Additional information to support river health assessment Dr Nick Bond

Talk outline

• Some additional ideas to think about in relation to river health assessment. – Things we may have overlooked in other talks

– Not necessarily linked to one another

1. Quality assurance

2. Site selection

3. Pressure indicators

4. Classification

5. Refinement and adaptation

1. Quality assurance

• Managers and the public expect a high level of

confidence in assessments.

• Requires

– A scientific basis for the assessment

– High standards of quality control & quality assurance (QA/QC)

• Field and laboratory work

• Data analysis and data storage

• Data interpretation

– Careful evaluation of the results (do they make sense?)

Sources of error in assessment

Scientists like to

make things

complicated

QA/QC – staff training

• Appropriate training and testing of

staff involved in field and

laboratory work

• EPA (Australia) ID 20% of

invertebrate samples twice for

consistency.

• Development of standard

operating procedures

• May involve collaboration between

organisations - universities,

research groups, central &

provincial govt.

Site selection

• Site selection strongly

influences assessment

results

• River health assessment

best served by random or

stratified random site

selection

– Guided by classification

and assessment of threats

• Worthwhile to develop

clear guidelines before

going into the field

found on the EMAP website:

(http://www.epa.gov/nheerl/arm/designpages/design&analysis.htm).

FIGURE 3-1. Examples of two-dimensional probabilistic sampling

designs.

Simple random samplingSimple random sampling

Stratified random sampling

strata

Stratified random sampling

strata

Quantifying trends in resource condition is often an important objective for regional assessments.

Although there are different approaches for allocating sampling effort over time, only two are

covered in this document: permanent station and serially alternating (Rathbun 1999). Permanent

station approaches use a random sample of n sites that are all sampled during each time interval.

This option provides the least spatial coverage but may provide the highest temporal resolution

of trends, if temporal autocorrelation is weak. It is noteworthy that if resources allow sampling

the entire population of large river segments, a permanent station temporal design is appropriate

3-8 Concepts and Approaches for the Bioassessment of Non-wadeable Streams and Rivers

Chapter 3.0

found on the EMAP website:

(http://www.epa.gov/nheerl/arm/designpages/design&analysis.htm).

FIGURE 3-1. Examples of two-dimensional probabilistic sampling

designs.

Simple random samplingSimple random sampling

Stratified random sampling

strata

Stratified random sampling

strata

Quantifying trends in resource condition is often an important objective for regional assessments.

Although there are different approaches for allocating sampling effort over time, only two are

covered in this document: permanent station and serially alternating (Rathbun 1999). Permanent

station approaches use a random sample of n sites that are all sampled during each time interval.

This option provides the least spatial coverage but may provide the highest temporal resolution

of trends, if temporal autocorrelation is weak. It is noteworthy that if resources allow sampling

the entire population of large river segments, a permanent station temporal design is appropriate

3-8 Concepts and Approaches for the Bioassessment of Non-wadeable Streams and Rivers

Chapter 3.0

sediment plume

Data analysis and storage

• Relatively complex datasets

– Large # of variables

– Taxonomy may change over

time

– Biological indicators often

derived from a series of

calculations

Importance of good data

management typically

overlooked whereas good

QA/QC demands it

Evaluating results

• Indicators are not perfect – sometimes results

will conflict with expectations

– Requires transparent process of review and

refinement.

– Often several possibilities

• Sampling error, natural disturbance effects (e.g. floods),

localised pollution event.

– Local expertise/input is valuable

– Look to explain conflicting patterns rather than

simply discarding the result.

2. Pressure indicators

Disturbance (pressure)

Ecolo

gic

al in

dic

ato

rs

• Good indicators respond predictably to

disturbance gradients

Pressure indicators

• Good indicators respond predictably to disturbance gradients

• Why not just measure the disturbance gradient to predict river health?

Disturbance (pressure)

Ecolo

gic

al in

dic

ato

rs

Pressure indicators

• Good indicators respond predictably to disturbance gradients

• Why not just measure the disturbance gradient to predict river health?

Disturbance (pressure)

Ecolo

gic

al in

dic

ato

rs

Two answers:

1. Sometimes we do

Pressure indicators

• Good indicators respond predictably to disturbance gradients

• Why not just measure the disturbance gradient to predict river health?

Disturbance (pressure)

Ecolo

gic

al in

dic

ato

rs

Same

pressure

different

management

Improved

management

Two answers:

1. Sometimes we do

2. Ecosystem health can

improve if best practice

management actions are

implemented

Example - urbanisation

• Impacts of urbanisation best

predicted by % effective

imperviousness

• Water sensitive urban design

reduces imperviousness

Forest

Grasslan

d Wetland

agricultur

e urban

Pressure indicators as an element of river

health assessment

• Generally desktop based

analyses

• Data increasingly

available at fine scales

• May incorporate a range

of threats (e.g.)

– Population density

– Agricultural production

– Agricultural water use

– Upstream/downstream

impoundments

Pressure indicators as an element of river

health assessment

• Help Identify ‘high risk’ areas

• Guides site selection – stratification by land-use

• Testing indicators

• Effective communication tool

River Disturbance Index =

Upstream Storage Volume

weighted by Catchment Area

3. Classification

• River health assessment must account for

natural variation in rivers

• River classification an important step in most

assessment programs

• Identifying appropriate indicators

• Scoring (targets and thresholds)

Requirements of a River

Classification to support

river health assessment

1. Discriminates ecologically meaningful variation in indicators

2. Based on data unaffected by human disturbance

3. Stable groupings that assist indicator selection & target setting

4. Derived using explicit, repeatable and transferable methods

5. Applicable to a range of stream types

Other applications of classification

• Identifying ‘comparable’ catchments outside of

the study basin

– Assessing transferability of published data to/from

different regions based on similarity in classification

Caveats on classification results

• Important to confirm classification is biologically

meaningful

– Most software will produce ‘classes’ even if these

are extremely similar to one another.

– Possibly try a range of classification algorithms and

input variables to determine sensitivity of the results

to particular attributes (e.g. soils, temperature,

rainfall).

USGS Hydro 1K global dataset

• DEM stream network

• Nested subcatchment codes (Pfaffstetter,

1989) • Allows linking of catchment data without complex

geoprocessing

• not as fine-scaled as some catchment

delineations so less well suited to local

analyses.

• Climate, ecosystem type layers also available

at global/national scales

Minimum catchment resolution

Supporting datasets – ecosystem types

4. Refinement and adaptation

• River health monitoring and environmental flows

assessment strategies will evolve over time

• 15+ years in Australia (>20 years in USA)

– Changes in indicators

– Refinement of targets and scoring systems

– Continues to evolve

• Many good Chinese examples of applying these

methods in a research context

• Incorporating into management is the next step

The process

Field trial Assess indicator

sensitivity to

disturbance

gradient

Identify suite of

potential indicators

Land-use

assessment to

define

disturbance

gradient

Adopt appropriate

standard

Did the indicator

respond as

expected

Consider for

inclusion in

scorecard

Can thresholds and

targets be established

from the data?

Do standards already

exist (chinese or

international)

Review

indicator

Include in

scorecard

River

Classification

yes

No

Consider for

future

programs

No

Yes

yes No

Conceptual

models