Effects of Hydrologic Variability on Macroinvertebrate-based Biological Assessments of Streams in Austin, TX
Date
2001-05
Authors
Scoggins, Matthew
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Abstract
The City of Austin, Texas, has been using Rapid Biological Assessments (RBA’s) in
urban and sub-urban streams for the last seven years in an effort to expand and improve
its environmental monitoring programs. Central Texas weather is characterized by flashy
spates, long dry periods and is distinct from the temperate climates where the RBA's were
developed. In addition to these naturally dramatic hydrological cycles, urbanization and
its high levels of impervious cover further exaggerate stream flow patterns, producing
greater runoff volumes, higher peak flows and less baseflow. Eleven hydrologic statistics
were calculated using historical USGS flow data for 11 study streams and compared to
available City of Austin benthic macroinvertebrate data using analysis of variance and
multiple regression. A field study was also conducted to evaluate the effects of
antecedent hydrologic conditions on biological assessments of three streams of differing
development condition (high, medium, low) during a 6-month spring flow season.
Results show that both long-term hydrologic character of streams in this area as well as
immediately antecedent hydrologic conditions have a significant affect on the results of
RBA’s, which is compounded in urbanized streams. Hydrologic variability should be
utilized as a template in interpreting biological assessments using RBA metrics.
Description
Keywords
Water quality, Rivers, Hydrology, Biological assessment
Citation
Scoggins, M. (2001). <i>Effects of hydrologic variability on macroinvertebrate-based biological assessments of streams in Austin, TX</i> (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.