the radar-graphic method for evaluation of the...

The SIJ Transactions on Advances in Space Research & Earth Exploration (ASREE), Vol. 1, No. 2, November-December 2013

ISSN: 2347 – 6087 © 2013 | Published by The Standard International Journals (The SIJ) 43

Abstract—Over the past decade in Taiwan, ecological engineering methods acted principally in river

remediation and slope protection. In order to examine the effectiveness of stream restoration, the Index of

Stream Restoration Guidance (ISRG) and Radar-Graphic Method (RGM) were used to describe the overall

stream condition. Six criteria must be considered in the evaluation of a stream’s ecological environment: water

quality, habitat quality, eco-hydrology, flood prevention, aesthetic and recreational demand, and bank stability.

Using the assessment results in the Jilong River overall improvement project, a river located in northern

Taiwan, five conclusions were drawn: (1) ISRG scores on stream’s ecological environment and biological

performance are higher at the upstream than at the middle and downstream; (2) good ecological performances

were observed under the condition of a gentle revetment and wider green belt; (3) type of revetment which are

porous and permeable will create better biodiversity; (4) the ecological performance at the middle and

downstream depends on the human disturbance; (5) the proposed methodology establishes a quantitative

assessment tool and provides a guide to planning and implementing stream restoration projects.

Keywords—Biodiversity; Index of Stream Condition; Jilong River; Radar-Graphic Method; Stream Ecological

Engineering; Stream Restoration.

Abbreviations—Ephemeroptera, Plecoptera, Trichopetera (EPT); Indexes of Biological Integrity (IBI); Index

of Stream Condition (ISC); Index of Stream Restoration Guidance (ISRG); Family-level Biotic Index (FBI);

Radar-Graphic Method (RGM); Rapid Bioassessment Protocol III (RBP III).

I. INTRODUCTION

UE to the increase of ecological awareness, Taiwan

started to seek advanced technology from other

countries in order to modify traditional civil

engineering practices which prioritized development and

human demands. In the late 1990s, a field research associated

with environment beautification was launched. The new

philosophy of ecological engineering began to attract

academic institutes’ attention gradually. Government also

initiated all sorts of funding for the purposes of a) the

possible limitation of applying it in Taiwan, and b)

establishing localized applicable methods in river

reconstruction. Slightly after the water resources related

agencies’ action, this new trend started to affect soil

conservation practices by introducing river bank stabilization

methods. Followed by valuing the advantage over water

quality control, ecological engineering also contributes to

Taiwan’s environmental engineering since 2003. This

abstract is a brief introduction to the subject of ecological

engineering method, which is a whole new concept in the

field of civil engineering. The advantages of using the

ecological engineering method are not only to satisfy the

demand of safety (i.e. natural hazards control) but also that of

protecting ecosystem and landscape aesthetic.

In Taiwan, typhoons are very common during the

summer and bring huge amount of precipitation with them.

The development and management works of the rivers in

Taiwan were, in the early days, primarily focused on water

control for hydraulic facilities, but also considered overall

eco-environment. The requirement of landscape creation and

eco-environment protection from people are on the rise with

the recent ecological protection concepts. For this reason,

Taiwan Water Resource Agency executed the “Jilong River

Overall Master Plan (Earlier Plan)” from 2002 to 2005

[National Taipei University of Technology, 2012] to reduce

D

*Assistant Professor, Department of Civil Engineering, National Taipei University of Technology, Taipei, TAIWAN, ROC.

E-Mail: [email protected]

**Professor, Department of Civil Engineering, National Taipei University of Technology, Taipei, TAIWAN, ROC. E-Mail: [email protected]

***Chief Secretary, Water Resources Department, New Taipei City Government, New Taipei City, TAIWAN, ROC.


****Master, Department of Civil Engineering, National Taipei University of Technology, Taipei, TAIWAN, ROC.


Chia-Chun HO*, Jen-Yang LIN**, Tsung-Ming YANG*** & Kuan-Han CHOU****

The Radar-Graphic Method for

Evaluation of the Effectiveness of

Stream Ecological Engineering



the risk of flooding and improve the environment. Figure 1

below shows the failure of the Jilong River revetment which

suffered a serious flooding in 2001. Because of this,

ecological engineering methods were adopted to rebuild the

revetment. Figure 2 shows the current status of this revetment

using gabion method and vegetation blanket. In order to

understand the effectiveness of revetment while using

ecological engineering method, the ecological investigation

and basis of construction work of the Jilong River was

divided between the upstream, midstream and downstream.

