Projections of declining fluvial sediment delivery to major deltas worldwide in response to climate change and anthropogenic stress
Projections of declining fluvial sediment delivery to major deltas worldwide in response to climate change and anthropogenic stress
复制标题
DOI：
10.1088/1748-9326/ab304e
复制
发表时间：
2019-08-01
影响因子：
6.7
通讯作者：
Fekete, Balazs M.
中科院分区：
文献类型：
--
作者：
Dunn, Frances E.;Darby, Stephen E.;Fekete, Balazs M.
三角洲是资源丰富的低洼地区，自然和人类造成的下沉和地心海平面上升加剧了洪水的脆弱性，威胁到在这些环境中经常发现的大量人口。三角洲的“溺水”有可能被三角洲表面的沉积物沉积所抵消，这使得河流沉积物向三角洲的输送成为抵消相对海平面上升的关键平衡控制，前提是沉积物可以分散到水下三角洲。在这里，我们分析了在12种环境变化情景下，21世纪世界上47个主要三角洲河流沉积通量的预测变化。12个情景是利用四条气候路径(代表集中路径2.6、4.5、6.0和8.5)、三条社会经济路径(共享社会经济路径1、2和3)和一个水库建设时间表构建的。考虑到各种情景的平均值，预计到本世纪末，大多数被调查的三角洲(33/47)将经历沉积物通量的减少，1990-2019年和2070-2099年期间的平均和最大降幅分别为38%和83%。这些下降是由人为活动(改变土地管理做法和大坝建设)的影响压倒了未来气候变化的影响所致。这些结果勾勒出了全球主要三角洲未来可持续发展的程度和规模。它们强调河流沉积物通量动态的直接(如筑坝)和间接(如气候变化)变化的后果，并强调需要对个别三角洲进行进一步深入分析，以帮助制定适当的管理措施。
Deltas are resource rich, low-lying areas where vulnerability to flooding is exacerbated by natural and anthropogenically induced subsidence and geocentric sea-level rise, threatening the large populations often found in these settings. Delta 'drowning' is potentially offset by deposition of sediment on the delta surface, making the delivery of fluvial sediment to the delta a key balancing control in offsetting relative sea-level rise, provided that sediment can be dispersed across the subaerial delta. Here we analyse projected changes in fluvial sediment flux over the 21st century to 47 of the world's major deltas under 12 environmental change scenarios. The 12 scenarios were constructed using four climate pathways (Representative Concentration Pathways 2.6, 4.5, 6.0 and 8.5), three socioeconomic pathways (Shared Socioeconomic Pathways 1, 2 and 3), and one reservoir construction timeline. A majority (33/47) of the investigated deltas are projected to experience reductions in sediment flux by the end of the century, when considering the average of the scenarios, with mean and maximum declines of 38% and 83%, respectively, between 1990-2019 and 2070-2099. These declines are driven by the effects of anthropogenic activities (changing land management practices and dam construction) overwhelming the effects of future climate change. The results frame the extent and magnitude of future sustainability of major global deltas. They highlight the consequences of direct (e.g. damming) and indirect (e.g. climate change) alteration of fluvial sediment flux dynamics and stress the need for further in-depth analysis for individual deltas to aid in developing appropriate management measures.