Community-based monitoring for flood early warning system An example in central Bicol River basin, Philippines Catherine C. Abon and Carlos Primo C. David National Institute of Geological Sciences, University of the Philippines, Diliman, Quezon City, The Philippines, and Guillermo Q. Tabios III National Hydraulic Research Center, University of the Philippines, Diliman, Quezon City, The Philippines Abstract 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. Keywords Philippines, Floods, Rivers, Communities, Modelling, Precipitation, Early warning, Geomorphology, Bicol River basin Paper type Research paper 1. Introduction Flooding is one of the most common natural hazards causing immense damage to agricultural production, destruction of infrastructure, and loss of lives. Flooding in most cases cannot be prevented (Chubey and Hathout, 2004); however, the associated damage due to floods can be significantly minimized through a community The current issue and full text archive of this journal is available at www.emeraldinsight.com/0965-3562.htm Disaster Prevention and Management Vol. 21 No. 1, 2012 pp. 85-96 r Emerald Group Publishing Limited 0965-3562 DOI 10.1108/09653561211202728 This work has been funded by the Christian Aid and Manila Observatory. Rainfall and hydrologic data from PAGASA-Bicol Region headed by Arturo Balang made the calibration of the model possible. Grateful acknowledgement goes to Arlene Dayao and to the countless people of Bicol who have patiently assisted the authors during field surveys. Thanks are also extended to laboratory members Stephanie Frogoso, Michelle dela Cruz, Darwin Riguer, David Chuy and Krystelle Banaag for assisting during the field surveys, and Jeremy Rimando and Jun Pellejera for the laboratory assistance, the UP CSWCD students Jesus Dominic Dizon and groupmates, supervised by Matt Wamil, and David Michael V. Padua who heads the TPC. 85 Community- based flood early warning