National Geographic : 2015 Aug
lake turkana 73 Studies Centre at the University of Oxford pub- lished a booklet collecting Avery’s work and summarizing his research on development along the Omo. His findings left him deeply depressed. “ When you take water out of the river and use it in irrigation in a climate like that, some of it will percolate back into the watershed,” he said. “But most of it will disappear.” Avery and other experts say the danger be- gins with the dam, which is Africa’s largest, an 800-foot wall of concrete. Dams inevitably harm ecosystems below them. Gibe III will cause in- tense, drought-like stress to the Omo and the lake during its first three years of operation, when up to 70 percent of the river’s flow will pass through a reservoir. Once the reservoir is full, the lake will slow- ly normalize—but then the sugar plantations come into play. Sugarcane is notoriously thirsty, and its cultivation in the dry lands of Ethiopia’s lower Omo Valley would be impossible without the dam to regulate the river. Tens of thou- sands of acres have been officially marked off for cane and cotton in southern Ethiopia, and according to Avery, tens of thousands more are slated for future plantations. Already plant- ing has begun, and all of the growth will be fed from a single tap: the Omo. Few Daasanach remain—they ’re now one of Kenya’s smallest, weakest ethnic groups.