I am using MODIS surface reflectance product (250m spatial resolution, 8 day composite) which comprises two bands: one is visible band and another is NIR Band. Is it appropriate to use NIR band for identification of flooded water as the surface reflectance of water is low in this band. Can anybody say approximate range of reflectance value for flood water.
In general, I think it may not be the best idea to use passive remote sensing to detect and delineate flood waters due to obvious reasons like frequent occurrence of cloud cover, inability to detect flooded areas under vegetation and other atmospheric obstructions in satellite images . Although the 'Surface Reflectance 8-Day 250m' MODIS is a scrupulous product with pixels containing the best possible observations during an 8-day period as selected on the basis of high observation coverage, low view angle, the absence of clouds or cloud shadow, and aerosol loading, still it cannot replace the pre-eminence of RADAR products. Therefore, a better alternative seems to be Synthetic Aperture Radar (SAR). Please check attached review article by Joyce et al. for importance of 'SAR in Flooding'. I recently tried my hands on the freely available Sentinel-1A C-Band SAR data to delineate flooded regions induced due to Typhoon Hagupit/Ruby in Philippines in Dec. 2014. The results showed considerable correspondence with official data from the 'International Charter on Space and Major Disasters'. Due to specular reflectance of water it appears relatively dark in radar images and thereby making it rather straightforward to detect and delineate them. I found them to be quite helpful in mapping inundated regions otherwise I had a hard time finding pre and post disaster Images from conventional sources like LANDSAT, MODIS etc. If you can manage to acquire cloud free VNIR images just after floods it would be worthwhile but very often it is not the case.
https://sentinel.esa.int/web/sentinel/home
https://scihub.esa.int/dhus/
http://www.disasterscharter.org/
http://ppg.sagepub.com/content/33/2/183.abstract
I had used SRTM to make a map inundation risk in media cities, but in plan areas. It's not interesting use low spatial resolution to make flood maps.
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