Linking groundwater recharge dynamics to traditional irrigation practices in a semiarid mountain-front system

Abstract

Groundwater recharge in mountain-front areas is a critical yet poorly constrained component of the water cycle in semiarid regions, particularly where traditional irrigation practices dominate. This study investigates the spatiotemporal dynamics of recharge induced by gravity-fed irrigation in the mountain-front of the Moroccan High Atlas, a key recharge zone for the Haouz aquifer. A simplified water balance approach, corrected for groundwater-based evapotranspiration, was applied to a 20-year dataset of irrigation diversions and remotely sensed evapotranspiration (MOD16A2), and validated against recharge estimates from the water table fluctuation (WTF) method. Results show strong spatial disparities, with upstream zones receiving disproportionately higher water allocations due to ancestral water rights, sustaining potential recharge in ∼90 % of months, while midstream and downstream zones consistently faced deficits. Despite local recharge events linked to flood years, statistically significant declining trends in recharge were observed across all zones, reflecting both reduced streamflow and intensified groundwater abstraction. Sensitivity tests revealed that neglecting rainfall and ΔS introduces only modest biases (≤12 % in upstream, ≤24 % in midstream zones), confirming the dominance of irrigation as the primary recharge driver. Potential recharge estimates aligned closely with WTF-derived values (differences of 5–14 %), further attesting to the reliability of the approach. These findings highlight the vulnerability of traditional irrigation systems under climate and human pressures and emphasize the urgent need for integrated water management strategies that safeguard ancestral irrigation practices while promoting adaptive measures such as managed aquifer recharge and climate-smart agriculture.