The countries of circum-Sahara Africa adversely affected by desertification, their sub-regional organisations, their Northern partners and the concerned international organisations of the United Nations System have created the Sahara and Sahel Observatory (OSS) in May 1992. OSS's mission is conducted within the international framework of the Convention to Combat Desertification (CCD) and Agenda 21 and aims to favour the development and the optimisation of its African partners' information wealth, for an optimal use of the means for combating desertification.

The informal settlements, townships, temporary camps and other human posts need at least basic services such as potable water, electricity and sanitation. Other services such as food supply, medical aid and shelters are usually arranged in case of disasters and large human migrations. A proper and efficient services need should be well estimated and simply implemented. All requirements can be achieved as results of evaluation with use of the geo information decision support system GDSS, suggesting services sorts and quantities.

The status of cadastral and land information systems in Africa is assessed, with specific reference to their capacity to assist decision-makers. Recommendations and guidelines are provided for the adaptation of existing systems and/or the development of new systems, so that they can be used for land reform, physical planning and integrated land administration. The guidelines take into account the need to create land information for decision-makers without creating unaffordable costs to the state, given that the average per capita income for Africa in 1995 was USD665.