In areas where surface water is not readily available (located far from areas of need), groundwater is the primary water source. Groundwater aquifers supply an estimated 20% of the global population living in arid and semi-arid regions. Despite their widespread presence, groundwater aquifers in arid areas receive only limited or seasonal recharge, making such aquifers susceptible to rapid depletion. The Northern Sahara Basin Aquifer, for example,...

A qanat is a water management system used to secure reliable water supply to human settlements or irrigation in semi-arid and arid regions. Probably originating in Persia, the qanat system has been adopted and developed further in large parts of Asia and Europe. Its widespread use is refected in the many names for the system and similar systems; kariz/kahan (Persian), khettara (Morocco), galeria (Spain), falaj (United Arab Emirates and Oman), ...

The bulk of water supply for Nairobi comes from Thika, Sasumua and Ruiru Dams, as well as the Kikuyu Springs. Over time water supply for the city has failed to meet demand. The current estimated water demand for Nairobi is 650 000 m3/day compared to the production of 482 940 m3/day (WRMA 2010). The difference between production and demand has been widening over time due to population growth, inadequacy of the carrying capacity of the distributio...