Mangroves and shoreline erosion in the Mekong River delta, Viet Nam
Mangroves and shoreline erosion in the Mekong River delta, Viet Nam
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DOI：
10.1016/j.ecss.2019.106263
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发表时间：
2019-10
期刊：
影响因子：
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通讯作者：
Manon Besset;N. Gratiot;E. Anthony;F. Bouchette;M. Goichot;P. Marchesiello
中科院分区：
文献类型：
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作者：
Manon Besset;N. Gratiot;E. Anthony;F. Bouchette;M. Goichot;P. Marchesiello
湄公河三角洲沿岸的海岸线受到严重侵蚀的问题在过去几年中变得越来越重要。与此相关的问题之一是它与红树林的关系。使用高分辨率卫星图像，我们比较了2012年海岸线边缘的红树林带的宽度与2003年至2012年之间3687个跨海岸断面的海岸线变化（前进，后退），间隔100米，因此覆盖了近370公里的三角洲海岸线。结果表明，没有显着的关系。我们由此推断，一旦侵蚀发生在持续的泥浆供应不足的海岸，海岸线的变化率是独立的红树林带的宽度。许多研究表明：（1）在细粒沉积物供应充足的地方，红树林促进海岸加积;（2）一个大而健康的红树林边缘带可以有效地保护海岸线，因为它比一个较窄的边缘带更有效地消散波浪能;（3）清除红树林会加剧正在进行的海岸线侵蚀。我们完全同意这一点，但提请注意，在沉积物供应减少和普遍侵蚀的情况下，红树林无法发挥其建设土地和保护海岸的作用。忽视这些总体条件意味着，对红树林保护和/或稳定湄公河三角洲海岸线以及侵蚀其他地方海岸线的高度期望将落空。这些错误的期望包括：（1）一个大而健康的红树林边缘足以稳定（侵蚀）海岸线，（2）减少一个大的红树林边缘的宽度，以利于其他活动，如养虾，对海岸线的位置无害，以及（3）海岸的大量红树林可以抵消人类活动导致的沉积物供应减少的影响。
The question of the rampant erosion of the shorelines rimming the Mekong River delta has assumed increasing importance over the last few years. Among issues pertinent to this question is how it is related to mangroves. Using high-resolution satellite images, we compared the width of the mangrove belt fringing the shoreline in 2012 to shoreline change (advance, retreat) between 2003 and 2012 for 3687 cross-shore transects, spaced 100 m apart, and thus covering nearly 370 km of delta shoreline bearing mangroves. The results show no significant relationships. We infer from this that, once erosion sets in following sustained deficient mud supply to the coast, the rate of shoreline change is independent of the width of the mangrove belt. Numerous studies have shown that: (1) mangroves promote coastal accretion where fine-grained sediment supply is adequate, (2) a large and healthy belt of fringing mangroves can efficiently protect a shoreline by inducing more efficient dissipation of wave energy than a narrower fringe, and (3) mangrove removal contributes to the aggravation of ongoing shoreline erosion. We fully concur, but draw attention to the fact that mangroves cannot accomplish their land-building and coastal protection roles under conditions of a failing sediment supply and prevailing erosion. Ignoring these overarching conditions implies that high expectations from mangroves in protecting and/or stabilizing the Mekong delta shoreline, and eroding shorelines elsewhere, will meet with disappointment. Among these false expectations are: (1) a large and healthy mangrove fringe is sufficient to stabilize the (eroding) shoreline, (2) a reduction in the width of a large mangrove fringe to the benefit of other activities, such as shrimp-farming, is not deleterious to the shoreline position, and (3) the effects of human-induced reductions in sediment supply to the coast can be offset by a large belt of fringing mangroves.