Waterborne Disease Risk Assessment and Mapping for a Floating Village by Combining 3D Hydraulic Simulation and Quantitative Microbial Risk Assessment

Spatiotemporal changes in waterborne disease risk were evaluated for the Chhnok Tru floating village in the Tonle Sap Lake by combining a hydraulic simulation and quantitative microbial risk assessment (QMRA). First, a three-dimensional (3D) hydraulic simulation was performed, and the transport of Escherichia coli (E. coli) was simulated. Prior to the simulation, by coupling satellite imagery analysis using the normalized difference water index (NDWI) and a sounding survey using an acoustic Doppler current profiler (ADCP), a new digital elevation model was generated for the complex channel network with high resolution. The results of the 3D hydraulic simulation revealed the flow regime and nonuniform pathogen distribution in the floating village. QMRA was performed for the village using the E. coli distribution calculated by the 3D hydraulic model. Subsequently, the disease risk in the village was visualized through an effective and easy-to-understand disease risk map. To demonstrate the usefulness of the hydraulic-simulation-based disease risk map, the map was used to quantitatively compare simple policies by evaluating their reduction in disease risk.