Flood Simulation in Downstream Area of Kud Ta Phet Reservoir due to Dam Break

Abstract

In the years 2021 and 2022, Lopburi Province experienced severe flooding due to the influence of Typhoon Dianmu and Typhoon Noru. This caused heavy rainfall in many areas, particularly in the northeastern part of the province, especially in Lam Sonthi districts and Chai Badan districts. As a result, a large volume of water flowed into the reservoirs within Lopburi Province, including the Kut Ta Phet Reservoir, located in Lam Sonthi District, Lopburi Province. This caused the water level in the Kut Ta Phet Reservoir to rise rapidly. Therefore, to plan and prepare for future disaster responses in the downstream areas of the Kut Ta Phet Reservoir, appropriate measures need to be developed. This study aims to simulate flood conditions in the downstream area of the Kut Ta Phet Reservoir due to dam failure using the HEC-RAS model. The study examines possible scenarios of dam failure at the reservoir under conditions of inflow floods with return periods of 50, 100, 500, 1,000, and 10,000 years. The result of study showed that the failure modes of reservoir dams crest in Trapezoidal Shaped Breach with Seepage Hole Formation was most critical damage at downstream area with peak outflow of 6,594.17 cms. within 2 hours after the initial breach formation. Resulting in the maximum flood level at km.21+483 at Lam Sonthi sub district, Lam Sonthi district, the water level at +91.79 msl Which higher than top bank 9.08 m. within 28 hours after the dam broke. The results of this study will provide guidance on prevention, planning, and reducing the impacts of flooding.