Tidal amplification and salt intrusion in the Mekong Delta driven by anthropogenic sediment starvation

We show that tidal amplification and saline water intrusion in the Mekong Delta develop with alarming paces

Sepehr Eslami; Piet Hoekstra; Nam Nguyen Trung; Sameh Ahmed Kantoush; Doan Van Binh; Do Duc Dung; Tho Tran Quang; Maarten van der Vegt

2019

Scholarcy highlights

  • Natural resources of the Mekong River are essential to livelihood of tens of millions of people
  • It is expected that the frequency of extreme high flow events increases and the frequency of extreme low flow conditions reduces. Both hydropower operations and climate change lead to increase in freshwater supply and act against dry season saline water intrusion, yet, SWI seems to be an every-year concern to the authorities
  • We show that the combined effect of deeper channels and amplified tides leads to increased SWI
  • Using previous observations and the updated tidal forcing in the analytical model, we demonstrate the combined impact of bed level change and tidal amplification on SWI
  • While this study does not quantify the contribution from sources of sediment starvation, we cannot ignore the concordance between bed level changes and the spatial distribution of sheer magnitudes of sand mining within the Vietnamese Mekong Delta
  • Mann-Kendall test of the highest 5% salinity measurements during the dry season shows an average 0.2 PSU yr−1 temporal increase over the last two decades at multiple stations
  • The combined effect of upstream sediment trapping, and downstream sand mining can lead to large scale channel erosions as it has been shown for coastal erosion in various cases
  • To show the sensitivity of saline water intrusion, we updated the calibrated analytical model of 200553 by feedback from the bed level changes and the barotropic response for tidal velocity amplitude

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