Doctoral Dissertation Research: Understanding Intermittent Water Sources and Impacts on Fish to Design Optimal Water Conservation Strategies

水资源方面的一个主要问题是如何在维持河流生态系统和渔业的溪流的同时，为人类提供用水。断断续续的溪流为鲑鱼提供了栖息地，也为农业提供了水资源，在夏末干涸成一系列互不相连的池塘。为了减轻河流压力，保护濒临灭绝的幼年鲑鱼的栖息地，社区越来越多地研究节约用水的替代方案，如雨水收集和地下水补给。最近的试点项目提供了一个及时和前所未有的机会，以解决关于环境变量、生态系统服务和日益稀缺的水资源的最佳管理之间的联系的跨学科问题。该项目预计将对基础科学做出新的贡献，包括了解与鱼类生存有关的过程，以及间歇性溪流中碳分解、径流和沉积物运输之间的相互作用。通过将鲑鱼的存活与可预测的环境特征联系起来，并更好地理解这些关键变量，研究结果可能适用于区域和全国范围内季节性干旱的流域。该项目将促进科学家和多个利益攸关方群体之间的互利互动，他们也将受益于管理其自然资源的新电子工具。研究结果将通过学术出版物和区域研讨会以及为利益攸关方编写的文件和公民科学门户网站传播。该项目具体解决了一个基本的知识差距：在夏季干旱时期，是什么栖息地条件导致一些池塘中的鲑鱼消失？该项目基于对加州索诺马公司鲑鱼溪两条支流进行的为期两年的实地研究：一条是贯穿整个夏季的制革厂溪，另一条是往往干涸成一系列孤立池塘的费溪。通过对这些相邻溪流的广泛采样，这项研究将检验这样一种假设，即冲洗不良的池塘中有机物质的积累会导致溶解氧的下降，从而导致鲑鱼类的损失。两条支流的鱼类调查将与温度、溶解氧、水深和流速、池塘体积以及有机碳浓度和质量的测量相结合。将在四个研究河段进行更深入的研究，重点是监测这些属性在溪流干涸时如何变化，并确定哪些含水层支持保护区池塘。使用线性混合模型，这项研究将量化地下水的贡献和流向为鲑鱼提供关键避难所的池的路径，并确定应该作为加强渗透的目标的含水层。这项工作还将评估雨水收集在有管理的地下水补给和没有管理的地下水补给的情况下对鲑鱼栖息地的影响。作为博士论文研究改进奖，该项目将为有前途的学生建立独立的研究生涯提供支持。更多地了解地下水和溪流之间的相互作用，将使居民和资源涵养区能够以节水和雨水收集项目为目标，这些项目将为溪流生态系统带来最大好处。致力于恢复鲑鱼的科学家将受益于通过便利的协作讲习班和项目开发的公民科学传播工具增加获取当地知识和观察的机会。

A major question in water resources is how to provide water for human uses while maintaining streamflow that sustains riverine ecosystems and fisheries. Intermittent streams, which provide habitat for salmonid fishes and water resources for agriculture, dry up into a series of disconnected pools in the late summer. To alleviate pressure on rivers and conserve habitat for juvenile salmon on the brink of extinction, communities are increasingly examining water conservation alternatives such as rainwater harvesting and groundwater recharge. Recent pilot projects provide a timely and unprecedented opportunity to address interdisciplinary questions about linkages among environmental variables, ecosystem services, and optimal management of increasingly scarce water resources. This project is expected to produce novel contributions to fundamental science, including understanding processes related to fish survival and the interactions among carbon decomposition, streamflow, and sediment transport in intermittent streams. By relating salmonid survival to predictable environmental characteristics and creating a better understanding of these critical variables, the research findings are likely to have applicability to seasonally dry watersheds region-and nation-wide. The project will facilitate mutually beneficial interactions between scientists and multiple stakeholder groups, who will also benefit from new e-tools for managing their natural resources. Findings will be disseminated through scholarly publications and at regional symposia as well as through documents developed for stakeholders and a citizen science web portal.This project specifically addresses a fundamental knowledge gap: what habitat conditions cause salmonids to disappear from some pools during the summer dry period? This project builds on a two-year field study in two tributaries of Salmon Creek (Sonoma Co., CA): Tannery Creek, which flows throughout the summer, and Fay Creek, which tends to dry into a series of isolated pools. Through extensive sampling in these adjacent streams, this research will test the hypothesis that accumulation of organic material in poorly flushed pools drives declining dissolved oxygen associated with a subsequent loss of salmonids. Fish surveys in the two tributaries will be paired with measurements of temperature, dissolved oxygen, water depth and velocity, pool volume, and organic carbon concentrations and quality. More intensive studies, focused on monitoring how these attributes change as the stream dries and determining which aquifers sustain sanctuary pools, will be conducted in four study river segments. Using linear mixing models, this research will quantify groundwater contributions and flowpaths to pools that provide critical refugia for salmon, and identify aquifers that should be targeted for enhanced infiltration. This work will also evaluate how rainwater harvesting will impact salmonid habitat with and without managed groundwater recharge. As a Doctoral Dissertation Research Improvement award, this project will provide support to enable a promising student to establish an independent research career. Increased understanding of interactions between groundwater and streamflow will enable residents and resource conservation districts to target water conservation and rainwater harvesting projects where they will yield the greatest benefit to stream ecosystems. Scientists working on salmonid recovery will benefit from increased access to local knowledge and observations via facilitated collaborative workshops and project-developed citizen science dissemination tools.