The Historical Flood in 2000 in Mekong River Delta, Vietnam: A Quantitative Analysis and Simulation

抄録

The Mekong River Delta is one of the world's largest deltas and plays an important role in Vietnam's economic development. Studies of flood propagation over the whole delta have been rare. In 2000, due to global climate change and La Niña phenomenon, the hydrological and meteorological situations were very complicated around the world in general, and in the Mekong River basin in particular. In Mekong Delta, flood occurred early and had two peaks in which the second peak was one of the highest in the past 80 years. This flood caused water levels in the upstream Mekong River basin to become about 1 to 3m higher than the third warning level, and caused extremely severe inundation downstream. In Vietnam, this flood caused damage totaling about 5, 000 billion VN dong (about 4 million US dollars at that time), and its level was used to consider the design elevation of flood control embankments. Thus, through study of this flood is necessary to mitigate flood damage and human suffering and to contribute to policy making and create the conditions for embankment elevation design.
In this paper, analysis of the main characteristics of the flood of 2000 was carried out based on the observed data since 1926. Also, simulations were conducted using hydraulic models with topographical, hydrological and meteorological data. The flood simulations using hydraulic model for Vietnamese part of delta were carried out, especially for Dong Thap Muoi and Long Xuyen quadrant to analyze (1) how the flood was distributed spatially and temporally, (2) how long each inundation depth lasted, (3) the extent of the area of the flood, and (4) the effect of flood on paddy fields in 2000. The observed data and simulated results show that this flood was extremely large and complicated, causing severe inundation with the depth of 2.5m lasting more than one month from mid-September to mid-October. Flood in August affected strongly the summer-autumn crop paddy field. The area inundated to the depth of 2.5m was more than one thousand km².