Validity of the Wetted Perimeter Method for Recommending Instream Flows for Salmonids in Small Streams

摘要

The validity of the wetted perimeter/inflection point method of recommending instream discharge for salmonids in small streams was evaluated. Studies were conducted on three sections of a small stream. Discharge in two sections was severely reduced by irrigation diversions while discharge in the third section was not artificially altered. Wild rainbow trout densities were increased in each section during relatively high flow. Emigration response of trout was related to reductions in discharge and flow-related habitat parameters. Trout abundance and biomass, however, decreased as flow decreased in all study sections; emigration lagged 11 and 15 days following flow reduction in two of the study sections.