Alarming decline of Iran’s Ramsar convention wetlands

Study region Iranian wetlands and lakes listed in Ramsar Convention Study focus Iran ranks second globally after Greece in wetland loss, with six of its wetlands listed on the Montreux Record. Despite this status, substantial gaps remain in quantifying long-term national wetland decline, associated economic losses, and the dominant drivers of desiccation. Here, we present the most comprehensive assessment to date of wetland loss in Iran over the past four decades (1986–2023), analyzing 23 Ramsar Convention-listed wetlands. We integrate Landsat 5/7/8 imagery processed with multiple water detection indices, Otsu-zero and Otsu-dynamic thresholding, Canny edge filtering, and stratified random sampling for validation. Methodological robustness is further confirmed through comparison with NASA-OPERA products and true-color images. New hydrological insights for the region We found that only six small wetlands have maintained near-natural conditions, while the remainder have experienced substantial shrinkage. Overall, wetland water-surface area declined by more than 57%, from 11,539 km 2 during the baseline period (1986–1995) to 4921 km 2 in 2023. This loss appears to be closely associated with state-led policies prioritizing agricultural self-sufficiency, resulting in extensive surface water diversion, groundwater over extraction, land-use changes. While our correlation analysis shows these associations, it does not establish causality, and the findings should therefore be interpreted as indicative rather than definitive. Economically, Iran now forfeits approximately US$2.415 billion annually in wetland-derived ecosystem services, while achieving a comparatively modest increase of about US$1.3 billion per year in agricultural value added. These policies are closely linked with widespread depleted aquifers across 421 of 609 national plains and disrupted river flows nationwide. The widespread desiccation of Iranian wetlands has generated profound environmental, economic, social, and public health consequences. Our findings underscore the urgent need for systemic water governance reforms to prevent further irreversible wetland loss.