The hierarchical approach and supervised method were used to assign the pixel value into land classes. Fig 2. shows the procedure used for this step. The digital processing of each image scene was digitally performed based on diverse criteria as follows
Distinguishing between water body and non water body was executed from an analysis of the threshold of the pixel values. The vegetation and non-vegetation cover classes were differentiated over the area of non-water body, performing the normalized vegetation index (NDVI) analysis. The NDVI, widely used and accepted for vegetation study is defined as NDVI = (ρNIR - ρRED)/ (ρNIR + ρRED), where ρNIR and ρRED represent the reflectance values in the near infrared and red bands respectively. Providing the NDVI value, the differential of vegetation from non-vegetation can be defined. To distinguish the riparian vegetation, creation of 300 m. and 500 m. buffer beyond the streams and river was performed,
resulting the masking areas under which the riparian vegetation could be classified.