Proceedings of the 2020 Mississippi Water Resources Conference

Year: 2020 Authors: Abera L.E., Surbeck C.Q.

Increased impervious land surfaces due to urbanization, construction, and development cause excess stormwater runoff and result in urban areas experiencing flooding events and erosion. Installation of Green Stormwater Infrastructure (GSI) is one sustainable way of reducing flooding events and preventing damage. In this study, computer simulations were conducted to assess the efficiency of GSI practices in flood reduction. Life-cycle cost analyses (LCCA) of stormwater infrastructure are also being performed to determine the cost-effectiveness of GSI practices, considering capital and operation and maintenance (O&M) costs, which are costs borne by different stakeholders. A proposed development located in Oxford, MS was used as a model site to perform the assessments. The HydroCAD stormwater modeling tool was used to perform hydrologic modeling for two types of GSI practices, permeable pavement and rain garden. The site was modeled using the curve number reduction method, which reduces the weighted average curve number of the site by implementing GSI practices. For multiple scenarios, the volume of stormwater runoff was estimated based on the city's design storms. Depending on the type and size of the GSI and the storm intensity, the simulation results showed that applying GSI reduced the volume of excess runoff by 3 to 17% on average, therefore potentially reducing the volume requirement for underground storage. For the constraints at the modeled site, compared to a rain garden, pervious pavement resulted in a higher reduction in the volume of stormwater runoff. Life-cycle cost analysis was performed using the Water Environment Research Foundation (WERF) Low Impact Development Cost Analysis Tools. Results of the cost analysis, and what it means for stakeholders, will be presented.