A method is proposed to separate active discharge, recharge and intermediate zones from the digital Thematic Mapper TM data. A case study-was carried out in a natural reserve Welenbos (Walen Forest) and adjacent areas in Belgium comprising a total area of 174:3 sq. km. A microcomputer based Geographic Information and Image Processing System have been utilised for the identification of the characteristic of Remote Sensing TM data favourable for hydrological applications. The histogram of remote sensing data showing the characteristics of discharge, recharge and intermediate zones are unique and can be utilised for mathematical modelling purposes. This has a large potential in hydrological applications.