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Deltaic response to climate change: The Holocene history of the Nueces Delta
Global and Planetary Change ( IF 3.9 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.gloplacha.2020.103213
Johnathan A. Rice , Alexander R. Simms , Pamela Buzas-Stephens , Elisabeth Steel , Daniel Livsey , Laura C. Reynolds , Yusuke Yokoyama , Todd Halihan

Abstract Deltas host large urban centers and expanses of coastal wetlands worldwide. As such, their future will play an important role in the economic and ecological health of many coastal communities. Although threats to deltas from drowning due to subsidence and accelerating sea-level rise are well-studied, far less is known about the physical effects of climate change on deltas. Here we map the location of the Nueces Delta shoreline of the northwestern Gulf of Mexico over the last ~8.0 ky to show that the delta retreated and prograded at rates greater than 10 m/yr and over distances of up to 22 km in a few centuries at the same time as independent proxy records of Holocene climate change indicate decreased and increased effective precipitation, respectively. These periods of retreat occurred at 5.0 and 3.2 ka; an earlier, previously documented period of retreat at 8.2 ka was driven by a rapid increase in the rate of sea-level rise. The Nueces Delta experienced periods of progradation at 6.6 ka, 3.8 ka and 2.2 ka. As some of these changes may have been driven simply by avulsion or other autogenic processes, we test the role of climate in driving these changes by quantifying the amount of sand, thought to be a conservative proxy for sediment flux, within the delta through the Holocene. The amount of sand delivered to the delta increased during periods of progradation and decreased during periods of retreat. These changes occurred despite decreasing rates of sea-level rise through the middle Holocene. These results suggest that deltas are susceptible to not only increasing rates of sea-level rise, but also other climatic-related forcings, such as those that modulate sediment supply. These stresses will be amplified in the future by decreased sediment supply to deltas due to the damming of their rivers.

中文翻译:

Deltaic 对气候变化的反应:Nueces Delta 的全新世历史

摘要 三角洲拥有世界各地的大型城市中心和广阔的沿海湿地。因此,它们的未来将在许多沿海社区的经济和生态健康方面发挥重要作用。尽管已经充分研究了由于沉降和海平面加速上升导致的溺水对三角洲的威胁,但对气候变化对三角洲的物理影响知之甚少。在这里,我们绘制了墨西哥湾西北部 Nueces 三角洲海岸线在过去 ~8.0 ky 的位置,以显示该三角洲在几个世纪内以大于 10 m/yr 的速度后退和退化的速度长达 22 km与此同时,全新世气候变化的独立代理记录分别表明有效降水减少和增加。这些撤退期发生在 5.0 和 3.2 ka;更早的,先前记录的 8.2 ka 撤退期是由海平面上升速度的迅速增加所驱动的。Nueces Delta 经历了 6.6 ka、3.8 ka 和 2.2 ka 的进积期。由于这些变化中的一些可能只是由撕脱或其他自生过程驱动的,我们通过量化沙子的数量来测试气候在驱动这些变化中的作用,沙子被认为是沉积物通量的保守代表,在三角洲内通过全新世. 输送到三角洲的沙子量在进积期间增加,在后退期间减少。尽管在全新世中期海平面上升速度下降,但这些变化还是发生了。这些结果表明,三角洲不仅容易受到海平面上升速度的影响,还容易受到其他气候相关强迫的影响,例如调节沉积物供应的那些。由于河流筑坝导致三角洲沉积物供应减少,这些压力将在未来被放大。
更新日期:2020-08-01
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