Human Impacts of Flood Disasters: A Global Systematic Review (1980–2025)

Floods are the most frequent and destructive natural hazards globally, yet the human impacts remain unevenly documented across regions. Evidence on mortality, displacement, health outcomes, and livelihood disruption remains incomplete, particularly in low- and middle-income countries. This review investigates global evidence on the human impacts of floods published from 1980 to 2025, focussing on vulnerability patterns, reporting gaps, and socio-spatial inequities. The systematic Scopus search yielded 19,105 records, where 82 met the inclusion criteria. The reviewed studies examined outcomes related to mortality, displacement, injuries, health effects, and livelihood consequences. A formal meta-analysis was not undertaken because of methodological heterogeneity. Instead, we applied narrative synthesis, complemented by methodological quality assessment using the Mixed Methods Appraisal Tool (MMAT). Among the outcomes examined, mortality was reported most consistently, appearing in 86.6% of studies, whereas displacement, health effects, and livelihood impacts were documented less consistently. The literature was geographically skewed toward Asia and North America, while Africa, Latin America, and the Middle East remained underrepresented despite substantial exposure and vulnerability. Risk was socially uneven, with older adults, children, low-income households, rural populations, and marginalized groups experiencing disproportionate vulnerability. Cross-study comparability and risk estimation are constrained by inconsistent reporting, limited outcome standardization, and the underrepresentation of non-fatal impacts. Flood impacts are strongly mediated by the interaction of hazard, exposure, governance, infrastructure, and social vulnerability. Global understanding remains constrained by systematic gaps in the literature, especially in relation to displacement, long-term health effects, and livelihood consequences. Expanding research coverage, standardizing reporting, and integrating social vulnerability metrics are critical to support evidence-based, equitable flood risk reduction strategies. • Systematic review synthesizes 82 studies on flood impacts globally (1980–2025). • Mortality is the most frequently reported outcome; displacement, health, and livelihoods are underreported. • Evidence is geographically uneven, with major gaps in Africa, Latin America, and the Middle East. • Vulnerability is socially differentiated; older adults, children, low-income households, and marginalized groups face higher risk. • Findings inform improved disaster risk reduction, standardized reporting, and equitable policy interventions.