due to the cancellation of contracts and loss of business confidence. This is in
addition to the actual loss of trading caused by closure of the business by flooding.
Loss of trading profit is a difficult value to assess and the magnitude of damages can vary
depending on whether the assessment is made at the local, regional or national level.
Differences between regional and national economic effects arise because of transfers between
the sectors, such as taxes, and subsidies such as flood relief returned to the region.
Some investigations have lumped this loss with indirect damages and have adopted total
damage as a percentage of the direct damage. In other cases, loss of profit has been related to
the gross margin of the business, ie. turnover less average wages. The former approach has
been adopted in this present study. Indirect damages have been taken as 50% of direct actual
damages.
For the purpose of the damage assessment it was assumed that clean-up cost was based on the
floor area of each enterprise, and estimated at $10/m2.
B5.3 Total Commercial and Industrial Damages
Murrurundi
Table B5.1 summarises estimated commercial and industrial damages within the township.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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TABLE B5.1
COMMERCIAL AND INDUSTRIAL DAMAGES IN MURRURUNDI
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
0
29
37
44
49
0
0
21
29
37
49
0
0
125
270
540
2,480
0
0
80
165
310
1,300
0
0
205
435
850
3,780
Damages to commercial and industrial buildings commence at around the 50 yr ARI. Flooding
for this event occurs mainly within the CBD area and is due to the overtopping of the levee on the
right bank of the Pages River upstream of Arnolds Bridge. A large portion of the water, which
overtops the levee, flows down Mayne Street at high velocity. Some floodwaters meander
between the buildings.
Blandford
Commercial properties within Blandford are flood free for design flood events up to and including
the 200 yr ARI. For the PMF event the Service Station becomes inundated. Table B5.2
summarises actual commercial and industrial damages for the study area.
TABLE B5.2
COMMERCIAL AND INDUSTRIAL DAMAGES IN BLANDFORD
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
0
0
0
0
2
0
0
0
0
0
2
0
0
0
0
0
60
0
0
0
0
0
30
0
0
0
0
0
90
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Page B-12
Lyall & Macoun
Consulting Engineers
Willow Tree
Table B5.3 summarises commercial and industrial damages for the township.
TABLE B5.3
COMMERCIAL AND INDUSTRIAL DAMAGES IN WILLOW TREE
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
0
0
0
0
8
0
0
0
0
0
8
0
0
0
0
0
895
0
0
0
0
0
475
0
0
0
0
0
1,370
Commercial properties within Willow Tree are flood free for design flood events up to and
including the 200 yr ARI. The Bowling Club, which is situated on the right bank of Borambil
Creek has been built on a high section of land and floodwaters are around 1.3 m lower than the
building’s floor level at the 100 yr ARI event.
The considerable increase in depth at the PMF event leads to the inundation of 8 commercial
properties within the township, 6 of which are located to the east of the Great Northern Railway.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
B6. DAMAGES TO PUBLIC BUILDINGS
B6.1 Direct Damages - Public Buildings
Included under this heading are government buildings, churches, swimming pools and parks.
Damages were estimated individually on an areal basis according to the perceived value of the
property. Potential internal damages were assigned as follows:
Very low value $ 38/m2 (eg. park buildings)
Low value $280/m2
Medium value $420/m2 (eg. council buildings)
High value $650/m2 (eg. schools)
These values were obtained from the Nyngan Study (DWR, 1990) as well as commercial data
presented in the Forbes/Eugowra Water Studies report.
External and structural damages were taken as 12.5 and 15% of internal damages respectively.
An allowance was also made for damages to external buildings. It was estimated that 50% of
public properties had external buildings and for each, damages were taken as 25% of internal
damages to the main building.
B6.2 Indirect Damages - Public Buildings
Similar values were used to those given previously in Section B4.2, except that a value of $7,500
was adopted for the clean-up of each property. This value is based on results presented in the
Nyngan Study and adjusted for inflation. Total "welfare and disaster" relief costs were assessed
as 50% of the actual direct costs, as for commercial properties.
B6.3 Total Damages - Public Buildings
Murrurundi
Damages to public buildings commence for the 100 yr ARI. At the 100 yr ARI the Council
Chambers are inundated by a shallow depth of water. Table B6.1 summarises the damages to
public buildings in Murrurundi.
In the January 1996 flood event, floodwaters entered the rear of Chambers and damages
estimated at $17,000 were recorded. The cost of damages included:
remove and replace carpet
desilt lunchroom, stores and toilets
replacement of 2 refrigerators
remove and replace furniture
repair damaged gardens and landscaping
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
With increasing severity of flooding above the 100 yr ARI event, public buildings located on the
left bank of the Pages River become flood affected. For example, the Post Office, Uniting
Church and Pre-school located along the New England Highway become flooded at the 200 yr
ARI event. Additionally, within the CBD area both the Telecom exchange and the fire brigade
become inundated by floodwaters for this same event.
TABLE B6.1
DAMAGES PUBLIC BUILDINGS AT MURRURUNDI
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
0
2
8
14
20
0
0
0
3
8
20
0
0
0
15
65
1,315
0
0
0
20
85
800
0
0
0
35
150
2,115
Blandford
Table B6.2 summarises the damages to public buildings in Blandford.
TABLE B6.2
DAMAGES PUBLIC BUILDINGS AT BLANDFORD
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
1
4
4
4
5
0
1
2
2
4
5
0
4
19
30
100
495
0
10
24
30
80
285
0
14
43
60
180
780
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Lyall & Macoun
Consulting Engineers
Damage estimates for Public buildings commence at the 20 yr ARI with damages occurring at the
Public School to the north of the township. At the 100 yr ARI both the school and the Bottle
Museum sustain damages and St Lukes church is flood affected. At the PMF level all above
mentioned buildings are inundated as well as the local bush fire brigade building.
In the January 1996 event floodwaters surcharged the highway at Norvill Park and flowed
overland through the school grounds.
Willow Tree
Table B6.3 summarises the damages to public buildings in Willow Tree.
The Willow Tree Public School, located on Merriwa Road, is flood affected during minor storm
events. A levee located to the south of the school has been built to direct floodwaters around the
school buildings. During minor storm events floodwaters pond behind Merriwa Road and outflank
the levee while overtopping of the levee occurs during major storm events.
With increasing severity of flooding up to the 100 yr ARI the school buildings and main office
become flood affected while the school residence is flood free due to it being located on a
platform of fill. The 100 yr ARI flood level within the school grounds is marginally lower than the
floor level of the flood affected buildings. For events greater than the 100 yr ARI it would be
expected that the buildings will sustain damage due to inundation.
The school residence becomes flood affected at the 200 yr ARI flood and both it and the pre -
school become flooded at the PMF event.
TABLE B6.3
DAMAGES PUBLIC BUILDINGS AT WILLOW TREE
Flood
Event
Number of Properties Damage ($ x 103)
ARI
(years)
Flood
Affected
Damaged Direct Indirect TOTAL
5
20
50
100
200
PMF
0
1
2
5
6
7
0
0
0
0
5
7
0
0
0
0
22
370
0
0
0
0
48
240
0
0
0
0
70
610
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
B7. DAMAGES TO INFRASTRUCTURE AND COMMUNITY ASSETS
Infrastructure in the study area, such as electrical and telephone supply, sewerage and water
supply systems, and road network, are prone to damaging flooding. Community assets such as
parks and other recreational amenities also suffer damages. Council and relevant authorities
provided some data on damages experienced in the floods of January and October 1996, which
are reviewed below. The data are not sufficiently detailed to allow a quantitative estimate of
damages for the design flood events. However, a qualitative matrix of the effects of flooding on
these categories for each township are presented in Tables B7.1 to B7.3.
Table B7.1
QUALITATIVE EFFECTS OF FLOODING ON INFRASTRUCTURE AND COMMUNITY ASSETS
AT MURRURUNDI
Damage Sector
Flood Event
(ARI)
5 20 50 100 200 PMF
Electricity 0 0 0 0 0 1
Telephone 0 0 0 0 2 1, 2
Roads 0 0 3 3, 4, 5 3, 4, 5, 1, 3, 4, 5
Bridges 0 0 6 6, 7, 8, 9 6, 7, 8, 9 1, 6, 7, 8, 9
Sewerage Reticulation 0 10 10 10 10 1, 10
Water Supply 0 0 0 0 0 1
Parks and Gardens 0 0 0 11, 12 11, 12 1, 11, 12
Notes: 0 = No significant damages likely to be incurred
1= Due to significant increase in discharge and depth for PMF event, damages likely to be incurred
2 = Murrurundi telephone exchange flooded
3 = Mayne Street in CBD acts as floodway
4 = Mayne Street west of Arnolds Bridge acts as floodway
5 = Streets to north such as Munro, Bernard and Little flooded due to local creek system surcharging
6 = Eastern approach to Arnolds Bridge flooded
7= Western approach to Arnolds Bridge flooded
8= Swinging pedestrian bridge at Murrulla Street flood affected
9= Pedestrian bridge at Mount Street flood affected
10= Sewage Treatment Plant flood affected
11= Wilson Memorial Park and recreational facilities flooded
12= Remembrance Park flooded
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Lyall & Macoun
Consulting Engineers
Table B7.2
QUALITATIVE EFFECTS OF FLOODING ON INFRASTRUCTURE AND COMMUNITY ASSETS
AT BLANDFORD
Damage Sector
Flood Event
(ARI)
5 20 50 100 200 PMF
Electricity 0 0 0 0 0 1
Telephone 0 0 0 0 0 1
Roads 2 2, 3 2, 3 2, 3, 4 2, 3, 4 1, 2, 3, 4
Bridges 5 5 5 5 5 1, 5
Sewerage Reticulation N/A N/A N/A N/A N/A N/A
Water Supply N/A N/A N/A N/A N/A N/A
Parks and Gardens 6 6 6 6 6 6
Notes: 0 = No significant damages likely to be incurred
1= Due to significant increase in discharge and depth for PMF event, damages likely to be incurred
2 = Timor Road and Clarke Street flooded near New England Highway
3 = New England Highway flooded
4 = Streets such as Debenham Street on right bank of Warlands Creek act as floodways
5 = Western approach to Barsham Bridge flooded
6 = Norvill Park inundated by floodwaters
Table B7.3
QUALITATIVE EFFECTS OF FLOODING ON INFRASTRUCTURE AND COMMUNITY ASSETS
AT WILLOW TREE
Damage Sector
Flood Event
(ARI)
5 20 50 100 200 PMF
Electricity 0 0 0 0 0 1
Telephone 0 0 0 0 0 1
Roads 2, 3 2, 3 2, 3 2, 3 2, 3 1, 2, 3
Bridges 4, 5 4, 5 4, 5 4, 5 4, 5 1, 4, 5
Sewerage Reticulation N/A N/A N/A N/A N/A N/A
Water Supply 0 0 6 6 6 1, 6
Parks and Gardens 0 7 7, 8 7, 8 7, 8 1, 7
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Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
Notes: 0 = No significant damages likely to be incurred
1 = Due to significant increase in discharge and depth for PMF event, damages likely to be incurred
2 = Merriwa Road adjacent to Public School inundated
3 = Oaklyn Road inundated at Borambil Creek
4 = Northern approach to Hams Bridge inundated adjacent to Public School
5 = Causeway at Oaklyn Road inundated by floodwaters
6 = Well dirtied by creek overflow. (Note: damage occurs due to creek flooding, not Borambil Creek
flooding)
7 = Recreational Park affected by floodwaters and tennis courts
8 = King George V Park flooded by creek overflow. (Note: damage occurs due to creek flooding, not
Borambil Creek flooding)
B7.1 Infrastructure
B7.1.1 Electricity
Murrurundi
North Power supplies electricity from Tamworth to a substation located on the New England
Highway, immediately to the west of the township. The substation is located on rising ground
and is free from river flooding for events up to and including the PMF event. During the January
1996 event, the substation experienced around 100 mm depth of stormwater runoff, which
surcharged the highway drains. This depth was insufficient to incur damages to the substation.
All electrical facilities within the town are pole mounted and hence are not at high risk. To the
east of the town, in the vicinity of Campbells Creek, a pole mounted high voltage transformer was
damaged during the January event when the pole was knocked down by floodwaters. Loss of
electricity was experienced on the eastern fringes of the township.
Floodwaters that surcharged the levee on the right bank of the Pages River, upstream of Arnolds
Bridge, caused damages to both the North Power Showroom and depot located along Mayne
Street. The Showroom was inundated by around 300 mm of water while the depot was inundated
by around 50 mm. No direct damage was caused by the flooding, but clean up costs were
incurred.
Throughout the district switch boards and pumps were damaged by the flood and required
electrical repairs.
Blandford
All electrical facilities are pole mounted and hence are not at high risk. The substation located in
Murrurundi supplies the township’s electricity.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Page B-19
Lyall & Macoun
Consulting Engineers
In the January 1996 flood, Blandford experienced power failure due to the loss of the high
voltage transformer in the vicinity of Campbells Creek. To the north of the township, some low
voltage lines were knocked out, due mainly to lightening and wind damage.
Willow Tree
All electrical facilities are pole mounted and hence are not at high risk. Willow Tree receives
electricity from the power line which feeds the Murrurundi substation from Tamworth.
During the January 1996 flood, the inundation of King George V Park caused electrical damage
to the park barbeques and the water supply pump at the adjacent well.
B7.1.2 Telecom
Murrurundi
The telecom exchange is located on Mayne Street within the CBD area. Hydraulic modelling
indicates that the exchange could be expected to be flooded in the event of a 200 yr ARI flood.
In the January 1996 flood, Bush (1996) reported a depth of flooding of approximately 350 mm at
the rear of the property.
Blandford
The township of Blandford has no telecom exchange as it is serviced by the Murrurundi
exchange.
