Investigation on Floods in Can Tho City

The present chapter investigates seasonal fluvial flood hazards to the city of Can Tho in the Mekong Delta, a phenomenon which is likely to be exacerbated by future sea level rise (SLR). Unlike past research, which has mainly focused on flooding due to river discharge from upstream or heavy precipitation, the present chapter scrutinizes the influence of ocean tides, revealing how these can determine water elevation even in an upstream location such as Can Tho city, 80 km inland from the river mouth. In fact, river flow causes tidal damping and effectively reduces the energy of the incoming tides, an effect especially pronounced during the rainy season. Analysis based on the water levels monitored by the Mekong River Commission revealed that the ground near the riverbank of Can Tho had experienced inundation for a total of 215 h between July 2009 and June 2010 (2.5% of the time over a 1-year period). Assuming two scenarios of SLR, of 25 cm by 2050 and 60 cm by 2100, all based on the IPCC AR5’s projections, it was found that the duration of inundation will be prolonged from the present percentage of 2.5% to 7.5% and 24% of the year, respectively. Furthermore, field surveys carried out by the authors showed that recent inundation episodes reached a height of up to 47 cm above the roads of Can Tho’s downtown, highlighting the need for future adaptation measures in the city.