Beyond Concrete: Assessing the Role of Wetlands, Aquifers, and Mangroves in Sustainable Flood and Groundwater Management

Flooding represents one of the most tangible hydrological manifestations of global climate change, endangering low-lying coasts, adjacent ecosystems, and the underlying freshwater lens that sustains human and ecological communities. The present study assesses the comparative effectiveness of ecohydrological adaptation techniques in reinforcing shoreline resilience, mitigating flood hazards, and securing long-term groundwater integrity. Systematic analysis of restoration programmes implemented in the Mississippi River Delta, the Ganges–Brahmaputra Delta, and the Netherlands demonstrates that nature-based interventions, specifically wetland rehabilitation, managed aquifer recharge, and mangrove conservation, regularly surpass conventional engineered defences when measured against sustainability, cost, and ecological multifunctionality. Within the Mississippi River Delta, such measures lowered annual flood-related damages from roughly 500 million United States dollars to 300 million, a forty per cent decline, while curbing the incidence of damaging inundations from three events per year to 1.5. In the Ganges–Brahmaputra Delta, analogous initiatives reduced losses from 800 million to 450 million dollars and halved flood frequency from four to two events annually. Dutch projects exhibited similar success, cutting damages from 600 million to 350 million dollars and trimming event frequency from two to one. Beyond surface-water regulation, ecohydrological actions yielded notable subsurface benefits: in the Mississippi River Delta, groundwater salinity concentrations fell from 1,500 parts per million to 800 parts per million, whereas recharge rates rose from fifty to 120 millimetres per annum. These findings validate ecohydrological adaptation as a credible, scalable paradigm for climate-resilient coastal governance, underscoring the urgency of policy frameworks that embed ecosystem-based management within integrated watershed and marine planning regimes.