The project was completed over several years, mainly due to

the fact that the river ecological data had to satisfy the design

and guidelines of an eco-environment adapted for the river.

Thus, the investigation of the before and after conditions

were necessary. After reviewing the effect of the environment

due to the changes brought by the master plan, reinforcement

strategies and suggestions should be proposed as to reach

higher ecological environment influence.

(a) Upstream (b) Midstream

Figure 1: A Failure Cases of Revetment

(a) Upstream (b) Midstream

Figure 2: The Current Status after Construction

II. THE ASSESSMENT OF THE STREAM

CONDITION

The effectiveness of the stream remediation mostly focused

on the hydraulic structure safety. It is rarely from an

ecological point of view that we examine the effectiveness.

However, the performance of the biological environment

should be included in the assessment of stream remediation

projects. Researchers have published several studies on the

biotic index.

2.1. Biological Index

Previous studies proposed a different index for bio-

environment. Karr (1991) adopted fish to be a bio-indicator

and proposed the Indexes of Biological Integrity (IBI).

Depending on the IBI score, the biological condition can be

classified within four categories, as shown in Table 1.

Table 1: The Biological Condition Category and Score Range of IBI

Biological Condition Category Score Range

Non-impaired 30-39

Slightly impaired 21-29

Moderately impaired 11-20

Severely impaired 0-10

Base on the water quality and water pollution resistance

of fish, a Family-level Biotic Index (FBI) was proposed by

Hilsenhoff (1998). Table 2 shows the FBI score range.

Table 2: Water Quality and Score Range of FBI

Water Quality Score Range Water Quality Score Range

Excellent 0.00-3.75 Fairly Poor 5.76-6.50

Very Good 3.76-4.25 Poor 6.51-7.25

Good 4.26-5.00 Very Poor 7.26-10.00

Fair 5.01-5.75

Plafkin et al., (1989) adopted seven bio-indexes to

evaluate water quality and stream environment, and therefore

the Rapid Bio-assessment Protocol III (RBP III) was advised.

The indexes include taxa richness, Hilsenhoff biotic index,

ratio of scrapers/fil. collectors, ratio of EPT (Ephemeroptera,

Plecoptera, Trichopetera) and chironomid abundances,

contribution of dominant taxon (%), EPT index, and

community loss index. Table 3 shows the biological

condition scoring criteria.



Table 3: Biological Condition Scoring Criteria of RBP III

Water Quality Biological Condition Scoring Criteria

6 4 2 0

Taxa richness >80% 60%-80% 40%-60% <40%

Hilsenhoff biotic index >85% 70%-85% 50%-70% <50%

Ratio of scrapers/fil. collectors >50% 35%-50% 20%-35% <20%

ratio of EPT and chironomid

abundances >75% 50%-75% 25%-50% <25%

Contribution of dominant taxon (%) <20% 20%-30% 30%-40% >40%

EPT index >90% 80%-90% 70%-80% <70%

Community loss index <0.3 0.3-0.5 0.5-0.7 >0.7

2.2. Index of Stream Condition

The Index of Stream Condition (ISC) is the first complete and

comprehensive study of the environmental condition of rivers

anywhere in Australia and was also the first integrated

measure of river condition in Australia [Ladson & White,

1999].

Australian Governments are increasing their focus on

rivers via legislative, research and rehabilitation actions.

Within this environment, the Index of Stream Condition

(ISC) was developed in response to a managerial need to 'use

indicators to track aspects of environmental condition and

provide managerially or scientifically useful information'

[Ladson et al., 1999].

The ISC consists of five sub-indices, which represent key

components of stream condition (Table 4). Each sub-index

consists of indicators, which are calculated using data

collected in the field or by desk based methods. Each

indicator is then assigned a rating score (Table 5). Sub-index

scores are calculated by summing the component indicator

scores, and the overall ISC score is calculated by summing

the sub-index scores [Ladson et al., 1999].

