Streamflow losses beneath ephemeral and intermittent streams are potentially major contributors to groundwater recharge. Compared to ephemeral streams, intermittent streams often have more than one season of streamflow and often experience shorter zero‐flow periods during the dry seasons and typically longer wet season of steady streamflow. Intermittent streams losses are lacking significant investigation on their variability over wet and dry season, and on the influence on potential groundwater recharge of flooding streamflow compared with more gradual wet seasonal baseflow. To address these issues, both streambed‐sediment water content and temperature were continuously logged over a year for an intermittent stream (wadi) under semi‐arid conditions in Central Morocco. Water content measurements uniquely distinguished between downward percolation and upward advance of the wetting front due to the rise of the water table, whereas temperature modeling was used to estimate vertical fluxes of percolated water. For the year of data, more than 90% of the estimated potential recharge occurred during winter and spring, when the alluvium typically has a higher water moisture, with most recharge generated during flooding conditions. Winter and spring baseflow generally generated low infiltration, though importantly contributes to wetting the sediment for rapid, deep percolation during flooding. Alternatively, summer flashfloods over dry sediment resulted in shallower infiltration despite higher peak streamflows. Thus, clear seasonality (seasonal variation) in relations between amounts of streamflow, streamflow loss, and depth of wetting into the streambed were distinguished over the study year. Finally, lateral recharge was detected, leading to additional seasonal water‐table fluctuation beneath the wadi.

This study evaluates the use of remote sensing data to improve the understanding of groundwater resources in climate-sensitive regions with limited data availability and increasing agricultural water demands. The research focuses on estimating groundwater reserve dynamics in two major river basins in Morocco, characterized by significant local variability. The study employs data from Gravity Recovery and Climate Experiment satellite (GRACE) and ERA5-Land reanalysis. Two GRACE terrestrial water storage (TWS) products, CSR Mascon and JPL Mascon (RL06), were analyzed, along with auxiliary datasets generated from ERA5-Land, including precipitation, evapotranspiration, and surface runoff. The results show that both GRACE TWS products exhibit strong correlations with groundwater reserves, with correlation coefficients reaching up to 0.96 in the Oum Er-rbia River Basin and 0.95 in the Tensift River Basin (TRB). The root mean square errors (RMSE) were 0.99 cm and 0.88 cm, respectively. GRACE-derived groundwater storage (GWS) demonstrated a moderate correlation with observed groundwater levels in OERRB (R = 0.59, RMSE = 0.82), but a weaker correlation in TRB (R = 0.30, RMSE = 1.01). On the other hand, ERA5-Land-derived GWS showed a stronger correlation with groundwater levels in OERRB (R = 0.72, RMSE = 0.51) and a moderate correlation in TRB (R = 0.63, RMSE = 0.59). The findings suggest that ERA5-Land may provide more accurate assessments of groundwater storage anomalies, particularly in regions with significant local-scale variability in land and water use. High-resolution datasets like ERA5-land are, therefore, more recommended for addressing local-scale heterogeneity in regions with contrasted complexities in groundwater storage characteristics.

In semi-arid regions of Morocco, where the majority of water withdrawals are devoted to irrigation, optimizing irrigation practices in agriculture is a national priority in the face of recurring droughts and growing pressure on groundwater resources. However, the hydrological impacts of different drip-irrigation systems in the soil–plant–atmosphere continuum remain insufficiently understood. We monitored the stable isotope composition (δ²H, δ¹⁸O) across the two agricultural plots in Marrakech (Morocco) with surface drip and subsurface drip irrigation treatments for a complete hydrologic year (June 2022 to June 2023). Weekly to daily samples of rainfall, irrigation water, groundwater, and soil at various depths (5–50 cm) were sampled, and water from branch xylem was extracted using the cryogenic vacuum distillation method. We found that the subsurface irrigation treatment, which delivered water directly to the root zone, maintained narrow isotopic ranges in water of soils beyond 30 cm, as well as in branch xylem and leaf water. By contrast, surface irrigation treatment plots showed pronounced evaporative isotopic enrichment: summer topsoil water δ¹⁸O peaked at −1.1‰ (vs. −8.7‰ in subsurface irrigation treatment), and leaf water reached +13‰ (vs. +8‰ in subsurface). Despite this larger isotopic heterogeneity in surface irrigation site, branch xylem water δ¹⁸O remained within −6 to 2.5‰ across all soil depth, similar to subsurface irrigation treatment, which ranged between −5 and 0‰. This suggests that olive roots accessed soil water uniformly from the upper 50 cm under both irrigation treatments. Seasonal xylem isotopic enrichment in spring and midsummer mirrored shifts towards shallow, evaporatively altered soil water under surface irrigation, but not under the subsurface. The results suggest that subsurface drip irrigation can significantly improve drought resilience and water-use efficiency in the expanding olive sector of the Maghreb, while continuous isotope monitoring serves as a practical approach to enhance sustainable and adaptive water management in water-limited regions.

Piedmont areas are globally important hydrological systems as transitional zones between mountains (headwater basins) where water is produced and adjacent plains (basins floor) where water is consumed. In arid and semiarid areas, the water availability in piedmonts have made them adequate places for rural communities’ settlement and irrigation activities. The hydrochemical processes controlling groundwater chemistry in the piedmont areas might be influenced by the interaction with the mountain streamflow, the geology, the climate and the human activities. In this study we investigated the hydrochemistry of the groundwater in the piedmont of Ourika wadi that is coming from the High-Atlas of Marrakech Mountains (central Morocco). The HCO3-Ca-Na groundwater type, inherited form the streamflow, is the primary water facies in the area. It has its origin from carbonates dissolution and silicates withering in the High-Atlas mountains. In the irrigated area, the ion exchange processes are responsible of Ca and Mg enrichment. Currently, the groundwater salinity is low and the chemical quality is excellent thanks to the seasonal groundwater recharge from the mountain streamflow and to the practiced traditional agriculture that generally uses high amounts of irrigation and low amounts chemical fertilizers. However, major concerns about groundwater sustainability arise from two parameters. Firstly, the snowmelt-driven runoff supplying the groundwater recharge in piedmonts is in continuous decrease because of the snow cover reduction observed in the last decades and forecasted in the future under climate change, likely putting more pressure on groundwater resources. Secondly, due to the growing anthropogenic activities the traditional agriculture might change to intensive agriculture using more chemicals and inducing pollution.