Water redistribution and the fate and transport of chemicals in nonlevel landscapes

土壤水分是作物生产、洪水、径流和土壤温室气体排放的关键变量。农用化学品或废物的命运和运输也受到影响，它们通过径流进入地表水，导致地下水，排放到大气中，或被植物吸收。加拿大草原景观是不平坦的，这将改变水分通道，增加土壤水分的时空变异性。这项工作的长期目标是量化和发展理论来预测非水平景观中的土壤水动力学和化学物质的命运。在短期内，目标和研究方法将是：(1)开发单探针和圆柱探针热脉冲方法，用于测量热性质和土壤含水量；(2)利用分布式温度传感器在景观尺度上测量土壤含水量和热特性；(3)在土壤、坡面和景观尺度上量化土壤水热动态的主导控制因素。将沿着景观中的样带测量土壤含水量。评估土壤水分、根系水分吸收与地形之间的空间变异和尺度关系，确定主要的变异尺度；(4)建立和验证不同植被覆盖、土壤性质和地形条件下的土壤水热动态模型。在目标3的基础上，将开发一个考虑间歇性降雨入渗的模型，然后将其用作预测山坡和景观尺度上土壤水动力学总体趋势的工具。通过本研究获得的知识将进一步了解景观水文学，并最终在生态系统中土壤水动力学。后者将有助于在半干旱环境中量化植物演替、生物多样性和水质。

Soil water is a key variable in crop production, flooding, runoff, and greenhouse gas emission from soils. Also affected are the fate and transport of agrochemicals or wastes, via runoff to surface water, leading to groundwater, emission to the atmosphere, or uptake by plants. Canadian prairies landscapes are not level, which will change water pathways and increase both spatial and temporal variability of soil water. The long term objective to this work is to quantify, and develop theories to predict soil water dynamics and the fate of chemicals in non-level landscapes. In the short term, the objectives and the research approach will be to (1) develop single probe, and cylindrical probe heat pulse methods for measuring thermal properties and soil water content; (2) measure soil water content and thermal properties over the landscape scales using the distributed temperature sensor; (3) quantify the dominant controls of soil water and thermal dynamics at the pedon, slope, and landscape scales. Soil water content will be measured along a transect in a landscape. The spatial variation of and scaling relationships between soil water, root water uptake, and the topography will be evaluated and dominant scales of variation be identified; and (4) develop and validate models for soil water and thermal dynamics under different vegetation covers, and soil properties and topographies. Based on objective 3, a model taking into account of intermittent rainfall infiltration will be developed, and will then be used as a tool for predicting the general trend in soil water dynamics on a hillslope and at a landscape scale. The knowledge gained through this study will further the understanding of the landscape hydrology, and eventually the soil water dynamics in ecosystems. The latter will be useful for quantifying plant succession, biodiversity, and water quality in semi-arid environments.