Urbanization and climate change impacts on future urban flooding in Can Tho city, Vietnam

Urban development increases flood risk in cities due to local changes in hydrological and hydrometeorological conditions that increase flood hazard, as well as to urban concentrations that increase the vulnerability. The large-scale, global impacts due to climate variability and change could increase these risks. This paper presents the case of Can Tho, the biggest city in Mekong River Delta, Vietnam), which faces multiple future challenges, namely:

• the likely effect of sea level rise
• an expected increase of river runoff due to climate change as estimated by the Vietnamese government
• increased urban runoff driven by imperviousness
• enhancement of extreme rainfall due to urban growth-driven, microclimatic change (urban heat islands).

A set of model simulations were used to construct future scenarios, combining these influences. The results show that under the combined scenario of significant change in river level (due to climate-driven sea level rise and increase of flow in the Mekong) and ‘business as usual’ urbanisation, the flooding of Can Tho could increase significantly. The worst case may occur if a sea level rise of 100 cm and the flow from upstream happen together with high-development scenarios. However, the study concludes that detailed research on adaptation is necessary for future investments to be effective.