Remote Sensing of Watershed: Spectral Ratioing Study for Watershed Management

Abstract

River catchments are basic hydrologic units and are important from the point of view of water budget management. There are longitudinal and seasonal variations in the catchment due spatio-temporal differences in terms of lithology, rainfall condition, intensity, land use land cover. Geospatial techniques and satellite data provide cost effective information about watershed. It is easy and profitable to use these techniques as data acquisition is easy, processing is fast Ratioing is one of the digital image processing technique useful to extract information about catchment characteristics and parameters for watershed development and planning. Indices give subtle tonal variations to identify the features spectrally. It de-emphasizes the effect of sun illumination, effect of topographic factors and highlights the region as per spectral properties of specific features. It enhances the quality of image to study the features in detail. These indices are also used to improve the accuracy of classification algorithms. For the current study Landsat-8 OLI used to study NDMI, EVI2, EBI, BSI, MNDWI and MODIS product MOD11A2 and MOD13A2 has used to study TCI, VCI and VHI indices. The study indicates that indices are one of the good techniques to extract spatially and temporally varying features. NDMI provides moisture condition information across watershed. EBAI and BSI highlights built up area and give idea about impervious surface. BSI gives information about bare soil where erosion mostly very common. EVI2 enhance the vegetation and MNDWI emphasize the waterbodies which seasonally varies. TCI, VCI and VHI useful to study drought conditions. The correlation between TCI and VHI, VCI and VHI studied to get information about drought. The above indices useful to study and extract several parameters to study runoff, erosion, sedimentation, ground water condition etc. Indices provide unidealistic information at various wavelengths. Repetitive coverage allows to monitoring dynamic features like water, vegetation, soil. Indices enhance the spectral information, increase the reparability of the classes of interest, and improve the quality of mapping. Such kind of technique’s are beneficial for conservation and management of the earth resources for local government bodies to conserve the water and to reduce the intensity of the drought.