Simulation of Modeling Approach for Flood Condition and Proposed Flood Protection at Midstream of Chao Phraya River Basin, Thailand

2011 Thailand flood has resulted in serious impact to downstream of Chao Phraya River. Study on midstream of Chao Phraya River Basin has rarely been conducted. This research focuses on midstream of Chao Phraya RiverBasin, which includes confluence of Nan River and Yom River, also confluence of Ping River and Nan River. Flood condition at midstream is simulated using coupling of 1D and 2D hydrodynamic model, MIKE FLOOD to understand the flood generation. The model is calibrated and validated using flood marks measured at study area and streamflow data received from Royal Irrigation Department (RID). Furthermore, scenarios of flood control at 3 rivers are simulated and Geographic Information System (GIS) is used to calculate the flood distribution area and flood volume. Subsequently, 2 kinds of suitable flood control measurements are proposed. Results shows flood control at midstream helps reduce the risk of reflooding or flood return from small streams and flood plain into starting of Chao Phraya River. However, flood volume before confluence of Ping River and Nan River, which is Bung Boraphet area will be increased. Therefore, the land use planning and regulation at area nearby Bung Boraphet need to be considered.