A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Stream health index for the Puget Sound Lowland
10.1002/env.744.abs
Stream health is often measured by the multimetric benthic index of biotic integrity (B‐IBI). For Puget Sound Lowland (PSL) streams, the B‐IBI comprises ten metrics which quantify the well‐being of benthic inhabitants of the stream. Each metric is converted to a score of 1, 3 or 5, where a higher value indicates a healthier stream with respect to the metric. Summing the metric scores yields the B‐IBI. Stream health is then rated as very poor, poor, fair, good or excellent according to the index value.
Different metrics may be measured on different scales. A scoring scheme is therefore required to standardize values across metrics. Conventional scoring for the B‐IBI metrics requires subjective and space/time‐dependent input on the cutoff points for discretizing each metric. In contrast, simple statistical standardization (centering and division by the standard deviation) appears to be more natural, is non‐study‐specific, and maps the metric space onto a continuous scale centered at 0. Comprising the same ten metrics of the PSL B‐IBI, our stream health index for the Puget Sound Lowland (SHIPSL) is the sum of all statistically standardized scores. We use benthic taxonomy data on field samples from 1997 to develop a SHIPSL‐based rating scheme of grades A to F for stream health. We also discuss an alternative version of SHIPSL defined using ‘gold‐standard’ values.
Bootstrap simulations are used to compare the performance of the two versions of SHIPSL to B‐IBI in reflecting PSL stream health. Results show that both versions of SHIPSL are more efficient in measuring stream health. Without sacrificing information on underlying biological conditions, SHIPSL reduce bias and variability of the health index, and eliminates sensitivity of the rating to slight changes in the metric scoring scheme. Copyright © 2006 John Wiley & Sons, Ltd.
Stream health index for the Puget Sound Lowland
10.1002/env.744.abs
Stream health is often measured by the multimetric benthic index of biotic integrity (B‐IBI). For Puget Sound Lowland (PSL) streams, the B‐IBI comprises ten metrics which quantify the well‐being of benthic inhabitants of the stream. Each metric is converted to a score of 1, 3 or 5, where a higher value indicates a healthier stream with respect to the metric. Summing the metric scores yields the B‐IBI. Stream health is then rated as very poor, poor, fair, good or excellent according to the index value.
Different metrics may be measured on different scales. A scoring scheme is therefore required to standardize values across metrics. Conventional scoring for the B‐IBI metrics requires subjective and space/time‐dependent input on the cutoff points for discretizing each metric. In contrast, simple statistical standardization (centering and division by the standard deviation) appears to be more natural, is non‐study‐specific, and maps the metric space onto a continuous scale centered at 0. Comprising the same ten metrics of the PSL B‐IBI, our stream health index for the Puget Sound Lowland (SHIPSL) is the sum of all statistically standardized scores. We use benthic taxonomy data on field samples from 1997 to develop a SHIPSL‐based rating scheme of grades A to F for stream health. We also discuss an alternative version of SHIPSL defined using ‘gold‐standard’ values.
Bootstrap simulations are used to compare the performance of the two versions of SHIPSL to B‐IBI in reflecting PSL stream health. Results show that both versions of SHIPSL are more efficient in measuring stream health. Without sacrificing information on underlying biological conditions, SHIPSL reduce bias and variability of the health index, and eliminates sensitivity of the rating to slight changes in the metric scoring scheme. Copyright © 2006 John Wiley & Sons, Ltd.
Stream health index for the Puget Sound Lowland
Chiu, Grace (author) / Guttorp, Peter (author)
Environmetrics ; 17 ; 285-307
2006-05-01
23 pages
Article (Journal)
Electronic Resource
English
Stream health index for the Puget Sound Lowland
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