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变化水平，以提高对集水区内水的路径和停留时间的机制理解。过去六年来，新墨西哥州北部一直经历着严重的干旱。2006年水年的开始延续了这一干旱期，有记录以来的最低积雪量导致我们研究地点的一级、二级和一些三级河流在2006年夏季干涸。然而，2006年季风季节的特点是112年来最高的降水总量，这使2006年秋季以前干涸的河流恢复了流量。我们建议利用这一不寻常的事件，结合我们研究地点正在进行的生态水文学研究，开发降水变化的分布式水文响应的数据和模型。我们的研究设计包括八个嵌套的一级子集水区，这些集水区呈放射状分布在中央山脉周围。这八个子集水区汇入三个先前测量的溪流，随后从我们的研究地点连接形成一个单一的出口。虽然整个流域的植被和母质相似，但与坡向有关的水和能量的变化导致了土壤深度和发育的非常不同的模式。作为先前研究工作的一部分，进行了初步的河流地球化学监测，表明在这些方面，水的停留时间与这些模式有关。我们的项目将直接解决现场数据的需求，以实际测试集水区流动路径开发的模型，而不是简单地匹配模型。我们期望这项活动能够在理解对景观中水的时空变化的控制方面取得重大进展。此外，从山坡到小流域尺度的水运动的基于物理的、空间现实的表征将允许定量评估生物地球化学循环元素的产生和输出如何响应降水的变化。

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.