Balancing Water Demands and Increasing Climate Resilience: Establishing a Baseline Water Risk Assessment Model in Ethiopia
Water is essential to sustainable economic growth and climate change adaptation. Ethiopia’s growth and development are vulnerable to water security risks. Despite being known as the “water tower of Africa,” Ethiopia is naturally exposed to highly variable rainfall. Climate change and economic growth across sectors are increasing competing water demands.
Recognizing these challenges, the Government of Ethiopia has identified balancing water demands and improving climate resilience as national priorities. Managing water risks requires decision-relevant water risk information. Water managers need to understand hydrological cycles and water use across society to ensure secure and sustainable water availability across sectors. Decision-makers in other sectors also need to understand their exposure to water risks to reduce their vulnerability. However, in Ethiopia, the data required to understand water risks are often lacking or outdated, and the modeling required to assess risks can be complex and resource intensive.
This technical note describes the data and methodological approaches used to develop the baseline water risk model, presenting the results at a subbasin level. WRI developed new geospatially-explicit water withdrawal and consumption estimates for irrigation, livestock, domestic, and industry water use in Ethiopia, representing a 2015 baseline. We also extracted 36 years of remotely-sensed data to generate subbasin-level renewable water resources estimates.
We present a baseline model for mapping water risks across Ethiopia. Despite being a “water tower of Africa,” growing water demands and climate change threaten to undermine Ethiopia’s development goals. This baseline model aims to help decision-makers incorporate water and water-related climate risk information into development decisions across sectors, and to illuminate water resources management challenges. This technical note describes the data and methods used to develop the baseline water risk model and presents the results.
We developed new water withdrawal and consumption estimates for irrigation, livestock, domestic, and industrial water use, representing a 2015 baseline. Water withdrawal estimates were combined with satellite-based renewable water resources data to yield four water risk indicators: baseline water stress, months of water scarcity, seasonal variability, and interannual variability.
This model could be used in scenario analysis for development planning, by providing a baseline from which sectoral water withdrawal projections and climate change scenarios for water resources can be developed, as well as national monitoring of water risks. This model should be applied with due consideration of its methodological limitations, such as the exclusion of water storage and conveyance infrastructure.
The model is national, providing relevant information for countrywide research and policymaking efforts. The indicators constructed through this model — baseline water stress, months of water scarcity, seasonal variability, and interannual variability — are intended to provide valuable insight for decision-makers both within and outside the water sector. The model can also support scenario planning as well as ongoing water risk monitoring and reporting efforts for Sustainable Development Goal target 6.4.2.
Frequently Asked Questions (FAQ)
Q: How are the water risk indicators defined?
A: The definitions for each are below.
- Baseline water stress: Baseline water stress (BWS) represents total annual water withdrawal relative to available water resources.
- Months of water scarcity: Months of water scarcity represents the number of months where water stress is extremely high.
- Interannual variability: Interannual variability measures variation in water resources between years.
- Seasonal variability: Seasonal variability measures variation in water resources between months of the year.
Q: What is the definition of total water renewable water resources and how is it estimated?
A: Total renewable water resources represent the total water available annually at each subbasin, including water accumulated from upstream, not taking into account any water consumption. Water resources here include runoff, soil moisture, shallow groundwater and baseflow interaction. The water resources data for Ethiopia was directly extracted from NASA’s NOAH MP dataset developed from remote sensing.
Q: What data sources did the BWS analysis for Ethiopia use?
A: BWS for Ethiopia uses various data sources ranging from local government agencies to international organizations and remote sensing. The data sources and links for each of the sectoral water demand and water resources are provided and discussed in detail in the technical note.
Q: Why did you use NASA Nighttime Lights to distribute industrial water demand?
A: A location dataset for all industries, factories and manufacturing was not readily available in Ethiopia. We used NASA Nighttime Lights dataset as a proxy for industrial activity to distribute regional industrial water demand to hydrological boundaries of subbasins. The analysis assumes that areas with greater (brighter) lighting at night are also areas with greater presence of industries. It is worth noting the limitation of this assumption, which tends to attribute greater industrial water demand to urban settings due to lighting at night compared to rural areas. However, our estimate of 55% was comparative to a Stockholm International Water Institute (SIWI) study, which attributed 60% of Ethiopia’s industrial water demand to the Awash Basin.
Q: Is the irrigation efficiency value used representative for the whole country?
A: No, the irrigation efficiency used in this BWS analysis was obtained from the Awash Basin, one of 12 Ethiopian river basins. While we used an average of 44.3% efficiency for irrigation for medium- and large-scale irrigation schemes in the Awash Basin, efficiency in Ethiopia can range between low and high depending on the scale, type and location of the irrigation scheme. The 44.3 % average was used to be consistent across subbasins and provide apples to apples comparison.
Q: How did you calculate consumptive use and return flow?
