Mapping world’s coastal population facing water-related risks

• Six major water-related risks to world’s coastal-zone population were analyzed geospatially. • The method of UN Sendai Framework and IPCC was used, combining stressors, exposure, and vulnerability. • Our maps show their characteristic hotspots and patterns, and latitudinal profiles. • Exposure is peaked due to urbanization while the vulnerability map echoes inequalities. • Risk hotspots include the Chinese coast, Bay of Bengal, Gujarat, and Java. Embraced by opportunities of both land and ocean, coastal areas allure expanding human populations and economic activities. At the same time, they face growing societal and environmental pressures from both the above river catchments and the bordering sea due to climate change, ecosystem degradation, and expansion of built-up areas. Despite the accumulation of human population, economic activities, and environmental impacts, we lack social-ecological systems analysis on water-related risks to world’s coastal human population. To address this research gap, we analyze the spatial extent of six globally important water stressors to people within the world’s coastal zone (100 km from the coastal line) and classify this zone globally into 12 groups by distance from the coastline and elevation from the mean sea level. Adopting the approaches of the UN Sendai Framework and IPCC, we produce risk maps from the stressor maps by multiplying them with population exposure and vulnerability. For most risks, geographical hotspots are the Chinese coast, Bay of Bengal, Gujarat, and the Island of Java. The analysis reveals fundamental differences between water stressors and related risks, often mixed in scholarly literature. Both manifest specific geographic patterns and latitudinal profiles. Our study highlights the importance of high-resolution spatial analysis of vulnerability, exposure, and risks posed by water related stressors in the world’s coastal zone, in a manner prompted by key policy bodies to promote policy design and shared responsibility for managing stress-prone areas.