Water flow in a hummocky landscape in central Saskatchewan, Canada, II. Saturated flow and groundwater recharge

Abstract

Relatively few estimates of the rate of groundwater recharge have been obtained in the Interior Plains region of North America. The purpose of this study was to characterize the saturated flow system surrounding two sloughs in a hummocky upland area in central Saskatchewan and to estimate the groundwater recharge rate. The saturated flow system was dominated by two factors. First, deposits at the soil surface had a high hydraulic conductivity which resulted in rapid horizontal flow at shallow depth at the edge of the sloughs. Second, a low hydraulic conductivity layer at approximately 12 m depth impeded the rate of vertical flow. The annual fluctuation of the water table in the sloughs was in the order of 2 m, but this fluctuation was buffered by a 10 m deep saturated zone over the impeding layer, and the system approximated steady state flow. The groundwater recharge rates for the sloughs ranged from 250 to 300 mm yr −1. Accumulation of soluble salts, as indicated by electrical conductivity, and high soluble Mg 2+/Ca 2+ ratios above 5 m depth in the midslope and knoll positions indicated that minimal groundwater recharge had occurred in the past. A regional recharge rate of approximately 35 mm yr −1 or 10% of the annual precipitation was calculated based on the recharge rate and areal extent of sloughs.