Spatio-temporal variations of sea level around the Mekong Delta: their causes and consequences on the coastal environment

Abstract

This paper presents a comprehensive analysis of sea level variations around the Mekong Delta, and their causes and consequences on the environment, based on the tidal records from several stations. The results of the analysis revealed significant spatio-temporal sea level variations along the delta coast. Tidal fluctuations showed their local peaks around the river mouth with shallow bottom areas. The prevailing winds were identified as the factor governing the remarkable seasonal variability of the mean sea levels along the southern coast of the delta. From 1985 to 2010, the relative sea level along the southern coast of the delta rose by about 3.3 mm y -1 . This rate of rise combined with the effect of land subsidence renders the Mekong Delta alarmingly susceptible to frequent inundation. Moreover, the immediate impacts, including saline intrusion and occasional inundation due to seasonal sea level fluctuation, are also found to be critical and require urgent attention. These findings suggest the need to revise coastal management strategies to prioritize the immediate effects of short-term sea level fluctuations and to increase the focus on local management issues such as groundwater pumping causing land subsidence and local sea level trends in addition to the global threats.

Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream?

“…Sea levels in the East Sea surrounding the MD rose by 3.1 mm year −1 at My Thanh and 3.5 mm year −1 at Vung Tau during 1985-2010 (Hak et al, 2016), and sea level rise is expected to continue (IPCC, 2014). To make the situation even more alarming, several cities in the VMD suffer from local subsidence due to overexploitation of groundwater, for instance, 20 mm year −1 for Can Tho during 2006-2010(Erban et al, 2014.…”

“…Being a low-lying coastal region, the VMD is susceptible to both riverine and tidal floods, threatening agricultural production and the safety of people (Schumann et al, 2008;Kuenzer et al, 2013;Le et al, 2007;Dung et al, 2009;Dung et al, 2011;Van et al, 2012). Climate change and sea level rise are expected to increase the risk, not only due to flooding but also due to droughts and salinity intrusion (Wassmann et al, 2004;Khang et al, 2008;Toan, 2014;Hak et al, 2016). Further, the region faces severe sediment…”

Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream?

“…Another important implication resulting from the link between inundation dynamics and lower boundary is that flood levels in the central and coastal VMD have to be expected to increase in the coming decades. Sea levels in the East Sea surrounding the MD rose by 3.1 mm year −1 at My Thanh and 3.5 mm year −1 at Vung Tau during 1985-2010 (Hak et al, 2016), and sea level rise is expected to continue (IPCC, 2014). To make the situation even more alarming, several cities in the VMD suffer from local subsidence due to overexploitation of groundwater, for instance, 20 mm year −1 for Can Tho during 2006-2010(Erban et al, 2014.…”

Response to first reviewer's comments

“…Another important implication resulting from the link between inundation dynamics and lower boundary is that flood levels in the central and coastal VMD have to be expected to increase in the coming decades. Sea levels in the East Sea surrounding the MD rose by 3.1 mm year −1 at My Thanh and 3.5 mm year −1 at Vung Tau during 1985-2010 (Hak et al, 2016), and sea level rise is expected to continue (IPCC, 2014). To make the situation even more alarming, several cities in the VMD suffer from local subsidence due to overexploitation of groundwater, for instance, 20 mm year −1 for Can Tho during 2006-2010 (Erban et al, 2014).…”

“…Being a low-lying coastal region, the VMD is susceptible to both riverine and tidal floods, threatening agricultural production and the safety of people (Schumann et al, 2008;Kuenzer et al, 2013;Le et al, 2007;Dung et al, 2009;Dung et al, 2011;Van et al, 2012). Climate change and sea level rise are expected to increase the risk, not only due to flooding but also due to droughts and salinity intrusion (Wassmann et al, 2004;Khang et al, 2008;Toan, 2014;Hak et al, 2016). Further, the region faces severe sediment Published by Copernicus Publications on behalf of the European Geosciences Union.…”