A feasibility study on constructing a flood diversion channel

Abstract

The yearly floods of the Mekong Delta caused by the Mekong River have been considered a blessing; it purifies the agricultural lands and deposits a fresh layer of silt on the surface, which keeps the delta fertile. However, the growing demand for agricultural products internationally and nationally has pushed the farmers to harvest all year long, which has lead to a situation where the floods are more of a curse than a blessing. Besides the growing agricultural demand, the continuous urbanization has also caused the yearly flood to become less accepted. Furthermore, it is expected that the flooding problems will only increase even more in future due to climate change. A possible solution to reduce the frequency of flood risks is by constructing a flood diversion channel between the Mekong River and the Gulf of Thailand. The purpose of this flood diversion channel is to reduce the water level of the Mekong River during high water preventing it from flooding. The question is, if a flood diversion channel is a realistic measure to achieve this objective and to reduce flood risks. A feasibility study divided into two parts has been made, to find out how realistic a flood diversion channel, as measure is to reduce flood risks. The first part of the study is to find out what the required technical conditions are for constructing a flood diversion channel. The second part of the study concentrates on the question whether the effects of sediment deposition by the flood diversion channel into the Gulf of Thailand prohibits the construction of a flood diversion channel. The conclusion of this feasibility study is that a flood diversion channel can be a solution to reduce current flood risks caused by the Mekong River. However, when future climate changes are taken into account the diversion channel is only sufficient to reduce the increased flood risk of the Hau River; additional measures are necessary to also lower the water level of the Tien River. The concern of sediment deposition at Phu Quoc is unjustified. Deposition of sediment near the shore of the discharge location can even have a positive side effect for the eroding coastline. The preferred flood diversion channel is to construct a deep channel of approximately 70 km long and depending on the withdrawal necessities the width of the channel will be between the 340 and 680 meters. The flood diversion channel withdraws at Chau Doc, goes along the Vinh Te channel for as long as possible and crosses the K. Tam Ngan channel to eventually discharge at the Middle location into the Gulf of Thailand.