A multi-component GIS framework for desertification risk assessment by an integrated index

This study describes a GIS-based software tool for the qualitative assessment of desertification risk. The tool integrates results from several land degradation models into ArcGIS using the object-oriented programming language Visual Basic. The integration of GIS and models is based on different coupling approaches. The proposed methodology was developed and tested on Sardinia Island (Italy). Six driving factors of desertification (overgrazing, vegetation productivity, soil fertility, water erosion, wind erosion and seawater intrusion) were model-simulated over two time periods to investigate the spatio-temporal evolution pattern of desertification-prone areas. Model results were normalized, weighted and combined into an Integrated Desertification Index (IDI) ranging from 0 to 1 (representing the best and the worst conditions, respectively), and classified into five desertification risk levels. The implementation, performance of the methodology and benefits provided by the modelling approach to land management authorities for monitoring processes of land degradation are fully described in the paper. (C) 2009 Elsevier Ltd. All rights reserved.