A: The water extracted for any of the sectoral uses is either consumed (incorporated) or returns to the system. Consumptive use was estimated from total water withdrawal using the 2015 projection ratios of consumptive use to water withdrawal for East Africa/Sub-Saharan Africa obtained from Shiklomanov and Rodda 2004. Water that is not consumed is assumed to have returned to the system.
Q: Are Growth and Transformation (GTP II) targets of 2015 representative of domestic water use?
A: Domestic water use data is not readily available in Ethiopia. This is particularly true for secondary cities and rural areas. The GTP II water delivery targets for the 2015-2020 period was a proxy for domestic water demand across the country. While these targets indicate water demand, they may not represent actual water use — some places may use more water while others may use substantially less than the targeted volume.
Q: Is livestock water demand analysis done for all subbasins?
A: The livestock water demand analysis was performed using livestock head count transformed to Tropical Livestock Units (TLU). The livestock head count was provided by the Central Statistics Agency at the zonal administrative level. Data for one zone in the Afar and two zones in the Somali regions were not available. The subbasin-level water demand did not include potential livestock water demand from these three zones.
Q: Why is the subbasin delineation different from the current subbasin delineation used by the Government of Ethiopia?
A: The subbasin delineation availed by the Government of Ethiopia does not include flow direction and upstream-downstream relationship that is essential to perform flow accumulation and distribution. As a result, we relied on the subbasin delineation provided by Global Drainage Basin Database (GDBD), which provided this missing information.
Q: Is environmental flow considered?
A: An environmental flow is the water provided within an ecohydrological system to maintain ecosystem health and their benefits where there are competing water demands. Environmental flow requirements differ between river systems and even within reaches. In this analysis, environmental requirements were not considered because there was no uniform regulation or estimate governing environmental flows in Ethiopia. In the interest of uniformity across subbasins, environmental flow was left out of the analysis. If environmental flow requirements are considered, some subbasins currently designated as low stress will likely show more stress.
Q: Does the study include transboundary water?
A: The analysis in this BWS analysis does not account for transboundary obligations in any of the subbasins or basins. Accounting for transboundary water allocation will likely increase water risk in hydrological boundaries that have such a commitment.
Q: Does the study consider hydropower reservoirs?
A: The current installed hydropower capacity is 3,810 megawatts (mW), with an additional 8,864 mW of hydropower under development. While water use associated with these energy production values are significant from a water availability perspective, hydropower water demand was deemed primarily non-consumptive and was excluded from the water demand analysis to avoid double counting of total water withdrawal estimates. Users should keep in mind that evaporation from water storage facilities and reservoirs are consumptive and can be significant.
Q: Can areas designated as low water be water stressed in reality?
A: The BWS results are based on physical water availability and the baseline competition between sectoral water demands. This analysis does not consider economic water scarcity, which can result from a lack of sufficient investment in water infrastructure and lack of technical and institutional capacity to develop, access, transport and deliver the available water to satisfy water demands. Thus, areas designated as not water stressed may in actuality be water stressed.
Q: What is the uncertainty of the results?
A: Because of the lack of data availability and accessibility, the analysis relied heavily on secondary and proxy datasets. As such, users should keep in mind the limitations and associated uncertainties of individual analyses and the compounded effect of each error propagated from each parameter. For example, a 15% difference in irrigation water demand was observed from using two different irrigated area estimates from International Water Management Institute (IWMI) and Food and Agriculture Organization (FAO). Considering irrigation water demand analysis uses irrigated area, evapotranspiration, precipitation, effective precipitation and irrigation efficiency datasets, the uncertainty can be considerable. Improving data availability is critical to both understanding uncertainty and developing greater confidence in the results. That said, sectoral water demand results were comparative to individual studies in the Abbay and Awash basins.
Q: Can I get the datasets and results?
A: Yes, the raw data, pre- and post-processed data and results can be made available upon request. Please contact Zablon Adane and Tinebeb Yohannes.
Q: What is the best use of this data?
A: The objective of the BWS analysis was to support national-level planning, scenario planning and support ongoing water risk monitoring efforts. This analysis and associated datasets are not intended for local-level planning, trans-regional, trans-basin or trans-boundary planning and discussions without due considerations of the several limitations discussed in detail in the technical note.
Q: How are the results different from those of global AqueductTM?
A: The BWS analysis for Ethiopia was performed with local datasets when available. Further, to accommodate the use of local datasets, the approach employed to estimate domestic, livestock and irrigation water demand are very different from the methodology of the global Aqueduct Water Risk Atlas. Aqueduct also uses datasets that are common to all countries for ranking and comparison purposes. As such, the results of the water stress indicators for Ethiopia in this analysis may differ considerably from those in the global Aqueduct tool.
Water for Sustainable Development in Ethiopia
WRI is working with partners in Ethiopia to better understand water risk, improve water-wise planning, and advance integrated water resources management toward a more sustainable and resilient development path.Part of Water