Erosion potential of the Yangtze Delta under sediment starvation and climate change.
Erosion potential of the Yangtze Delta under sediment starvation and climate change.
复制标题
沉积物匮乏和气候变化下长江三角洲的侵蚀潜力
DOI：
10.1038/s41598-017-10958-y
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发表时间：
2017-09-05
影响因子：
4.6
通讯作者：
Yang Z
中科院分区：
文献类型：
--
作者：
Yang HF;Yang SL;Xu KH;Wu H;Shi BW;Zhu Q;Zhang WX;Yang Z
三角洲普遍受到沉积物匮乏和气候变化的威胁。侵蚀潜力是三角洲脆弱性的重要指标。本文对长江三角洲的侵蚀潜力进行了研究。研究发现，近半个世纪以来，由于三峡大坝的建设和水土保持，长江输沙量减少了80%，而三角洲地区的风速和浪高增加了5-7%，海平面以3毫米/年的速度上升。根据海底沉积物的水动力测量和分析，在正常天气条件下，由流波联合作用引起的床切应力超过侵蚀临界床切应力（τcr）的时间平均占总观测时间的63%，在风暴高峰时可达到100%。这就解释了为什么在水下三角洲的某些地区会发生净侵蚀。我们还发现，在沉积层序的最上面几米，τ危机值随深度的增加是非常缓慢的。因此，我们预计在本世纪的未来几十年甚至几个世纪里，长江水下三角洲将在泥沙饥饿和气候变化的影响下遭受持续的侵蚀。
Deltas are widely threatened by sediment starvation and climate change. Erosion potential is an important indicator of delta vulnerability. Here, we investigate the erosion potential of the Yangtze Delta. We found that over the past half century the Yangtze’s sediment discharge has decreased by 80% due to the construction of >50,000 dams and soil conservation, whereas the wind speed and wave height in the delta region have increased by 5–7%, and the sea level has risen at a rate of 3 mm/yr. According to hydrodynamic measurements and analyses of seabed sediments, the period when bed shear stress due to combined current-wave action under normal weather conditions exceeds the critical bed shear stress for erosion (τcr) accounts for 63% of the total observed period on average and can reach 100% during peak storms. This explains why net erosion has occurred in some areas of the subaqueous delta. We also found that the increase with depth ofτcris very gradual in the uppermost several metres of the depositional sequence. We therefore expect that the Yangtze subaqueous delta will experience continuous erosion under sediment starvation and climate change in the next decades of this century or even a few centuries.
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