Comparison of discharge methods and habitat optimization for recommending instream flows to protect fish habitat

摘要: Reliable methods are urgently needed for recommending minimum instream flows to protect aquatic life. For basinwide planning purposes, simple methods, which require little or nor field investigations, required. While these tend be conservative, the degree they habitat fish is seldom determined. We applied physical microhabitat models (PHABSIM) nine target species in four streams upper James River basin, Virginia, U.S.A., (1) identify optimum fauna, (2) investigate relationship between flow and average discharge, (3) compare our findings with recommendations based on discharge methods. Micohabitat availability riffle-dependent was most limited at low while pool-dependent high flows. At each study site there a rapid increase riffle as increased above zero. Optimum that maximized habitat-limited life stages. The recommended stream size but slope not constant; lower proportions of were required maintain habitat. Aquatic Base Flow (i.e. September median flow) provided varying, reasonable degrees protection. Montana method 10 per cent recommendation correctly identified degraded poor conditions 30 corresponded near small greater than large site. Seven-day, 1-in-10-year (7Q10) provide very amounts riffle-dwelling fishes. results basis making preliminary this region readily available data. Future studies will test assumptions need made.