Table 4: List of Indicators used in the Index of Stream Condition [Ladson et al., 1999]

Sub-Index Basis for Sub-Index Value Indicators within Sub-Index

Hydrology Comparison of the current flow

regime with the flow regime

existing under natural conditions.

Amended annual proportional flow deviation

Daily flow variation due to change of catchment permeability

Daily flow variation due to peaking hydroelectricity stations

Physical

Form

Assessment of channel stability

and amount of physical habitat. Bank stability

Bed stability

Impact of artificial barriers on fish migration

Instream physical habitat

Streamside

Zone

Assessment of quality and quantity

of streamside vegetation. Width of streamside zone

Longitudinal continuity

Structural intactness

Cover of exotic vegetation

Regeneration of indigenous woody vegetation

Billabong condition

Water

Quality

Assessment of key water quality

parameters.

Total phosphorus

Turbidity

Electrical conductivity

Alkalinity / acidity

Aquatic Presence of macro invertebrate

families

SIGNAL

AusRivAS

The ISC uses a rating system to assess stream condition.

The use of a rating system is designed to provide as much

resolution as possible, within the constraint that there is

'limited knowledge of the relationship between a change in

the indicator and environmental effects' [Ladson & White,

1999]. Values for each indicator are assigned a rating on the

basis of comparison with a reference state (Figure 3). These

ratings are summed to produce an overall score that reflects a

continuum of stream conditions from excellent to very poor.

In calculating the overall ISC scores, the scores for each sub-

index and for each indicator can be weighted, depending on

the perceived importance of each, or the availability of data

[Ladson & White, 1999].



Figure 3: Assessment of Stream Condition using the ISC [Ladson et

al., 1999]

2.3. Index of Stream Restoration Guidance (ISRG)

Base on the Index of Stream Condition (ISC) and

incorporation factors unique to Taiwan, Lin et al., (2005)

proposed the Index of Stream Restoration Guidance (ISRG)

and developed six indices for evaluating stream restoration

projects using the ecological engineering methods. These

indices include considerations for stream ecological

environment, water quality and habitat, eco-hydrology, flood

prevention, aesthetics and recreation demands, and bank

stability requirements. The indicators and score within those

six indices are shown in Table 5. According to the score of

those six indices, the Radar-Graphic Method (RGM) was

used to evaluate the effectiveness of stream ecological

engineering. Figure 4 shows the best performance of RGM on

stream restoration. Three of the indices scores (flood

prevention, aesthetics and recreation demands, and bank

stability requirements) are very low. It indicates not only that

the hydraulic design for this stream is satisfactory but also

that the effectiveness of ecological environment is superior.

Table 5: Indicators used in the Index of Stream Restoration Guidance [Lin et al., 2005]

Sub-Index Indicators within Sub-Index Score

(X) Conversion Coeff. Sub-Index Score

A. Stream ecological environment

Width of streamside zone 0-4

(X)(10/10) 0-10 Longitudinal continuity 0-4

Cover of vegetation 0-2

B. Bank stability requirements

Geology of river bank

0-4 (X)(10/4) 0-10 Erosion of river bank

Erosion of bank toe

C. Water quality and habitat River pollution index 0-16

(X)(10/20) 0-10 Fish species and populations 0-4

D. Flood prevention

Protected targets

Flood history

Flood damages

Investment cost

0-10 (X)(10/10) 0-10

E. Eco-hydrology

Ecological instream flows 0-10

(X)(10/18) 0-10 Aquatic habitat environment 0-4

Bed stability 0-4

F. Aesthetics and recreation

demands

Landscape aesthetics

Promenade recreation

Environmental education

Irrigation

0-10 (X)(10/10) 0-10

Figure 4: Illustration of the Best Performance of RGM on Stream

Restoration

This paper is a case study using ISRG and furthermore

the ecological environment investigation was carried out in

great detail to confirm the feasibility of RGM.

