Effect of Erosion on the Hydrogeological Behaviour of Badland Surfaces in Western Canada

Climatic conditions and in situ lithology govern the hydrogeological behaviour of badland surfaces in western Canada. Based on field observations, samples representing three distinct surfaces in the Avonlea badlands (60 km SSW of Regina) of Saskatchewan were collected. The influence of erosion on the engineering properties of this typical indigenous badland profile was investigated by measuring the grain size distribution (GSD) using dry sieving and wet sieving along with hydrometer analysis and estimating the soil water characteristic curves (SWCC) from the two sets of laboratory data. Results indicated that the various selected sediments respond differently to the same weather changes and that the angle of repose slopes at the site closely correspond to possible erosion patterns. Based on an increase in fines (material finer than 0.075 mm), grain size thinning was found to be highest in weathered mudrock (75%) followed by basal pediment (32%) and then by cemented sandstone (16%). The estimated air entry values (AEV) corresponding to dry sieving and wet sieving plus hydrometer analysis followed the same trend: 0.6 kPa and 2340 kPa; 1.6 kPa and 7 kPa; and 1.6 kPa and 1.6 kPa for the three materials, respectively.