In the mountains of south-eastern Zimbabwe lie the ruins of the first great city in southern Africa. The place is known as Great Zimbabwe, which would come to mean "the great stone house" in the Shona language, a Bantu language that is also spoken in Mozambique, Zambia and Botswana.
The place, which was already the capital of the Shona kingdom in the 11th century, flourished and welcomed many people for centuries (reaching 20,000 inhabitants), until it was totally abandoned in the 17th century. Located in a particularly arid area, on a plateau overlooking the upper reaches of the Sabi River, its main challenge was to ensure a stable supply of water for both people and livestock.
South African, Danish, British and Zimbabwean researchers have used modern excavation and remote sensing methods to study a series of large depressions in the landscape known as 'dhaka' pits, which have never been analyzed because they were thought to have been used only for collect clay to build the city.
The work led by geologist Søren Munch Kristiansen, from Aarhus University, shows that the pits were probably also used to store and manage water from Great Zimbabwe, which eventually gave its name to the country that exists today and where the bird that has ended up becoming a national symbol.
The ruins of the settlement cover an area of seven square kilometers and consist of three distinct spaces: the Hill complex, the Valley complex, and the famous Great Fence. What archaeologists know as The Acropolis was a space built as a palace on top.
The researchers point out, in an article published in the journal Anthropocene, that there are clear indications that the depressions were excavated in places where they could collect surface water, and at the same time filter and store groundwater for use during dry periods of the year.
More 'dhaka' wells were found during the site survey than previously known, and they have been found in spaces near small streams that naturally traverse the landscape when it rains or where groundwater percolates. This has convinced experts that its purpose was to act as a smart system to ensure a stable water supply, by storing resources that could be used outside of the rainy season.
The people of Great Zimbabwe devised climate-smart methods to store and manage water in an area characterized by three different climates, with a very hot and dry season, a hot and humid season, and finally a warm and dry winter.
"Understanding past water management is crucial to address contemporary human environmental challenges in sub-Saharan Africa, where urban growth is affecting the availability and supply of water," the specialists write in their study.
The “dhaka” wells were part of a “large-scale management system that exploited catchment hydrology and groundwater through reservoirs and artificial springs to ensure supplies for subsistence services, agriculture, livestock, rituals and ceremonies," they add. These water reservoirs could have been essential in creating an urban society that required a constant supply for daily life.