Willow Tree
The township of Willow Tree has a telecom exchange located adjacent to the Post office on the
New England Highway. The exchange is located on rising ground and is flood free at the PMF.
B7.1.3 Roads, Bridges and Railway
In 1996, damage to roads and bridges occurred in both the January and October floods. A large
proportion of these roads and bridges are located outside the study area in rural areas. The total
cost for the restoration of roads in Murrurundi Shire as a result of the January flood was
approximately $2 million. In the later flood, damage to the road infrastructure was less severe
with restoration works costing around $330,000.
Murrurundi
Within Murrurundi roads and bridges are relatively flood free for events up to the 50 yr ARI. For
floods greater than this event the Pages River surcharges its banks and the roadways act as
floodways.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Page B-20
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Consulting Engineers
Arnolds Bridge is flood free at the 100 yr ARI level but the approaches to the bridge are
inundated. The causeway at Murrulla Street is inundated by minor storm events but due to the
nature of flooding in Murrurundi, closure of the causeway will only be for a short period of time.
Roads to the north of the town, such as Munro, Bernard and Little Streets are susceptible to local
catchment flooding when catchment runoff surcharges both Unnamed and Cohens Gullies.
The railway line runs to the south of the township and crosses Halls Creek approximately 200 m
upstream of its confluence with the Pages River. The railway line is flood free for major storm
events.
In the January 1996 flood, clean up costs were incurred across most of the town. Damage to the
pavement within the CBD area occurred due most likely to the relatively high velocity of flow
experienced down Mayne Street. The swinging Bridge at Murrulla Street was damaged and the
cost of repair of one of the approach spans was around $13,500.
Blandford
Both Blandford Bridge on the Pages River and Barsham Bridge on Warlands Creek are flood free
at the 100 yr ARI. Hydraulic modelling indicates that Warlands Creek breaks its right bank
upstream of Barsham Bridge for events less than the 100 yr ARI. Floodwaters traverse the
floodplain and flow across the Timor Road near its intersection with the New England Highway.
In January 1996 floodwaters surcharged Warlands Creek and flowed across the New England
Highway and Timor Road. Floodwaters used the road network within Blandford as floodways and
water travelled in a southerly direction as shallow sheet flow before rejoining either the Pages
River or Warlands Creek to the east of Blandford Bridge.
Willow Tree
Due to the town being located on relatively high ground to the east of Borambil Creek a majority
of the road network is flood free. Some of the roads located to the east of the Grea t Northern
Railway are susceptible to local catchment flooding as was experienced in the January 1996
flood.
Merriwa Road crosses Borambil Creek south west of the town. The bridge, known as Hams
Bridge, is flood free for the 100 yr ARI. During flood events in excess of the 5 year ARI, the
creek breaks its banks upstream of the bridge and floodwaters traverse the right floodplain in a
northerly direction before crossing Merriwa Road between the bridge and the Public School.
During major flood events 300 m of roadway can be expected to be inundated with depths up to 1
m in the 100 yr ARI flood event.
Oaklyn Road crosses Borambil Creek immediately to the west of the township via a causeway.
Three 1000 x 600 RCBCs and 2 x 900 RCPs convey minor flows beneath the roadway. In the
event of a 100 yr ARI the causeway will be inundated by around 5 m of water. On the right bank
the road is inundated out to the intersection of Recreation Road for the 100 yr ARI. On the left
bank Borambil Creek its banks upstream of the Oaklyn Street causeway and floodwaters
traverse the floodplain at depths of around 700 mm for the 100 yr ARI event. Oaklyn Road is
inundated by this floodplain flow for a distance of around 250 m to the west of the causeway.
The Great Northern Railway runs in a north-south direction between the New England Highway
and Borambil Creek. The railway line is flood free for major storm events.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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Consulting Engineers
B7.1.4 Sewerage Reticulation
Murrurundi
Murrurundi Shire Council maintains the sewerage system in the area. The Sewage Treatment
Plant (STP) is located on the right bank of the Pages River, approximately 500 m east of the
township. In the vicinity of the STP the Pages River has a wide flat floodplain and once
floodwaters break the banks of the river, the floodplain is inundated as far as the New England
Highway, a distance of around 270 m.
Results of the Flood Study indicate that inundation of the floodplain will occur for events larger
than 5 year ARI. Due to the large conveyance capacity of the floodplain depths of inundation
increase by only around 400 mm between the 5 to 100 yr ARI events.
In January 1996, areas of the STP were flooded. The STP is surrounded by a levee system
which prevented inundation by floodwater but boundary fences surrounding the plant were
damaged during the flood and the cost of repairing the fence and removing debris was estimated
at around $12,000.
A sewer main within the township was damaged during the flood and the cost of repair was
estimated at $5,500. This occurrence could be seen as a one off and may not necessarily re-
occur during a similar flood event.
Blandford & Willow Tree
Both townships have a in ground septic tank arrangement.
B7.1.5 Water Supply
Murrurundi
The township water supply is from a dam located on to the south of the township on a tributary
creek of the Pages River. Water is pumped to the dam from 2 intake wells situated on the Pages
River, approximately 5 km upstream of the township.
No damage to the dam or intake wells was reported in the January 1996 event.
Blandford
Blandford has no reticulated water supply.
No damage to water supply was reported at Blandford for the January 1996 event.
Willow Tree
The township of Willow Tree obtains its water from a groundwater well situated adjacent to King
George V Park.
During the January 1996 event, the well was dirtied by silt. Works were undertaken to clean the
well and desilt the pump station and its surrounds at a cost of around $5,500.
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Murrurundi, Blandford and Willow Tree
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B7.1.6 Gas
Murrurundi, Blandford and Willow Tree
No gas supply is present in either of the three townships.
B7.2 Community Assets
This category comprises damages to recreational amenities, such as parks, tennis courts and
swimming pool.
Murrurundi
Wilson Memorial Park & Recreation Facilities
The park is located on the left bank of the Pages River immediately downstream of the Arnolds
Bridge. The park contains a circular playing field and amenities.
In January 1996, the Pages River broke its banks upstream of Arnolds Bridge in several locations
between Boyd Street and the Bridge. Water flooded the park via two major flow paths. The first
is the New England Highway, which acted as a floodway. Floodwaters made their way along the
Highway to Arnolds Bridge where then flowed through the park and rejoined the river downstream
of the bridge. The second flow path is a depression which runs parallel with the Highway and on
its northern side. This depression crosses Murrulla and Mount Streets before running to the
north of the oval and into the Pages River. Flood damage within the park comprised clean up
costs to remove silt and debris from the oval and amenities. This work was estimated at around
$3,000.
Both swimming and tennis facilities are located to the west of the playing field. Flooding of these
facilities occurred during the January 1996 event and clean up costs, namely for the swimming
pool, were estimated at around $2,000.
In general, flooding within the park can be expected for events, which surcharge the left bank of
the Pages River upstream of the Arnolds Bridge. Hydraulic modelling indicates that this is likely
for events greater than 50 year ARI.
Remembrance Park
The park is located on the left bank of the Pages river downstream of Mount Street.
In January 1996 it was reported that a major break out of floodwaters occurred at the Park (Bush,
1996). Water reportedly flowed overland to the New England Highway and thence onto the
Wilson Memorial Park and Recreational Facilities.
Damage to the park due to these floodwaters was minimal, with the only clean up of park toilets
being necessary.
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Murrurundi, Blandford and Willow Tree
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Blandford
Norvill Park
The park is located to the north of the township at the intersection of the New England Highway
and Timor Road.
In January 1996 floodwaters entered the park from two directions. The first was due to
surcharging of the right bank of Warlands Creek, upstream of Barsham Bridge. The second was
from floodwaters which surcharged the left bank of the Pages River upstream of Benhams
Bridge, and flowed along the northern side of the New England Highway for over 2 km before
joining floodwaters from Warlands Creek. The New England Highway is raised approximately
600 mm above natural surface in the vicinity of the park which may promote ponding and
exacerbate the extent of inundation within the area. Clean up costs in the order to $13,000 were
incurred by the 1996 January event. A large amount of tree branch debris left by the flood was
removed.
Willow Tree
Recreational Ground
The recreational ground is located on the right bank of Borambil Creek downstream of the
Oaklyn Road causeway. Available mapping and cross-sectional survey indicates that an area of
high land exists upstream of the ground in the vicinity of the Bowling Club, but natural surface
levels reduce in the vicinity of the playing fields which lead to floodwaters inundating the fields
during major flood events.
During the January 1996 event damages were incurred to the value of $37,000. This cost
included:
repairing or replacement of up to 1,200 m of fencing
the replacement of the entry control building which was flattened by the force of the
floodwaters, and
the removal of debris and silt from the playing fields.
Flood markers noted after the event (Bush, 1996) indicate that water inundated the fields by up to
800 mm depth.
King George V Park and Tennis Courts
This park is located to the east of the Great Northern Railway and is not affected from flooding
from Borambil Creek for events up to and including a 200 yr ARI event. The park is however
susceptible to local catchment flooding and in January 1996 sustained minor damages due to
surcharging of local creeks. Costs incurred by this flood totalled around $600 which included the:
removal of debris from boundary fences
removal of silt and the cleaning of the public toilets, and
removal of gravel washed onto the grassed surface from the roadway.
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Murrurundi, Blandford and Willow Tree
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The tennis courts are located adjacent to the park. During the January 1996 event, flooding
caused damage to the playing surface and was substantial enough to require its replacement.
Fencing surrounding the courts was also damaged and required repairs. The total cost of works
was estimated at around $13,500.
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Murrurundi, Blandford and Willow Tree
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B8. SUMMARY OF TANGIBLE DAMAGES
Flood damages under existing conditions have been computed for Murrurundi, Blandford and
Willow Tree for a range of flood frequencies from 5 year ARI to the PMF event. The total
damages for each flood event are shown on Tables B8.1 to B8.3. Cumulative average annual
damages were assessed and are also shown. Figure B8.1 shows the resulting damage -
frequency curves and Figure B8.2 shows the cumulative average annual damage curve for
Murrurundi. Similarly, Figures B8.3 to B8.6 show the respective curves for the townships of
Blandford and Willow Tree.
TABLE B8.1
TOTAL DAMAGES AT MURRURUNDI
Flood
Event
No. of Properties Flooded Total
Dam
Cum
AAD
ARI Residential Commercial/
Industrial
Public $x10
3 $x10
3
A D A D A D
5
20
50
100
200
PMF
0
2
21
36
60
127
0
0
14
24
41
121
0
0
29
37
44
49
0
0
21
29
37
49
0
0
2
8
14
20
0
0
0
3
8
20
0
0
310
695
1,480
8,755
0
0
6
11
19
41
Note: A - flood affected property (includes flooding in allotments and above floor flooding
D - flood damaged property (above floor flooding)
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Murrurundi, Blandford and Willow Tree
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TABLE B8.2
TOTAL DAMAGES AT BLANDFORD
Flood
Event
No. of Properties Flooded Total
Dam
Cum
AAD
ARI Residential Commercial/
Industrial
Public $x10
3 $x10
3
A D A D A D
5
20
50
100
200
PMF
0
1
7
11
21
46
0
1
1
2
10
45
0
0
0
0
0
2
0
0
0
0
0
2
0
1
4
4
4
5
0
1
2
2
4
5
0
26
58
80
245
2,120
0
2.3
3.5
4
5
11
TABLE B8.3
TOTAL DAMAGES AT WILLOW TREE
Flood
Event
No. of Properties Flooded Total
Dam
Cum
AAD
ARI Residential Commercial/
Industrial
Public $x10
3 $x10
3
A D A D A D
5
20
50
100
200
PMF
0
0
0
1
1
23
0
0
0
0
1
20
0
0
0
0
0
8
0
0
0
0
0
8
0
0
0
5
6
7
0
0
0
0
5
7
0
0
0
0
79
2,420
0
0
0
0
0.4
6.4
Average annual damages (also termed expected damages) are determined by integrating the
area under the damage-frequency curve. They represent the time stream of average damages,
which would be experienced year by year. Using an appropriate discount rate, average annual
damages may be expressed as an equivalent present worth value of damages and used in the
economic analysis of potential flood management measures.
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Murrurundi, Blandford and Willow Tree
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For example, the cumulative average annual value at Murrurundi of damages for all floods up to
the 100 year ARI level is around $11,000. A flood management scheme which has a 100 year
ARI level of protection will eliminate damages up to this level of flooding. If the scheme has no
mitigating effect on larger floods, then these damages represent the benefits of the scheme.
Under current Treasury guidelines, economic analyses are carried out assuming a 30 year
economic life for the project and discount rates of 7% pa. (best estimate) and 11% and 4% pa.
(sensitivity analysis).
For a discount rate of 7% pa, the present worth value of damages up to the 100 year ARI level at
Murrurundi is $140,000. Therefore a scheme costing up to $140,000 could be economically
justified if it eliminated damages up to the 100 year ARI level. More expensive schemes would
have a benefit/cost ratio less than 1, but may still be justified according to a multi -objective
approach which considers other criteria in addition to economic feasibility (see Section 6 of the
Main Report).
Unless the scheme is designed to give protection against all flood events up to the probable
maximum flood (PMF), there will be residual damages, which will still be experienced under post -
scheme conditions. From Table 8.1, the cumulative average annual value of damages for all
floods at Murrurundi would be of the order of $41,000. Therefore the residual damages for a
scheme with a 100 year ARI design flood is $41,000 - $11,000 = $30,000 per annum. These
annual damages have a present worth value of $370,000 at a 7% discount rate.
The present worth value of damages in the three townships for all floods is about $720,000 for
the 7% pa. discount rate.
