Remote sensing analysis of desertification trend in Eastern Sicily

The present climatic framework characterizing the Mediterranean countries exhibits a slow and steady increase of average temperatures and seems to reflect at smaller scale the global warming trend.
This work focus on the Sicily island (Italy) that, given its central position in the Mediterranean sea, represents an important indicator for the main climatic evolution of the whole region. The study concerns the analysis of Landsat multispectral images and the comparison with the available thermo-pluviometric data to investigate the possible desertification patterns of the Sicilian territory, with particular attention to the Eastern region. The remotely sensed data, derived from Landsat imagery, have been selected to cover a 20 year time span, from the late 80’s to date.
We have tried to study the relationships between vegetation cover, rainfall and temperature data measured at climatic stations scattered through the Sicilian territory. A regional scale study of the vegetation cover and related characteristics, represented here by the Normalized Differences Vegetation Index (NDVI), can only be achieved by the application of RS processing techniques. Being NDVI a widely accepted standard parameter used to define vegetation stress, it is of fundamental importance, for the understanding of the dynamics and evolution of desertification processes, that the satellite-derived data are integrated with direct measurements of rainfall and temperature patterns.
To this end, a series of vegetation change maps based on NDVI value evolution through time has been elaborated and compared to rainfall and temperature data covering a wider time range, larger than a half-century. The analysis of such climatic information reveals a complex framework characterized by a fairly large local variability that exhibits a general drift towards desertification favorable conditions (increasing annual average temperatures, decreasing number of rainy days, higher frequency of extreme events). Such conditions are further enhanced by human activities, such as agriculture, connected with groundwater overexploitation.
This contribution summarizes the preliminary results of the comparison of RS analysis and climatic data in order to quantify the correlation between causes and effects, to identify the possible consequences of the present day trends and to provide an estimation of desertification processes in Eastern Sicily.