Flood Inundation Mapping and Hazard Assessment for Mitigation Analysis of Local Adaption Measures in Upper Ping River Basin, Thailand

Abstract

Annual monsoon flooding phenomena have caused disastrous impacts on the Upper Ping River basin and its inhabitants over the years. The existing administration set-up for flood mitigation and adaptation measures lacks effective utilization of locally available resources for complete flood protection. This study addressed this gap by flood hazard assessment at a lower administration scale (sub-district level) and performance evaluation of local adaptation measures was performed. 1D and 2D hydrodynamic models were developed and calibrated against observed discharge and water level (1D) and flood extent (2D), respectively. Flood inundation and hazard maps were reproduced and categorized into different classes based on defined critical depths for 2, 5, 10, 25, 50 and 100 years return periods. A maximum flood inundated area of 996.9 km2 (3.94% of total basin area) was simulated in a 100-year return period. The flood hazard results represent that the largest flooded area categorized under “high hazard”, followed by “very high hazard” and “low hazard” categories, and least flooded area was classified under “medium hazard” category. The current administration set-up for flood adaptation and mitigation needs to update based on an integrated flood management approach to improve its effectiveness for future flood protection.