Effectiveness of Low Impact Development Practices in Reducing Urban Stormwater Runoff Under Land Use and Climate Change Scenarios

Urbanization and climate change are the two major environmental concerns in today’s world. It is important to quantify their effects on future runoff for sustainable water resources management. This study focused on measuring the increase in streamflow caused by land use and climate change using the Personal Computer Storm Water Management Model (PCSWMM). It was also desired to see the extent of stormwater reduction after a watershed-scale implementation of two main low impact development (LID) practices- namely rain garden and rain barrel. The model was successfully calibrated and validated for the baseline scenario with calibration period of 10 years (2006 to 2015) and validation period of 6 years (2000 to 2005). The corresponding values of NSE and R2 were obtained to be 0.79 and 0.81 for calibration period and 0.81 and 0.83 for validation period respectively. For the increase in urban land use from 32.44% in 1992 to 81% in 2050, runoff was found to increase by 53.49%. Similarly, when the level of urbanization increased from 10% to 70%, runoff increased by a range of 24% to 120%. Evaluation of five high resolution NARCCAP climate change models predicted 36.44% to 70.12% increase in runoff. In the baseline case, the runoff decreased by 10% when using rain barrel only, by 21.3% when using rain garden only and by 34% when using both. Both LID practices were able to reduce runoff by 26.8% when installed in the future climate and urbanization case. It is recommended that LID practices be used synergically with improved drainage facilities for the successful management of stormwater in the imminent urbanization and climate change situation