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Murrurundi, Blandford and Willow Tree
Appendix B - Assessment of Flood Damages
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B9. REFERENCES
Bush, S. (1991) “Preparation of Flood Study Information”. Report prepared for Murrurundi Shire
Council.
Bush, S. (1996) “Preliminary Research into the Severe Flooding in Murrurundi Shire on 25th
January 1996”. Report prepared for Murrurundi Shire Council.
Department of Water Resources, NSW (1990) "Nyngan April 1990 Flood Investigation".
Lyall, Macoun and Joy, Willing and Partners Pty Ltd (1985) "Camden Floodplain Management
Study". Report for Water Resources Commission and Camden Municipal Council.
Sinclair Knight Merz (1994) "Forbes Floodplain Management Report and Draft Floodplain
Management Plan, Volume 1". Report prepared for Department of Land and Water
Conservation.
Water Studies (1986) "The Sydney Floods of August 1986", Volume I Residential Flood
Damage Survey, Report prepared for CRCE Water Studies Pty Ltd for the NSW PWD.
Water Studies (1992) “Forbes Flood Damage Survey, August 1990 Flood.” Report prepared for
Department of Water Resources.
MURRURUNDI, BLANDFORD
AND WILLOW TREE
FLOODPLAIN MANAGEMENT STUDY
APPENDIX C
COMMUNITY CONSULTATION
Note: The Word version of the document was reformatted in December 2014 which has led to minor
differences in its structure when compared to the original report. No hard copy version of this
Appendix was available at the time of compiling. As a result, the Community Flyer and Brochure were
reproduced from a Word document which was assumed to have been used to compile the original
report.
Job No: NX518
J:\NX518\docs\APPC.doc
Date: 03/06/98
Rev: 3.0 Author: SAB
Reviewer: BWL
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix C - Community Consultation
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Consulting Engineers
TABLE OF CONTENTS
Page No.
C1. INTRODUCTION ......................................................................................................... C-1
C2. COMMUNITY BROCHURE AND QUESTIONAIRE ...................................................... C-1
C2.1 Murrurundi ................................................................................................. C-2
C2.1.1 Summary of Community Questionnaire Responses ............................. C-2
C2.1.2 Summary of Respondent Comments ................................................... C-5
C2.1.3 Assessment of Questionnaire Responses............................................ C-5
C2.1 Blandford ................................................................................................... C-7
C2.2.1 Summary of Community Questionnaire Responses ............................. C-7
C2.2.2 Summary of Respondent Comments ................................................... C-9
C2.2.3 Assessment of Questionnaire Responses.......................................... C-10
C2.3 Willow Tree ............................................................................................. C-11
C2.3.1 Summary of Community Questionnaire Responses ........................... C-11
C2.3.2 Summary of Respondent Comments ................................................. C-13
C2.3.3 Assessment of Questionnaire Responses.......................................... C-14
C3. PUBLIC DISPLAY AND MEETINGS ......................................................................... C-15
C4. NEWSPAPER ARTICLES ......................................................................................... C-16
C5. LOCAL AUTHORITY CONSULTATION .................................................................... C-16
ATTACHMENTS
1. Community Questionnaire & Respondents
2. Public Display
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
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C1. INTRODUCTION
Community consultation provides critical information needed to make decisions about floodplain
management issues and remedial options. The community consultation program developed for
Murrurundi, Blandford and Willow Tree includes providing information by way of brochures and
displays, as well as opportunities for the community to express views and concerns through a
questionnaire and involvement in the Floodplain Management Committee.
These various consultation activities were ongoing throughout the preparation of the Floodplain
Management Plan.
Community concerns relating to flooding issues were identified through consultation with local
residents, relevant public utilities and the Council.
The consultation program was developed with the objectives of:
obtaining local information on flood behaviour and possible mitigation measures
obtaining feedback on community issues and concerns
informing and educating the public about the nature of the flood threat and options for
managing the threat
encouraging future ownership of the Floodplain Management Plan by local residents.
Community awareness was raised through various media including:
Community questionaries
Newspaper articles
Public displays
C2. COMMUNITY BROCHURE AND QUESTIONAIRE
An information brochure and questionnaire was prepared by LMCE and was aimed at informing
residents about the study and allowing property owners within the three townships to comment on
issues such as:
what their experience was during the flood of January 1996,
what damages were incurred and how long a warning time did they receive,
and, what they saw as effective future planning measures.
The questionnaire was delivered through the local post office and via personal delivery to all properties
in low lying areas close to Warlands and Borambil Creeks and the Pages River. A copy of the
questionnaire is provided as Attachment 1. A total of 500 questionnaires were delivered with 36
responses return mailed. A list of respondents is contained in Attachment 1. The following sections
summarise the questionnaire responses received from each township.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
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C2.1 Murrurundi
C2.1.1 Summary of Community Questionnaire Responses
Total number of respondents 27
Question 1 Personal and property details
No.
% of
total
1.1 House or business House
Business
House/business
Other
Not noted
14
4
2
2
5
(52%)
(15%)
(7.5%)
(7.5%)
(18%)
1.2 Period of residency in town 1 – 70 yrs
average 22 yrs
1.3 Period of residency at current house/shop 1 – 70 yrs
average 13 yrs
1.4 Building type superstructure Weatherboard/fibro
Brick veneer
Full brick
Combination
Not noted
15
3
4
2
3
(56%)
(11%)
(15%)
(7%)
(11%)
Building type foundations
Piered
Slab on ground
Combination
Not noted
14
3
2
8
(52%)
(11%)
(7%)
(30%)
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Question 2 Experience of January 1996 flood
No.
%
of
total
2.1 Effects of the flood
a Inconvenience YES 21 (78%)
b Unable to access medical assistance YES 4 (15%)
c Dangerous depth or velocity of flow YES 17 (63%)
d Flooding of land adjacent to house/business YES 19 (70%)
e Flood water in house/business YES 5 (19%)
f Power supply cut YES 6 (22%)
g Telephone cut YES 4 (15%)
2.2 Total damages to properties
a Carpets/floor coverings $1000 1 (4%)
b House structure $24,000 2 (7%)
c Furniture and appliances $500 1 (4%)
d Belongings $1,000 1 (4%)
e Outside the house $16,800 7 (26%)
2.3 Amount of flood warning received 0 – 120 min.
average 12 min.
2.4 Source of flood warning
A Council official/SES 3 (11%)
b Neighbour 3 (11%)
c Local media 0 (0%)
d Other (eg. Observation) 18 (67%)
2.5 Time for home/business to return to normal 2 – 500 hours
average 75 hrs.
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Question 3 Future Planning
3.1 Required amount of warning 30 – 120 min.
average 80 min.
3.2 Amount prepared to pay for flood mitigation 0 – $200
average $35
Question 4 Interest in further involvement
No.
%
of
total
a Would like to receive further information YES 18 (67%)
b Would like to be involved in meetings YES 10 (37%)
c Would be willing to be interviewed YES 8 (30%)
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C2.1.2 Summary of Respondent Comments
From the comments received the people of Murrurundi noted the following issues.
Since 1932 the invert of the Pages River has risen due to the ongoing deposition of silt and
stones.
There is a strong consensus that dredging of the Pages River will lessen the severity of flooding
within the township.
The construction of levee banks is seen as a useful flood mitigation measure. The levees should
be built in areas where major breakouts occurred in the January 1996 flood. This will reduce the
amount of floodwaters flowing along the street system.
The construction of a levee on the northern side of the highway will reduce the effects of flooding
ie replacement of an old levee that has washed away on the right bank of the Pages River
immediately downstream of Arnolds Bridge. This would prevent the passage of high velocity flood
waters traversing numerous properties along the highway.
Remove trees planted by WC&IC as they are seen as restricting the passage of flood waters.
Remove weeds and rubbish from the river.
Implementation of a Flood Warning System.
Preparation and adoption of a Floodplain Management Plan. This would:
a) Allow the control of future development within flood prone/affected areas.
b) Protect existing buildings and structures.
Installation of proper kerb and guttering in town streets is required.
Continuous maintenance of creek and road culvert system should be undertaken to reduce the
amount of water surcharging the creeks and roadside drains. Also look at increasing the size of
culverts within the town.
C2.1.3 Assessment of Questionnaire Responses
Of the twenty-seven respondents, twelve were directly affected by floodwaters surcharging the banks
of the Pages River. The remaining fifteen respondents were directly affected by either a) the
surcharging of the minor creek system and/or road drainage system to the north and south of the
township or, b) inconvenienced due to the surcharging of the road system within the township.
The majority of the dollar damages reported within the township, in the vicinity of 75% of the total,
were due to main river flooding.
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Murrurundi, Blandford and Willow Tree
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On the issue of flood warning the following points are noted:
Of the 12 respondents influenced by main river flooding, 11 were warned of the flood by
either their neighbours or by “other” means, namely personally viewing the river rising.
Of the twelve, seven respondents recorded a warning time of 0 minutes. This would
seem to indicate that respondents answered this question by interpreting a warning as the
real time flooding of their properties.
No warning was heard via the local media.
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Murrurundi, Blandford and Willow Tree
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C2.1 Blandford
C2.2.1 Summary of Community Questionnaire Responses
Total number of respondents 6
Question 1 Personal and property details
No.
%
of
total
1.1 House or business House
School
5
1
(83%)
(17%)
1.2 Period of residency in town 2 – 67 yrs
average 23 yrs
1.3 Period of residency at current house/shop 2 – 67 yrs
average 18 yrs
1.4 Building type superstructure Weatherboard/fibro
Brick veneer
Full brick
Not noted
3
1
1
1
(50%)
(16.7%)
(16.7%)
(16.7%)
Building type foundations Piered
Slab on ground
4
2
(67%)
(33%)
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Question 2 Experience of January 1996 flood
No.
%
of
total
2.1 Effects of the flood
a Inconvenience YES 6 (100%)
b Unable to access medical assistance YES 0 (0%)
c Dangerous depth or velocity of flow YES 2 (33%)
d Flooding of land adjacent to house/business YES 4 (67%)
e Flood water in house/business YES 1 (17%)
f Power supply cut YES 1 (17%)
g Telephone cut YES 2 (33%)
2.2 Total damages to properties
a Carpets/floor coverings $0 0 (0%)
b House structure $0 0 (0%)
c Furniture and appliances $0 0 (0%)
d Belongings $0 0 (0%)
e Outside the house $12,250 4 (67%)
2.3 Amount of flood warning received 0 – 120 min.
average 40 min.
2.4 Source of flood warning
a Council official/SES 1 (17%)
b Neighbour 1 (17%)
c Local media 0 (0%)
d Other (eg. Observation) 2 (33%)
2.5 Time for home/business to return to normal 2 – 720 hours
average 200 hrs.
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Murrurundi, Blandford and Willow Tree
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Question 3 Future Planning
3.1 Required amount of warning 10 – 60 min.
average 45 min.
3.2 Amount prepared to pay for flood mitigation 0 – $50
average $25
Question 4 Interest in further involvement
No.
%
of
total
a Would like to receive further information YES 3 (50%)
b Would like to be involved in meetings YES 2 (33%)
c Would be willing to be interviewed YES 3 (50%)
C2.2.2 Summary of Respondent Comments
From the comments received the people of Blandford noted the following issues.
Levee banks are required to divert water away from homes in danger of flooding. The levees
could be built approximately 1 m in height and be situated at locations where observed breakouts
of floodwaters occurred
Dredging of both the Pages River and Warlands Creek is required due to the build up of material
in the waterways.
Halt the raising of roads in the area above the level of the floodplain, as this is seen as a cause of
flood exacerbation.
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C2.2.3 Assessment of Questionnaire Responses
Locating the properties of respondents was difficult due to the names of the houses being given,
rather than street numbers.
Financial damages were experienced by 67% of the respondents with all damages occurring to
structures outside the house. This is an indication of the shallow sheet flow, which was experienced
through the northern part of town, where flood waters did not reach a sufficient depth to inundate
houses.
About 75% of respondents were warned of the flood by either neighbours or personal observation. Of
these, only 1 respondent reported a warning time greater than 0 minutes. This would seem to indicate
that respondents answered this question by interpreting a warning as the real time flooding of their
properties.
Of particular concern is the location of the Blandford Public School downstream of a major surcharge
point. The school received little to no warning of the approaching flood in January 1996. The school
Head Master reported that a warning time of around 60 minutes would be required to organise the
school bus and evacuate the school children. Additionally the closure of the highway during major
flooding could hamper evacuation procedures.
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C2.3 Willow Tree
C2.3.1 Summary of Community Questionnaire Responses
Total number of respondents 3
Question 1 Personal and property details
No.
%
of
total
1.1 House or business House
Business
School
1
1
1
(33.3%)
(33.3%)
(33.3%)
1.2 Period of residency in town 2 – 8 yrs
average 4 yrs
1.3 Period of residency at current house/shop 2 – 8 yrs
average 4 yrs
1.4 Building type superstructure Weatherboard/fibro
Brick veneer
2
1
(67%)
(33%)
Building type foundations Piered
Not noted
2
1
(67%)
(33%)
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Question 2 Experience of January 1996 flood
No.
%
of
total
2.1 Effects of the flood
a Inconvenience YES 2 (67%)
b Unable to access medical assistance YES 1 (33%)
c Dangerous depth or velocity of flow YES 0 (0%)
d Flooding of land adjacent to house/business YES 2 (67%)
e Flood water in house/business YES 2 (67%)
f Power supply cut YES 0 (0%)
g Telephone cut YES 0 (0%)
2.2 Total damages to properties
a Carpets/floor coverings $200 1 (33%)
b House structure $0 0 (0%)
c Furniture and appliances $0 0 (0%)
d Belongings $200 1 (33%)
e Outside the house $4,500 1 (33%)
2.3 Amount of flood warning received 0 min.
2.4 Source of Flood Warning
a Council official/SES 0 (0%)
b Neighbour 0 (0%)
c Local media 0 (0%)
d Other (eg. Observation) 1 (33%)
2.5 Time for home/business to return to normal 2 – 500 hours
average 75 hrs.
