Establishing sustainable sediment budgets is critical for climate-resilient mega-deltas
Establishing sustainable sediment budgets is critical for climate-resilient mega-deltas
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DOI：
10.1088/1748-9326/ac06fc
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发表时间：
2021-06
影响因子：
6.7
通讯作者：
G. Vasilopoulos;Q. Quan;D. Parsons;S. Darby;V. Tri;N. Hung;I. Haigh;H. Voepel;A. Nicholas;R. Aalto
中科院分区：
文献类型：
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作者：
G. Vasilopoulos;Q. Quan;D. Parsons;S. Darby;V. Tri;N. Hung;I. Haigh;H. Voepel;A. Nicholas;R. Aalto
世界上许多主要的河流三角洲面临可持续性危机，因为它们受到盐度上升的威胁，以及海平面上升、河流流量变化和河道几何形状共同作用所迫使的潮汐带范围的威胁。这些因素对未来潮汐范围增加的相对贡献仍然不受限制，之前的大多数工作都强调了气候驱动的海平面上升的作用。在这里，我们使用来自湄公河三角洲的新的现场数据来测量河流流量的变化和河道几何形状的变化，并将其投射到未来。我们将这些与未来海平面上升的预测结合到一个二维水动力数值模型中，并量化了不同驱动因素对未来潮汐向三角洲延伸的影响。我们表明，在接下来的20年里，由于河道加深(92%)，进入湄公河三角洲的潮汐延伸将增加多达56公里，这主要是由人为沉积物饥饿驱动的。此外，即使在强有力的缓解情景下，沉积物饥饿仍然推动着对未来潮汐延伸的长期承诺。具体地说，到2098年，预计海平面上升对预计的延长只会有轻微的贡献。这些发现表明，政策制定者迫切需要采取循证措施，扭转沉积物负预算的局面，这种负预算推动潮汐向沉积物匮乏的三角洲延伸。
Many of the world’s major river deltas face a sustainability crisis, as they come under threat of increases in salinity and the extent of tidal zones forced by combinations of sea-level rise, changes in river discharge and channel geometry. The relative contribution of these factors to future increases in tidal extent remains unconstrained, with most prior work emphasising the role of climate-driven sea-level rise. Here we use new field data from the Mekong delta to measure variations of river discharge and changes of channel geometry, and project them into the future. We combine these with projections of future sea-level rise into a 2D hydrodynamic numerical model and quantify the influence of the different driving factors on future tidal extension into the delta. We show that within the next two decades, tidal extension into the Mekong delta will increase by up to 56 km due to channel deepening (92%), dominantly driven by anthropogenic sediment starvation. Furthermore, even under strong mitigation scenarios, sediment starvation still drives a long-term commitment to future tidal extension. Specifically, by 2098 eustatically rising sea-levels are predicted to contribute only modestly to the projected extension. These findings demonstrate the urgent need for policy makers to adopt evidence-based measures to reverse negative sediment budgets that drive tidal extension into sediment starved deltas.