Sistema de avaliação e comparação espacial do processo de desertificação no seridó potiguar e paraibano, semiárido brasileiro.

Abstract

Desertification is a global phenomenon characterized by the degradation of land in the arid, semi-arid and dry sub-humid areas for which environmental, social, economic and institutional factors compete. Define a set of actions to address it requires knowledge of the complex relationships established between society and the environment to identify and monitor the causes and consequences of the process. The modeling of this reality remains a challenge for researchers worldwide, especially in Brazil, due to the large number of aspects to be considered for which there is not always reliable and available information. To reduce this gap, this study structured a system of evaluation and spatial comparison of desertification for the 32 municipalities of Seridó geographical microregions in Paraíba and Rio Grande do Norte from a set of 27 indicators recommended in the related literature, organized according to the conceptual model DPSIR - forces, pressures, state, impacts, and responses. The indicators, either discrete or continuously distributed, were calculated, normalized, adjusted for the direct or inverse relationship with desertification, weighted by experts from different areas of knowledge and organized into raster type information plans. Multicriteria decision analysis techniques incorporated into a geographic information system were used to develop multicriteria desertification indexes for each DPSIR category as instruments for assessing the structural causes, direct causes, susceptibility, consequences and society’s responses to the problem. The results pointed out that the structural causes of the process, including land concentration, social inequality and consumption culture, hold 49.7% of the area in a moderate, strong or very strong level of desertification. Direct causes, represented by deforestation and inadequate land management, affect 19.7% of the area in the same way. Regarding environmental, economic and social susceptibility, 83% of the area is subject to initiate or aggravate desertification processes at moderate, strong and very strong levels. The impacts of the process, observed by migration from the countryside to the city and by the decline of agriculture and livestock’s contribution to local GDP, occur equally in 73.5% of the area. Finally, only 19.9% of the area is relatively prepared to tackle the problem through the organization of government and civil society. In an overall assessment, 59.7% of the region is subjected to moderate, strong or very strong levels of desertification, considering all the 27 descriptors of the problem. Most of the region, according to the study, demand actions of governments and society to expand rural population access to land, income generation or transfer programs, universal basic education, agroecological technical assistance, native vegetation recovery programs, social protection services for the contingents that migrate to the cities, among other initiatives, aiming to confront the desertification process and mitigate its consequences.