Paper short abstract:

Dams on the Omo river in Ethiopia have ended a seasonal flood on which downstream communities previously depended for flood-retreat agriculture. Using ethnography, household survey, and remote sensing (satellite) data we estimate this hidden economic cost.

Paper long abstract:

In Ethiopia's lower Omo valley, official narratives of development are dominated by large infrastructure projects - a cascade of large dams (including the Gibe III dam, completed in 2015) and irrigated plantations, which are supposed to raise local living standards at the same time as they deliver electricity to the national grid and foreign currency revenues to the state. Missing from these narratives is consideration of the impact of the dams on indigenous systems of production that depended on the natural seasonal flooding of the river, a flood that ceased with the completion of the Gibe III dam. In this paper, we highlight the large - and hitherto unquantified - socio-economic costs of the end of flood retreat farming, which was previously fundamental to local livelihoods. Our data come from a retrospective household survey of domestic production comparing farming yields before and after the dam, ethnographic research in communities along the Omo river, and satellite image analysis to determine changes in the extent of flooding over a thirty-year period. Together, these data allow us to estimate productivity per unit area and total area under cultivation along the river before and after the end of the flood. Our findings provide clear evidence of the impact of dam-led development on local production. We compare our results with ethnographic reports on flood retreat agriculture in the Omo valley, and with other extended case studies of development and socio-environmental change in sub-Saharan Africa.