Evaluation of flood volume and inundation depth by GIS midstream of Chao Phraya River Basin, Thailand

Abstract

Chao Phraya River has small flow capacity downstream. When excessive water flows upstream into it the water level downstream increases with the possibility of flood risk. The purpose of this research is to clarify the flood condition midstream and recommend proper flood management measures. In this research, flood inundation depth is calculated with a Geographic Information System (GIS) in order to understand the temporal, spatial scale and transition. Furthermore, flood volume is calculated to understand the total flood volume needed to be stored midstream before reaching downstream. Results clearly demonstrated excessive streamflow at gauging station located at the beginning of Chao Phraya River, which is midstream of the Chao Phraya River Basin. Flooding of the Yom River and Nan River also has significant impact midstream. Results show that if flood volume of 0.7 billion m 3 flow from upper and middle reaches the lower reach could decrease, it will decrease flood volume at gauging station C.2 simultaneously. By controlling the flood storage volume midstream, there are possibilities of preventing the excessive streamflow capacity and the flooding damage downstream.