In the 1910s, engineers proposed digging a canal from the Mediterranean Sea to the Qattara Depression in northwestern Egypt, flooding the below-sea-level basin to generate hydroelectric power. The plan was studied intermittently for more than a century before Egypt scrapped it this year.
According to a 1933 summary in Nature of surveyor John Ball's work, the Qattara Depression has an average floor depth of about 60 meters (200 feet) below sea level, with a maximum depth of roughly 133 meters. The basin spans an estimated 20,000 square kilometers (about 7,700 square miles). Since no rivers flow into it, the basin remains dry.
How the plan was supposed to work
Seawater would travel from the coast through a tunnel or canal, dropping down into the depression and spinning turbines as it went. Once inside the hot desert basin, the water would likely evaporate quickly, drawing in more seawater behind it. That was the part that made the idea attractive: it could generate power almost continuously. But keeping the water level steady meant constantly balancing incoming seawater against evaporation, and over time, the basin would slowly fill with the salt left behind.
