Ethiopia depends on rain-fed agriculture with limited use of irrigation for agricultural production. More than 90% of the food supply in the country comes from low productivity rain-fed smallholder agriculture. Since the livelihoods of many farmers depend on rainfed agriculture, this paper investigates how smallholders adapt to climate variability. Dhidhessa sub-basin of the Blue Nile river basin is home to many vulnerable immigrant smallholders from other parts of Ethiopia. Our study focuses on this sub-basin to understand how crop production and patterns have depended on rainfall. Secondary data on land cover and croplands, the number of households growing crops, crop yields, crop prices and area covered by three major crops (teff, maize, and sorghum) are analyzed over a period 2000–2019 and interpreted in light of a primary household survey of 135 farmers in the basin. Results show that almost 40% of the basin is under crop cultivation, and the area under cultivation has been growing 8.6‰ per year. Irrespective of rainfall variability, the number of households practicing crop cultivation has also been growing over the years. This means that more farmers are moving into the basin to cultivate. Analysis reveals that adaptation strategies are at play. Farmer decisions to grow which crops are sensitive to rainfall and their expectations of crop prices resulting from rainfall variability. Their decisions and crop prices are endogenous to the smallholder sociohydrology of the basin, leading more farmers to grow Teff relative to other crops in years of lower rainfall. These decisions are due to the lower sensitivity of Teff prices to rainfall variability and farmers' expectations of higher Teff prices relative to other crops as rainfall decreases. Such behavior also induces climate resilience, enabling farmers to respond to climate variability rather than migrating out of the basin. Moreover, it allows more farmers to migrate in and engage in crop cultivation within the basin. Such an adaptive strategy based on past experiences offers a way forward to incorporating adaptation mechanisms in sociohydrological models to simulate and assess water futures for similar basins worldwide.

The Dhidhessa River Basin (DRB), in the Abbay River Basin in Ethiopia, is undergoing large-scale dam construction for sugarcane irrigation. We focused on the dynamics of population migration, settlement, relocation and water resource development in the DRB using primary and secondary data. Two major migration waves were observed in the basin: the first in 1984–1986 during a severe drought and the second during 2005–2017. Most rural migrants were “pulled” by government initiative in the period 1984–2017, while a few migrated of their own accord due to famine. We found that the first migration wave from eastern Ethiopia (Harar) to DRB was due to scarcity of water, land and rainfall and the migration positively affected migrant livelihoods. In the second phase, dam construction displaced settled farmers and migrants, adversely affecting their livelihoods. Analysis is needed that considers the wellbeing of the displaced agrarian society and the migrant population in the dam-affected area.