III. THE EVALUATION RESULTS OF JILONG

RIVER USING RGM

“Jilong River Overall Master Plan (Earlier Plan)” was

proposed after permission of the Taiwan Executive Yuan in

May, 2002. The 3 year plan was executed between 2002 to

2005 and received a funding of $12 billion US dollars. The

plan has now been completed for 7 years and has undergone a

Indicator

RatingCorresponding reference category

Example values:

pH range

4 Very close to reference state 6.5-7.5

3 Minor modification from reference state 6.0-<6.5 or 7.5-8.0

2 Moderate modification from reference state 5.5-<6.0 or 8.0-8.5

1 Major modification from reference state 4.5-<5.5 or 8.5-9.5

0 Extreme modification from reference state <4.5 or >9.5

Overall ISC score Stream condition

45-50 Excellent

35-44 Good

25-34 Marginal

15-24 Poor

<14 Very poor

1. Calculate ratings for indicators

2. Calculate ISC score

Ratings are summed within each sub-

index, then sub-index scores are summed

to produce an overall ISC score.

Repeated for each indicator.

Reference ranges are derived

from existing literature.

02468

10A

B

C

D

E

F

A: Stream ecological environment

B:Bank stability requirements

C:Water quality and habitat

D:Flood prevention

E:Eco-hydrology

F:Aesthetics and recreationdemands



number of typhoons. In order to know the performance of this

plan, RGM was used to evaluate of the effectiveness of

stream ecological engineering in this study. Further analysis

of significant improvement master methods has been

performed to provide as criterion for further master plan of

other reaches. Assessment of non-significant master methods

has been executed and reinforcement strategies have been

proposed in this study. In order to understand the

effectiveness of stream ecological engineering, three survey

stations were investigated which were located upstream,

midstream and downstream. According to the six sub-index

of the ISRG, to calculate their scores and graph the RGMs.

3.1. Upstream of Jilong River

The upstream channel of Jilong River, with a length of

11.7km and a mean height of 12.6m, was improved using

gabion, stone-paved and geo-grid reinforced revetment. River

investigation of current status and the change of environment

before and after master plan have been executed to review the

influence and improvement of the master plan. The

assessment results at the upstream are shown on Table 6.

Table 6: The Assessment Results of ISRG at the Upstream of Jilong River

Sub-index Indicators within sub-index Point



Width of streamside zone 3

7(10/10) 7.0 Longitudinal continuity 3

Cover of vegetation 1



1 1(10/4) 2.5 Erosion of river bank

Erosion of bank toe

C. Water quality and habitat River pollution index 12

16(10/20) 8.0 Fish species and populations 4

D. Flood prevention

Protected targets

Flood history

Flood damages

Investment cost

1.8 1.8(10/10) 1.8

E. Eco-hydrology

Ecological instream flows 10

16(10/18) 8.9 Aquatic habitat environment 3

Bed stability 3

F. Aesthetics and recreation demands




Irrigation

3 3(10/10) 3.0

Radar-Graphic Method (RGM)

A. Stream Ecological Environment

The sub-index of stream ecological environment includes

width of streamside zone, longitudinal continuity and cover

of vegetation. Figure 5 shows the current situation of stream

ecological environment. The width of the streamside zone is

127.5 meters and it is 2.56 times the breadth of the river’s

active channel. This area shows a good performance from the

vegetation except the zone under the bridge, furthermore the

vegetation cover rate at the upstream is 78% done by

shrubbery and grass. The comprehensive improvement

observed in result to our field investigation ensued in a sub-

index score of 7.0 on stream ecological environment.

Figure 5: The Current Situation of Stream Ecological Environment

at the Upstream of Jilong River [Ho et al., 2013]

02468

10A

B

C

D

E

F




D:Flood prevention

E:Eco-hydrology

F:Aesthetics and recreation demands



B. Bank Stability Requirements

In order to know the river bank stability and its erosion

situation, the bathymetry survey of each cross-section were

employed in this study. Choosing one of the cross-sections at

the upstream and comparing its bathymetry results between

the 2006 and 2011 survey (see Figure 6), we can notice a

slight difference in the improvement works completed after 1

year (2006) and 6 years (2011) of Section K-70. We can

therefore say that the bank stability requirement is very low

and scored 1.0 point; hence the sub-index score is 2.5.

