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

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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.