The selection of the best possible Landsat TM band combination for delineating salt-affected soils

A quantitative approach was pursued for identifying the most appropriate three-band combination of Landsat Thematic Mapper (TM) reflective bands data for delineating salt-affected soils of the Indo-Gangetic alluvial plain. The standard deviation and correlation coefficients values of the TM data were used for computing a statistical parameter called the 'Optimum Index Factor' (OIF) that is indicative of the information (variance) content of the data. Amongst all the 20 three-band combinations considered, the band combination 1, 3 and 5 was found to be the best in terms of information content. The normally used band combination 2, 3 and 4 ranked relatively very low. The validation of this conclusion with the accuracy estimates of the delineation of salt-affected soils using the same data revealed a mixed relation between the ranking obtained from the OIF values and the accuracy estimates, thereby pointing towards further investigation in other areas with similar terrain conditions.