Deteriorating Water, Sanitation, and Hygiene Accessibility and Gender Equity in Protracted Displacement: A Spatiotemporal Remote Sensing Study of Rohingya Refugee Camps

Background Lack of access to Water, Sanitation, and Hygiene (WASH) services is a major public health concern in refugee camps, where extreme crowding accelerates the spread of communicable diseases. The Rohingya settlements in Cox’s Bazar, Bangladesh, exemplify these conditions, with large populations living under severe spatial constraints. Methods We develop a semi-supervised segmentation framework using the Segment Anything Model (SAM) to map shelters from multi-temporal sub-meter remote sensing imagery (2017–2025), improving detection in complex camp environments by 4·9% in F1-score over strong baselines. Findings The detected shelter maps show that shelter expansion stabilized after 2020, whereas continued population growth reduced per capita living space by ∼14% between 2020 and 2025. WASH accessibility, measured with an enhanced network-based two-step floating catchment area (2SFCA) method, declined from 2022 to 2025, increasing facility loads and exceeding global benchmarks. Gender-disaggregated scenarios that incorporate safety penalty further reveal pronounced inequities, with female accessibility ∼27% lower than male. Interpretations Our results demonstrate that remote sensing–driven AI diagnostics can generate equity-focused evidence to prioritize WASH investments and mitigate health risks in protracted displacement settings.