Tunisia is currently hosting the 4th session of the International Congress “Geo Tunisia 2009″ under the motto “Survey of water resources and desertification by using the geographic information systems (GIS), remote sensing and numerical designing.” The conference, which began on December 16, runs through December 20, is part of Tunisia's push for new technology in the fight against climate change. The Tunis International Centre for Environmental Technologies (CITET), is hosting the event in coordination with the ministry of environment. The congress is organized by the Tunisian Association of Digital Geographic Information in cooperation with a significant number of universities, organizations and institutions concerned with geographic information systems and space science. Several researchers, academics and institutions, research centers and private companies, are taking part in the event as Tunisia moves forward on previous announcements it is looking into renewable energy sources and new means of tackling global warming problems facing the country. The congress will present studies, applied research, workshops, in addition to the geo-technological exhibition that will be organized by major international institutions specializing in geographic information systems, remote sensing and their various applications to water resources and desertification sectors. The problem of water resources and desertification, are one of the major challenges faced by the region and has prompted a number of researches and studies for professionals so as to find solutions to curb this natural phenomena. BM