Abstract:
Soil salinity is one of the main environmental problems affecting extensive areas of land in both
developed and developing countries. It changes the fertile land to unproductive land, which
ultimately results in the economic loss. In Sri Lanka, salinity problems have been reported in the
dry and semi-dry zone districts including Hambanthota. Therefore, identification of salt-affected
lands and their various salinity levels are important for land use planning and restoration of
salt-affected lands. A study was carried out in the Welipatanwila and the Nonagama grama
niladhari (GN) divisions situated in Ambalanthota Divisional Secretariat Division in Hambantota
district. The main objective of this study was identifying and mapping salt-affected land by using
Geographical Information System (GIS). Specific objective was identification and demarcation of
soil salinity according to EC and pH measurement, mapping soil salinity levels and pH Levels
using GIS techniques. Salt-affected lands were identified and demarcated into different
categories according to the salinity levels using GIS. After the sampling was done with an iron
auger, Electrical Conductivity and pH of the samples were determined. The Inverse Distance
Weighted (IDW) interpolation technique in ArcView 10.1 software was performed to prepare
spatial distribution maps. According to the results of EC, the coastal area was highly salinized,
where salinity is >16 dsm-1. The salinity levels of 99% of the lands under paddy cultivation were
4-8 dsm-1and 8-16 dsm-1, respectively. The total land area of these GN divisions is 5.75km2.
According to the results of pH, percentage of land area with slightly alkaline 0.17%, moderately
alkaline 3.65%, strongly alkaline 52.17% and Very strongly alkaline 44.17% have distributed at
the soil depth of 0-30cm. According to this information, it is essential to follow proper
reclamation methods immediately to reduce the salinity levels before it becomes a severe
problem.
