Multi-scale controls of soil water dynamics and connectivity

虽然土壤水在全球水文循环中所占的比例不到0.001，但它是地球陆地生态系统所有居民维持生命的资源。粮食、纤维和燃料的生产在很大程度上取决于土壤水对植物的供应。它还决定各种生态系统服务，如食物和淡水，调节洪水，控制农用化学品和废物的溶解度和运输（通过径流）。了解土壤水和土壤水内可溶性物质（例如营养物质，农用化学品）的储存和运输方式需要了解水的流动速度（地表和地下径流）以及到达溪流和河流的路径。然而，这些过程经常被在不同点之间产生（断开）连接的优先流动路径中断。我把这种（不）连接在运输过程中的“土壤水连通性”。研究连通性对于地球科学中出现的一些重要的基础和应用问题至关重要，包括土壤水动力学在全球水循环中的作用和保护地表水体免受污染。拟议的研究重点是渗流区（根区）内土壤水的连通性，并将使用先进的现场和实验室为基础的工具和计算机模型。在此期间，我的核心研究问题是：1）连接到底是什么，2）我们如何定义，测量和建模连接，以及3）我们可以将连接与最近的研究联系起来吗？这些问题将通过四个可检验的假设进行研究3博士和2硕士学生的帮助下，4个本科暑期实习生在未来5年。这些研究将：1）更好地定义集水区内不同尺度的土壤水连通性动态，这将导致土壤水被纳入更多的水文、气候和地表模型; 2）显示土壤水对于洪水管理（通过径流的开始、流动连接）、减轻扩散污染以及改善环境健康的关键性质。从长远来看，该研究计划将解决多个空间/时间尺度上的包气带水文动力学及其参与全球水循环的基本问题。这项研究计划将保持和建立加拿大在水资源管理方面的形象，这在今天特别重要，因为全球关注维持饮用水供应和保护淡水水体免受污染，以促进人类和环境健康。

Although soil water represents <0.001 of water in the global hydrological cycle, it is a life-sustaining resource for all inhabitants of Earth’s terrestrial ecosystems. Food, fiber and fuel production is strongly dependent on the availability of soil water for plants. It also determines various ecosystem services such as food and freshwater, regulates flood, and controls the solubility and transport of agrochemicals and wastes (via runoff). Understanding how storage and transport of soil water and soluble materials within the soil water (e.g. nutrients, agrochemicals) occurs requires knowledge about how fast water travels (as surface and subsurface runoff) and which path it takes to reach streams and rivers. However, these processes are often disrupted by preferential flow paths that create (dis)connection between different points. I refer this (dis)connection in transport processes as ‘soil water connectivity’. Examining the connectivity is essential for a number of important fundamental and applied problems that have emerged in the geoscience including the role of soil water dynamics in global water cycle and protection of surface water bodies from pollution. The proposed research focuses on the connectivity of soil water within the vadose zone (root zone) and will use advanced field and laboratory based tools and computer models. During this grant period, my core research questions are: 1) what exactly is connectivity, 2) how can we define, measure, and model connectivity, and 3) can we relate the connectivity to recent research? These questions will be examined through four testable hypotheses in studies conducted by 3 PhD and 2 MSc students with the help of 4 undergraduate summer interns over the next 5 year. These studies will 1) better define the dynamics of soil water connectivity at different scales within a catchment which will lead to soil water being included in more hydrologic, climate and land-surface models and 2) show the critical nature of soil water for flood management (through the onset of runoff, flow connections), diffuse pollution mitigation and thus the improvement of environmental health. Over the long term, the research program will address fundamental questions about vadose zone hydrological dynamics at multiple spatial/temporal scales and their participation in the global water cycle. This research program will maintain and build Canada’s profile in water resources management, which is particularly relevant today due to the global concern about sustaining the supply of potable water and protecting fresh water bodies from pollution, for human and environmental health.