Development of ravine vulnerability index for identifying potential zones of reclamation in ravine lands of Western India

The ravine is considered as the worst manifestation of land degradation by water erosion throughout the globe. About 120.7 M ha land in India, suffers from various forms of land degradation, out of which 3.67 M ha of land is affected by ravine. The extending ravine into the nearby 50 m of buffer zone tends to deprive the farmers of their occupations forcing them to work as landless laborers for their livelihood. Ravine reclamation is a cost intensive activity, due to which it is financially not feasible to go for reclamation in the entire ravine lands, simultaneously. Therefore, there is a need to identify the potential zones of reclamation for planning of reclamation work in a phased manner. In this study, an innovative hybrid approach was used for development of ravine vulnerability index for Mahi ravine in Western India. The potential zones or active sites in the 50 m buffer zone of the delineated ravine covering an area of 63031 ha was identified for reclamation works. The spatial database was used for preparation of raster layers using Arc GIS 10.3 software. The sand, silt, clay, organic carbon, soil erodibility factor, slope, stream power index, topographic wetness index, sediment transport index and cover factor were identified as important parameter for development of ravine vulnerability index. The weights were assigned to different parameters in pairwise comparison on the scale of 1 to 10, based on the relative importance of the each parameter with respect to another in the decision matrix of analytical hierarchical process. The number of iterations were made to obtain the consistency ratio less than 10% to obtain the final priority weights of each parameter. The priority weights obtained for each layer was then assigned in the raster calculator in the Arc GIS interface. The highest weight of 28.5 was obtained for sand parameter and minimum weight of 1.4 for sediment transport index parameter. The ravine vulnerability index validated through ground truth shows that 16703 ha (26.50%) area of Mahi ravine in Western India was found be under very high priority and was identified as potential zones or active sites for reclamation. The land capability classification for reclamation of the Mahi ravine in Western India shows that 20275 ha (32.16%) area of arable land falls under Class-III followed by 18687 ha (29.65%) of non-arable land under Class-VI for suitable soil and water conservation measures.