The International Hydrological Programme (IHP) develops, among other tasks, methodologies for the sustainable management of water resources in arid and semi-arid areas through integrated approaches. Within the framework of the fifth cycle of IHP a special project on wadi hydrology has been developed in the Arab region to help understand hydrological processes under arid conditions. A regional network on Groundwater protection has simultaneously been established in the same region.

Particular attention has been given to fossil groundwater systems in Sub-Saharan Africa where studies have been initiated in co-operation with countries sharing aquifer systems.

Development in arid and semi-arid regions is limited by the scarcity of water resources. With the high population growth rate of almost all the countries in these regions, this situation could lead to a serious water crisis in the forthcoming years and to possible conflicts in the case of shared water resources.

There is therefore an urgent need for developing a global research and capacity building programme on hydrology and water resources management of arid and semi-arid zones in order to help the countries concerned to solve their fast growing water problems.

In arid and semi-arid zones, the understanding of hydrological processes, in particular rainfall characteristics, recharge conditions, evaporation and evapo-transpiration needs to be improved.

The modalities for assessing available water resources in large basin aquifers shared by several countries is often a common feature which needs to be established and which change from one region to another.

Water being scarce in the arid and semi-arid zones, its management has to be carefully undertaken. Consideration must be given to the close relationship between surface water and ground water, periods of drought, the possibility of recharging aquifers from runoff excess during the rainy season and the possible re-use of waste water after treatment. Water conservation is a must in arid and semi-arid conditions if sustainable management is to be attained.