Detail Abstract

Evolution of bank erosion and morphological changes in the Vietnamese Mekong Delta

Abstract

The Vietnamese Mekong Delta (VMD) is shrinking and sinking, thus is drowning. It has recently changed from depositional to erosional phase as a consequence of a reduction in sediment supply from the Mekong mainstem and an increase in sand mining. Studies quantifying morphological changes in the VMD were largely at local scales due to limited data availability, thus morphological evolution in the entire VMD remains little known. In this study, we attempt to quantify long-term riverbed and riverbank evolution in the main rivers of the entire VMD using remote sensing techniques and extensive field-surveyed data covering a total riverbank length of about 1200 km. Riverbanks extracted from remote sensing are validated using georeferenced coordinates of the riverbanks recorded during a field survey in February 2022. The results from this study provide a quantitative understanding of how sediment in the VMD has been lost or gained over the past three decades. Such results are useful in policymaking and sustainable development of the delta.