Multi-scale controls of soil water dynamics and connectivity

虽然土壤水占全球水文循环水量的0.001，但对于地球陆地生态系统的所有居民来说，它是一种维持生命的资源。粮食、纤维和燃料的生产在很大程度上依赖于植物所需的土壤水分。它还决定各种生态系统服务，如食物和淡水，调节洪水，并控制农用化学品和废物的溶解和运输(通过径流)。要了解土壤水和土壤水中的可溶性物质(如养分、农用化学品)的储存和运输是如何发生的，需要了解水的流动速度(作为地表和地下径流)以及它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创建(断开)连接的优先流动路径破坏。我把运输过程中的这种(非)联系称为‘土壤水分连通性’。对地学中出现的一些重要的基础和应用问题，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，研究连通性是至关重要的。拟议的研究重点是包气带(根区)内土壤水的连通性，并将使用基于现场和实验室的先进工具和计算机模型。在这一资助期间，我的核心研究问题是：1)连接性到底是什么，2)我们如何定义、测量和建模连接性，以及3)我们能否将连接性与最近的研究联系起来？这些问题将在未来5年由3名博士和2名硕士学生在4名本科生暑期实习生的帮助下通过四个可检验的假设进行检验。这些研究将1)更好地定义流域内不同尺度上的土壤水连通性动态，这将导致土壤水被纳入更多的水文、气候和陆面模型中；2)展示土壤水对于洪水管理(通过径流的开始、流动的连接)、扩散污染缓解以及环境健康改善的关键性质。从长远来看，该研究计划将解决有关包气带在多个空间/时间尺度上的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，这一点在当今特别重要，因为全球都在关注维持饮用水供应和保护淡水免受污染，以及对人类和环境健康的影响。

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.