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Relating Hydrologic Metrics to In-Stream Aquatic Life in Semi-Arid Areas

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  21st Century Watershed Technology: Improving Water Quality and Environment Conference Proceedings, 21-24 February 2010, Universidad EARTH, Costa Rica  701P0210cd.(doi:10.13031/2013.29419)
Authors:   Roger H Glick, Leila Gosselink, Baolin Bai, Chris Herrington
Keywords:   Hydrology, aquatic life, water quality, hydrologic metrics

Abstract: 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 cross-correlation 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 90th percentile flow, was developed using step-wise regression. The resulting model has an adjusted r2 = 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 90th percentile flow. The second model has an adjusted r2 = 0.702. This model will be used to predict aquatic life potential in Austin-area streams using modeled flows under different development scenarios.

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