Figure 6: The Results of the Bathymetry Survey in 2006 and 2011.

(Section K-70)

C. Water Quality and Habitat

There are 5 water quality monitoring stations at the upstream

of Jilong River. Their evalutation of the average value for

total phosphorus in 2011 is 0.005 mg/L, turbidity is 8.97

NTU, conductivity is 182 mho/ cm-25°C, and pH is 7.8.

According to the scoring criteria of ISRG, the score for the

river pollution index is 12 points.

Moreover, the aquatic life in Jilong River was

investigated from 2010 to 2012 and recorded 14 species of

fish at the upstream. All of the fish are native species

including the Varicorhinus barbatulus, Acrossocheilus

paradoxus, Zacco platypus, Formosania lacustre, and so on

(Figure 7). Hence, in accordance with the scoring criteria of

ISRG, the score of fish species and populations is 4 points.

Consequently, the sub-index score of water quality and

habitat is 8.0.

(a) Varicorhinus barbatulus (b) Acrossocheilus paradoxus

(c) Zacco platypus (d) Formosania lacustr

Figure 7: The Native Fishes at the Upstream of Jilong River

D. Flood Prevention

The land purpose surrounding the Jilong River’s upstream is

predominantly based on agriculture and forestry. The

protected targets in potential flooding regions consist of only

some of the constructions such as roads, bridges, and

buildings. The heavy rainfalls brought by typhoon NARI in

September 2001 had not caused significant damages to roads

and properties at this area. In view of the above, the sub-

index score of flood prevention is 1.8.

E. Eco-Hydrology

The score for the ecological instream flows is 10 because the

flow rate throughout the year has been consistently greater

than 0.5 cms, even without lateral construction in the river

channel at the upstream. It is a near ideal aquatic habitat with

numerous pieces of coarse wood debris from indigenous

species and so scored 3 points. Furthermore, it has good

vegetative cover, some minor isolated erosion, and no

continuous damage to the bank structure or vegetation itself,

bringing the indicator for the bed stability to 3 points. Finally,

when calculating the sub-index for the eco-hydrology, we get

a score of 8.9.



F. Aesthetics and Recreation Demands

The upstream of Jilong River has some small-scale farms by

the streamside which makes use of stream water for

irrigation. Therefore, the sub-index score of aesthetics and

recreation demands is 3.0.

The chart of Radar-Graphic Method is also show in

Table 6. It indicates the steep riverbank caused by the poor

performance of vegetation at the upstream; hence the score of

sub-index A is not high. The good water quality and flow rate

provide an excellent biological environment and

consequently got the high score on sub-index C and E.

Moreover, the riverbank is located on the bedrock, and

therefore does not produce the erosion of bank toe. For this

reason, the score on bank stability requirement is low.

Briefly, the ecological engineering method achieved

remarkable improvement in the upstream and the shape of the

RGM presents a triangle arrow.

3.2. Midstream of Jilong River

The midstream channel of Jilong River has a length of

19.9km and a mean height of 10.2m. Besides gabion, stone-

paved and geo-grid reinforced revetment, the revetment

improvement works used a number of concrete banks to

protect the residents living by the river side as well as spread

vegetation blanket on the surface of concrete banks.

Investigation of the river’s current status and the before and

after environment change of the master plan have been

executed to review the influence and improvement of the

master plan. The assessment results at the midstream are

shown on Table 7.

Table 7: The Assessment Results of ISRG at the Midstream of Jilong River


(X)

Conversion

Coeff.

Sub-Index

Score







1 1(10/4) 2.5 Erosion of river bank

Erosion of bank toe

C. Water quality and habitat

River pollution index 11

14(10/20) 7.0 Fish species and

populations 3

D. Flood prevention

Protected targets

Flood history

Flood damages

Investment cost

4.0 4(10/10) 4.0

E. Eco-hydrology


12(10/18) 6.7 Aquatic habitat

environment 2

Bed stability 2


demands




Irrigation

7.5 7.5(10/10) 7.5



Figure 8 shows the current situation of stream ecological

environment. The width of the streamside zone is 136.7m and

it is 3.12 times the breadth of the river’s active channel.

