Evaluation of Water Circulation by Modeling: An Example of Nonpoint Source Management in the Yeongsan River Watershed

Owing to urbanization, impervious areas within watersheds have continuously increased, distorting healthy water circulation systems by reducing soil infiltration and base flow; moreover, increases in surface runoff deteriorate quality increasing the inflow of nonpoint sources. In this study, we constructed a Hydrological Simulation Program—Fortran (HSPF) watershed model that applies area can set medium- long-term management goals for sub-areas. The was tested using case study from Yeongsan River watershed, Korea. results show land-cover accounts 18.47% upstream reach which Gwangju City is located; approximately twice average whole watershed. Depending on reduction scenario, direct source load could be reduced up 56% 35%, respectively; rate improved 16%. Selecting requires consideration both policy objectives budget. For urban with large cover, designation required. new cities, it necessary introduce (e.g., low impact development techniques) improve rainwater penetration recharge activate preemptive circulation.