The Flooded Areas Assessment in Ubon Ratchathani Province with MIKE FLOOD Model

Abstract

Ubon Ratchathani experienced the great floods in 1938, 1978, 2002 and most recently in September 2019. Flooding in 2019 was stronger than in 2002. The water level in 2019 is 115.88 m msl and the water level in 2002 is 115.77 m msl. The purpose of this study is to assess flooded areas from rainfall and runoff at the 10-year, 20-year, 50-year and 100-year return periods using MIKE FLOOD model. The flooded areas affected by runoff at the 10-year, 20-year, 50-year and 100-year return periods are 487.59, 696.55, 837.63 and 944.57 km², respectively. The flooded areas are from the end of Rasi Salai dam to Pak Mun dam, including the Mun river, the Chi river and the branch river that flows into the Mun river. Heavy flooding occurred in Mueang Si Sa Ket district, Kanthararom district, Si Sa Ket province, and Khuang Nai district, Mueang Ubon Ratchathani district, Warin Chamrap district, Ubon Ratchathani province. On the other hand, flooded areas affected by rainfall at the 10-year, 20-year, 50-year and 100-year return periods are 206.03, 214.54, 228.31 and 259.76 km², respectively. Rainfall in both of Si Sa Ket district and Ubon Ratchathani province are not the main cause of flooding in these two provinces because the flooded areas increase only slightly in each return period. Since runoff from upstream basin is included in runoff data that input to the MIKE FLOOD model, flooded areas affected by runoff is more than flooded areas affected by rainfall. Then, the main cause of flooding in Si Sa Ket district and Ubon Ratchathani province is the runoff from upstream basin.