Assessment of watershed characteristics with limited water quantity and quality data

The evaluations of water quantity and quality and then modeling of its phenomenon are required for water quality protection in Brady Creek watershed. This study is to predict the monthly flow, reservoir storage volume, and salinity; estimate the benefit of brush and aging flood-retardation dam control; and evaluate the impact of evaporation and discharge from Waste Water Treatment Plans (WWTP). The Soil and Water Assessment Tool (SWAT) model is verified with the monthly flow developed for pre-dam construction condition and shows the difference of − 9% and 10% than measured average flow for calibration and validation periods, respectively. The SWAT monthly flows are adjusted by 1963–2010 yearly conversion factors and are used as the input in the Water Rights Analysis Package (WRAP) model. The WRAP model verified with measured reservoir storage volume and total dissolved solid shows the average differences of simulated reservoir storage volume and salinity by − 13% lower and 11% higher for calibration period and 0% and 3% higher for validation period than measured average value, respectively. The impacts from brush and dams controls increase the runoff but also increase the water quality parameters. The impact of evaporation and WWTP discharge provide the information of relative impact for watershed phenomenon.