The role of hummocky terrain in governing runoff routing and focussing groundwater recharge in the Northern Prairies of North America is widely recognised. However, most hydrological studies in the region have not effectively utilised information on the surficial geology and associated landforms in large‐scale hydrological characterization. The present study uses an automated digital elevation model (DEM) analysis of a 6500‐km² area in the Northern Prairies to quantify hydrologically relevant terrain parameters for the common types of terrains in the prairies with different surficial deposits widespread in the prairies, namely, moraines and glaciolacustrine deposits. Runoff retention (and storage) capacity within depressions varies greatly between different surficial deposits and is comparable in magnitude with a typical amount of seasonal snowmelt runoff generation. The terrain constraint on potential runoff retention varies from a few millimetres in areas classified as moraine to tens of millimetres in areas classified as stagnant ice moraine deposits. Fluted moraine and glaciolacustrine deposits have intermediate storage capacity values. The study also identified the probability density function describing a number of immediate upstream neighbours for each depression in a fill‐and‐spill network. A relationship between depression parameters and surficial deposits, as well as identified depression network structure, allows parametrisation of hydrologic models outside of the high‐resolution DEM coverage, which can still account for terrain variation in the Prairies.

This study evaluates the applicability of the chloride mass balance (CMB) method for groundwater recharge estimation in a semi-arid region in Canada, where recharge largely occurs under topographic depressions. The CMB applicability was tested at three scales: point-scale recharge rates at different topographical positions; average recharge rates incorporating multiple topographical positions on a local scale; and an identification of spatial trends of recharge on a regional scale. Agricultural chloride inputs were shown to be a major factor affecting chloride concentrations at all three scales, where elevated chloride concentrations in the shallow subsurface affected by agricultural inputs surpassed background concentrations by an order of magnitude. The propagation depth of elevated concentrations varied among study sites from being largely confined to the unsaturated zone to extending well into the saturated zone. Lateral chloride redistribution further affected the CMB applicability for point-scale recharge rates. Specific solutions enabling the CMB application in these conditions are presented, including runoff concentration measurements for point-scale estimates, using groundwater age tracers on a local scale, and using the harmonic mean concentration of a large number of samples on a regional scale.

Abstract. Snowpack accumulation and depletion are important elements of the hydrological cycle in the prairies. The surface runoff generated during snowmelt is transformed into streamflow or fills numerous depressions driving the focused recharge of groundwater in this dry setting. The snowpack in the prairies can undergo several cycles of accumulation and depletion in a winter. The timing of the melt affects the mechanisms of snowpack depletion and their hydrological implications. The effects of midwinter melt were investigated at three sites in the Canadian prairies. Unlike net radiation-driven snowmelt during spring melt, turbulent sensible heat fluxes were the dominant source of energy inputs for midwinter melt occurring in the period with low solar radiation inputs. Midwinter melt events had lower runoff ratios than subsequent spring melt events and had strong impacts on the timing of the focussed recharge. Remote sensing data have shown that midwinter melt events regularly occur under the present climate throughout the Canadian prairies.

Abstract Application of stable isotope methods to evaluate the contribution of different water sources to groundwater recharge relies on the knowledge about isotopic signatures of these sources. The data collected at study sites in the Canadian Prairies show that snowpack isotopic signatures exhibit a high spatial variability over a small scale (