Use of Landsat ETM+ data for delineation of water bodies in hilly zones

Abstract

The remotely sensed Landsat Enhanced Thematic Mapper Plus (ETM+) dataset is used for the detection and delineation of water bodies in hilly zones. The water bodies were detected using Surface Wetness Index (SWI), Normalised Difference Vegetation Index (NDVI) and a slope map. The assessment of areas under dense vegetation in water bodies is omitted in the combined map prepared using classified raster images showing (1) the distribution of ‘water’ and ‘non-water’ based on SWI and (2) the distribution of ‘vegetation’ and ‘non-vegetation’ based on NDVI. The shadows' effect in estimated areas under water bodies is detected and delineated using the combination of (1) a combined raster image (classified SWI and NDVI) and (2) a slope map. About 3.8% (1370 ha) of the total area reviewed is estimated under water bodies with 91.74% overall accuracy. The water bodies include (1) major and minor dams, (2) watered streams, (3) springs distributed in foothill zones and (4) small dams on minor streams. The relatively smaller water body objects, i.e. streams and springs, have estimated less producer's (92–96%) and user's (85–92%) accuracy than the major water bodies, i.e. 96.77% producer's and 100% for user's accuracy.