Improvement in Flood Disaster Damage Assessment Using Highly Accurate IfSAR DEM

Abstract

Flood damage to agriculture (rice crops) was assessed in the Pampanga River basin of the Philippines. Flood damage to agriculture was defined as a function of hazard characteristics, such as flood depth and flood duration, exposure, and growth stage of rice crops, and estimated in terms of yield loss using a depth-duration-damage function. The assessment of flood damage to agriculture in the Pampanga River basin was conducted using Digital Elevation Model data of the Interferometric Synthetic Aperture Radar (IfSAR-DEM) and Digital Elevation Model data of the Shuttle Radar Topography Mission (SRTM-DEM). The results were further improved using highly accurate IfSAR-DEM. To assess flood disaster damage, a hazard assessment was conducted using the Rainfall Runoff Inundation model. Estimated values from the agricultural damage assessment during the flood event from September 26 to October 4, 2011 were compared with reported values. The accuracy of flood hazard assessment and flood disaster risk assessment highly depends on the quality of topographical data, and better results can be obtained by using highly precise topographical data. Flood disaster risk assessment in the agricultural sector was also conducted for a recent flood in October 2015 and flood events with different return periods of 10, 25, 50, and 100 years. The assessment results based on the different return periods of flood events were then used to estimate the probability of agricultural damage for most frequently damaged and rarely damaged areas. The results of flood damage assessment in the Pampanga River basin provide a basis to identify areas at risk, and these results can be useful for planners, developers, policy makers, and decision makers in establishing policies required to reduce flood damage.