Predicting terrain erosion susceptibility from drainage basin morphometry using ALOS-PALSAR DEM: analysis from PCA-weighted AHP approach in a river system of Eastern India

In this paper, an attempt has been made to ascertain the erosion susceptibility of the Mayurakshi Drainage System in Eastern India using the 12.5 m resolution ALOS-PALSAR DEM dataset by the morphometric attributes viz. relief, surface, drainage texture and topography. The Analytical Hierarchy Process (AHP) was carried out for ascertaining the erosion susceptibility of the area under consideration. The methodology followed essentially differs from the traditional AHP technique because while assigning weights to multiple parameters, the study has depended on the Principal Component Analysis (PCA) instead of the opinion of the experts which are often contradictory. The relative importance of each parameter was calculated from the loading ratios of different parameters under PCA. Furthermore, instead of taking only one PC, we have taken six PCs with a cumulative explained variance of 99.13%. Finally, these AHP-based erosion susceptibility maps were weighted with respect to their explained variances (obtained from PCA for individual component) and the final map displaying the spatial variation of erosion susceptibility in the Mayurakshi Drainage System was obtained. Analysis reveals that, by and large, the area is characterized by lower susceptibility scores with the solitary exception of the middle domain of the Mayurakshi Basin and the upper reach of the Dwarka River. Here, the erosion susceptibility is greatly elevated due to the fact that the rivers have to encounter and incise across a number of low-lying hills which may be considered to be offshoots of the Chhotanagpur Plateau. In other areas, the susceptibility of erosion is reasonably modest.