| An approach was developed to synthesize stream ecological elements in the design of best management practices (BMPs) for stormwater management. Application of this approach would ensure that BMPs achieve their objectives of protecting both physicochemical characteristics and ecological features of receiving waterbodies. Benthic macroinvertebrates were used as indicators of stream environmental quality. The benthic macroinvertebrates data were collected by the Virginia Department of Environmental Quality at 164 benthic sampling sites in 1st through 4th order streams located in Virginia, from 1994 through 2001.; This study consisted of two main parts: First, statistical analysis of benthic macroinvertebrates, physicochemical, and habitat data was performed to quantify relationships between benthic macroinvertebrates and stream environmental variables. The statistical methods that were used include principal component analysis, generalized additive modeling and non-parametric changepoint analysis. Five benthic metrics (i.e., taxonomic richness, percent of the two most dominant taxa, percent of sensitive taxa, percent of tolerant taxon, and percent of shredders) were used to represent benthic macroinvertebrate community structure and function. Twenty environmental variables, of which eight were physicochemical and twelve were habitat related, represented stream environmental conditions. The physicochemical variables were total suspended solids (TSS), total phosphorus, nitrate, dissolved oxygen (DO), water temperature, conductivity, flow rate, and pH. The habitat variables were bank stability, bank vegetative protection, channel alteration due to man-induced activities, channel flow status, embeddedness of stream, epifaunal substrate, grazing or other bank disruptive pressure, in-stream cover, frequency of riffles, riparian vegetation zone width, sediment deposition in stream, and velocity-depth regimes of stream. Results of analysis indicated that taxonomic richness decreases as TSS concentration and flow rate increase. The percent of sensitive taxa increases as DO concentration increases, while the percent of tolerant taxon and the two most dominant taxa decrease with increasing DO concentrations. None of the physicochemical variables showed a significant effect on the percent of shredders.; Second, watershed modeling was performed to evaluate the adequacy of BMPs designed using a conventional performance-based BMP design approach, in providing favorable stream conditions to support an acceptable composition of benthic macroinvertebrates. (Abstract shortened by UMI.)... |