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Question 3 Future Planning
3.1 Required amount of warning 30 min.
average 30 min.
3.2 Amount prepared to pay for flood mitigation 0 – $200
average $100
Question 4 Interest in further involvement
No.
%
of
total
a Would like to receive further information YES 0 (0%)
b Would like to be involved in meetings YES 0 (0%)
c Would be willing to be interviewed YES 2 (67%)
C2.3.2 Summary of Respondent Comments
From the comments received the following issues are of concern to the people of Willow Tree.
Floods over the past 2 years have been exacerbated due to a build up of rubbish within the creeks
and road drains.
Flows surcharge the creek and drainage systems on the east side of town and flow in an
uncontrolled manner to lower streets and Highway.
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C2.3.3 Assessment of Questionnaire Responses
Two of the respondents are located on the eastern side of the Main Railway and are not influenced by
major flooding on Borambil Creek. Flooding issues are related more so with the surcharging of two
small creeks, which flow in a westerly direction, passing the town to the north and south. Additionally,
overland flow from the hillside directly to the east of the town causes nuisance flooding.
One respondent indicated that a 30-minute warning time would be appropriate. Due to the nature of
flooding to the east of the railway line no official warning would seem possible.
On the western side of the railway, the Willow Tree Public School was inundated by floodwaters during
the January 1996 event. The School Master indicated that no warning was given of the approaching
flood. The existing levee to the south of the school would allow some protection during the early
stages of a major flood and the build up of floodwaters behind the levee could be used as an indication
of the need to evacuate school children. Evacuation could be possible to the north along Merriwa
Road towards the township or to the east where land behind the school rises towards the railway
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C3. PUBLIC DISPLAY AND MEETINGS
At the commencement of the Floodplain Management Study a public display piece was prepared and
viewed within Council Chambers. Attachment 2 contains a reduced version of the display pieces.
The display consisted of brief summaries of:
The Floodplain Management Process.
The Murrurundi, Blandford and Willow Tree Flood Study.
Characteristics of flooding in the three townships.
Accompanying the summary were plans of the three townships. Overlaid on the plans was the
indicative extent of inundation for the 100 yr ARI design flood event and the preliminary high hazard
associated All displays were of A1 paper size and were presented in colour. The size and colour of
the display would make it more noticeable and assist in the understanding of the information
presented.
LMCE attended Floodplain Management Committee meetings as well as meetings which were open to
the public.
At the preliminary stages of the study LMCE attended a Committee meeting where the following points
were discussed:
A report on the progress of the Floodplain Management Study, including an outline of the
“drive by” field survey for the assessment of flood damages
Possible flood mitigation measures which could be modelled hydraulically
Arrangements for consultation with the community
Procedures for decisions regarding future planning controls
The draft Floodplain Management Study was also presented to the Committee in December 1997.
Comments received from stakeholders have been incorporated in the final report.
Floodplain Management Study
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C4. NEWSPAPER ARTICLES
Several articles were published in regional newspapers to inform the community of the Floodplain
Management Study. Issues covered included:
An invitation to view the draft Murrurundi, Blandford and Willow Tree Flood Study Report
in Council Chambers and a notification of the commencement of the Floodplain
Management Study. The advertisement was published in the local community newsletter
called “The Links” and the Scone Advocate Newspaper.
Two articles outlining work being undertaken by LMCE within the townships. The articles
also emphasised the need to fill in and return the community questionnaires to allow
LMCE to gain a better appreciation of views held by the community. The articles
appeared in the Quirindi Advocate and the Hunter Valley News.
C5. LOCAL AUTHORITY CONSULTATION
Local public authorities and relevant statutory authorities were contacted to obtain comments on the
flooding situation in the area and/or the environmental impacts of possible flood management
measures. The following bodies were contacted:
North Power Tamworth
Murrurundi Shire Council Murrurundi
DLWC Newcastle
EPA Newcastle
Optus Sydney
Police Murrurundi and Willow Tree
RTA Tamworth
SES Local and Head Office
Telstra Newcastle
Council, DLWC and other stakeholder comments have been incorporated into the Main Report and
relevant Appendices. The SES's comments have been incorporated into Appendix D - Flood
Preparedness and Response.
ATTACHMENT 1
COMMUNITY BROCHURE AND QUESTIONNAIRE
Dear Resident,
MURRURUNDI SHIRE COUNCIL : FLOODPLAIN MANAGEMENT STUDY
Lyall & Macoun Consulting Engineers have been engaged by Council to prepare a Floodplain Management Study. This study will form the basis for Council’s Floodplain Management Plan, which will have the objective of minimising the long-term impact of flooding on the community. This brochure provides some background to the steps involved in preparing the Floodplain Management Plan and asks for your assistance in a number of ways : 1. Complete and return the attached questionnaire. 2. Attend meetings which will be held in the next 2-3 months. 3. Comment on the draft plan when it is put on public exhibition in about three months’ time. The preparation of the Floodplain Management Plan is being subsidised by the State and Federal Governments. Once a plan has been accepted by the Community and adopted by Council, further subsidy may be available from government sources to implement the plan (eg levees, channel clearing, flood warning system). The available funds for such works are severely limited and there is strong competition between the various towns and shires for these funds. One of the factors which government uses to judge between the competing requests for funds is the degree of community involvement in developing the Floodplain Management Plan.
To give the Council the best chance to obtain subsidised funding to help the community, you need to
be involved!
The attached questionnaire asks a range of questions relating to your own experiences in recent floods and the impact these have had on you and your family. One of the first steps in a Floodplain Management Study is to assess the impact of flooding on the community in terms of financial loss and social impact. The attached questionnaire will assist us in making these assessments. Later in the study we will be seeking further input and comment regarding community preferences for ways in which the impact of floods can be reduced. These opportunities will be publicised at the time, but we would like to know if you are likely to be interested in being consulted or attending meetings. Please take a moment to complete the questionnaire. Any answers given will be used to give us an idea of how floods impact on the community as a whole. All information provided will be strictly confidential and not be used in any way which identifies individual residents. We are aware that some similar information may have been provided to Council in connection with the Mayor’s Relief Appeal after the flood of January 1996. We are asking for some of it again, to ensure we have a complete picture of the overall effect of flooding on the community. We would like you to provide your street address so that we can correlate the information about the effect of floods with our own analysis of the depth and speed of flood water. If you have any concerns or questions, please provide written comments on the attached questionnaire or ring Steve Perrens at Lyall & Macoun on (02) 9413 3411 or Graeme Turnbull at Couincil on (063) ...... . I look forward to hearing from you and to working with the community to minimise the future devastation caused by flooding. Yours faithfully
LYALL & MACOUN CONSULTING ENGINEERS
Dr Stephen J Perrens FIE Aust, CPEng.
FLOODPLAIN MANAGEMENT STUDY Mail-Back Questionnaire
1. PLEASE TELL US A LITTLE ABOUT YOURSELF AND YOUR HOUSE/SHOP 1.1 This questionnaire refers to my house/shop (delete one). 1.2 How long have you lived in the town? years
1.3 How long have you lived in your current house/shop? years
1.4 How is your house/shop constructed? ( tick one on each line)
a. Weatherboard/
Fibro
Brick Veneer
Full Brick
b. Piered foundations
Slab on ground
2. WHAT WAS YOUR EXPERIENCE IN THE FLOOD OF JANUARY 1996? 2.1 What were the major effects of the flood on you?
( tick where appropriate) a. Inconvenience (eg roads closed, shops shut) b. Unable to access medical assistance c. Dangerous depth or velocity of flow d. Flooding of land adjacent to house/shop e. Flood water in house/shop f. Power supply cut g. Telephone cut 2.2 What, if any, damage was caused to your property?
(Please insert an estimate of the value of damage caused)
Carpets/flood coverings $
House structure $
Furniture and appliances (including TV, etc.) $
Belongings (eg clothes, books, etc.) $
Outside the house (garage equipment, mower, etc) $
2.3 How much warning did you have that a flood was coming? minutes
2.4 How did you get to know that a flood was coming ( tick one)
Council official/SES Neighbour Local media Other
2.5 How long after the flood did your home/business return to “normal”? hours
days
3. PLANNING FOR THE FUTURE
3.1 One of the most cost effective ways of reducing flood damage is the
installation of a flood warning system to allow residents to remove or raise movable items. How much warning would you need to take
effective action? minutes
3.2 If Council was unable to obtain sufficient funding from government sources to fully implement the proposed Floodplain Management Plan, would you be prepared to pay a special rate for flood mitigation
purposes, if so how much per year? ( tick one)
$0 $20 $50 $100 $200 $500 PLEASE NOTE: THIS QUESTION DOES NOT IMPLY THAT SUCH A
RATE WOULD BE CONSIDERED. IT IS ONLY TO TEST HOW THE COMMUNITY VALUES REDUCTION OF FLOOD DAMAGE.
3.3 DO YOU HAVE ANY SUGGESTIONS FOR EFFECTIVE WAYS TO
REDUCE THE IMPACT OF FLOODING ON THE TOWN?
................................................................................................................... ................................................................................................................... ................................................................................................................... ...................................................................................................................
4. Would you like to receive further information or be involved in
future meetings? (please tick appropriate box)
a. I would like to receive further information. b. I would like to be involved in meetings concerned with
Floodplain Management.
c. I would be happy to be interviewed about the effects on the
community (please tick)
Name ...................................................................................
Address ...................................................................................
...................................................................................
...................................................................................
Contact Phone:
......................................................................... (Work)
......................................................................... (Home)
THANK YOU FOR YOUR HELP PLEASE FILL IN YOUR NAME, ADDRESS AND PHONE NUMBER ON THE REVERSE SIDE AND
RETURN YOUR QUESTIONNAIRE IBY 31 MAY 1997
More detailed written comments are welcome. Please staple any sheets with your comments to this questionnaire and fold them together before mailing.
QUESTIONNAIRE RESPONDENTS - MURRURUNDI
Number Name Address
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Leo Purcell
David Flanagan
Heritage Hardware
JB O'Hare
Kenneth S White
Mr R Weber
Murrurundi Retirement
Homes Assoc Inc
Barry and Janene Nolan
L. Tappenden
Mrs W Saunders
Ken and Barbara Mitchell
Keith Casey
Jack Goldsmith
William Scotcher
CR Drake-Brockman
Miss RA Ellis
Mr A Gimbert
L Mathieson
Murrurundi PO and Nursery
Graham D Turnbull
Jack Wood
G and D Lamey
Peter Coffey
Elizabeth Feast
B & W Gurst
Shell Murrurundi
Miss Elizabeth Beith
13 Liverpool Street, Murrurundi
28 Cohen Street, Murrurundi
8-10 Mayne Street, Murrurundi
91 Mayne Street, Murrurundi
84 Murulla Street, Murrurundi
89 Timor Lane, Murrurundi
Murravale Hostel, 6-10 Haydon Street, Murrurundi
36 George Street, Murrurundi
Royal Hotle, 144 Mayne Street, Murrurundi
33 Wood Lane, Murrurundi
3 Wades Lane, Murrurundi
208 Mayne Street, Murrurundi
PO Box 23, Murrurundi
20 Mayne Street, Murrurundi
21 Mayne Street, Murrurundi
93 Mayne Street, Murrurundi
130 Little Street, Murrurundi
62 Mayne Street, Murrurundi
89 Mayne Street, Murrurundi
89 Mayne Street, Murrurundi
244 New England Highway, Murrurundi
40 Liverpool Street, Murrurundi
"Glenvale" New England Highway, Murrurundi
34 Haydon Street, Murrurundi
BP Murrurundi, 148 Mayne St, Murrurundi
3 Mayne Street, Murrurundi
30 Haydon Street, Murrurundi
QUESTIONNAIRE RESPONDENTS - BLANDFORD
Number Name Address
1
2
3
4
5
6
Barbara Mary Mitchell
MJ Norvill
Doug and Robin Munro
Norman and Traci Gimbert
VG Baker
Dennis Madden
Lot 1 Debenham St, Blandford
Debenham St, Blandford
"Winkle Farm", Old North Road, Blandford
"Tanona", Blandford
New England Highway, Blandford
Public School, Blandford
QUESTIONNAIRE RESPONDENTS – WILLOW TREE
Number Name Address
1
2
3
Willow Tree Public School
Ron Biffin (General Store)
Mr and Mrs R Blackmore
Merriwa Road, Willow Tree
20 New England Highway, Willow Tree
"Little Willow" Station Road, Willow Tree
ATTACHMENT 2
PUBLIC DISPLAY
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix C - Community Consultation
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1. THE FLOODPLAIN MANAGEMENT PROCESS
The State Government's Flood Policy is directed at
providing solutions to existing flooding problems in
developed areas and to ensuring that new development is
compatible with the flood hazard and does not create
additional flooding problems in other areas. The Policy
provides for technical and financial support by the
Government through the following four sequential stages:
1. Flood Study
- determines the nature and extent of
flooding.
2. Floodplain Management Study
- evaluates management options for the
floodplain in respect of both existing and
proposed development.
3. Floodplain Management Plan
- involves formal adoption by Council of a
plan of management for the floodplain.
4. Implementation of the Plan
- construction of flood mitigation works to
protect existing development.
- use of Local Environmental Plans to
ensure new development is compatible
with the flood hazard.
2. FLOOD STUDY
The draft Murrurundi, Blandford and Willow Tree Flood
Study (1997) constitutes the first stage of the management
process for this area and has been prepared for Murrurundi
Shire Council to define flood behaviour under present day
conditions. The Floodplain Management Study (FMS) is
currently being prepared for Council. A copy of the draft
Flood Study is available at Council offices for perusal by
interested residents and will remain on exhibition for the
next 4 months. During that time Council welcomes
comments from the public on its contents and results.
