Abstract Surface water supply for a watershed relies on local water generated from precipitation and water connections with other watersheds. These connections are confined by topography and infrastructure, and respond diversely to stressors such as climate change, population growth, increasing energy and water demands. This study presents an integrative simulation and evaluation framework that incorporates the natural and anthropogenic water connections (i.e., stream flows, inter-basin water transfers, water withdrawals and return flows) among the 2099 8-digit Hydrologic Unit Code (HUC-8) watersheds across the conterminous United States. The framework is then applied to investigate the potential impacts of changes in climate and water use on regional water availability and water stress (the ratio of demand to supply). Our projections suggest that highly water-stressed areas may expand from 14% to 18% and the stressed population would increase from 19% to 24% by 2070–2099. Climate-change mitigation practices (e.g., energy structure reform, technology innovation) could largely offset these trends by reducing demand and enhancing supply. At the watershed scale, the spatially inhomogeneous responses to future changes suggest that regional water connectivity could significantly buffer the potential stress escalations due to the redistribution of water resources and diverse changes in consumptive uses and water supplies in different source areas. However, the detrimental future changes (e.g., depleting river discharges, larger demands of water withdrawal) may aggravate conflicts over water rights among regions and challenge our current water infrastructure system. This study provides new insights into the critical role of regional water connectivity in water supply security, and highlights the increasing need for integrated monitoring and management of water resources at various spatial levels in a changing world.

中文翻译：

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了解区域水连通性在减轻气候变化对美国地表水供应压力的影响方面的作用

摘要 流域的地表水供应依赖于当地降水产生的水以及与其他流域的水连接。这些联系受地形和基础设施的限制，并对气候变化、人口增长、能源和水需求增加等压力因素做出不同的反应。本研究提出了一个综合模拟和评估框架，其中包含 2099 年 8 位水文单位代码 (HUC-8) 流域之间的自然和人为水连接（即河流流量、流域间调水、取水和回流）横跨美国本土。然后应用该框架来研究气候和用水变化对区域水资源可用性和水资源压力（供需比）的潜在影响。我们的预测表明，到 2070 年至 2099 年，高度缺水的地区可能会从 14% 扩大到 18%，而受压人口将从 19% 增加到 24%。减缓气候变化的做法（例如，能源结构改革、技术创新）可以通过减少需求和增加供应在很大程度上抵消这些趋势。在流域尺度上，对未来变化的空间不均匀响应表明，区域水连通性可以显着缓冲由于水资源再分配和不同源区消费用途和供水的多样化变化而导致的潜在压力升级。然而，未来不利的变化（例如，河流流量枯竭，取水需求增加）可能会加剧地区之间的水权冲突，并挑战我们当前的水利基础设施系统。