Dynamics of salt intrusion in the Mekong Delta: results of field observations and integrated coastal–inland modelling

Abstract. On the list of challenges facing world largest deltas, increased saline water intrusion (SWI) in surface system and its role jeopardizing freshwater supply are often ranked very high. Yet, detailed process-based studies SWI at whole delta scale limited, trends regularly associated with global sea level rise. Here, using field measurements a sophisticated 3D model that integrates riverine, rural, estuarine, coastal dynamics within one numerical domain, we study Mekong Delta extensive detail. While many downscale problem to topic an estuary, show physical processes on continental shelf, such as monsoon-driven ocean surge, directly influence salinity delta. Typical values 20–40 cm surge over shelf contribute up 10 km further SWI. The delta's estuarine is also more sensitive than other systems variations river discharge. Furthermore, spring–neap variability plays key from stratified mixed between neap spring tides develops circulation tidal straining become main upstream salt transport mechanisms. nature dynamics, downstream processes, suggests compromising dimension or extent domain can limit accuracy predictions showcases fact riverbed incision response anthropogenic sediment starvation last 2 decades has stratification activated magnified subprocesses amplify transport. With all external forces delta, namely climate change altered hydrological regime by dams, due deeper channels (driven sand mining impoundments) compared near past, itself far vulnerable even mild natural events. This exemplifies fundamental importance preserving budget levels protecting world's deltas against