Quantitative dynamic flood monitoring with NOAA AVHRR

The analysis of the spatial extent and temporal pattern of flood inundation from remotely sensed imagery is of critical importance to flood mitigation . With a high frequency of global coverage, NOAA/AVHRR has the advantage of detecting flood dynamics during devastating floods. In this paper, we desc ribe a systematic approach to flood monitoring using AVHRR data. Four criti cal issues for successful flood monitoring with AVHRR were identified: corr ect identification of water bodies, effective reduction of cloud contaminat ion, accurate area estimation of flood extent, and dynamic monitoring of fl ood processes. In accordance with the spectral characteristics of water and land in AVHRR channels, a simple but effective water identification method was developed with the ability to reduce cloud influences. The area of flo oded regions was calculated with the consideration of areal distortion due to map projection, and mixed pixels at water/land boundaries. Flood dynamic s were analysed from flood distributions in both space and time. The maximu m spatial extent of floods, generated by compiling the time series of flood maps, was informative about flood damages. We report a successful use of t his approach to monitor the Huaihe river flood, a centennial devastating di saster occurred in the Huaihe river basin of China in the summer of 1991.