It is low in the mountain and desert zones, where it is concentrated around the oases. Climate Average annual rainfall is 340 mm, but varies from more than 450 mm in the north, where rainfed agriculture is possible, to less than 150 mm towards the south-east, where irrigation is absolutely necessary. The most important rivers are equipped with dams, allowing surface water to be stored for use during the dry seasons. Of this total of 11 km3, 7.5 km3 was surface water and 3.5 km3 groundwater. A major effort is being undertaken, starting in 1996, to increase this percentage within the next eight years.
Energy costs represent a large part of the total costs.
The schemes in the mountains mostly use springwater, distributed by gravity. In all schemes, the water distribution is based on rotating turns. This unit also forms the basis for the dimensions of the canals in the large schemes. It is in charge of water distribution control in urban areas and in some rural municipalities. The DGH, which is in charge of providing irrigation water for the large schemes.