Study on flood pattern of Bangladesh using flood inundation maps generated from modis images

Abstract

Remote sensing technologies can allow a quick mapping of large regions and may provide valuable support in flood crisis management. In Bangladesh, Flood Forecasting and Warning Center (FFWC) generates flood inundation map from hydrodynamic model output. In this study, a comparison has been conducted between flood inundation maps generated from MODIS images and inundation maps generated from model output by FFWC from the year 2004 to 2014. From this comparison it has been found that, among the five BWDB zones, inundation maps generated by FFWC in Northwest zone (NW) (R2=0.915), North central zone (NC) (R2=0.896), Northeast zone (NE) (R2=0.929) and Southeast zone (SE) (R2=0.959) have a strong correlation with the inundation maps generated from MODIS images of that zones. MODIS inundation maps have a very poor correlation in Southwest zone (SW) (R2=0.058) which is because of fewer water level measuring stations in that zone and the model which has been used to prepare flood maps, does not consider tidal effect of this zone.. It has also been found that, correlation between MODIS inundation maps and FFWC inundation maps of a zone depends on the number of water level observing station presents in the that zone. However the overall correlation between these two types of inundation maps has been found as R2=0.701. Studying flood pattern of Bangladesh was also an objective of this study. It has been seen that, flood pattern found from MODIS inundation maps has a good consistency with observed data found in annual flood reports of FFWC. Besides, the method that developed in this study has been found very effective in the area where ground observation data are not available. It can also be very useful for regular monitoring of flood situation in daily basis because of the freely available MODIS images in website. From this study, it can be concluded that, this method of flood inundation mapping from MODIS image has a huge potential of observing and monitoring flood pattern and flood extent in Bangladesh.