Diagnosing Water Mismanagement: Spatially Decoupling Land Degradation from Climate Trends in a Critical Arid Basin

Land degradation in arid ecosystems is a critical threat to sustainability. This study investigates the spatio-temporal patterns of land degradation in Iran’s Jazmourian basin from 2000–2022. Using satellite-derived precipitation (CHIRPS) and vegetation (MODIS NDVI) data, we quantified long-term trends with non-parametric tests. Our results reveal a distinct spatial dichotomy: while mountainous rangelands showed ‘greening’ in response to slightly increased precipitation, other areas significantly declined. Despite a positive basin-wide trend, statistically significant vegetation decline (‘browning’) was highly concentrated in the historical Hamoun-e Jazmourian wetland and adjacent agricultural plains. Crucially, this browning occurred where local precipitation was stable or increasing, indicating a clear decoupling of ecosystem health from climatic trends. This paradox points to non-climatic pressures consistent with a ‘hydrological failure,’ likely driven by water mismanagement, which has overridden any climatic benefits in these critical zones. Our findings underscore the need for integrated water and land management to combat these spatially focused degradation hotspots.