Study of river flood hydrology in Bangladesh with AVHRR data

Abstract

Abstract This paper examines the applicability of NOAA satellite AVHRR imagery to monitoring and studying the river floods and associated hydrological conditions in Bangladesh and the adjoining regions. The flood period considered is that of the last 10 days of September 1984, when Bangladesh experienced one of the worst floods in recent years. Imagery from dry winter conditions have also been used for comparison. The analysis involved the calibration of the NOAA-7 Advanced Very High Resolution Radiometer (AVHRR) IB data tapes, linearization of pixel sizes and geometric rectification of the image to ground reference points. The imagery showed that a vast area of Bangladesh was flooded and rivers were highly turbid. Comparisons have been made between the major rivers, particularly the Ganges and the Brahmaputra, during the flood season. It has been found that the Ganges has higher albedo (is more turbid) and is warmer than the Brahmaputra during the flood season. The Brahmaputra shows a gradual increase in albedo level downstream, the reverse of which is observed in the Ganges. The turbidity and temperature distribution in the coastal area have also been studied. The results of this study are based on the physical interpretation of the high-quality AVHRR radiometric imagery. It has not been possible here to supplement and test the results of this study with conventional surface measurement data, which is intended to be done in the future.