Snowpack and groundwater recharge in the Atlas mountains: New evidence and key drivers

• Published in: Journal of hydrology. Regional studies Vol. 49; p. 101520
• Main Authors: Rhoujjati, Nadia, Ait Brahim, Yassine, Hanich, Lahoucine, Rhoujjati, Ali, Rafik, Abdellatif, Ouatiki, Hamza, Chehbouni, Abdelghani, Bouchaou, Lhoussaine
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2023; Elsevier
• Subjects: Atlas mountains; GRACE; Groundwater; Isotopes; Recharge; Snowmelt; Atlas mountains; Snowmelt; Recharge; Groundwater; Isotopes; GRACE
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2023.101520

The Atlas Mountains of Morocco, specifically the High Oum Er-rbiaa (HOER) and Ourika catchments.
to identify the recharge processes within the semi-arid watersheds, in the Atlas Mountains, through monthly monitoring of snow, rainfall, surface water, and groundwater isotope signal, but also the usage of remote sensing data.
The spatial-temporal analysis of groundwater and precipitation isotopes reveals significant spatial heterogeneity, primarily influenced by the geological variations in each aquifer. Temporal variations indicate that direct recharge occurs in response to winter precipitation, whereas a delayed response is observed during the summer when snow replenishes groundwater towards the end of the melting season. The findings are further supported by the "Gravity Recovery and Climate Experiment" (GRACE) dataset, which demonstrates that high values of Total Water Storage (TWS) align with groundwater isotopes. This highlights the substantial groundwater abstraction rate between March and June to compensate for the lack of precipitation during this period. The analysis of isotope data indicates that 50% of groundwater recharge in the upstream Jurassic aquifer and 80% in the downstream Triassic-Paleozoic aquifers in the HOER catchment is sourced from snowmelt. Similarly, in the Ourika catchment, snowmelt contributes 30% and 50% of groundwater recharge in the upstream and downstream portions of the catchments respectively. This disparity is due to different melting rates across altitudinal ranges and variations in the lithology of each catchment.
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•The main objective of the research is to identify recharge processes in semi-arid watersheds in the Atlas Mountains.•The used approach combines stable isotopes with remote sensing data.•The isotope signals from groundwater and precipitation display significant spatial heterogeneity due to geological differences in aquifers.•Groundwater recharge responds belatedly to snowmelt during the melt season with peak isotope depletion during March.•High values of TWS are in correspondence with groundwater isotopes, indicating that significant pumping occurs between March and June.•Significant pumping is due to the need to compensate for the insufficient precipitation during that period.•The HOER catchment shows that snowmelt recharge 50% of Liassic aquifer upstream, and 80% in Triassic aquifer downstream.•The Ourika catchment shows that 30% of snowmelt contributes to groundwater recharge upstream and 50% downstream.•The difference in altitudinal ranges and lithology of the catchment causes this varying contribution of snowmelt.