SGER: How Do Hillslope-to Catchment-Scale Flowpaths Develop in Response to an Extreme Drought Followed by Record Precipitation

这项研究将利用新墨西哥州北部前所未有的降水量变化水平，从机制上改善对集水区内水的路线和停留时间的理解。在过去的六年里，新墨西哥州北部一直在经历严重的干旱。2006年水年的开始延续了这一枯水期，降雪量达到了有记录以来的最低水平，导致我们研究地点的一级、二级和一些三级溪流到2006年夏季干涸。然而，2006年季风季的特点是总降雨量是112年来最高的，这使过去干燥的溪流在2006年秋季恢复了流量。我们建议利用这一不同寻常的事件，结合我们研究地点正在进行的生态水文学研究，开发分布式水文对降水变化的响应的数据和模型。我们的研究设计包括八个嵌套的一阶子流域，呈放射状分布在一座中心山脉周围。这八个子集水区汇入三条以前用仪器测量过的溪流，然后汇合在一起，形成我们研究地点的一个出口。尽管整个流域的植被和母质相似，但与坡向相关的水和能量的变化导致土壤深度和发育的模式非常不同。作为之前研究工作的一部分，最初的河流地球化学监测表明，与这些模式相关的水在方面的停留时间非常不同。我们的项目将直接满足对现场数据的需求，以实际测试集水区径流发展的模型，而不是简单地匹配模型。我们期待这项活动在了解对景观中水的空间和时间变化的控制方面取得重大进展。此外，从物理和空间上真实地表示从山坡到小流域尺度的水运动，将使我们能够定量评估生物地球化学循环元素的生产和出口如何对降水的变化作出反应。

This study will take advantage of an unprecedented level of variability in precipitation in northern New Mexico to improve the mechanistic understanding of the routing and residence time of water within catchments. Northern New Mexico has been experiencing a severe drought for the last six years. The beginning of the 2006 water year continued this dry period with the lowest snowpack in recorded history resulting in first, second, and some third order streams at our study site running dry by summer 2006. The 2006 monsoon season however was characterized by the highest precipitation totals in 112 years which has reestablished flow in the formerly dry streams through the fall of 2006. We propose to take advantage of this unusual event, combined with ongoing studies in the ecohydrology of our study sites, to develop both the data and the model representations of the distributed hydrological response to variability in precipitation. Our study design includes eight nested first order sub-catchments located radially around a central mountain. These eight sub-catchments drain into three previously-instrumented streams, which subsequently join to form a single outlet from our study site. Although vegetation and parent material are similar throughout the catchments, variability in water and energy related to aspect result in very different patterns in soil depth and development. Initial stream geochemical monitoring, conducted as part of previous research efforts, suggests very different residence times of water related to these patterns in aspect. Our project will directly address the need for field data to actually test models of catchment flow path development, rather than simply match models. We expect this activity to make significant advances in understanding the controls on the spatial and temporal variation of water in the landscape. Furthermore, the physically-based, spatially-realistic representation of water movement at the hillslope to small catchment scale will allow a quantitative evaluation of how the production and export of biogeochemical cycling elements respond to variability in precipitation.