Urban Flood Hazard Modeling for Noida City

Abstract

This contemporary work unveils the usage of a new methodology to carry out an accurate hazard mapping of urban flood footprints. It is based on wetness transformation. It is a procedure of conversion of multi-spectral-bands into three dimensional feature space. The present study embraces conversion of thematic mapper (TM) imagery of Landsat to a three dimensional array; brightness, wetness and greenness, followed by the technique of change detection to locate inundated areas in urban regions. Efficient thresholding of the normalized difference image generated during change detection has shown promising results in identifying the flood extents which include standing water due to flood and mud surge caused by the flood. Prior to wetness transformations, dark object subtraction has been used in lower wavelengths to avoid errors due to scattering in urban areas. The study shows promising results in eliminating most of the problems associated with urban flooding like misclassification due to presence of asphalt, scattering in lower wavelengths and delineating mud surge. The methodology is implemented over Noida, business capital of state of Uttar Pradesh, India and tested on September 1980 flood event. The results are validated by satellite imageries on Google Earth to bolster the methodology of accurate extraction of urban flood footprint.

Keywords: Urban flood footprint, image classification, image transformation, wetness transformation