更多的信息以支持河流健康评估

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)
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.)
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.
– – – – Population density Agricultural production Agricultural water use Upstream/downstream impoundments
Forest Grasslan d Wetland agricultur e urban
Improved management Disபைடு நூலகம்urbance (pressure)
Example - urbanisation
• Impacts of urbanisation best predicted by % effective imperviousness
• Water sensitive urban design reduces imperviousness
sediment plume
Site selection
found on the EMAP website: (http://www.epa.gov/nheerl/arm/designpages/design&analysis.htm).
• Site selection strongly influences assessment results • River health assessment found on the EMAP website: best served by random or (http://www.epa.gov/nheerl/arm/designpages/design&analysis.htm). stratified random site Simple random sampling selection
Additional information to support river health assessment
Dr Nick Bond
Talk outline
• Some additional ideas to think about in relation to river health assessment.
Ecological indicators
Disturbance (pressure)
Pressure indicators
• Good indicators respond predictably to disturbance gradients • Why not just measure the disturbance gradient to predict river health?
– Things we may have overlooked in other talks – Not necessarily linked to one another
1. 2. 3. 4. 5.
Quality assurance Site selection Pressure indicators Classification Refinement and adaptation
• 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
Evaluating results
• Indicators are not perfect – sometimes results will conflict with expectations
– Requires transparent process of review and refinement. – Often several possibilities
– Guided by classification and assessment of threats
Simple random sampling
Stratified random sampling
strata
• Worthwhile to develop clear guidelines before going into the field
2. Pressure indicators
• Good indicators respond predictably to disturbance gradients
Ecological indicators
Disturbance (pressure)
Pressure indicators
• Good indicators respond predictably to disturbance gradients • Why not just measure the disturbance gradient to predict river health?
Requirements of a River Classification to support river health assessment
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
Two answers: 1. Sometimes we do
Ecological indicators
Disturbance (pressure)
Pressure indicators
• Good indicators respond predictably to disturbance gradients • Why not just measure the disturbance gradient to predict river health?
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
• River classification an important step in most assessment programs
• • Identifying appropriate indicators Scoring (targets and thresholds)
1. Discriminates ecologically meaningful variation in indicators
• 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
Pressure indicators as an element of river health assessment
• Help Identify ‘high risk’ areas • Guides site selection – stratification by land-use • Testing indicators
• 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.
Stratified random sampling
FIGURE 3-1. Examples of two-dimensional probabilistic sampling designs.
Quantifying trends in resource condition is often an important objective for regiona strata Although there are different approaches for allocating sampling effort over time, o covered in this document: permanent station and serially alternating (Rathbun 1999 station approaches use a random sample of n sites that are all sampled during each
Two answers: 1. Sometimes we do
Ecological indicators
Same pressure different management
2. Ecosystem health can improve if best practice management actions are implemented