Risk assessment of riverbank erosion in Ho Chi Minh City due to climate change and flood discharge from Dau Tieng and Tri An reservoirs

Abstract

To support disaster management in Ho Chi Minh City, this study will focus on quantitatively and visually predicting spatial and temporal risk of riverbank erosion in the context of future climate change. The main method used here is a fuzzy logic approach in the ArcGIS environment combined with the Mike hydrodynamic model (11 and 21) to predict and construct riverbank erosion risk maps for the main river system corresponding to different simulation scenarios, including: (i) Current scenario; (ii) Future climate change scenarios published by the Ministry of Natural Resources and Environment; (iii) Flood release scenario from two upstream reservoirs (Dau Tieng reservoir and Tri An reservoir) corresponding to flood frequencies of 5% and 1%, respectively. Compared to the current scenario, the results show that climate change more or less increases the risk of riverbank erosion, specifically: increasing the area of ​​high-risk zones (potential erosion) by 12% to 13%; while the area of ​​very high and extremely high-risk zones tends to decrease. Furthermore, the results of flood release scenarios from upstream reservoirs corresponding to two frequencies of 5% and 1% also show that flood releases will significantly increase the area of ​​extremely high-risk zones by 6% and 8% respectively, but by 2.1 to 2.4 times the length along the riverbank. Therefore, although the impact of climate change is not severe, the city still needs to have solutions to mitigate risks and proactive response plans to riverbank erosion before it actually occurs.