Incorporating social demand for Flood-Regulating Ecosystem Services into biophysical assessments: A conceptual...

Flood-regulating ecosystem services (FRES) help reduce hydrological hazards by improving water infiltration and storage, which lowers runoff and flooding. Despite their importance, FRES are still not sufficiently integrated into Ecosystem-Based Disaster Risk Reduction (Eco-DRR) strategies. This study systematically reviewed 18 spatially explicit FRES assessments (2005-2023) and related them to social and socio-ecological vulnerability research to identify conceptual and methodological gaps. In total, 451 unique indicators were identified, with only 75 overlapping, revealing differing vulnerability perspectives across disciplines. FRES assessments were populated by environmental (40%) and land-cover (21%) indicators, while social data were more limited (8% on demographics, 2% on well-being). Among FRES studies, 55.5% included some socioeconomic indicators, 5.5% used a social vulnerability index, and 39% did not consider vulnerabilities, viewing social demand as a lack of biophysical FRES supply. Conversely, social vulnerability research rarely incorporated environmental indicators, whereas socio-ecological studies offered more integrated links between FRES, vulnerability, and disaster risk, emphasizing human reliance on ecosystem services. These findings reveal ongoing disconnects between assessments of ecological processes and human needs. A social-ecological systems framework is proposed to integrate ecosystem functions, social demands, and human dependence on ecosystems, thereby enhancing the application of FRES assessments in disaster risk management.