Saed Shannak (Dallas, USA), Fouad Jaber - Texas A&M University
Urban stormwater runoff is a leading factor for impairing surface water quality and quantity, public health, biological resources and aquatic life. Sub-hourly time step SWAT (Soil Water Assessment Tool) model was calibrated and validated to evaluate the potential impact of Low Impact Development (LID) practices on aquatic life in the Blunn Creek Watershed. This watershed encompasses 3.73 square kilometers and has 54 % impervious cover and based on census projection it will reach 65% by 2040. The evaluation of LID practices performance was based on incorporating and representing these practices into SWAT model, studying output flows, and assessing watershed hydrological responses and their impact on aquatic life communities in the Blunn Creek. Reducing peak flows and increasing both baseflows and Aquatic Life Potential values were the factors used to assess flows coming out of LID practices. Stream flows using 15-min time step were successfully calibrated and validated for a 2-year period. During the calibration period; Nash-Sutcliffe (NS) value and R2 were 0.78 for sub-hourly and during validation; R2 was 0.70 and a NS was 0.67. Results showed that a combination of permeable pavement and raingarden resulted with the highest percentage of increase in AQP values and baseflows and greatest reduction in peak flows. Detention pond had the lowest percentage of increase in AQP and baseflows as well as the lowest percentage of reduction in peak flows.