Because of the wide and gentle beach, the vegetation shows a

nice performance in this area. Furthermore, the vegetation

cover rate at the midstream is 89% done by shrubbery and

grass. The comprehensive improvement observed in result to

our field investigation ensued in a sub-index score of 9.0 on

stream ecological environment.

02468

10A

B

C

D

E

F




D:Flood prevention

E:Eco-hydrology





D:Flood prevention

E:Eco-hydrology





at the Midstream of Jilong River [Ho et al., 2013]


Figure 9 shows a comparison of the results of the bathymetry

survey performed in 2006 and 2011. Some minor isolated

erosion cases could be noticed on the river bed from the

improvement works completed after 1 year (2006) and 6

years (2011) of the Section K-88. However, the surface of the

river bank and its toe are still stable as well as no

displacement happened from 2006 to 2011. So the sub-index

of bank stability requirement score is 2.5.


(Section K-88)


A total of 4 water quality monitoring stations were

established at the midstream of Jilong River. Their evaluation

of the average value for total phosphorus in 2011 is 0.0143

mg/L, turbidity is 18.54 NTU, conductivity is 325 mho/cm-

25°C, and pH is 7.5. According to the scoring criteria of

ISRG, the score of river pollution index is 11 points.


investigated from 2010 to 2012 and recorded 19 species of

fish at the midstream. At this particular segment of the river,

not only native fishes were found but also exotic ones such as

Cyprinus carpip, Oreochromis sp., Channa striata,

Hypostomus placostomus, and so on (Figure 10). Hence, in

accordance with the scoring criteria of ISRG, the score of fish

species and populations is 3 points. Consequently, the sub-

index score of water quality and habitat is 7.0.

(a) Cyprinus carpip (b) Oreochromis sp

(c) Channa striata (d) Hypostomus placostomus

Figure 10: The Exotic Fishes at the Midstream of Jilong River

D. Flood Prevention

The land purpose of Jilong River’s midstream is

predominantly based on agriculture and small town. The

protected targets in potential flooding regions include roads,

bridges, and buildings. Hence, the sub-index score of flood

prevention is 4.0.



E. Eco-hydrology

The score of ecological instream flows is 8 due to the flow

rate throughout the year being greater than 0.5 cms, achieved

with some lateral construction in the river channel. It is a

moderate variation from an ideal aquatic habitat with

moderate visible pieces of coarse wood debris from

indigenous species, therefore the scored attributed if of 2

points. Furthermore, as the banks were held by discontinuous

vegetation and showed a generally stable toe, the indicator of

bed stability received 2 points. Finally, the calculated sub-

index score of eco-hydrology is 6.7.


The riverside of the midstream has a number of bicycle paths,

parks, and river-accessible spaces. Therefore, the sub-index

score of aesthetics and recreation demands is 7.5.

The chart of Radar-Graphic Method is also show in

Table 7. The current situation displays a nice result on

vegetation of gabion revetment wall and provides a good

biological habitat environment. Thus the score of sub-index

A, C and F are high; nevertheless, they are lower than the

score observed at the upstream. That can be explained by the

bad results in water quality and a higher human disturbance

than at the upstream. In addition, the aesthetics and recreation

demands are higher than at the upstream.

3.3. Downstream of Jilong River

The downstream channel of Jilong River has a length of

15.2km and a mean height of 8.7m. Because it is adjacent to a

dense residential area, a large number of concrete banks were

adopted in its improvement project. In order to build a good

ecological environment, vegetation blankets were spread on

the surface of some concrete banks. . Investigation of the

river’s current status and the before and after environment

change of the master plan have been executed to review the

influence and improvement of the master plan. The

assessment results at the downstream are shown on Table 8.