The area investigated in the Flood Study included the 12.5
km long reach of the Pages River from Murrurundi to
Blandford, as well as the 4.5 km section of Borambil Creek
in the vicinity of Willow Tree. Flood behaviour in the two
streams was modelled using computer based mathematical
models to provide information on flows, levels and flooding
behaviour for floods of frequencies ranging between 5 years
and 100 years average recurrence interval (ARI).
The average recurrence interval is the average period (in
years) between the occurrence or excedence of a flood of a
given size. For example, a 5 year flood is a relatively
frequent event and would be equalled or exceeded once in 5
years on the average. On the other hand, a 100 year flood
is a much larger and rarer flood and would be exceeded
once in 100 years on the average.
The ARI is defined by the average time between floods over
a long period of time (several thousand years). Because of
the random nature of floods, the occurrence of a flood (say
100 year ARI) in any year does not mean that a larger flood
will not occur for another 100 years. The chances of such a
flood occurring next year remain exactly the same,
regardless of what has happened before.
The probable maximum flood (PMF) was also modelled.
The PMF is the largest flood, which could reasonably be
expected to occur at a particular location, and is an
exceedingly rare event. It defines the upper limit of flood
prone land.
Plans showing the extent of flooding for floods ranging
between 5 years and 100 years ARI are contained in the
flood study. These plans also show high hazard areas in
the floodplain for each flood. Flood hazard at a particular
location depends on the depth and velocity of flooding and
varies for each flood. High hazard areas are zones of deep
water and/or where the velocity of flow is high. Conversely,
low hazard areas are zones where the depth of flooding is
shallow and/or velocities are low.
The attached diagrams show the extent of flooding and
the areas of high flood hazard for a 100 year ARI flood
at Murrurundi, Blandford and Willow Tree.
3. FLOODING IN MURRURUNDI
Murrurundi is the most flood prone of the three townships
investigated in the Flood Study, with nine
significant floods experienced in the past 40 years since the
record flood of October 1949.
On two recent occasions, in January and October 1996,
floodwaters surcharged the right bank of the Pages River
(looking in the downstream direction) just upstream of
Arnolds Bridge and flowed down Mayne Street. At
Murrurundi, the January 1996 flood was a major event, with
the peak discharge approximating that of a 100 year ARI
flood, but was less severe further downstream at Blandford
Floodplain Management Study
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Appendix C - Community Consultation
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Lyall & Macoun
Consulting Engineers
where it approximated a 50 year ARI flood. The October
flood was a smaller event, approximating 50 year ARI at
Murrurundi and 20 year ARI at Blandford.
The Pages River breaks both its left and right banks during
large flood events :
Floodwater leaves the right bank at Boyd Street
and rejoins the Pages River at the suspension
bridge at Murulla Street.
Floodwater leaves the left bank between Murulla
Street and Arnolds Bridge. Water flows down
both the New England Highway and along a
natural depression to the north of the Highway.
This flow bypasses Arnolds Bridge and rejoins
the river downstream of Wilson Memorial Park.
The river surcharges the man-made levee on the
right bank upstream of Arnolds Bridge.
Floodwaters travel through properties causing
flood damages. Floodwaters travel down Mayne
Street with a high velocity and rejoin the river
downstream of the township near Brooke Street.
Flooding occurs to the north of the New England
Highway, surcharging some of the minor creeks
and gullies. Floodwaters surcharging these
waterways follow the small drainage swales,
which border the roads, before joining the Pages
River.
4. FLOODING IN BLANDFORD
Flooding from Pages River
A steep right bank and mainly lucerne paddocks on the left
bank border the river. Upstream of the New England
Highway crossing at Blandford Bridge, floodwaters are
mainly confined to the immediate vicinity of the river,
although a property on the left bank upstream of Blandford
Bridge is susceptible to flooding eg January 1996.
Downstream of Blandford Bridge the capacity of the river
channel is smaller and floodwaters spread out towards
Warlands Creek.
The Pages River breaks its left bank upstream of Benhams
Bridge. During times of major flooding, flood waters flow
along the northern side of the New England Highway
towards Norvill Park. However, most of the flow is
conveyed over the highway before it reaches Norvi ll Park.
Flooding from Warlands Creek
Warlands Creek flows from rugged country to the north of
the township. The creek meanders past the eastern side of
the township. During times of major floods, the river breaks
its banks along most of its length and causes flooding within
the township.
The river breaks its right bank upstream of the Barsham
Bridge. Floodwaters flow into Norvill Park where they
surcharge the highway and inundate the school ground.
Floodwaters then flow over lucerne paddocks to join the
Pages River.
Downstream of Barsham Bridge floodwaters which escape
the river flow through the street system before rejoining the
combined Warlands Creek and Pages River flows.
5. FLOODING IN WILLOW TREE
Borambil Creek has a wide, sparsely developed right
floodplain in the vicinity of the township of Willow Tree.
Development has been mainly to the east of the railway line
on high ground and consequently flooding has only a minor
effect on the township.
Some development has occurred to the west of the railway
line. However, only rare events (greater than the 100 year
ARI flood) would cause flooding.
During the January 1996 flood, which was approximately a
100 year ARI event at Willow Tree, minor damage was
caused along Merriwa Road.
Flooding occurred at the Willow Tree Public School when
floodwaters surcharged the right bank upstream of Hams
Bridge and followed Merriwa Road to the school. Flooding
of this nature occurs relatively frequently but the
construction of a levee beside the school prevents all but
major flood events inundating the school grounds.
Some minor flooding was experienced due to insufficient
drainage capacity and blockage of culverts within the town,
eg the culvert on the northern side of Sisson Street.
Job No: NX518
J:\NX518\docs\appd.doc
Date: 03/06/98
Rev. No. 3.0
Author: SAB
Reviewer: BWL
MURRURUNDI, BLANDFORD
AND WILLOW TREE
FLOODPLAIN MANAGEMENT STUDY
APPENDIX D
FLOOD PREPAREDNESS
AND RESPONSE
Note: The Word version of the document was reformatted in December 2014 which has led to
minor differences in its structure when compared to the original report. No hard copy version of
this Appendix was available at the time of compiling. As a result, Figure D.1 could not be
reproduced, while Figure D.2 was reproduced from a Word document which was assumed to
have been used to compile the original report.
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix D - Flood Preparedness and Response
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TABLE OF CONTENTS
Page No.
D1. INTRODUCTION AND SCOPE ..................................................................................... D-1
D1.1 Elements of Flood Warning and Response System ......................................... D-1
D1.2 Location .......................................................................................................... D-1
D1.3 SES Arrangements in Murrurundi Shire ........................................................... D-2
D1.4 Scope of Review ............................................................................................. D-2
D2. FLOOD WARNING AND RESPONSE ........................................................................... D-3
D2.1 Institutional Arrangements for Flood Warning and Response ........................... D-3
D2.2 Murrurundi and Quirindi Flood Plans................................................................ D-4
D3. REVIEW OF THE MURRURUNDI AND QUIRINDI EMERGENCY MANAGEMENT
SYSTEM ....................................................................................................................... D-6
D3.1 Identification of Areas at Risk .......................................................................... D-6
D3.2 Flood Predictions and Warning ........................................................................ D-6
D3.3 Dissemination of Warnings .............................................................................. D-7
D3.4 Response to Warnings .................................................................................... D-8
D3.4.1 Existing Situation ................................................................................. D-8
D3.4.2 Commentary ........................................................................................ D-9
D3.5 Flood Recovery ............................................................................................... D-9
D4. IMPROVEMENTS TO THE FLOOD WARNING SYSTEM ........................................... D-11
D4.1 Flood Warning ............................................................................................... D-11
D4.2 Flood Response and Communication ............................................................ D-12
D5 SUMMARY ................................................................................................................. D-14
D6. REFERENCES ............................................................................................................ D-15
FIGURES
D.1 Rainfall and Stream Gauging Stations
D.2 Distribution of Flood Warnings
Floodplain Management Study
Murrurundi, Blandford and Willow Tree
Appendix D - Flood Preparedness and Response
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D1. INTRODUCTION AND SCOPE
D1.1 Elements of Flood Warning and Response System
Implementation of an effective flood warning system is a strategy increasingly being used as a
means of mitigating flood damage. A flood warning system also incorporates measures for an
effective response. The overall system consists of the following elements:
forecasting the time of arrival and height of flood stages and the flood peak
interpretation of the prediction and identification of the areas at risk from flooding
the preparation and dissemination of warnings to flood prone residents
response to the warnings by the agencies involved and the community, possibly
involving the evacuation of people and possessions from flood threatened areas
the recovery of the community in the flood aftermath
review of the system after the flood event
This Appendix reviews the flood warning and response system presently in place in the Shire of
Murrurundi and examines possible measures for improving the system in the townships of
Murrurundi, Blandford and Willow Tree.
D1.2 Location
Murrurundi, Blandford and Willow Tree are situated in the foothills of the Liverpoo l Range north
of the town of Scone. The Liverpool Range, a part of the Great Dividing Range with elevations
ranging between 600 and 1200 m, forms the northern boundary of the Hunter River catchment
and is the watershed between the coastal Hunter River system and inland Namoi system.
The Pages River has its source near the eastern end of the range, from where it flows in a south -
east direction through the townships of Murrurundi and Blandford to join the Hunter River in its
headwater region. Warlands Creek flows through Blandford and joins the Pages River
immediately downstream of the township. The catchment area of the Pages River at Murrurundi
is 72 km2. Warlands Creek has a catchment area of 103 km
2 at Blandford. The combined
catchment area of the two streams at the gauging station downstream of Blandford amounts to
300 km2.
Borambil Creek, a tributary of the Mooki River, rises on the northern side of the Liverpool Range
in the Namoi River catchment and flows in a northerly direction parallel with the New England
Highway. A short distance upstream of the township of Willow Tree it is joined by Chilcotts
Creek, which drains the foothills of the range to the east. Borambil Creek continues past Willow
Tree towards Quirindi. At the junction with Chilcotts Creek the total catchment area is 183 km2 of
which Borambil Creek contributes 49 km2.
The streams within the Shire have steep gradients and floods typically rise quickly with a time to
peak of two hours or less. Flooding within the towns is classed as “flash” flooding with a very
short potential warning time.
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Murrurundi, Blandford and Willow Tree
Appendix D - Flood Preparedness and Response
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D1.3 SES Arrangements in Murrurundi Shire
Typically, a single SES Local Controller controls flood management within each Council area.
However, within the Shire of Murrurundi, the Liverpool Ranges is the watershed between the
Hunter and Namoi River Valleys. By agreement between the Murrurundi and Quirindi SES Local
Controllers, responsibility for flood management (including flood warning and response) has been
divided into the following two areas:
1) On tributaries of the Hunter River (east of the Liverpool Range): - Murrurundi Local
Control
2) On tributaries of the Mooki River (west of the Liverpool Range): - Quirindi Local
Control
D1.4 Scope of Review
A review of the current flood warning and response system in the three townships is presented in
this Appendix and has been prepared with input from State and Local SES officers and the
Bureau of Meteorology.
State wide arrangements for flood warning and response, which involve the interaction of seve ral
co-operating government agencies, are briefly reviewed in Section D2. A review of the
Murrurundi and Quirindi Emergency Management System is provided in Section D3, while
possible improvements to the system are discussed in Section D4.
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D2. FLOOD WARNING AND RESPONSE
D2.1 Institutional Arrangements for Flood Warning and Response
A range of Local, State and Federal Authorities participate in these processes. Flood forecasting
is the designated responsibility of the Commonwealth Bureau of Meteorology (BOM), although
water authorities, local councils and the State Emergency Service also produce flood forecasts
and play a part in the flood warning process in some areas. The warning phase is generally
under the supervision of the State Emergency Service (SES) acting through its local unit, often
with considerable local council input. The SES generally supervises evacuation, although the
Police Service will often be involved, especially if the number of evacuees is large. If necessary,
the Defence Forces will be brought in to provide assistance to the civil authorities through
Emergency Management Australia. Finally, volunteers and welfare agencies play a key role in
the recovery phase, along with councils and state government agencies.
In recent years, Flood Warning Consultative Committees have been established in all States. In
NSW membership comprises the BOM (chair), Public Works and Services Department,
Department of Land and Water Conservation, Department of Local Government, Sydney Water,
the SES and the Floodplain Management Authority. This committee provides a suitable vehicle
for the review of flood warning procedures and responsibilities. Recently, the Upper Hunter
Division Controller has been added to the Committee and Local Government represented by the
Shire and Local Government Association. Putting the Floodplain Management authority on the
Committee also enhances the community’s representation.
Flood forecasting, warning, response and recovery are crucial elements in the effectiveness of a
flood warning system. Flood warning schemes interpret and add to flood forecasts (predictions
of gauge heights) by linking them to something meaningful to the public such as flood depths in
specific areas, extents of flooding, road closures, properties inundated etc and then providing
advice on appropriate response. Warning schemes must ensure the message is effectively put
together, disseminated, understood and acted upon.
It is essential that a formal preparedness, response and recovery plan ("Flood Plan") be prepared
for each area at risk. This Plan, which is prepared by the SES covers the range of activities
relevant to real time flood management and incorporates input from various other organisations
and ideally from the community at risk. It is the critical flood education document and is available
to the public. The Plan must address wider issues such as community awareness, public
education and mock emergency practices, and most importantly, community acceptance of the
need for and involvement in management measures. Other documents, including the Operation
Manual, Resource Manual and Standing Operating Procedures, contain details of areas of
responsibility, chains of command, activities to be undertaken during floods and available
resources.
