Towards a new spatial representation of faecal sources and pathways in unsewered urban catchments using open-source data

Spatial representation of sanitation infrastructure and service coverage is essential for management planning and prioritising services. The provision of sanitation services in developing countries is inherently unequal because the sanitation infrastructure is lacking, and onsite sani-tation is managed individually. Here, we developed a prototype method for creating a spatial representation of faecal sources and movement in a small area in Rajshahi city in northwest Bangladesh, which is representative of 60 other such secondary cities. We demonstrate an approach to estimate spatial variability in faecal production at the building scale by combining widely accessible buildings, ground elevation, and population data. We also demonstrate an approach to attribute potential faecal movement pathways by integrating drainage data, and faecal production at the building scale. We made use of free and open-source data and provide answers to the broader topic of spatial representation of faecal mobility in unsewered urban settings which has implications in a similar setting in developing countries.