Table 8: The Assessment Results of ISRG at the Downstream of Jilong River









1.8 1.8(10/4) 4.5 Erosion of river bank

Erosion of bank toe

C. Water quality and habitat River pollution index 10

12(10/20) 6.0 Fish species and populations 2

D. Flood prevention

Protected targets

Flood history

Flood damages

Investment cost

8.0 8(10/10) 8.0

E. Eco-hydrology


10(10/18) 5.6 Aquatic habitat environment 2

Bed stability 1


demands




Irrigation

8.5 8.5(10/10) 8.5



Figure 11 shows the current situation of the downstream

ecological environment. The downstream width of the

streamside zone is 102.3m and it is 0.67 times the breadth of

the river’s active channel. In this region, the concrete banks

hold a discontinuous vegetation and has a cover rate of 63%

achieved by shrubbery and grass. The comprehensive

02468

10A

B

C

D

E

F




D:Flood prevention

E:Eco-hydrology





D:Flood prevention

E:Eco-hydrology




improvement observed in result to our field investigation

ensued in a sub-index score of 5.0 on stream ecological

environment.


at the Downstream of Jilong River [Ho et al., 2013]


Figure 12 shows a comparison of the results of the

bathymetry survey performed in 2006 and 2011. An obvious

erosion of the river bed of Section K-101 can be noticed from

the improvement works completed after 1 year (2006) and 6

years (2011); moreover, some damage to the bank structure

and vegetation can be clearly noticed. The situation of this

region is moderate bed degradation and therefore the sub-

index of bank stability requirement score is 4.5.


(Section K-101)


A total of 4 water quality monitoring stations were placed in

the downstream of Jilong River and their monitored average

value for total phosphorus in 2011 is 0.0265 mg/L, turbidity

is 27.9 NTU, conductivity is 383 mho/cm-25°C, and pH is

7.6. According to the scoring criteria of ISRG, the score of

river pollution index is 10 points.


investigated between 2010 and 2012 and recorded 22 species

of fish at the downstream. Most of the exotic fishes and the

peripheral division freshwater fishes in midstream were also

reported to be living in the downstream, such as Mugil

cephalus, Nematalosa nasus, Awaous melanocephalus,

Acanthopagrus schlegeli, and so on (Figure 13). Hence, in

accordance with the scoring criteria of ISRG, the score of fish

species and populations is 2 points. Consequently, the sub-

index score of water quality and habitat is 6.0.

(a) Mugil cephalus (b) Nematalosa nasus

(c) Awaous melanocephalus (d) Acanthopagrus schlegeli

Figure 13: The Peripheral Division Freshwater Fishes at the Downstream of Jilong River

D. Flood Prevention

The land surrounding the Jilong River’s downstream is

predominantly urban. It is a densely inhabited district and the

protected targets in potential flooding regions include roads,

bridges, and buildings. This region also is an important

business area. Heavy rainfalls brought by typhoon NARI in

September 2001 caused serious damages to the roads and

properties at this area. Hence, the sub-index score of flood

prevention is 8.0.



E. Eco-hydrology

The score of ecological instream flows is 8 due to the flow

rate throughout the year being greater than 0.5 cms, achieved

with some lateral construction in the river channel. It is a

moderate variation from an ideal aquatic habitat with

moderate visible pieces of coarse wood debris from

indigenous species, therefore the scored attributed if of 2

points. Furthermore, as the banks were held by discontinuous

vegetation and showed a generally stable toe, the indicator of

bed stability received 1 point. Finally, the calculated sub-

index score of eco-hydrology is 5.6.


The downstream riverside has a number of bicycle paths,

parks, playground, tennis court, and river-accessible spaces.

Therefore, the sub-index score of aesthetics and recreation

demands is 8.5.

The shape of RGM for the downstream section (Table 8)

is different to the results shown at the upstream and

midstream sections. Because of the dense human habitation

surrounding the downstream, the flood prevention, aesthetics

and recreation demands are more important than for the

upstream and midstream. This results in a higher score on

sub-index D and sub-index F. A concrete revetment was used

to protect the inhabitants living adjacently to the river. Due to

the steep and smooth surface of the concrete revetment, a

poor plant growth was observed. These conditions paired

with some serious human disturbance results in a poor

biological performance in the downstream and consequently

the score of sub-index A, C and E was lower than for the

upstream and midstream.

IV. CONCLUSIONS

The shape of RGM is represented in the form of a

triangle arrow for the upstream. It indicates the

excellent effectiveness of stream ecological

engineering. Moreover, the scores of ISRG for the

stream ecological environment and biological

performance are higher than for the middle and

downstream.