It is also imperative that flood forecasting procedures, responsibilities and the necessary
resources and their disposition be reviewed to ensure that forecasts are accurate and timely.
Such procedures and responsibilities need to be incorporated into the flood plans for affected
communities.
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Flood warning systems should also be subjected to an on-going assessment. After each
significant flood event, the performance of the particular "system" needs to be reviewed as a
matter of course and, if necessary, response planning altered.
Further detail on flood management arrangements in NSW is to be found in the State Flood Plan,
Division (Regional) flood plans and Local flood plans. The last are normally written at the level of
the individual Local Government area.
D2.2 Murrurundi and Quirindi Flood Plans
A draft Flood Sub-Plan has been prepared for the area of the Murrurundi Shire to the east of the
Liverpool ranges (Murrurundi Local Control). Due to the nature of flooding within the area, and
the relatively small number of properties affected by flooding, the document only forms an
annexure to the Murrurundi Local Disaster Plan (DISPLAN) rather than a separate document.
The plan covers the following topics:
the flood management arrangement within the Council area, dividing responsibilities
between Quirindi and Murrurundi SES,
definition of the flood threat, including flood producing mechanisms, locations of road
closures and areas inundated in Murrurundi and Blandford.
activities which are undertaken by the Local Controller with respect to flood warnings
and response.
In 1994 the draft Quirindi Local Disaster Plan (DISPLAN) was prepared. The plan includes a
Local Flood Plan for Quirindi which covers:
preparedness measures, the conduct of response operations and the co-ordination of
immediate recovery measures for flooding within the Quirindi and Murrurundi Council
(northern portion) areas.
operations for all levels of flooding and caters for both SES control of operations and,
where appropriate, the handover of control of part or all of operations from the SES
Local Controller to the Local Emergency Operations Controller.
The Plan is issued under the authority of the State Emergency and Rescue Management Act
1989 and the State Emergency Service Act 1989. It has been accepted by the State Emergency
Service Namoi Division Controller and the Quirindi Local Emergency Management Committee.
The Plan is a much larger document than its Murrurundi counterpart and covers the following
topics:
Part 1 Introduction - Purpose
- Authority
- Area Covered by the Plan
- Responsibilities
- Review of the Plan
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Part 2 Preparedness - Public Education
- Activation
- Flood Intelligence
- Warnings
- Preliminary Deployments
Part 3 Response - Control
- Operations Centres
- Liaison
- Communications
- Information
- Road Control
- Flood Rescue
- Evacuations
- Logistics and Resupply
Part 4 Recovery - Welfare
- Registration
- All Clear
- Recovery Coordination
- Debrief
Several annexures providing specific information on the flooding situation in the shire are
appended to the Local Flood Plan, as follows:
A. The Flood Threat
B. Specific Risk Areas
C. Gauges Monitored by the SES Local Controller
D. The Distribution of SES Flood Bulletins
E. Guide to the Content of Evacuation Warning Messages
F. Coepolly No. 2 Dam Failure Warning System
Within the Murrurundi and Quirindi areas, the Flood Plans provide information on the
dissemination of warnings/information to the public through the media, the Police, other
emergency services and by telephone or direct radio contact.
The respective SES Local Controllers activate the Flood Plans when flooding is predicted to
occur at either of the townships, after they obtain information on prospective and actua l flooding
from:
Bureau of Meteorology Flood Alert (previously called Confidential Flood Advice). The
information is received by telephone and fax from the SES Upper Hunter and Namoi Division
Headquarters.
flood gauges located at Arnolds Bridge at Murrurundi and Hams Bridge at Willow Tree,
neighbouring Controllers
a network of local river-watch readers, Council crews and Police.
In practice, due to the “flash flooding” behaviour of the catchments, real activity would only be
triggered by signs that flooding had actually commenced.
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D3. REVIEW OF THE MURRURUNDI AND QUIRINDI EMERGENCY MANAGEMENT
SYSTEM
D3.1 Identification of Areas at Risk
The general pattern of flooding in the townships has been identified by SES from historic
flooding. Peak water surface levels in the Pages River and Warlands and Borambil Creeks for 5,
20, 50, 100 and PMF floods have been presented in the draft Flood Study report (LMCE, 1997).
The indicative extent of flooding has been shown on plans supplied to Council. As part of this
present Floodplain Management Study, floor levels of flood affected properties have been
surveyed. Consequently, there is now sufficient information available to more precisely identify
areas at risk from flooding for the full range of events likely to tr igger flood response procedures
in the three townships. It is also to be noted that the “wall of water” effect noted on the Warlands
Creek catchment in the January 1996 flood could conceivably occur on the Pages River.
D3.2 Flood Predictions and Warning
The primary responsibility for flood prediction within NSW rests with the BOM. Through the
collection and analysis of rainfall and stream flow data from telephone telemetered rainfall and
stream flow gauges the BOM undertakes the following activities:
Provision of early indications that a meteorological situation is developing which could
lead to flood producing rains in the Hunter and Namoi catchments.
A preliminary assessment of the scale of flooding.
Ongoing predictions of river heights at key locations during flood producing rains and
until the river level has fallen below the minor flood level.
Summaries of actual rainfall and river height readings as the flood develops, peaks and
recedes.
The BOM is generally responsible for providing flood warning advice on major river systems
where warning times exceed six hours. The rapid rate of rise of floods within Murrurundi Shire
does not allow sufficient time for BOM to issue Flood Warnings, although under certain
circumstances, BOM may issue Flood Alerts or more specifically Severe Thunderstorm Advice
when there is a likelihood that predicted rainfall will be sufficient to cause flooding. Within the
Upper Hunter Valley catchment these warnings are sent to Muswellbrook and Gunnedah within
the Namoi catchment and then to Local Controllers. During the operational phase, flood
warnings are the responsibility of the Local Controller who, through a network of gauges and
river-watch readers, Council crews, Police and neighbouring Controllers, may predict the onset of
a flood event.
Within or adjacent to the Pages River catchment, there are two pluviographic rainfall gauges
located at Scone and Blandford and a HYDROMACE reporting rain gauge located at Murrurundi
(see Figure D.1). The three gauges form part of the instrumentation for the Hunter River Valley
Flood Warning System. Also located on the Pages River at Blandford, is a stream gauging
station. Two privately read daily rain gauges are located on the Pages River catchment,
upstream of Murrurundi and are denoted A and B on Figure D.1.
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Within the Borambil Creek catchment, there are presently no pluviographic rainfall gauges.
However, one BOM daily rain gauge is located upstream of Willow Tree.
D3.3 Dissemination of Warnings
Due to the rapid rise of floodwaters within the Council area , the mechanism for dissemination of
flood warnings does not follow the well established pattern for NSW shown in Figure D.2. The
short period of time of rise of flood peaks means that it is not possible for BOM to issue e ffective
flood warnings.
BOM issue a Flood Alert based on an advanced appreciation of a developing meteorological
situation which could produce flood rainfall. It contains, when possible, a preliminary assessment
of the severity of flooding which could occur in particular river valleys. It is issued for planning
purposes and is not disseminated to the media or public.
The Flood Alert is issued by BOM as an alerting mechanism for the SES and other directly
affected agencies when it is assessed that predicted rainfall will be sufficient to overcome the
moisture deficit within a catchment and cause flooding. The assessment of moisture deficit uses
a concept known as the antecedent precipitation index (A.P.I.) which is calculated on a
continuous basis from rainfalls experienced prior to issuing the flood advice.
The Flood Advices are transmitted direct to the SES Divisional Headquarters, where the relevant
Local SES units are alerted by phone.
Within the Local Flood Plans there are guidelines for the activation of the respective plans and
the issuing of warnings including lists of names of all relevant authorities and organisations,
responsibility levels of the various parties and procedures for activities and mobilisation of
Divisional and Local Headquarters.
Upon receiving information from sources such as the network of gauges and river -watch readers,
Council crews, Police and neighbouring Controllers, of the possibility of a flood event, the Local
Controllers contact all relevant authorities and organisations. East of the ranges, the Murrurundi
Local Controller informs the Murrurundi Police and Council. Information is also provided to the
Upper Hunter SES Division Headquarters which is then relayed to radio stations at Muswellbrook,
Tamworth and Gunnedah. The Division Headquarters also advises the Scone and Muswellbrook
SES Local Controllers if flooding within their Council areas appears possible as a result of
flooding in Murrurundi Shire.
West of the ranges, the Quirindi Local Controller contacts the Willow Tree Police Sector
Commander who acts as an SES agent. The Police Sector Commander then controls:
any evacuations in the area resulting from flash flooding,
road control operations in conjunction with the Quirindi and Murrurundi Councils.
The NSW Fire Brigade situated at Willow Tree may also be called upon to assist the Police in the
above activities.
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Upon receipt of information of possible flooding, the Quirindi Local Controller will contact the
Namoi Division Headquarters who will undertake similar tasks outlined above for the Upper
Hunter region. Additionally, TV stations in Tamworth are notified when deemed appropriate.
All SES Units have been issued with copies of "Flood Warning: an Australian Guide" which offers
suggestions as to how the utility of the BOM predictions can be maximised (for example, by
estimating flood effects), and deals with identifying the best methods of dissemination for
different situations. The key elements are the translation of the height predictions into likely
consequences and the effective distribution of this information and appropriate advice for people
to follow.
D3.4 Response to Warnings
D3.4.1 Existing Situation
Reaction to flood warnings and response procedures are outlined in the Local Flood Plans and
deal with the provision of a coordinated response to the flooding. Aspects covered include:
Control and Responsibilities - Most flood operations within Murrurundi Shire are
controlled by the respective SES Local Controller in accordance with the State
Emergency Service Act, 1989. This will usually include the coordination of support from
other agencies. Operations are controlled from SES Local Headquarters located at
Murrurundi and Quirindi.
Communications - The primary means of communication between SES personnel in the
field is via:
Murrurundi SES UHF radio east of the ranges
the Quirindi SES UHF Tactical radio network west of the ranges.
The Quirindi unit also operates a UHF CB radio station which provides communications
with most rural properties in the area and a station on the Namoi SES Division UHF
Strategic radio network as backup. Other valuable back-up is also provided by the radio
services of Quirindi Council, the Rural Fire Service and the Quirindi District Rescue
Squad.
Flood Advice – Both the Murrurundi and Quirindi SES Local Headquarters provide
phone-in information services to the public in relation to river heights, flood behaviour,
road closures and confirmation of evacuation warnings. The Local Controllers provide
road status reports for all roads in the Shire to the Upper Hunter and Namoi SES Division
Headquarters. Division Headquarters distributes information on major roads to SES units
and the media outlets as part of Flood Bulletins.
Road Control - Road closures are undertaken by Murrurundi Council as agents for the
RTA, as appropriate. NSW Police Services also has the authority to close and re-open
roads but will normally only do so (if the Council has not already acted) if public safety
requires such action.
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Flood Rescue - The respective SES Local Controller coordinates flood rescues. If
required, Flood Rescue Boats and Crews may be obtained through the Namoi SES
Division Headquarters. Due to the nature of flooding in the vicinity of the three towns, the
time taken to aquire the boats would negate their use and would be more appropriate
further down the valleys.
Evacuations - SES Local Controllers control evacuations which are conducted by SES,
police and Rural Fire Service personnel. In the Murrurundi area, the Local Control ler will
provide advice and assistance as required. In the Willow Tree area, evacuations will be
controlled by the Willow Tree Police Sector Commander. It is expected that evacuees
would proceed to the houses of friends and relatives until the flood subs ided, but
Evacuation Centres would be opened if necessary.
D3.4.2 Commentary
The reaction phase of the flood warning cycle depends on human nature, preparedness and the
credibility of the flood warning. Effective response to warning information will depend upon the
quality of information; the ability of people to understand it and the SES's ability to ensure they
receive it. The effectiveness of evacuation operations depends on the SES's ability to determine
in advance who will need to be evacuated and to ensure those people understand that need (eg
by door knocking). However, in the case of the three townships there is little time to carry out
evacuations and the best that could probably be achieved is an announcement over radio
stations that flooding is imminent. There is no local community radio by which flood warnings
can be disseminated to the community.
The residents of Murrurundi, Blandford and Willow Tree are part of a wider community
throughout the catchment and region. Community contacts provide a widespread informal
network of people who exchange information as a flood situation develops and then “spread the
word” amongst friends and neighbours in townships. These informal means of communication
can provide the SES with a valuable means of disseminating flood information but also provide a
vehicle by which misleading rumours can spread in the absence of “official” warnings. The SES
should seek to take charge of information dissemination, to keep the community informed from
an official source. This will allow the community to plan ahead, without necessarily taking steps
to move furniture and stock.
A further improvement would be to erect temporary signs on the major roads at the last major
intersection before arriving at the town with a contact phone number so that travellers and people
from out of town can obtain information regarding flooding. Adequate supplies of barricades and
signs are required to effect road closures.
It is recommended that the SES consults the local community to identify exactly what information
they require in relation to flood advice and the best way of communicating it. This could be
achieved by advertisement in the local press and as part of the display process of the draft
Floodplain Management Plan.
D3.5 Flood Recovery
Part 4 of the Quirindi Local Flood Plan addresses this phase. Within the Murrurundi Flood Plan,
Flood Recovery has not been addressed.
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Aspects covered within the Quirindi plan include:
Registration of evacuees and catering for their long term welfare.
Issuing "all clear" message signifying response operations are completed.
Implementing Recovery Plan and debriefing.
Experience gained through mock flood emergencies could be used to refine Flood Plans.
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D4. IMPROVEMENTS TO THE FLOOD WARNING SYSTEM
The Flood Plan formalises the procedures used in previous flood events. Due to the recent
major flood which occurred in January 1996, and previous floods in the 1990’s, the local
community is very flood aware (although the flooding mainly occurred in the Upper Hunter
catchment) and the procedures documented in the Plan are based on this flood awareness.
