Groundwater recharge in the Canadian Prairies: mechanisms, constraints, and rates
Date
2019-01-08
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Abstract
A combination of dry climate and extensive cover of low-permeability sediments reduces groundwater recharge in the Canadian Prairies to just a few percent of annual precipitation. Such recharge scarcity increases the importance of knowing recharge rates for adequate management of water resources and, simultaneously, complicates recharge rate evaluation. The present study addresses this problem by using a combination of surface conditions monitoring, geochemical methods, and remote sensing to identify recharge mechanisms and physiographic constraints on recharge, and to quantify recharge rates. The analysis of stable-isotopic data shows that groundwater recharge in the Canadian Prairies is dominated by the snow-melt-driven depression-focussed recharge pathway. The potential recharge through this pathway is limited by the volume of snow-melt that is retained within topographic depressions and, thus, is mostly constrained by just two factors: runoff generation and the available depression storage capacity. The latter is shown to be generally comparable in magnitude with typical runoff values and, thus, serves as a hard upper limit on recharge rates. The identified link between depression storage capacity values and specific types of surficial sediments allows to estimate limit on groundwater recharge rate based on the surficial geology maps. Unlike depression storage capacity, the limit on recharge rate associated with runoff volume varies over time and is sensitive to the atmospheric forcing with mid-winter melts, which are shown to be an important factor affecting both volume of snow-melt runoff and timing of groundwater recharge. The regional recharge rates are consistent with identified limiting factors and are estimated to be 8─14 mm per year in the parkland ecoregion and 3.5─6 mm per year in the grassland ecoregion.
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Keywords
groundwater recharge, DEM, stable isotopes of water, runoff, snow
Citation
Pavlovskii, I. (2019). Groundwater recharge in the Canadian Prairies: mechanisms, constraints, and rates (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.