IDENTIFYING AND MAPPING SALT-AFFECTED LANDS IN HAMBANTOTA DISTRICT, SRI LANKA: AN INTEGRATED GIS AND REMOTE SENSING APPROACH

Abstract

Since available lands in Sri Lanka is decreasing every year mainly due to degradation oflands, it is very important to restore these lands for useful agricultural production. In thisregard, identification of salt-affected lands and differentiates into salinity levels wouldhelp to take necessary actions to restore these lands.

An extensive soil survey was conducted throughout the Hambantota district in order to10 0 to to KA•••••.•.identify the salt-affected lands in the district The sampling was done at different depths(i.e. O-lOcm, IO-20cm, 20-30cm, 30-4Ocm and 40-50cm) by using a manual soil auger.The distance between sampling sites was approximately 3km. The exact position of

sampling points in latitude and longitl!c!~ ~ identified by GP~ (Global PositioningSystea), A total number of 100 points and 400 samples were collected. Topographicmaps of survey of Sri Lanka used in the study were Timbolketiya (82), Kataragama(83),Yala(l4), Hambantota(88) and Tissamaharama(89) of scale 1:50,000. Digital thematicmaps of same map sheets and Scale of I :25000 digital maps were also been used.The samples were taken to the laboratory of the Department of Crop Science, Faculty ofAgriallture, University of Ruhuna, where EC and pH measurements were taken using theEC meter and the pH meter. AIl the locational data taken using GPS system, entered intoa database. EC and pH data also been entered to the database. Using ArcView software, apoint map was generated using all the locational data including EC and pH values asattribstes. By applying interpolating techniques, salinity maps were produced.