WSC Category 3: Propogating Climate-Driven Changes in Hydrologic Processes and Ecosystem Functions across Extreme Biophysical and Anthropogenic Gradients

在世界上许多干旱和半干旱地区，包括美国西部的大部分地区，水资源管理计划是基于这样一种假设，即积雪容纳了大部分的水，随着水库的供水量被计量以满足人类的水和电力需求以及环境流量要求，积雪逐渐融化以补充水库。 这一点在加州的内华达州山脉最为明显，这一偏远而人烟稀少的山脉为数百万人提供了水和电力。 虽然众所周知，这一山脉的陡峭的海拔梯度、土壤和植被使其对气候变化极为敏感，但人们对这些地区的基本水文过程与水可持续性问题之间的联系并不十分了解。 该项目将量化一系列记录在案的气候变化情景对融雪、径流、高海拔水库运行（水电、防洪和娱乐）和低海拔多用途水库运行（灌溉、防洪、环境流量和娱乐）的影响。 圣华金河流域将作为本研究的原型，其结果将转移到其他积雪控制的河流流域。 拟议项目的科学目标是将我们对气候对山区水文过程的影响以及由此产生的变化的新的过程层面的理解与河流对由水维持但由人类价值观和政策决定的生态系统服务的反应联系起来。 假设是美国西部半干旱地区的气候变化，由此导致的冰雪流域年径流量提前的转变将产生涟漪反应，沿着山前向下传播，迫使人类做出反应，改变高海拔水电和低地供水水库的运作，从而改变低地水生和河岸生态系统的功能。 我们将使用当前的水文过程模拟模型来测试这一假设，该模型整合了来自NSF南部Sierra临界区观测站、州（加州水资源部）和联邦机构（美国垦务局、美国鱼类和野生动物管理局）的现有数据。 这些模拟模型将由2010 - 2099年存档的全球气候模型（GCM）输出（温度、降水）驱动。该项目将澄清可能的气候变化情景、河流流量、水库储存和释放以及依赖降雪的河流流域地下水储存和提取之间的联系。 此外，通过与河流流域主要利益攸关方的接触，该项目将产生实用指南，指导如何最好地使政策适应不断变化的水文条件，以维持未来的供水、能源和水生生态系统需求。 圣华金河流域被选为研究主题，因为它体现了半干旱西部的水和可持续性问题，因为（1）由于依赖积雪和水库网络进行水电、防洪和供水，易受气候变化的影响;（2）2009年秋季开始的大规模低地鲑鱼恢复工作。

1204841HarmonIn many arid and semi-arid regions of the world, including much of Western U.S., water resources management plans are predicated on the assumption that the snow pack holds the majority of the water, gradually melting to replenish the reservoirs as their supplies are metered out to satisfy human water and power demands, and environmental flow mandates. Nowhere is this more evident than in the Sierra Nevada Mountains in California, the remote and sparsely populated mountain range providing the water and power for millions of people. While it is known that this mountain range's steep gradients in elevation, soils and vegetation render it extremely sensitive to climate change, the connection between the underlying hydrologic processes and the water sustainability issues in these regions is not well understood. This project will quantify the effect of a range of documented climate change scenarios on snow melt, runoff, high elevation reservoir operation (hydropower, flood control and recreation) and low elevation multi-purpose reservoir operation (irrigation, flood control, environmental flows and recreation). The San Joaquin River Basin will serve as the prototype for this study, the outcomes of which will be transferrable to other snowpack-controlled river basins. The scientific goal of the proposed project is to connect our emerging process-level understanding of climatic influences on mountain hydrologic processes and resulting changes to the stream response to the ecosystems services sustained by water but dictated by human values and policies. The hypothesis is that changing climate variability in the semi-arid western U.S., and the resulting shift toward an earlier annual runoff in snow-dominated watersheds will create a ripple effect, propagating down the mountain front to force human responses in the form of changes to high elevation hydropower and lowland water supply reservoir operations, and therefore changes to lowland aquatic and riparian ecosystem functions. We will test this hypothesis using current hydrologic process simulation models integrate existing data from the NSF Southern Sierra Critical Zone Observatory, and from state (California Department of Water Resources) and federal agencies (U.S. Bureau of Reclamation, U.S. Fish and Wildlife Service). These simulation models will be driven by archival Global Climate Model (GCM) outputs (temperature, precipitation) for the years 2010 - 2099.This project will clarify the connection between likely climate change scenarios, stream flows, reservoir storage and releases, and groundwater storage and extractions for snow-dependent river basins. Furthermore, through engagement with key river basin stakeholders, the project will result in practical guidelines to how best to adapt policy to the changing hydrologic conditions in order to sustain water supply, energy and aquatic ecosystem needs in the future. The San Joaquin River basin was selected as the subject of study because it embodies water and sustainability issues in the semi-arid West given (1) its vulnerability to climatic variation due to its reliance on snow pack and a network of reservoirs for hydropower, flood control, and water supply; and (2) its massive lowland river salmon restoration effort, which was initiated in Fall 2009.