Fears over Ethiopian dam’s costly impact on environment, people
that the dam would create a positive water balance for the lake, with the consequential irrigation abstraction impact on the lake not taken into account.
There were independent efforts by international donors, namely the European Investment Bank and the African Development Bank, to assess the impact of the project. But these were gazumped when Chinese donors agreed to fund it. The Chinese did no independent environmental or social reviews.
Another controversy is that the Omo’s cascade of power stations has replaced the river’s natural flow cycle with regulated, man-made cycles. These depend on the electricity demands from the Ethiopian national grid and its international connections. A consequence of this is that the river’s annual floods are smoothed out and the low flows will be increased. It has been claimed that this flood management is beneficial as floods can lead to loss of life. But people in Lower Omo depend on the annual floods, as they traditionally cultivate the riverbanks.
What is its impact on the environment?
There are serious environmental concerns. First, Gibe III’S flow regulation and water abstractions will permanently alter the Omo’s natural hydrology. This will potentially destroy Lake Turkana’s ecology and fisheries.
Second, Gibe III’S river regulation has enabled irrigated plantation development. A potential of 450,000 hectares of agricultural development in the Omo-gibe Basin has been mentioned. So far, 100,000 hectares from within the Omo and Mago National Parks and Tama Wildlife Reserve are being developed into sugar plantations. And downstream, 50,000 hectares have been allocated to a cotton plantation developer. There will be other schemes requiring water too.
Through abstracting irrigation water, these plantations will deplete the Omo river influx to Lake Turkana. The lake is already semi-saline, said to be on the salinity brink for some species, and depletion of inflows will increase the salinity levels. Also, chemical releases from the plantations may adversely affect the lake.
Third, the dams will cause a massive drop in Lake Turkana’s water level. When the Gibe III reservoir was filled in 2016, it caused the lake to fall two metres. The Gibe IV dam, also called Koysha, will be next in the Gibe cascade to be built, and this will deplete the lake by 0.9 metres during its filling, forecast for 2020.
In 1996, the Omo-gibe River Basin Integrated Development Plan had forecast that the Basin’s water demand in 2024 would require 32 per cent of river’s discharge, 94 per cent being for irrigation. This is becoming a reality, with recent studies demonstrating that the lake level could fall 10-20 metres. As the lake is on average about 30 metres deep, the potential environmental consequences are significant.
What of the future for Lake Turkana?
Warnings of environmental impact have been sounded for decades, with recommendations of a bilateral agreement between Kenya and Ethiopia before tampering with the Omo.
Time will tell, but at least there is now a trans-boundary forum brokered by Unep albeit belated, and somewhat lethargic in its progress. It is hoped that this initiative will be sustained and will critically review the development options and impacts.