D4.1 Flood Warning
The effectiveness of any form of warning system is ultimately measured by the response to the
warnings. This response is affected by many factors, the most important being the need to
minimise the delays between the occurrence of the event and its subsequent notification, the
awareness of this by the forecasting authority and the initiation of the emergency response plan.
As mentioned previously, the primary responsibility for flood prediction rests with the BOM. With
the Murrurundi Shire area being located in the shadow of the Liverpool Ranges, flooding in the
area is of a “flash” flooding nature.
To provide a “flash” flood warning system it would be necessary to install several radio
telemetered rain gauges within the upper reaches of the catchment. The technology utilised in
these systems can vary depending on the needs and economies of the situation. Cheaper and
more reliable modern electronics have resulted in a trend towards more automated systems,
such as the ALERT (Automated Local Evaluation in Real Time) system. The Bureau of
Meteorology has specifically adopted the philosophy of event based radio telemetry as embodie d
in the ALERT system. This system would provide a continuous source of information of actual
rainfall events. The gauges would be linked to a base station computer which could be located at
either SES Local Controller headquarters or Council Chambers and would monitor the incoming
rainfall readings. Rainfalls would be converted to predictions of flows and water surface levels in
the streams using the computer models developed in the Flood Study. A gauge would be
required within each catchment area (Pages River above Murrurundi, Warlands Creek above
Blandford and Chilcotts Creek above Willow Tree) to monitor the areal variability of rainfall.
Installation of such a system would be undertaken by BOM at an indicative cost of around
$100,000. Upkeep of the stations would be Council’s responsibility.
Implementation of an ALERT system would not greatly increase the warning time and does not
therefore appear justified. A more cost effective measure may be to maximise the effectiveness
of the present network of local river and rain watchers. The education of these watchers in what
events may constitute a flood event and subsequent procedures for notification of relevant
authorities, namely the SES Local Controller could greatly benefit the community. One system
which has been implemented in other catchments, for example Mullumbimby, is the supply of
plots of rainfall intensity–frequency-duration to rain gauge readers. These plots allow the reader
to interpret rainfall intensities as they occur.
The flood warning system is heavily reliant on telephone contact between SES and gauge
readers. The security of this communication during a major flood should be checked with
Telstra. The possibility of a radio link between river and rain watchers could be consider ed.
The Murrurundi Council area would benefit from a Doppler Radar system which could better track
and predict flood producing rain. At present there are two Doppler Radars in the whole of
Australia with one system centred in Sydney. The range of the Sydney radar extends as far north
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as Newcastle. However, the cost of one of these radars is estimated at around $20 M and the
implementation of a radar that covers the upper reaches of the Hunter and Namoi Rivers is
therefore unlikely in the near future.
D4.2 Flood Response and Communication
During major flood events the depth of flow passing through the three townships is relatively
shallow and the act of sandbagging certain properties may prevent inundation by floodwaters. It
is advised that an adequate store of sandbags be supplied in a location which is readily
accessible to residents and shop owners. Locations of sandbags should be noted on the Flood
Plans and they should be regularly inspected and maintained by SES. A priority list of areas to
be protected should be compiled using information on flooding contained in the Flood Study for
the three townships. When planning the locations of the sandbag stockpiles the following should
be noted:
a) Murrurundi township - due to the nature of major flooding, the CBD area will be severed from
the western side of the Pages River. Stockpiles of sandbags are therefore required on each
side of the Pages River to provide adequate coverage.
b) Blandford township – during major flood events, properties located on the r ight bank of
Warlands Creek experience shallow sheet flow and storage should be concentrated in that
area. There are few flood effects from Pages River.
c) Willow Tree township - flooding is generally of a local drainage nature with the surcharging
of culverts to the east of the railway line. Flooding due to surcharging of Borambil Creek
occurs at the public school, located along Merriwa Road.
Within the townships of Murrurundi and Blandford a number of key emergency organisations are
located within the flood liable area including Fire Stations and the Murrurundi telephone
exchange. It is also to be noted that within the township of Murrurundi, inundation of the New
England Highway in the vicinity of Arnolds Bridge may effect the response ability of certain
authorities. Police, Fire and Council are located on the eastern side of the Pages River while the
SES Local Headquarters are located on the western side. The Murrurundi Flood Plan may need
to address the issue of responsibilities in the absence of SES personnel.
The main improvements to the system could be made to communications between the SES and
the local community both when a flood situation is developing and then during the flood.
The short travel time of the flood peak from the township of Murrurundi to Blandford may require
an agent of the SES to be located within Blandford, say the Fire brigade. This needs to be
formalised within the Flood Plan.
At the townships of Blandford and Willow Tree, the public schools are susceptible to flood flows
surcharging Warlands and Borambil Creeks respectively. The Murrurundi and Quirindi Flood
Plans need to appreciate that children are at risk, and an effective means of flood warning and
evacuation incorporated into the Plan.
One approach which could be considered is an alerting system similar to that adopted in Coffs
Harbour.
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When significant rain has fallen and flooding is possible, the SES Local headquarters will issue
Preliminary Flood Alerts for immediate broadcast by radio and television stations. The following
are also advised:
a. School principals
b. School bus companies
c. President, Coffs Harbour Chamber of Commerce and Industry (when flooding of
the Coffs Harbour Central Business District is possible), for transmission by
telephone to the owners of commercial premises.
The SES needs to consult the local community on their requirements for information and
improved communications and how these requirements can be fulfilled.
The Flood Plan needs to be updated to incorporate information from both the Flood Study and
this Floodplain Management Study and to cross-reference with Council’s Floodplain Management
Plan. Both Plans need to developed in partnership and complement each other.
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D5 SUMMARY
This section has reviewed the existing flood warning and response system.
In the Shire of Murrurundi, the division of responsibility is such that the Murrurundi SES Local
Controller has responsibility for flood management in Murrurundi and Blandford, while the
Quirindi Local Controller covers Willow Tree.
A draft Flood Sub-Plan has been prepared for the area east of the Liverpool Ranges which
defines the nature of the flood threat including flood producing mechanisms, locations of road
closures and areas inundated in Murrurundi and Blandford and sets out procedures undertaken
by the Local Controller with respect to flood warnings and response. A draft Quirindi Local
Disaster Plan has been prepared which covers the headwaters of the Namoi system, including
Willow Tree.
While the general pattern of flooding in the townships has been identified from historic flooding,
the results of the Flood Study along with floor levels of flood affected properties will allow more
precise identification of areas at risk from the full range of flood events likely to trigger flood
response procedures in the three townships. This information should be incorporated in the
Flood Plans. Attention should also be given to covering situations such as experienced on
Warlands Creek in January 1996 where very heavy localised rainfall resulted in a “wall of water”
type floodwave.
BOM currently issue a Flood Alert (previously called Confidential Flood Advice) as an alerting
mechanism for the SES. These advices are of a qualitative nature only. There is no formal flood
prediction system in operation for the three townships. Due to their small size and steepness,
flooding on the catchments is of a “flash flooding” nature with only around 1 -2 hours between the
occurrence of heavy rainfall and the resulting flood peak. Implementation of a flood forecasting
system based on the ALERT system is not likely to be effective for the three townships, although
it may be useful in downstream flood affected locations where the response time of the
catchments is longer.
Some formalisation and expansion of the network of local river and rain watchers, along with
training and strengthening of communications, is considered appropriate to maximise the
available warning time and the effectiveness of the system. Some suggestions are given in
Section 4.1 of this Appendix. Mock trials of the system should also be undertaken to test its
effectiveness in a real flood.
Along the Pages River, the surcharging of the New England Highway may cause difficulties in
respect to emergency response to the townships of Murrurundi and Blandford. It is
recommended that consideration be given to including in the Murrurundi Flood Plan procedures
for issuing a Preliminary Flood Alert and advice to key residents likely to be flood affected
(Section 4.2).
The relatively shallow depth of flooding for events up to and including major flood events means
that sandbagging can be an effective means of preventing inundation by floodwaters to a large
number of properties. The formalisation of sandbag storage areas, namely within the town ships
of Murrurundi and Blandford is recommended. A priority list of areas to be protected should be
compiled using information presented in the Flood Study. Due to the short flood warning time,
the stockpiles of sandbags should be readily accessible to the public to allow them to quickly
respond to any flood warning. An education plan could be implemented to make the public
aware of their locations.
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D6. REFERENCES
Australian Water Resources Council (1992). "Floodplain Management in Australia Volume 2:
Main Report." Water Management Series No. 21.
Carroll D.G. (1993). "Prophet - The Brisbane City Council Creek Flood Monitoring and
Forecasting System." National Local Government Engineering Conference Adelaide.
Emergency Management Australia (1995). "Flood Warning: An Australian Guide."
Ismes Consulting Group (May 1992). "Sydney-Newcastle-Wollongong Flash Flood Warning
System." Report No. PWD92096.
McKay G. (1991). "Flood Forecasting in New South Wales by the Bureau of Meteorology." 31st
Annual Flood Mitigation Conference, Port Macquarie.
NSW State Emergency Service (1994). "draft Quirindi Local Flood Plan.”
NSW State Emergency Service (1996). "draft Murrurundi Flood Sub-Plan.”
Sullivan, P. (1992). "New South Wales Flood Warning Consultative Committee - how it can help
you." 32nd Annual Flood Mitigation Conference, Bankstown.
Wyllie, S.J. and Ribbons, C. (1991). "Real time data acquisition systems developed by Public
Works Department's Manly Hydraulics Laboratory and its application to flood warning." 31st
Annual Flood Mitigation Conference, Port Macquarie.
INPUT INPUT
M eteorologic System Bureau DLWC { River Gauges
Antecedent Precip . o f BOM { Rain Gauges
Index M eteorology SES { Gauge Readers
Conf ident ia l Pre l iminary F lood Warnings
F lood Adv ice Warnings Bul le t ins (SES) and
Pred ict ions
SES SES SES SES MEDIA SES SES
NAT DIV NAT DIV NAT DIV
HQ HQ HQ HQ HQ HQ
SES SES SES
LOCAL LOCAL LOCALMEDIA
PUBLIC PUBLIC
MURRURUNDI, BLANDFORD & WILLOW TREE
FLOODPLAIN MANAGEMENT STUDY
Figure D.2
Distribution of Flood Warnings
Job No: NX518 J:\NX518\docs\APPE.doc
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Author: NK Reviewer: BWL
MURRURUNDI, BLANDFORD
AND WILLOW TREE
FLOODPLAIN MANAGEMENT STUDY
APPENDIX E
PLANNING AND LAND USE CONTROLS
Note: The Word version of the document was reformatted in December 2014 which has led to minor differences in its structure when compared to the original report. No hard copy version of this
Appendix was available at the time of compiling. As a result, Figures E.1 and E.2 were reproduced from an AutoCADD file which was assumed to have been used to compile the original report.
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TABLE OF CONTENTS
Page No.
E.1 INTRODUCTION .......................................................................................................... E-1
E.2 EXISTING LAND USE PLANNING CONTROLS ........................................................... E-1
E.3 COMMENTARY ON EXISTING LAND USE PLANNING CONTROLS ........................... E-2
E.4 PLANNING OPTIONS .................................................................................................. E-5
E.4.1Floodplain Management Plan/Development Control Plan ........................................ E-5
E.4.2.Environmental Protection Zone .................................................................................. E-5
E.5 SUMMARY ................................................................................................................... E-6
FIGURES
E.1 Floodplain Zoning Murrurundi Township E.2 Floodplain Zoning Blandford Township
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E.1 INTRODUCTION
Murrurundi Shire Council has resolved to prepare Floodplain Management Plans (FMPs) for the
Murrurundi, Blandford and Willow Tree town areas. As part of the preparation of those FMPs
there is a requirement that the existing planning controls which relate to those areas be reviewed,
and suggestions made regarding the means by which those controls could be amended and/or
supplemented with regard to land which is potentially impacted by flood waters.
This report provides Council with a summary of the land use planning controls which currently
apply to flood liable land in the Shire, and provides a series of options for the consideration of
Council for amendment of the existing controls.
E.2 EXISTING LAND USE PLANNING CONTROLS
Land use within the Murrurundi Shire is generally regulated by the Murrurundi Local
Environmental Plan (LEP), 1993. Advice from Council is that there are no Development Control
Plans accompanying the Local Environmental Plan.
The Murrurundi LEP, 1993 contains some references to the management of development on
flood liable land. Clauses which refer to either flooding or flood liable land are:
Clause 5 (1) - Interpretation
The following definition is contained within Clause 5:
"flood liable land" means the land within the township of Murrurundi or the
village of Blandford or Willow Tree or elsewhere which is affected by flood as
indicated on the map;"
A review of the map indicates that there are no areas within the Shire notated as being flood
liable land.
Clause 6 - Model Provisions
This clause adopts the Environmental Planning and Assessment Model Provisions, 1980 except
for, inter alia, Clause 34 which essentially states that a person shall not erect a building or carry
out work on land within a flood prone area without the consent of Council. This clause is of little
relevance in Murrurundi Shire because, except for agriculture in the rural zones, all development
in the Shire requires the consent of Council. As such, the exclusion of Clause 34 is justified.
Clause 19 - Flood Liable Land
This clause, despite the need for development consent for all development other than agriculture
in any zone within the Shire, provides for the requirement of Clause 34 of the Environmental
Planning and Assessment Model Provisions, 1980 that no development on flood liable (prone)
land shall be undertaken without the consent of Council. Clause 19 states that:
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"19 Notwithstanding any other provision of this plan, the Council shall not
grant consent to the carrying out of any development on flood liable land, unless it
has made an assessment of:-
(a) the effect of the proposed development on the flow of flood waters on that
land or land in its immediate vicinity;
(b) the safety of the proposed development in the time of flood;
(c) whether the proposed development involves any risk to life, human safety
or private property in time of flood;
(d) whether the floor level of any dwelling-house or other habitable building
on the land will be at least 500 millimetres above the highest known f lood
in the vicinity; and
(e) whether adequate measures have been or will be taken to offset the likely
effects of flooding on the development."
