Urbanization influence on surface water loss across USA watersheds

Surface water resources (i.e., rivers, lakes, reservoirs, and wetlands) are severely affected by anthropogenic activities, and their rapid depletion is threatening water security, posing a critical challenge for sustainable development. By 2050 about 70% of the world population is expected to live in cities, and the associated urban sprawl will likely increase water demand and accelerate water usage. Under this scenario, the impacts of urbanization on surface water are becoming a global issue, stressing the need for new management strategies that regulate water consumption in order to prevent water crisis and guarantee equitable access to freshwater resources. Therefore, it is crucial to understand the influence of human settlements on the reduction of surface water availability. Remote sensing plays a key role in monitoring environmental change at global scale. The high spatial and temporal resolution of Earth Observation (EO) allows to detect the extent and track the spatiotemporal variation of surface water and human settlements. Despite the availability of many consistent global products obtained from EO sensors that accurately describe surface water dynamics and the spatial allocation of urban areas, the potential of an integrated analysis of such geospatial information has not been fully explored yet. The research presented here exploits the advantages of remotely sensed data to investigate the relationship between the decrease in surface water resources and the process of urbanization. Remote sensing data are processed and employed to identify built-up areas and locations that experienced surface water loss during the last 35 years in the USA watersheds. To estimate the influence of human settlements on the spatial distribution of surface water depletion, surface water loss is evaluated as a function of distance from urbanized areas. The results of this analysis reveal that surface water loss is enhanced and occurs more frequently close to urban areas. Overall, this trend is observed both at the basin and continental scale. The adopted approach looks promising for the identification and possibly the forecast of surface water loss globally.