Soil moisture patterns: linking hydrological processes at the event and inter-event time scales

土壤-植被-大气传输（SVAT）模型和气候模型需要更好地预测气候变化或土地利用变化的影响。要做到这一点，他们必须描述的横向水分通量，并占土壤水分的空间变异性比目前更现实，因为在植物有效水的异质性可以有很大的影响，对地表能量和水收支。拟议的研究的目的是获得一个系统的了解三维土壤水分动态和环境或现场条件控制的发展空间土壤水分模式和空间变异性的侧流。现场实验侧重于事件和事件间的时间尺度将结合建模实验。田间试验将在Malcolm克纳普研究森林进行。实地测量将遵循嵌套的方法，以包括所有景观单元，并能够探索规模效应。将在多个地点人工测量整个土壤剖面的土壤湿度，并在多个地点连续测量。为了确定土壤水分和蒸腾作用之间的反馈，将用恒热液流传感器测量液流。3D土壤水分模式将与降水事件期间的横向流动模式相关，因为内部地下水位动态也将被表征。在雨季和旱季的示踪剂实验将支持确定的空间变异性和发生的横向地下流。这些现场试验的数据将用于开发和验证分布式水平衡模型，该模型将用于虚拟试验和情景测试模式。该模型将用于确定在何种环境条件下形成特定的土壤水分模式。在未来，这一新的信息将被纳入决策树的方法，以确定什么类型的土壤水分的空间变异可能会发生在一个地区，什么将是一个适当的代表性的横向水通量。这将导致在SVAT模型中横向水文过程的更具体的表现，并更好地预测土地利用或气候变化的影响。

Soil-Vegetation-Atmosphere-Transfer (SVAT) models and climate models need to better predict the effects of climate change or land use change. To do so they must describe the lateral moisture fluxes and account for the spatial variability in soil moisture more realistically than at present because heterogeneity in plant available water can have a strong impact on the surface energy and water budgets. The objective of the proposed research is to obtain a systematic understanding of the 3D soil moisture dynamics and the environmental or site conditions controlling the development of spatial soil moisture patterns and spatial variability in lateral flow. Field experiments focusing on both the event and the inter-event time scales will be combined with modeling experiments. The field experiments will be conducted in the Malcolm Knapp Research Forest. The field measurements will follow a nested approach in order to include all landscape units and to be able to explore scale effects. Soil moisture will be measured manually throughout the soil profile at many locations and continuously at several locations. To determine the feedbacks between soil moisture and transpiration, sapflow will be measured with constant heat sapflow sensors. The 3D soil moisture patterns will be related to lateral flow patterns during precipitation events as the internal water table dynamics will be characterized as well. Tracer experiments in the wet and the dry season will support the determination of the spatial variability and occurrence of lateral subsurface flow. The data from these field experiments will be used to develop and validate a distributed water balance model, which will be used in a virtual experiment and scenario testing mode. The model will be used to determine under which environmental conditions specific soil moisture patterns form. In the future this new information will be incorporated in a decision tree approach to determine what type of spatial variability in soil moisture is likely to occur in an area and what would be an appropriate representation of the lateral water fluxes. This will lead to more site specific representations of lateral hydrological processes in SVAT models and better predictions of the effects of land use or climate change.