OH MY COD

 

(Mimi Abebayehu, 2021)

Previously, I unpacked the complexities of tripartite GERD and the damage it created for the water supply and food security for downstream riparians, Next, I will transport you to the Omo-Turkana region to explore the effects of the Gibe III dam on food.

The Gibe III hydroelectric project was constructed on the Omo River, in the Omo-Turkana region in southern Ethiopia and northern Kenya. Over 300,000 people depend on Lake Turkana, which provides water for grazing livestock, drinking and agriculture, both for subsistence and income (Otachi et al., 2015).  However, the building of the Gibe III will likely reduce these flows by 60-70% (Car 2012), which alongside a population expected to double every 20 years (Avery, 2012), will cause catastrophic hydrological and ecological consequences. During the 2015-16 filling period of Gibe III, Lake Turkana's water level declined 2 m; Altering the natural hydrological cycles and lake level variability, and in turn the ecology of water which is vital for fishing and flood-retreat farming  (Avery & Tebbs 2018). 

The Lower Omo Valley in Ethiopia, and Lake Turkana in Kenya (Hodbod et al., 2019)

Not so sweet

Further, planned large-scale plantation developments have cleared 30,000 hectares of land in the Lower Omo for planned large-scale plantation developments such as the Kuraz Sugar plantation , which aim to replace the basin's natural capital (ibid.). The plantations will force a transition to year-round monocropping on artificially irrigated land, inevitably causing a reduction in biodiversity and deprived many species of their habitat, thus tampering food webs and narrowing the portfolio of subsistence opportunities (Hodbod et al. 2019; Buffavand 2016). Avery and Tebbs (2018) found the proposed the large-scale irrigation schemes for the plantations will abstract 50% of the Omo river, diminishing the lake level. Following the 2015 floods, most populations in the northern Lower Omo are reliant on corporation-controlled irrigation systems, creating vulnerability to famine (Stevenson and Buffavand 2018). And as seen with GERD, there were neither prior trans-boundary consultations nor agreements with directly affected parties.

Can’t [Chloro]Phyll our stomachs

Remote sensing was employed by Tebbs et al (2020) to assess the influence of these altered hydrological patterns on large-scale phytoplankton concentrations. According to the model, annual mean Lake Turkana chlorophyll levels decreased by 30% during the Gibe III filling. Prior to dam completion, seasonal phytoplankton blooms aligned with annual floods from the River Omo, indicating a strong correlation between lake levels and quantity of chlorophyll. Due to the lakes limited nutrients (Kallqvist et al. 1988), chlorophyll is the main primary producer, thus its depletion will destroy economically significant specialist species for Turkana like Tilapia zilli (Gownaris et al. 2016; Tebbs et al. 2015).

Its Krilling The Fish! 

Lake Turkana’s unique colour is caused by high concentrations of cyanobacteria, which are pivotal to the sustain the fisheries of the lake (Kolding 1993). As Turkana’s lake level decreases so does bacterium concentration. The 60 different fish species present in lake Turkana depend on the fluctuating flows and flood pulses to reproduce, and the construction of Gibe III has regulated the river, not signalling fish to breed, declining populations (Gownaris et al, 2015). With lake levels dropping, biomass is expected to fall to 42% of its sustainable level, reducing fisheries habitats, while increasing salinity through concentrations of salt. To exemplify, Kolding (1993) found a 70% reduction in open-water pelagic endemic fish as a direct consequence of falling lake level.

To Conclude… 

The Gibe III dam could present major consequences for Lake Turkana, reducing nutrients, and in turn reduced fish populations and disruptions to food chains. With a worst case scenario being the complete disappearance of Lake Turkana, following analogies of the Aral Sea disaster (Avery 2012). 

How cod this effect indigenous people?
Tuna in next time to find out!
;)