Abstract:
Soil salinity is a serious problem in irrigated area of Pakistan. Existing methods for the assessment of soil salinity are costly and time consuming. Geographic Information System (GIS) and Remote Sensing (RS) technologies are emerging as important tools for assessing the saline area. An attempt has been made to assess saline area in the lower Chaj Doab using SPOT satellite images. Land cover classification, normalized difference salinity index (NDSI) and normalized difference vegetation index (NDVI) were analyzed to delineate the saline area. Land cover classification of satellite images was done on the basis of spectral signatures recorded at different bands, using maximum likelihood classifier, which provides reasonably good results. The buffer analysis along canals was used to identify waterlogged and saline area around canals. Later on geostatistical analysis conducted on water table depth and groundwater quality data to generate classes according to their importance for soil salinity. Weighted overlay was performed by considering all parameters to get vulnerable area to soil salinity. The results showed that 20 per cent of study area lies in saline zone which was further classified into four classes namely: non saline, slightly saline, moderately saline and strongly saline. A comparison with the surface salinity map developed by WAPDA showed a close agreement. Therefore, GIS & RS can be used with confidence are useful tool to detect soil salinity and has potential in evaluating and improving land and water management. This would definitely help in saving cost, time and labor.
