Distinct Effects of Soil Moisture on Surface Water Availability in Nearshore and Inland Drylands

Abstract Soil moisture (SM) substantially influences the change of surface water availability (precipitation minus evapotranspiration, P‐E) in water‐limited drylands by altering evapotranspiration and atmospheric water vapor inflow. While the overall significance of SM‐P‐E feedbacks is recognized, the spatial variability and consistency across different dryland types remain unclear. Here, we investigate these feedbacks across nearshore and inland drylands, revealing substantial heterogeneity in their responses. Using land‐atmosphere coupling experiments and atmospheric moisture budget analysis, we demonstrate contrasting mechanisms: in nearshore drylands, reductions in SM trigger increased moisture convergence, mitigating precipitation decline and even elevating P‐E; conversely, in inland drylands, enhancements in SM further suppress precipitation by diminishing moisture inflow, leading to a decline in P‐E. These findings uncover region‐specific SM‐water cycle feedbacks, providing new insights into drylands water dynamics and implications for water resources management under changing climate conditions.