ĐÁNH GIÁ SỰ THAY ĐỔI SỨC TẢI LŨ TRÊN SÔNG SÀI GÒN
Abstract
The aim of this article is to summarize the result of evaluation the flow transport capacity of the Sai Gon River using historical data, topographical survey and results from numerical models (MIKE11) in the state-level scientific research project KC08.07/16-20 "Research and propose solutions to improve water use efficiency, ensure the safety of main works and downstream Dau Tieng reservoir in the conditions of climate change and extreme weather ".
The comparisons of water levels and flow discharges correspondingly along the Saigon River showed that the flow transport capacity of the Saigon River increased in the upstream part and decreased in the downstream part. Specifically, at the cross-section of Dau Tieng station, with the flood water level of 6.0 m, the discharges in 1984 was only 650 m3/s, in 2005 reached 1,300 m3/s and reached 2,200 m3/s by 2017, ie increased up to 47 m3/year, equivalent to about 7.2% per year. Along the Saigon River the flow transport capacity increased from Km 0 (the dam site) to Km 100. Conversely, the flow transport capacity of the Saigon River is reduced from about Km100 to downstream.
The increase in flow transport capacity on the Saigon River at the upstream part is mainly due to changes in topography. River beds tend to be deeper due to the impact of post-dam construction erosion, or it may be due to sand mining that made river bed lowering from upstream sections to Km100. In contrast, from Km100 downstream, the river bed tends to accret, and in addition, possibly due to due to encroachment (urbanization), or by dike embankments leading to the narrow cross sections, making flow transport capacity reduced.