NSF Rapid Proposal: Flows of the future: Capitalizing on an extreme weather year to evaluate future summer streamflows in the Cascades

雪是太平洋西北部和美国西部森林、水生生态系统和社区的重要水分来源。2014-2015年的冬天是有记录以来最温暖的冬天，随后是一个异常温暖，干燥的春天，导致历史上较低的流量和早期宣布整个俄勒冈州西部的干旱状况。 这种水文干旱代表了可以方便地通过下游水位计监测的径流量的总体减少。 然而，下游流量计难以评估流量减少对上游的影响。 因此，有必要评估源头河流对降雨量减少和气象干旱的反应。 了解如何源头流的反应（以及通过什么机制）气象干旱将使上游生态响应方面的流计记录的解释。实地活动将为本科生提供有价值的实地培训，进行科学上令人兴奋和社会相关的研究。这项研究工作还将为博士后研究人员提供指导和培训本科生的机会。 调查人员将通过一系列协调的活动来利用这一机会，包括：1）与公共和私人供水和电力公司会面，为未来流量预测提供框架; 2）与联邦和州土地和水管理人员会面，分享调查结果，讨论低流量对水资源可用性和生态后果的影响; 3）与记者合作，传播准确的实时调查结果（类似于每月的降雪报告）。 这一建议假定，源头河流可以通过横向或纵向收缩来应对干旱。 而且，春季供水的河流将从连续的春季流出水平“跳跃”，而表面流供水的河流将收缩。 这些水源地区将有不同的化学特征，他们可以跟踪。 研究区域包括：（a）表面流为主的西瀑布流域，代表一个快速的基流衰退和非常低的夏季流量的山洪暴发的径流制度;和（B）春季喂养的高瀑布流域，代表一个缓慢响应的径流制度，长期和持续的基流衰退，保持夏季后期的径流通过深层地下水的贡献，高容量的冷水泉。 研究人员将使用基于实地的方法收集和分析整个旱季（大约从6月到10月（或第一次降雨事件））的春季和地表径流主导流域的数据。夏季径流衰退将使用美国地质勘探局的主干计和项目阶段高度/流量关系，为我们的小溪流。将通过重复测量每个流域的渠道水头位置和持续监测水源泉的水温（水存在/不存在的指示）来检验纵向收缩假设。河流的横向收缩假设将通过重复调查每条河流的多个断面来检验。

Snow is a crucial moisture source for forests, aquatic ecosystems, and communities in the Pacific Northwest and across the western US. The winter of 2014-2015 was the warmest winter on record followed by an anomalously warm, dry spring resulting in historically low streamflows and early declarations of drought conditions across western Oregon. This hydrologic drought represents an overall decrease in streamflow that can be monitored conveniently by downstream gages. However the upstream impact of decreased streamflow is difficult to assess from downstream gages. It is therefore necessary to assess how headwater streams react to decreased rainfall and meteorologic drought. Understanding how headwater streams react (and by what mechanisms) to meteorologic drought will enable the interpretation of stream gage records in terms of upstream ecological response. The field campaign will provide undergraduates with valuable field training, conducting scientifically exciting and societally relevant research. This research effort will also provide the post-doctoral researcher with an opportunity to mentor and train undergraduates. The investigators will capitalize on this opportunity through a coordinated set of activities including: 1) meeting with public and private water supply and power utilities to provide a framework for future flow forecasting; 2) meeting with Federal and State land and water managers to share findings and discuss implications for water availability and ecological consequences of low flows; and 3) working with journalists to disseminate accurate real-time findings (similar to the monthly snow report). This proposal posits that headwater streams can respond to drought by contracting laterally or longitudinally. And that spring fed streams will respond with "jumps" from sequential spring outflow levels whereas surface flow fed stream will contract. These source regions for water will have chemically differing signatures which they can track. The study region includes (a) surface-flow dominated Western Cascades watersheds, representing a flashy streamflow regime with rapid baseflow recession and very low summer flows; and (b) the spring-fed High Cascades watersheds, representing a slow-responding streamflow regime with a long and sustained baseflow recession that maintains late summer streamflow through deep-groundwater contributions to high-volume coldwater springs. The investigators will use a field-based approach to collect and analyze data from both spring-fed and surface flow-dominated watersheds throughout the dry season, from approximately June through October (or first rainfall event of consequence). Summer streamflow recession will be monitored using USGS mainstem gages and project stage height/stream discharge relationships developed for our small streams. The longitudinal contraction hypotheses will be tested by repeat measurements of channel head locations in each watershed and continuous monitoring of water temperature (an indication of presence/absence of water) at headwater springs. The lateral contraction hypotheses of streams will be tested by repeat surveys of multiple transects per stream.