Estimating blue and green water resources availability in Ethiopia
Abstract
Although there is not a proper estimate of the water resources potential of Ethiopia, the country is hailed as the water tower of Africa. In contrast, rainfed agriculture, which is the main source of livelihood for the majority of the Ethiopian population, is frequently affected by rainfall variability. The reference to Ethiopian water resources potential is solely focused on blue water resources, which is the amount of water flowing into rivers, lakes and deep groundwater. However, recent research highlighted that there is a substantial amount of green water resources in sub-Saharan Africa. Green water is the water stored in the soils (green water storage) and evapotranspired from the soil and plant canopy (green water flow). This study used a grid-based Soil and Water Assessment Tool (SWAT) to estimate the blue-green water resources in Ethiopia. The findings showed that there is a substantial amount of blue-green water potential in Ethiopia, but with significant blue water and green water flow variability. The total long-term average annual (1990-2010) blue water was 376 billion m3. While the total long-term average annual green water storage and green water flow were 139 billion m3, and 584 billion m3, respectively. Allocating 30% of the blue water for environmental flow requirement, and biophysical limitation to access 15% of the green water, we observed that ~50% of the country have chronic blue water shortage (<1000 m3/capita/year). Blue water shortage was not observed in the western part of the Upper Blue Nile basin, lower parts of Baro, Omo Gibe, Rift Valley basins, a large part of Genale basin, upper Wabi Shebele basin, and Denakil basin. When the blue water and green water storage were considered in the analysis, only 24% of the country has a water shortage, which has a threshold of <1,300 m3/cap/year for a combined green-blue water accounting. The water shortage area was further reduced to 21.6% when the total blue-green water was considered. A focus only on the blue water resource showed that ~72 million people are under water shortage. This figure decreased to ~46 million when the total blue-green water was considered. The findings of this study provide valuable information to policymakers in prioritizing interventions that improve agricultural production, and household income and nutrition.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H51H1569T
- Keywords:
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- 1804 Catchment;
- HYDROLOGY;
- 1805 Computational hydrology;
- HYDROLOGY;
- 1807 Climate impacts;
- HYDROLOGY;
- 1895 Instruments and techniques: monitoring;
- HYDROLOGY