Evolution of Water Levels at Coastal Hydrological Stations of the Mekong Delta

Abstract

From the historical hourly water level data during 29 years, from 1988 to 2016, annual mean water level, annual highest high water level, annual lowest low water level, annual maximum range of tide and some others levels at coastal hydrological stations of the Mekong delta are computed. Results show that at these stations, the annual mean water level and the volume of sea water entering in the delta with tide are increasing; the volume of inland water evacuated to the sea with tide tends to decrease. Evolution of the annual lowest low water level shows an increasing trend, faster in the last 14 years at most of the coastal stations. During 1988–2016 the annual maximum range of tide increases in the eastern coast stations, decreases at Nam Can, and in the western coast stations except Xẽo Ro, but decreases at most of stations during 2003–2016 except Binh Đại, Xẽo Ro and Rạch Gia. The changes of the water levels at the estuarine areas reported in this chapter are informative for the planning of water regulation works in the Mekong Delta, especially relating to the construction of the sluicegates Cai Lớn and Cai Be currently under study and the planned ones on the Tiền River branches such as Ham Luong and Cổ Chien. Whether and how the changes of water levels highlighted at Nam Can station are relevant to the confluence and interaction between the tides of the East Sea (South China Sea) and the West Sea (Gulf of Thailand) in the context of global climate change, sea level rise, is an open issue.