Résumé
Study region: The Haouz Plain, Tensift basin, central Morocco.Study focus: The Haouz region has undergone a clear trend toward aridification over the last fourdecades, with a severe drought from 2019 through 2025. This study investigates how contrastingirrigation practices influence groundwater quality and quantity using a multi-indicator approachcombining tryptophan-like fluorescence (TLF), nitrate, microbial indicators (E. coli, S. enterica),stable isotopes (δ¹⁸O, δ²H), and tritium (³H). Traditional surface-water irrigation areas exhibitelevated TLF (up to 11.3 QSU), nitrate (>15 mg/L), and microbial contamination, indicatinginfluence from wastewater and surface-derived inputs. Shallow water tables (<40 m) and hightritium (>3 TU) confirm recent recharge pathways facilitating contaminant migration. Incontrast, modern drip-irrigated areas relying on intensive groundwater abstraction show limitedcontamination (TLF ≤0.9 QSU; nitrate mostly <20 mg/L; the absence of fecal coliforms), longermean residence times (>60 years), extraction of older groundwater, and groundwater storagedepletion.New hydrologic insights for the region: Results reveal a trade-off in dryland agricultural systems:traditional irrigation sustains recharge but increases vulnerability to contaminant transport,whereas modern irrigation limits contaminant propagation yet accelerates depletion of storedgroundwater reserves. Wastewater infiltration may occur independently of irrigation practices,but abstraction intensity largely governs aquifer storage declines. Under intensifying droughtconditions, sustainable groundwater management in the Haouz Plain requires integrated strate-gies combining optimized irrigation, controlled abstraction, and strengthened wastewater treat-ment and reuse.