MSGID: 1:317/3 6275f5f9   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Saving the Mekong delta from 'drowning'    
    Policy must address drivers, not just symptoms, of subsidence    
      
     Date:   
         May 6, 2022   
     Source:   
         Stanford Woods Institute for the Environment   
     Summary:   
         Southeast Asia's most productive agricultural region and home to 17   
         million people could be mostly underwater within a lifetime. Saving   
         the Mekong River Delta requires urgent, concerted action among   
         countries in the region to lessen the impact of upstream dams and   
         better manage water and sediments within the delta, according to   
         an international team of researchers who outline solutions to   
         the region's dramatic loss of sediment essential to nourishing   
         delta land.   
      
      
      
   FULL STORY   
   ==========================================================================   
   Southeast Asia's most productive agricultural region and home to 17   
   million people could be mostly underwater within a lifetime. Saving the   
   Mekong River Delta requires urgent, concerted action among countries   
   in the region to lessen the impact of upstream dams and better manage   
   water and sediments within the delta, according to an international   
   team of researchers. Their commentary, published May 5 in Science,   
   outlines solutions to the region's dramatic loss of sediment essential   
   to nourishing delta land.   
      
      
   ==========================================================================   
   "It's hard to fathom that a landform the size of the Netherlands and with   
   a comparable population might disappear by the end of the century," said   
   study co-lead author Matt Kondolf, a Professor of Landscape Architecture &   
   Environmental Planning at the University of California, Berkeley.   
      
   "The Mekong Delta is truly outstanding in terms of agro-economic value   
   and regional importance for food security and livelihoods," said study   
   co-lead author Rafael Schmitt, a senior scientist at the Stanford Natural   
   Capital Project. "Without rapid action, the delta and its livelihoods   
   could become victims of global and regional environmental change."   
   On its journey from skyscraping Tibetan peaks to the sea, the Mekong River   
   picks up sediment from eroding uplands in China, Myanmar, Laos Cambodia,   
   Thailand and Vietnam. The nutrient-rich sediment has accumulated in the   
   Mekong Delta and enabled the lower Mekong region to produce up to 10%   
   of all rice traded internationally. It has also fed fisheries that feed   
   tens of millions of people. Like any river delta, the Mekong Delta can   
   only exist if it receives a constant sediment supply from its upstream   
   basin, and if water flows can spread that sediment across the low-lying   
   delta surface to build land at a rate that is equal to or greater than   
   global sea level rise.   
      
   Hungry for renewable energy, countries in the basin have built numerous   
   hydropower dams that block fish migrations, trap sediment and reduce   
   downstream flows. If all planned dams are built, they will trap 96% of   
   the sediment formerly reaching the delta. Additionally, sediment supply   
   from tropical cyclones, which deliver about 32% of the suspended sediment   
   load reaching the delta, is decreasing as cyclone tracks shift north.   
      
   Sediment that manages to reach the lower Mekong is mined for sand used   
   in construction and land reclamation. Over pumping of groundwater and   
   high dikes built to control floods and enable high intensity agriculture   
   exacerbate the problem.   
      
   To slow and reverse damages, the researchers recommend that policymakers:   
       * Design dams to enable better sediment sediment passage, place them   
         strategically to reduce their downstream impacts, or replace them   
         with wind and solar farms, where possible.   
      
       * Strictly regulate sediment mining and reduce use of Mekong sand   
       through   
         sustainable building materials and recycling.   
      
       * Allow floodwaters to spread out over the Delta and deposit their   
         sediments   
       * Limit groundwater pumping in the Mekong Delta * Reevaluate intensive   
       agriculture in the Mekong Delta for sustainability.   
      
       * Implement natural solutions for coastal protections on a large scale   
         along the delta's coast   
   Most efforts to rehabilitate the delta have involved individual countries   
   approaching isolated engineering challenges, and proposing solutions   
   on local scales, according to the researchers. Making meaningful   
   progress will require coordination among countries, development banks   
   development agencies and other private and civil society stakeholders,   
   the researchers write.   
      
   "We are seeing signs that governments and nongovernmental actors are   
   beginning to work together on these issues," said Schmitt. "We hope   
   our commentary will elevate the topic on the regional policy agenda,   
   empower conservation in the basin, and act as a wake-up call to address   
   key drivers for land loss on a system scale."   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Stanford_Woods_Institute_for_the_Environment. Original written by Rob   
   Jordan. Note: Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. G. M. Kondolf, R. J. P. Schmitt, P. A. Carling, M. Goichot,   
      M. Keskinen,   
         M. E. Arias, S. Bizzi, A. Castelletti, T. A. Cochrane, S. E. Darby,   
         M.   
      
         Kummu, P. S. J. Minderhoud, D. Nguyen, H. T. Nguyen, N. T. Nguyen,   
         C.   
      
         Oeurng, J. Opperman, Z. Rubin, D. C. San, S. Schmeier, T. Wild. Save   
         the Mekong Delta from drowning. Science, 2022; 376 (6593): 583 DOI:   
         10.1126/ science.abm5176   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2022/05/220506141128.htm   
      
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