For the downstream, high quality and hard

protective works had to be used to ensure the safety

of the dense human habitation and therefore induce a

poor performance of the ecology environment.

Good ecological performances were observed under

the condition of gentle revetment and wider green

belt at the midstream.

Revetment including porous and permeable

functions will create better biodiversity, such as

gabion, stone-paved and geo-grid reinforced

revetment.

The ecological performance at the middle and

downstream was greatly affected by human

disturbance.

ISRG and RGM establish a quantitative assessment

tool and provide a guide on how to plan and

implement stream restoration projects.

REFERENCES

[1] National Taipei University of Technology (2012), “Closure

Report of Investigation and Evaluation after Jilong River

Overall Master Plan (Earlier Plan)”, Chapter No.5, 10th River

Management Office, Water Resource Agency, Taiwan, Pp.1–46.

(in Chinese).

[2] J.R. Karr (1991), “Biological Integrity: A Long-Neglected

Aspect of Water Resource Management”, Ecological

Applications, Vol. 1, Pp. 66–84.

[3] W.L. Hilsenhoff (1998), “A Modification of the Biotic Index of

Organic Stream Pollution to Remedy Problems and Permit its

Use throughout the Year”, Great Lakes Entomologist, Vol. 31,

Pp. 1–12.

[4] J.L. Plafkin, M.T. Barbour, K.D. Porter, S.K. Gross & R.M.

Hughes (1989), “Rapid Bioassessment Protocols for Use in

Streams and Rivers: Benthic Macroinvertebrates and Fish”.

U.S. Environmental Protection Agency, Office of Water

Regulations and Standards, Washington, D.C. EPA 440–4-89-

001.

[5] A.R. Ladson & L.J. White (1999), “An Index of Stream

Condition: Reference Manual”, Department of Natural

Resources and Environment, Melbourne, Australia.

[6] A.R. Ladson, L.J. White, J.A. Doolan, B.L. Finlayson, B.T.

Hart, P.S. Lake & J.W. Tilleard (1999), “Development and

Testing of an Index of Stream Condition for Waterway

Management in Australia”, Freshwater Biology, Vol. 41, Pp.

453–468.

[7] J.Y. Lin, F.C. Yu & M.S. Wu (2005), “Using the Radar-

Graphic Method as a Guide for Stream Ecological Engineering

Methods”, Journal of Chinese Soil and Water Conservation,

Vol. 36, No. 1, Pp. 89–99. (in Chinese)

[8] C.C. Ho, J.Y. Lin & K.H. Chou (2013), “An Evaluation of the

Effectiveness of Stream Ecological Engineering using the

Radar-Graphic Method”, 2013 International Congress on

Natural Sciences and Engineering, ICNSE-511, Pp. 60–67.

Chia-Chun HO Education: Ph. D., Hydrology and

Environment, Joseph Fourier University,

France

Position: Assistant Professor, Department of

Civil Engineering, National Taipei

University of Technology

Research interest: Environmental and

Ecological Engineering, Geotechnical

Engineering, Geosynthetics Application, Erosion Behaviour of

Revetments

Number of papers published: 8

Number of conferences/seminars attended: 26

Jen-Yang LIN

Education: Dr.-Ing., Civil Engineering,

Kassel University, Germany

Position: Professor, Department of Civil

Engineering, National Taipei University of

Technology

Research interest: Watershed Modelling and

Management, Ecological Engineering





Tsung-Ming YANG

Education: Master, of Construction

Engineering, National Taiwan University of

Science and Technology, Taiwan

Position: Chief Secretary, Water Resources

Department, New Taipei City Government,

New Taipei City, Taiwan

Research interest: Water resource

Management、Waste water Treatment、Flow

Measure



Kuan-Han CHOU Education: Master, Civil Engineering,

National Taipei University of Technology,

Taiwan

Position: Engineer, 5th River Management

Office, Water Resource Agency, Taiwan

Research interest: Geosynthetics application,

Erosion behaviour of revetments



the radar-graphic method for evaluation of the...

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