Determining the Rational Dimension of Thoa River to Ensure Drainage during the Crop Period Considering Climate Changes

Abstract

The major Thoa river is located in Mo-Duc and Duc-Pho districts. It originates from the Ve river to the My-A estuary. Aiming to protect crops of the hollow region of the Thoa river system, many canals and hydraulic works were built for irrigation and drainage, preventing saline intrusion from Bau-Sung to My-A estuary. However, this hollow region is often experienced inundation during the crop period because of heavy rain, especially under climate change conditions, a flood that results from water depression caused by a narrow river, bendy reaches, and strongly tidal influence downstream: My-A estuary. On the other hand, flooding overflow from other places: Ve river, other valleys, waterlogging, concentrates in this region. So, it is very difficult to drainage. In this paper, the authors find the effective schema of the Thoa river system for drainage during the crop period. Then they apply the HEC-RAS model to find out the specific and reasonable dimensions of the cross-section of the major Thoa river to drain during the crop period for protection of the crops of the hollow regions of the Thoa river system under the influence of climate change.