Feasibility of low impact development measures to mitigate inundation in tidal – impacted urban area: A case in Ho Chi Minh City, Vietnam

Abstract

Recently, urban inundation is becoming more severe in Ho Chi Minh City. Many structural measures have been proposed, but low impact development (LID) measures have not been sufficiently considered. This study quantitatively investigated the possibility of LID measures in District 12, Ho Chi Minh City using modelling approach. Based on the collected secondary data on land use, sewer network, and terrain elevation, a semi-two-dimensional storm water management model (PCSWMM-2D) was constructed and calibrated against heavy rainfall and high tidal event on 26 September 2016. Errors between measured and simulated inundated depths at several positions was smaller than 5%; thus, the calibrated model was at reliable accuracy to predict design scenarios. Using 10-year return period scenarios of tidal levels at Sai Gon River and rainfall at Tan Son Hoa gauging station, the model was used to analyse several designed LID measures including green roof, pervious pavement, and storage or flood retention lake/pond. The simulated results indicated that if green roof and pervious pavement are separately applied, the average magnitude of inundation depth can be reduced by 11.4% and 14.0%, respectively. Meanwhile, when a well-designed storage system including a gated-flood retention lake in combination with suitable conduits and a pumping station is constructed, the flooding situation is completely controlled. In conclusion, it is suggested that to manage urban inundation in terms of sustainable development for Ho Chi Minh City, a well-designed storage system is needed prior to the urbanizing area. In addition, those LID measures should be widely applied as long-term strategy for flooding management in Ho Chi Minh City.