Pourquoi la gestion des cours d'eau est si importante pour protéger l'une des zones humides les plus importantes du monde

A new study led by Swansea University has revealed that effective river management plays a critical role in safeguarding the Mesopotamian Marshes, one of the world’s most vital wetlands. Published in Scientific Reports, the research underscores how water flow from the Tigris and Euphrates rivers significantly influences the health of the marshes, challenging previous assumptions that local rainfall alone determines their condition. The Mesopotamian Marshes, situated in southern Iraq, have long been recognized for their ecological and cultural significance. Designated a UNESCO World Heritage Site, the area supports diverse wildlife and preserves remnants of ancient civilizations. Following the 2003 reflooding initiative, which aimed to restore the degraded wetlands, the marshes saw some recovery. However, recent years have brought renewed threats, including climate change, upstream dam projects, and regional water policy decisions. Researchers analyzed satellite data spanning nearly two decades, from 2000 to 2023—to assess the factors affecting the marshes. They used imagery from NASA MODIS, EU Copernicus Sentinel-2, and JRC Global Surface Water, paired with records of river flow and rainfall. Their findings indicate that while vegetation and surface water levels initially improved after restoration, these gains were frequently disrupted by sharp declines linked to environmental and human-induced pressures. Two notable periods of decline occurred between 2008–2009 and 2022–2023. These intervals corresponded with regional droughts, operational activities at upstream dams, and strategic water management choices. During these times, the marshes experienced substantial reductions in coverage and vitality, highlighting the vulnerability of the ecosystem to external controls over water supply. The study concluded that river flow, rather than local precipitation, is the primary determinant of the marshes’ condition. Increased streamflow correlated with better vegetation growth, whereas local rainfall had little measurable effect. Additionally, the researchers observed a link between vegetation density and land surface temperature. Areas with dense marsh cover remained cooler, while vegetation loss resulted in higher temperatures, suggesting a reinforcing cycle that exacerbates environmental stress. These insights emphasize the necessity of coordinated international efforts to manage the Tigris-Euphrates river system. Countries sharing the basin must work together to ensure consistent water delivery to the marshes, particularly during dry seasons. Such collaboration could help maintain the ecological balance and support the region’s biodiversity and cultural heritage. Lead author Akram Alqaraghuli, currently pursuing a Ph.D. in the GEMEO group at Swansea University, noted that maintaining river flows is essential for the preservation of the Mesopotamian Marshes. He also highlighted the wetlands’ role in regulating local temperatures, underscoring their broader environmental function. Co-author Professor Peter North emphasized the value of long-term satellite monitoring in distinguishing human impacts from natural climatic variations. He stated that the study contributes to the sustainable management of a globally significant resource and reinforces the need for cross-border cooperation in water governance. The research provides a detailed understanding of the complex interactions shaping the Mesopotamian Marshes. It calls attention to the delicate balance between human activity and natural processes, urging stakeholders to prioritize adaptive strategies that protect this ecologically rich area for future generations.