Due to increasing water use, diversion and salinization, along with subsidence and sea-level rise, deltas in arid regions are shrinking worldwide. Some of the most ecologically important arid deltas include the Colorado, Indus, Nile, and Tigris-Euphrates. The primary stressors vary globally, but these deltas are threatened by increased salinization, water storage and diversion, eutrophication, and wetland loss. In order to make these deltas sustainable over time, some water flow, including seasonal flooding, needs to be re-established. Positive impacts have been seen in the Colorado River delta after flows to the delta were increased. In addition to increasing freshwater flow, collaboration among stakeholders and active management are necessary. For the Nile River, cooperation among different nations in the Nile drainage basin is important. River flow into the Tigris-Euphrates River delta has been affected by politics and civil strife in the Middle East, but some flow has been re-allocated to the delta. Studies commissioned for the Indus River delta recommended re-establishment of some monthly water flow to maintain the river channel and to fight saltwater intrusion. However, accelerating climate impacts, socio-political conflicts, and growing populations suggest a dire future for arid deltas.

中文翻译：

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干旱环境中的三角洲

由于用水量增加、分流和盐碱化，以及沉降和海平面上升，干旱地区的三角洲正在全球范围内缩小。一些最具生态重要性的干旱三角洲包括科罗拉多河、印度河、尼罗河和底格里斯河-幼发拉底河。主要压力源在全球范围内各不相同，但这些三角洲受到盐碱化、蓄水和分流、富营养化和湿地丧失的威胁。为了使这些三角洲随着时间的推移可持续发展，需要重新建立一些水流，包括季节性洪水。在科罗拉多河三角洲的流量增加后，已经看到了积极的影响。除了增加淡水流量外，利益相关者之间的合作和积极管理也是必要的。对于尼罗河来说，尼罗河流域不同国家之间的合作很重要。流入底格里斯河-幼发拉底河三角洲的河流受到中东政治和内乱的影响，但部分流量已重新分配到三角洲。为印度河三角洲委托进行的研究建议每月重新建立一些水流量，以维护河道并对抗咸水入侵。然而，加速的气候影响、社会政治冲突和不断增长的人口预示着干旱三角洲的前景堪忧。