Flood inundation mapping using NOAA AVHRR data

The river Brahmputra flowing through the state of Assam (India) floods every year. The analysis of spatial extent and temporal pattern of flood-inundated areas is of prime importance for mitigation of floods. With the development of remote sensing techniques, flood mapping for large areas can be done easily. In case of flood affected area mapping of large area it will not be feasible to use high-resolution data, because the whole area will be covered in number of scenes. Therefore use of NOAA (National Oceaongraphic Atmospheric Administrative) data is quite useful in such type of studies. NOAA-AVHRR (Advanced Very High Resolution Radiometer) data have the potential for flood monitoring due to high frequency of global coverage, wide swath, high repetivity and low cost. In this study, NOAA-AVHRR data have been used for mapping of flood-affected area during the year 2003. On the basis of spectral characteristics of land and water, a methodology for water identification is presented. The maximum spatial extent of floods, generated by compiling the available cloud free maps, is informative about flood damages. Analysis of results reveals that in the months of July and August almost 25-30% of the area was flood affected. Also the result indicates that in some districts, the flood-affected area is very high.