Soil salinity is caused by natural or human induced process and considered to be a major environmental hazard. Nearly 20% of all irrigated land in India was salt affected and this proportion tends to increase in spite of considerable efforts dedicated to land reclamation. This requires careful monitoring of the soil salinity status and the variation to the curb degradation trends and secure sustainable land use and management. This study area Nagapattinam district was affected by salinity, the situation became worse after tsunami salinity level has increased that makes portable water un-utilizable and change in cropping pattern even at some places saltpans are available for extracting salt by salt industry. The paper attempts to demonstrate a tool for identifying and mapping salt affected areas and also deriving different levels of soil salinity in order to cope with increasing and sustaining the productivity of crops from remote sensing data using various threshold levels.