Use of remote sensing and geographical information system (GIS) for salinity assessment of Vaal-Harts irrigation scheme, South Africa

Soil salinity is a critical environmental problem in many countries around the world especially the arid and semi-arid countries like South Africa. This problem has great impact on soil fertility which in turns has a great effect on soil productivity. Landsat enhanced thematic mapper plus (ETM+) data of Vaal-Harts irrigation scheme acquired were analyzed along with other field data sets and topographical maps to show the spectral classes and salt-affected areas for the years under assessment (1991 to 2005). False colour composite and supervised classified image shows that most of the salinity problems are located along the entire scheme. The results of the study indicated that a serious salinity problem exists and may get worse. The Normalized Difference Vegetation Index (NDVI) tends to be higher along the irrigation canals. There is therefore an urgent need for management program to control the spread of the menace and therefore reclaim the damaged land in order to make the scheme more viable.