Integration of remote sensing techniques for monitoring desertification in Mexico

Desertification is considered one of the most serious threats to arid, semiarid, and sub-humid environments. In this study, several remote sensing techniques were integrated for monitoring desertification in a semiarid region of the central Mexican plateau ( state of Queretaro). Landsat TM images were used to compute the Normalized Difference Vegetation Index ( NDVI), Bare-Soil Index ( BSI), and albedo ( alpha). A change vector analysis ( CVA) examined changes in the direction and magnitude of indicators during the 1993-2011 period in order to detect degradations or improvements in land conditions over a period of time. In addition, a desertification degree index ( DDI) was applied based on the NDVI-alpha relationship. The results indicated that in the semiarid zone of the state of Queretaro, 48.3% of land use corresponds with agricultural areas; 2.7% of the area does not present any degree of desertification, while 49% presents the following degrees of desertification: 5.5% extreme, 10.9% severe, 18.9% moderate, and 13.7% low. The DDI applied in this approach for evaluating this phenomenon at the regional and municipal level is an effective tool for identifying areas at risk of desertification, in addition to monitoring changes in the degree or direction of desertification.