The Use of Optical Remote Sensing For Mapping Flooded Areas

Flood maps are a crucial tool to support emergency management, disaster recovery and risk reduction planning. Traditional flood mapping methods are time-consuming, labor intensive, and costly. Our goal in this paper is to introduce a novel technique to aggregate knowledge and information to map coastal flooded areas. We proposed a Difference of Normalized Difference Water Indices (DNDWI) derived from two LANDSAT-5/TM surface reflectance product acquired before and after the passage of Hurricane Ike, for Upper Texas in September of 2008. The reference flooded area was delineated interpolating the maximum surge in each location using a spline with barriers method with high tension and a 30 meter Digital Elevation Model (DEM). It was noticed that NDWI values decreased after the hurricane landfall on average from 0.226 to 0.122 for flooded area. However for the non-flooded areas it increased from 0.292 to 0.300. Results from the Monte Carlo simulation showed that mapping flooded areas with DNDWI got an accuracy of 85.68% while the non-flooded areas got an accuracy of 92.13%. Thus, DNDWI is promising tool for mapping flooded areas since it is a cheaper and simple technique which can be applied rapidly for several areas of the planet.