Page 259 - Freshwater-Biology-and-Ecology-Handbook

3.2.3 Invertebrate Impact

Assessment Tool

This tool has been produced to help assess the impact of
high frequency discharges from combined sewer overflows
(CSOs) on receiving waters. It does this by assessing
the degree of difference between abundance weighted
WHPT NTAXA and WHPT ASPT from samples collected
immediately upstream and downstream of an outfall. It uses
estimates of replicate sampling uncertainty (the variation
in observed values of WHPT NTAXA and WHT ASPT
between replicate samples taken at the same site on the
same day), in conjunction with a Monte Carlo approach
to simulate a distribution of possible observed values for
NTAXA and ASPT.

Invertebrate Impact
Assessment Tool

This allows the impact of high frequency discharges
from combined sewer overflows (CSOs) on receiving
waters to be assessed.

Instructions, which include more details, can be downloaded
from the user guide page of the RICT2 website RICT2 SOAF
CSO Impact Assessment Instructions.
This tool is similar in aim to RIVPACS Compare, but instead of
comparing EQRs and status class, it compares the value of
biotic indices. This is described in a report to the Environment
Agency by Clarke and Davy-Bowker (2017). (121)

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