Flood Management in MAHACHAI-SANAMCHAI Polder System

Abstract

MAHACHAI-SANAMCHAI Polder System. It is project to speed up the drainage of flood water from the west area of Chao Phraya River in Bangkok Metropolitan area to the sea as soon as possible. Components of water management are water gate and pumping stations. KAEM LING MAHACHAI-SANAMCHAI will collect the flood from upper area and store in Mahachai-Sanamchai canal, main canal for receiving water of this project and pumping to the Tha Chin river and to the gulf of Thailand. In this study, focusing on water management in Mahachai-Sanamchai canal to alleviate flooding problems caused high sea level and increasing of water in Mahachai-Sanamchai canal. Especially, Bang Kradi, community in Bang Khun Thian, Bangkok. In this study, Simulation the hydrodynamic model with Mike11 Hydrodynamic model. The upstream control is at the Sanamchai pumping station and the downstream control is at the Mahachai watergate. Calibration and validation result with Manning’s n 0.030 is proper value with RMSE and R2 0.26 m. and 0.97 respectively. As a result, Water level from simulation in the program is 1.1 – 1.8 m. MSL. For protection flood problems from high level of the water in Mahachai-Sanamchai Canal, the recommended method is using water retaining wall at a height of 1.8 m. MSL with 100 years return period along the river bank of Mahachai-Sanamchai canal to alleviate flood problem.