Stormwater Runoff Analysis for the University of Arkansas Campus Area.

Stormwater runoff accumulates and transports nutrients, sediments, chemicals, and pathogens to surface water bodies. Managing this stormwater is crucial in preserving water quality, especially in rapidly developing urban watersheds like in Northwest Arkansas. The study area was defined as the watershed containing part of the University of Arkansas-Fayetteville campus. Runoff from this watershed drains into the West Fork of the White River, which has been designated as an impaired water body due to siltation. This study sought to develop a methodology to test existing stormwater drainage infrastructure, to identify potential areas of improvement, and to estimate potentially contaminated runoff volumes by combining two widely-used prediction models. The United States Department of Agriculture Natural Resource Conservation Service curve number (CN) method calculates quantitative runoff depths and volumes, while a flow-direction model integrates topography, land use, hydrography, and stormwater drainage infrastructure in a geographic information system. This study merged the CN and flow-direction models in a single geodatabase to develop a water flow direction/quantity model. Varied by the antecedent moisture content, three models were developed for 5-, 10-, 25- 50-, and 100-year flood events. These models contained flow direction of the existing stormwater drainage network, the total volume of runoff associated with each flood, and a hypothetical flood analysis model. Results showed that between 24,000 m3 (5-year flood) and 60,000 m3 (100-year flood) of water for any single storm event would runoff into the West Fork. The methodology developed and results generated will help city and stormwater planners to better visualize localized runoff, adapt existing drainage networks to accommodate stormwater runoff, prevent flooding and erosion, and improve the quality of runoff entering surface water bodies.