In the past, we've discussed the use of mesh nets to collect dew and send it to water storage containers below. These are particularly useful in areas that have high humidity but low rainfall. But what if you have low humidity and low rainfall, what do you do to collect water?
Fortunately, there are oases from which to collect water but unless you're a nomad and know where these water springs are you could be out of luck.
How however, a NGO in Ethiopia has developed a water pyramid which will act as a "greenhouse" and an irrigation system. The video shown here demonstrates exactly how it works. But in essence, during the heat of the mid-day sun, it traps the hot air and humidity to provide ideal growing conditions for a wide variety of plants and then, in the evening, when temperatures cool, the farmer can pull a rope and drop the sides of the top of the pyramid to create a funnel which feeds water into a reservoir where it can be used for irrigation or drinking.
Since it also covers the plants it protects them from insects which may destroy the crop.
This is only one solution, but since it's a compact system and relatively cheap, it may be of use to semi-nomadic framers throughout Africa who continue to struggle to water their cattle and grow plants.