Community‐based monitoring for flood early warning system: An example in central Bicol River basin, Philippines

Purpose - The purpose of this paper is to integrate the proactive role of communities and the use of flood modeling in the implementation of a flood early warning system. Design/methodology/approach - Manual rain gauges were installed in 20 houses of volunteers living within the Bicol River basin to monitor rainfall. Rain information is sent twice daily via SMS message to a receiving computer. The received data are used to run a basin model that was developed in HEC-HMS, which converts precipitation excess to overland flow and channel run-off. Findings - Different watershed models were developed for different rainfall events. Geomorphic analysis using 3 s SRTM Digital Elevation Model (DEM) processed in a GIS platform was also done to refine the overland flow. The derived hydrographs were used in the HEC-RAS hydraulic model which has as main output threshold values for the rain-flood relationship. Research limitations/implications - Although SRTM DEM that was used for the geomorphic analysis was sufficient for the purpose of the study, higher resolution DEMs can further improve the mapping of spatial extent of flood areas. Practical implications - The results are used for the forecast of flood and the timely issuance of flood bulletins. Originality/value - This study is the first to incorporate the involvement of the community in establishing a flood early warning system. The method can also be used as a prototype for other flood models in other parts of the country.