Soil hydrodynamics and controls in prairie potholes of central Canada

Abstract

The soil moisture contents of the upland soils surrounding prairie wetlands are significant in regulating processes (e.g. infiltration, run-off and evapotranspiration) that control the prairie wetlands' water balances and fluctuations. In this research, the soil moisture data were collected with Time Domain Reflectometer (TDR) and their distributions were characterised across sites with varying climatic regime, basins with varying wetland classes and various topographic positions, during the snow-free period. The soil moisture contents of basins were variable among regions of Prairie Potholes Region (e.g. Hartt = 0.35 m3 m−3 and Old Wives = 0.18 m3 m−3) and their variability was related to regional Precipitation–Potential Evapotranspiration (P-PET) gradient, particularly for the northern sites (r2= 0.98). Additionally, the soil moisture statuses was temporally variable during the snow-free period (e.g. June = 0.27 m3 m−3 and August = 0.17 m3 m−3) and the variability displayed considerable relationship with daily P-PET (r2= 0.63). At a local scale, the soil moisture content of the basins were structured by wetland class, position within the prairie basin (uplands = 0.17 m3 m−3 and lowlands = 0.27 m3 m−3), reflective of topographic effects, and the presence and permanence of wetlands (e.g. Class I = 0.18 m3 m−3, Class II = 0.21 m3 m−3, Class III = 0.22 m3 m−3 and Class IV = 0.24 m3 m−3).