干旱区生态环境知识资源中心

Water quality and aquatic health data collected as part of the City of Austin (COA) Environmental Integrity Index (EII) were compared to stream flow characteristics using forty-four metrics derived from daily average flows collected by the U.S. Geological Survey (USGS) and COA. Water quality data were highly correlated with impervious cover (r = -0.911). Most of the flow metrics were correlated with each other, as was expected, resulting in a redundancy of information and the possibility of crosscorrelation when performing additional analyses. A statistical relationship between aquatic life data and two flow metrics, average number of dry durations per year and the natural log of the 90(th) percentile flow, was developed using step-wise regression. The resulting model has an adjusted r(2) = 0.755. The intended use of this relationship was to predict EII aquatic life scores under different scenarios using modeled flows. Current COA flow models do not predict number of dry durations adequately at this time so a second model using dry fraction, baseflow fraction and the natural log of the 90(th) percentile flow. The second model has an adjusted r(2) = 0.702. This model will be used to predict aquatic life potential in Austin-area streams using modeled flows under different development scenarios.