Abstract
The Sai Gon-Dong Nai Basin plays a very important role in the socio-economic development of Vietnam. The area of Ho Chi Minh (HCM) City is about 2095 km2, 60% of which lying under 2 m above MSL. Its population is about 8.136 million. Economic development has led to flood-related problems. The causes of floods are monsoon rainfalls, high tides, and outflows from the Dau Tieng Reservoir, upstream of HCM City. This paper proposed a plausible solution for flood mitigation in HCM City by uplifting the Dau Tieng dam crest. This solution can be recommended based on the results of an extensive simulation study which used: (i) a statistical downscaling procedure for evaluating the climate change (CC) impacts on precipitations; (ii) the MARINE model for simulating the rainfall-runoff process; (iii) the Telemac2D model for simulating the inundation; and (iv) the GIS tool for representing the inundated areas under different CC scenarios. It was found that under the A2 scenario an increase of rainfall by 2050s and added 40% of this rainfall (assuming due to tropical depression), the maximum regulated discharges released from the Dau Tieng dam could reach 1650, 500 and 300 m3s−1 without any enhancement then with the dam enhancement of 1.0 and 1.5 m, respectively. As comparing to event occurred on July 21, 2009 due to the combined effect of a heavy rainfall and a high tide condition, the inner city flooding area increases by 1.2, 1.3 and 8.2% with the dam enhancement of 1.5, 1.0 m and without dam enhancement, respectively. Results of this study have therefore provided critical information for making a logical decision concerning the possibility of uplifting the height of the crest of the Dau Tieng dam to mitigate the urban flooding in HCM City under the threat of CC and sea level rise.
Highlights
Urban flooding is often caused by heavy rainfall, overbank flows from rivers, high tides and/or storm surges (Tingsanchali, 2012; Cheng et al, 2017; Verwey et al, 2017)
An innovative approach has been proposed in this study for flood mitigation in Ho Chi Minh (HCM) City in consideration of the potential impacts of Climate Change
The proposed approach was based on a combination of a Statistical Downscaling Model to assess the impacts of Climate Change on precipitations over the Dau Tieng Reservoir watershed and the lower Sai Gon-Dong Nai Basin area, MARINE (Model of Anticipation of Runoff and INundation for Extreme events) and Telemac2D models to simulate the flood flows from upstream of the reservoir and the inundated downstream area – in HCM City
Summary
Urban flooding is often caused by heavy rainfall, overbank flows from rivers, high tides and/or storm surges (Tingsanchali, 2012; Cheng et al, 2017; Verwey et al, 2017). During high water years, the water level in water supply reservoirs must be drawn down before the arrival of heavy rains. This can cause conflicts between different stakeholders with different conflicting water demands in the basin as a whole.
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