In the Ruaha National Park in Tanzania, there is virtually no surface water in early October. The rivers are still there, but they are flowing underground, so they are called sand rivers.
Elephants find places where the water is near the surface, and create mud wallows:
and they drill deep artesian wells down into the sand to reach the clean water:
This is enough to drink, or have a shower:
But for other animals it is harder. Some get all the water they need from their food, but some, including lions, need to drink. So they wait till the elephants have moved on, and use their holes:
The few rivers that used to have year-round water, especially the Great Ruaha River itself, are now regularly dry for several months each year, largely because of over-use by upstream rice farms, which were originally financed by the African Development Bank. The consequences have been dire, with a substantial decrease in populations of the larger animals such as elephant, buffalo and lion.
This remote Ruaha-Ruangwa ecosystem has long been famous for its large elephant populations but the combined pressures of water shortages and direct human aggression have resulted in a horrifying decline. In 2009, the population was 30,000, before plummeting to only 8,272 in 2014, a 76 percent decline over five years. The largest single cause of this is poaching. (Figures from Great Elephant Census 2014).
However, there are reasons for hope. The 2019 survey showed a big rebound, and the population is now thought to be stable at around 20,000 (although the survey area may be sightly different which makes it hard to compare the numbers directly.).