Modeling the Present and Future Desertification Risk State: A Case Study in Kolli Hill, Eastern Ghats of Tamil Nadu, India

Desertification is a global land degradation problem faced both in the developed and developing countries alike. Kolli hill is one of the hills of the Eastern Ghats of India, currently undergoing conspicuous land degradation to such an extent, that it has already begun to witness an altered forest stand. Hence, the main goal of this study is to identify areas under actual and potential desertification risk by means of a modelling approach in which four indicator thematic layers (soil, climate, vegetation and anthropic pressure buffers) were overlaid in GIS environment. The cartographic data were transformed to structured numerical data (weighted layers) such that each of the layers was assigned knowledge based weightage values in relation to their influence and contribution to the process of desertification to get the final desertification risk state of the forest region. Climate models suited for the Indian condition were utilized to determine the areas under potential risk of desertification and three Representative Concentration Pathways were employed to study the pattern of desertification by the middle and the end of this century. The results of the study show the present scenario with an area of 200 km2 falling in the medium risk state and an area of 7 km2 falling in the high-risk state. On average, about 215 and 214 km2 of the forest area fall under the medium risk category, while an area of 9.5 and 8.94 km2 belong to the high risk state for the years 2050 and 2070 respectively. The areas experiencing these risk states belong to the foothills and mid slopes of the forest region and fall within the semiarid–dry sub-humid aridity zonation.