Monitoring of land use change impact on stormwater runoff and pollutant loading estimation in Yongin watershed Korea

This study investigates the preliminary assessment of land use changes and their specific effects on hydrological characteristics and stormwater quality in Yongin watershed. Two experimental catchment sites comprising of mix land uses including urban and construction areas were monitored and tested for major stormwater quality parameters. It was observed that dry field, paddy field, forest, and ground cover were changed to bare land about 61, 96, 13, and 9%, respectively, at Site 1 from June 2011 to December 2011 due to construction activities for new development. The findings indicate that increase in bare soil resulted in reduction of stormwater runoff. Overall pollutograph shape for the entire stormwater events for most of the water quality parameters showed multiple peaks of equivalent magnitude, reflecting the rainfall intensity distribution. A wide range of Event mean concentrations (EMCs) for individual runoff event was measured for each water quality constituent based on the flow rate and concentration data. These wide EMC distributions did not show relationship with antecedent dry period, rainfall intensity, and runoff duration due to continuous modifications in monitoring sites. Pollutant loading at Site 2 was higher as compared to Site 1 because of the urban area impact and the difference of catchment area.