Geo-environmental analysis and identification of degraded areas susceptible to desertification in a semi-arid, tropical ecozone: the Acaraú river basin in northeastern Brazil

INTRODUCTION Over the past three decades discussions have been held regarding environmental issues including evaluations and studies on natural and social sustainability with the purpose of mitigating the increasing degradation of the environment. The UN Conference on the Human Environment in Stockholm in 1972 and the UN Conference on Environment and Development in Rio de Janeiro in 1992 are worthy of mention in this respect. Scientific and governmental authorities, as well as the technical media, have been discussing and announcing the results of reseacrh work on the subject of environmental degradation, especially with regard to dry ecozones susceptible to desertification, considered a problem of worldwide proportions (Rubio, 1992). Agenda 21, Chapter 12.2, of the United Nations Environment Programme, defines desertification as “land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities”. In Brazil, the Northeastern region―the country’s largest arid ecozone―has been the focus of political and economic interventions for the mitigation of the effects of droughtinduced desertification since Vasconcelos Sobrinho’s pioneering studies on the subject in 1976 up to the establishment of the National Program for the Prevention of Desertification and Mitigation of the Effects of Drought (PAN-Brasil, 2004). Thus, the Brazilian government