E.3 COMMENTARY ON EXISTING LAND USE PLANNING CONTROLS
Apart from the above-mentioned areas within the Murrurundi LEP, 1993, there is no control on
development on flood liable land within the Shire of Murrurundi.
The following comments are made in order that Council can consider ways in which it can
strengthen the existing provisions of the Murrurundi LEP, 1993 to account for the effect of
flooding on development within the Murrurundi Shire and indeed the effect of development on the
flood regime.
Part 1 - Preliminary
The Murrurundi LEP, 1993 is an aims and objectives based planning instrument. Clause 2 detai ls
the general aims and objectives of the plan, with the specific objectives of each zone contained in
the Table to Clause 9 of the LEP.
There is no aim or objective of the plan for the control of development on flood liable land. It is
recommended that such an objective be included in Clause 2 of the LEP. A possible objective is:
"2. (1) (c) to reduce the incidence of damages and hazard in areas subject
to flooding by restricting development on flood liable land."
Clause 5 of the LEP defines "flood liable land" as:
"flood liable land" means the land within the township of Murrurundi or the
village of Blandford or Willow Tree or elsewhere which is affected by flood as
indicated on the map;"
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As indicated above, the map shows no land within the Shire as being flood liable, and as such the
definition has little value in the control of development within the Shire.
Council commissioned Flood Studies in Murrurundi, Blandford and Willow Tree which were
submitted in draft form by Lyall and Macoun Consulting Engineers (LMCE, 1997). Those studies
have identified areas which are subject to flooding and assessed the flood hazard in accordance
with the NSW Government "Floodplain Development Manual" (PWD, 1986). As such, Council
now has information on the flood regime within those townships to enable it to resolve that certain
sections of each township fall within the definition of "flood liable land".
It is recommended that Council resolve to prepare mapping which delineates the flood liable land.
In doing so, it is also recommended that Council consider an amendment to the definition of flood
liable land contained within the LEP. At present, the definition requires the land classified as
flood liable to be denoted on the map, i.e. the LEP Map.
As Council will appreciate, the map attached to the LEP forms part of the legislation of NSW and
any amendment to that map requires an amendment to the legislation. To effect such a change,
an amending LEP must be prepared, exhibited and then made by the Minister for Urban Affairs
and Planning.
It is apparent that the land which is considered to be flood liable may alter in the light of further
flood experience and refinement of the analysis of flood patterns and hazards. It is
recommended that Council adopt a means of noting flood liable land in graphic format which
allows revision and refinement in future.
It is recommended, rather than have the flood mapping tied to the LEP map, that there be a
separate series of maps held by Council which delineate land which has been determined as
flood liable. Such an approach will allow Council to make reference to those maps in the
definition of flood liable land contained in the LEP, while at the same time allowing Council to
amend its flood mapping without the need for a formal amendment to the LEP. This approach
would also allow Council to prepare additional maps for rural areas of the Shire should Council
consider that flood related planning controls be appropriate for dwellings and certain types of
rural industries (eg. intensive animal housing) In this regard, a suggested amendment to the
definition of flood liable land is:
"flood liable land means land identified by the Council as being liable to flooding
and indicated as flood liable land on a map marked "Flood Liable Land Map".
Part 2 - General Provisions
The Table to Clause 9 of the LEP contains the objectives of each zone in the LEP. None of the
zones within the LEP contain a specific objective for the control of development on flood liable
land.
If Council adopts the Flood Study results as being the basis for the delineation of flood liable
land, and subsequently amends the LEP as indicated above, then it is recommended that Council
also considers an amendment to the objectives of each of the three zones which appl y to the
Shire to provide further re-enforcement of Council's concern for the control of development in the
flood liable areas of the Shire.
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A possible objective for inserting into the Table for each zone is:
"To ensure that development of land which is flood liable is carried out in a
manner appropriate to the flood hazard."
Part 3 - Special Provisions
Clause 19 of the LEP contains a standard clause which controls development on flood liable land.
Whilst this clause has merit, it is considered that it can be strengthened to provide greater control
on such development. It is recommended that Council consider an amendment to that clause as
follows:
Flood liable land
19. (1) Notwithstanding any other provision of this plan, the Council shall
not grant consent to the carrying out of development or works for
any purpose on flood liable land without the consent of Council.
(2) The Council shall not grant consent to the carrying out of
development or works for any purpose on land that is flood liable
unless it is satisfied that:
(a) the development or work would not unduly restrict the flow
characteristics of flood waters; and
(b) the development or work would not unduly increase the
level of flooding on land in the vicinity; and
(c) the structural characteristics of any building or work, the
subject of the application, are capable of withstanding
flooding; and
(d) any proposed building is adequately flood proofed.
(3) The Council shall not grant consent required by this clause unless
it has taken into consideration:
(a) the cumulative effect of the development or work on flood
behaviour; and
(b) the risk of pollution to the waterways caused by the
development or work; and
(c) the availability of flood free access to the development or
work.
(4) The Council may require the floor level of habitable rooms of a
building to be erected at a height which is sufficient, in its opinion,
to obviate the frequent flooding of the building or work."
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It is considered that the above replacement clause will allow more control over development on
flood liable land while at the same time allowing more flexibility with regard to floor levels of
buildings.
Section 149 Certificates Under the Environmental Planning and Assessment Act, 1979
Advice from Council is that Annexure Item 3 to all s.149 Certificates issued by Council simply
quotes the existing Clause 19 of the LEP. As indicated above, there is no flood liable land
identified on the LEP Map, and as such the s.149 Certificate has little or no effect in this regard.
It is recommended that Council amend the Annexure to the s.149 Certificates in accordance with
the above-recommended amendments to the LEP.
E.4 PLANNING OPTIONS
In addition to the above recommendations for the general controls within the LEP, there are other
means by which Council can further strengthen its planning controls over flood liable land.
E.4.1 Floodplain Management Plan/Development Control Plan
The Floodplain Management Plans being prepared for Council will provide for a set of specific
development and flood protection guidelines which will assist in the control of development on
flood liable land.
It is recommended that a series of graded controls apply to land which is flood liable depending
upon the flood hazard which is identified for a particular parcel of land and the proposed use of
that land. These graded controls could, and should, form the basis of a Development Control
Plan for each township.
Having regard to the limited resources available to Council, it is recommended that the completed
Floodplain Management Plan for each township be adopted by Council as a Development Control
Plan. This will allow Council to have more specific controls on development and indeed provide
for a dynamic approach to development control in flood liable areas.
The adoption of the FMPs as DCPs may require a further amendment to the LEP to provide for
the creation of those DCPs. In this regard, a further proposed objective of the LEP could be:
"2 (1) (d) to provide a basis for development control plans to supplement
the broad controls of this plan with more detailed provisions for
regulating the carrying out of development."
E.4.2. Environmental Protection Zone
The preceding sections of this report have discussed measures which should be implemented by
Council to provide for a more effective LEP as far as the control of development on flood liable
land is concerned.
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It is recommended that Council also consider further strengthening controls on land which is
identified in the Flood Study as being “floodway” and/or “high hazard”. This could be achieved by
a further amendment to the LEP 1993 to include a new zone – Environmental 7(f) floodway.
A draft amending LEP is attached for the consideration of Council (Attachment A) . It is
recommended that, as part of the preparation and exhibition of the draft LEP, Council also exhibit
the Floodplain Management Plan (FMP) for each township as a Development Control Plan. The
provisions of this draft LEP should also be incorporated into any other changes contained within
this report which Council considers warranted. The exhibition of that FMP as a DCP will provide
detailed environmental planning controls for both the newly created 7(f) (Environmental
Protection - Floodway) Zone and other flood liable land within the Shire.
Figures E.1 and E.2 are plans of Murrurundi and Blandford respectively, which show the
approximate extent of flooding for the 100 year ARI, the high hazard areas for that flood and
existing land use zoning. The high hazard - floodway areas which are suitable for inclusion in the
7(f) (Environmental Protection-Floodway) Zone have been identified.
It is to be noted that the standard of contour mapping in Blandford and Willow Tree is poor, being
restricted to 1:25000 scale topographic maps with 10 m contours. The flood information shown on
these plans is based on the (limited) number of cross sections of the floodplain which were
surveyed for the Flood Study. There is no reliable connection to Australian Height Datum (AHD)
in the township of Willow Tree and therefore the hydraulic analysis and presentation of results
were undertaken to an arbitrary datum. Connection of the arbitrary datum to AHD and additional
survey to better define the extent of flooding are recommended for the two townships.
In the case of Murrurundi, 1:1000 scale sewer maps with 1 m contour spacing are available which
are considered to provide a reasonable base for presenting flood information, although some
additional work may be required to identify the flood extent.
Final position of the boundaries of the proposed 7(f) zoning will also need to take into account
conditions such as location of existing development, community reaction to the proposal etc.
E.5 SUMMARY
This appendix has identified a number of measures which should be taken to strengthen the flood
related planning controls available to council. In essence these include:
1) Council should resolve to prepare an amendment to the LEP 1993 to:
Add an objective related to control of development on flood liable land (Clause
2(1)(c))
Add a further objective (2(1)(d)) which would allow Council to adopt the Floodplain
Management Plan for each township as a Development Control Plan
Amend the definition of “flood liable land” (Clause 5) to refer to a separate series of
maps which are not tied to the LEP map. This will allow Council to amend such maps
in the light of future flood experience without the need for a formal amendment of the
LEP.
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Amend the objectives for three zones to include mention of flooding considerations in
the Table to Clause 9.
Strengthen Clause 19 to provide greater control of development on flood liable land.
2) As part of the preparation and exhibition of the draft LEP, Council should also exhibit the
Floodplain Management Plan for each township as a Development Control Plan.
3) Council should also consider strengthening planning controls on land which is identified
as “floodway” or “high hazard” by further amending the LEP 1993 to include a new zone –
Environmental Protection 7(f) Floodway.
The high hazard-floodway areas in the three townships which could be affected by this
proposal are shown on Figures E1 to E3.
It is to be recognised that all existing, "lawful" development within the proposed 7(f) zone which
would be prohibited by the amending LEP would, upon gazettal of the amending LEP, be "non-
conforming uses" and as such will have "existing use rights" pursuant to the Environmental
Planning and Assessment Act, 1979. It is also to be understood that significant development
"rights" will be removed from vacant land within the newly created 7(f) zone.
It is recommended that Council implement a voluntary purchase scheme for land within the 7(f)
zone as part of the rezoning of that land. Such a scheme will provide for compensation to
landowners.
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ATTACHMENT A – DRAFT AMENDMENT
ENVIRONMENTAL PLANNING AND ASSESSMENT ACT 1979
MURRURUNDI LOCAL ENVIRONMENTAL PLAN 1993
(AMENDMENT No.XX)
I, the Minister for Urban Affairs and Planning, in pursuance of section 70 of the Environmental
Planning and Assessment Act 1979, make the local environmental plan set out hereunder. (file
number)
CRAIG KNOWLES MP
Minister for Urban Affairs and Planning
Sydney, xxx
----------------------------
Name of plan
1. This plan is called the Murrurundi Local Environmental Plan 1993 (Amendment
No.xx).
Aims, objectives etc.
2. The aim of this plan is to provide for control of development on flood liable land
identified as floodway.
Land to which the plan applies
3. This plan applies to the land shown edged black on the map marked "Murrurundi
Local Environmental Plan 1993 (Amendment No.xx)" deposited in the office of the
Murrurundi Shire Council.
Relationship to other environmental planning instruments
4. This plan amends Murrurundi Local Environmental Plan 1993 in the manner set
out in Clause 5.
Amendment of Murrurundi Shire Local Environmental Plan 1993
5. Murrurundi Shire Local Environmental Plan 1993 is amended:
(i) by inserting into Clause 5 after the definition of "flood liable land" the
following definitions:
"floodway" means an area that carries a significant discharge of water
during a flood, and even if only partially blocked, would cause significant
redistribution of flow or a significant increase in flood levels .
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(ii) by inserting into the definition of "the map" in Clause 5 the following:
Murrurundi Local Environmental Plan 1993 (Amendment No.xx)
(iii) by inserting into Clause 8 the following:
Zone No.7(f) (Environmental Protection - Floodway) - edged black and
lettered "7(f)"
(iv) by inserting into the Table to Clause 9 the following:
Zone No. 7(f) (Environmental Protection - Floodway)
1. Objective of zone
The objective of this zone is to provide for the proper management
of the floodway as identified in accordance with the Floodplain
Development Manual, 1986.
2. Without development consent
Nil.
3. Only with development consent
Agriculture (other than intensive livestock keeping establishments
and which does not involve the clearing of trees); camp and
caravan sites; landscaping; recreation areas; subdivision; utility
installations (other than gas generating works).
4. Prohibited
Any purpose other than a purpose included in item 3.
(v) by inserting at the end of Clause 20 the following:
20A. (1) The Council may vary the boundary between zone 7(f) and
an adjoining zone.
(2) In determining a zone boundary under subclause
(1), the Council shall not determine that zone
boundary until it has had regard to a report
prepared by an appropriately qualified Engineer
which assesses the likely impact of the variation of
the zone boundary on both the flood regime and
flooding of any development which may be
permissible on the land following any variation to
the zone boundary.
(3) In determining a zone boundary under subclause (2), the
Council shall also have regard to clause 19 of this plan.