Editors’ Choice
2019 Skyscraper Competition
Carlo Alberto Guerriero
Italy
In Africa, in the Sahel regions, the drying of wetlands is proving catastrophic for both biodiversity and the economy of local populations. In fact, the fall in rainfall, exacerbated by the poor management of water by man, is leading to the fight against desertification, and more and more villages are held in the dry grip of the Sahara. All this has pushed thousands of environmental refugees to flee to Europe and caused the emergence of numerous internal conflicts.
Lake Chad is emblematic of the natural and human drama that the Sahel is experiencing. Lake Chad has always been a fundamental habitat for the survival of sub-Saharan populations and an important cultural crossroads. But in just 60 years Lake Chad has lost more than 90% of its surface, currently reaching a size of 2,500 km2, with the forecast of a total disappearance in the coming decades.
To determine such a change, as well as a decrease in precipitation, it was the construction of large dams on the Yobe rivers (in Kano in Nigeria) and Logone (in Maga in Cameroon) the main tributary of the Chari. Both rivers have lost almost 80% of their flow, with the consequent loss of alluvial areas necessary for agriculture, a reduction of pastures and a strong limitation of fishing activities. For millennia the Lake Chad basin has been subject to great variations, but today unlike in the past, about 10 million people survive thanks to the lake.
SOLUTION
The idea of the Water Source Tower derives from the need to counteract the drying process of Lake Chad. The structure, retaining the humidity of the air, is able to obtain and accumulate huge quantities of water. A series of Water Source Towers, located at key points in the basin, would create a system of water sources that can significantly increase the water level by bringing Lake Chad back to “Chad Normal” conditions. As a result, many arid areas would return to being wetlands, rich in pastures, agricultural land and fishing waters, with enormous economic benefits for local populations.
The Water Source Tower that uses common technologies such as photovoltaic panels, air dehumidification systems and water pumps is able to counteract the drainage of the lake by acting in 2 phases:
1 – Water production
Water Source Tower has about 200 000 m2 of condensing surface and manages to process over 1.82 km3 of air per hour. The humid air enters the tower in a forced manner thanks to the continuous work of large fans, and passing through the evaporator gives up all its water. In this way each tower collects an average of 147 million m3 of water a year.
2 – Water Distribution
About 10% of water produced is fed into a water supply for domestic use in villages near the tower. The remaining 90% of the water is released into the surrounding environment and allowed to flow naturally towards the Yobe River or Lake Chad.
RESULT
The system of Water Source Towers with approximately 1.32 km3 of water (equal to 90% of the 1.47 km3 produced) positively brings the balance between the volume of water lost by the lake and the contribution of the rivers and rains.
Over a period of 10 years, the Water Source Towers lead to an increase in the lake level of 1.5 m and an extension of the navigable surface of almost 20 000 km2.
