Hydropower has been increasingly seen as a two-fold solution, as it provides renewable, low carbon and endogenous energy while increasing water storage capacity. However the extended deployment or large and small scale hydropower projects at a basin scale have been reported to have important environmental impacts. Several studies have raised concern over the higher cumulative impacts posed by large successions of cascading small hydropower projects, which can reach or even outweigh those of a large hydropower project providing the equivalent energy output. In the particular case of Spain, this issue gets major dimensions and especial relevance as hydroelectricity involves the star pieces playing the main role in the Spanish water use stage – dams and agriculture – while playing a 15% share of national electricity production.
This study assesses the differential contributions of the large (LHP) and small (SHP) scale hydropower development to regional water and energy security in the largest Spanish transboundary basin (the Duero basin), as well as the related cumulative environmental impacts. The results suggest that large hydropower has higher contributions and plays a critical role to ensuring regional water and energy security, with better performance in 10 of the 12 indicators assessed. Currently SHP generates higher cumulative impacts per unit of power generated in the basin for the four impact categories considered, mainly due to the massive number of existing plants. In absolute terms, LHP shows higher values for impact indicators on Disturbance of the river regime and Habitat loss, whereas SHP shows higher impacts on Connectivity and Disturbance of ecosystems. Based on observations from the analysis, the authors consider that LHP has great potential to lead Spain towards a low carbon, low water footprint and import independent energy system if the possibilities that enhanced hydraulic pumping systems coupled to intermittent renewables offer are envisioned and exploited. They also estimate that there might be great potential for optimization of the hydropower system by tapping all the possible services provided by existing reservoirs, some of which are single purpose, and concentrating hydropower production around existing infrastructure with potential for energy production (existing reservoirs or irrigation or distribution canals). This would enable reduced impacts compared to an extended development of small individual projects that require their own diversion device. Besides, the appropriateness of using the installed capacity as the standard for setting the difference between LHP and SHP is discussed. It is believed to fail in setting up two homogeneous categories of technological alternatives with significant similarities and inter-differences in terms of environmental and sustainability performance, thus providing poor elements of judgement to inform decision making on future energy technology roadmaps.
Finally, an emerging lesson from the Duero and Spanish experience that could be scalable and transferable to water planning in other basins is the importance of prioritizing the premise of the maximum value with minimum intervention. Tapping and maintaining all the potential services provided by certain infrastructures like dams can prevent from the need of additional developments, thus reducing the cumulative impacts and maximizing the economic and sustainability value of the projects.
Presentation

Water desalination is a promising solution for the arid and semi-arid areas of the world. Particularly in the Middle East and North Africa (MENA) region, seawater desalination can offer additional freshwater supplies and alleviate the water scarcity problem of the domestic, agricultural and industrial users. Despite its great potential for increasing freshwater availability, water desalination is also associated with several constraints. For instance, the high energy costs of the desalination process and the limited access of remote communities are among the respective economic and social constraints, whereas the use of fossil fuels for energy requirements causes environmental pollution and increased emission of greenhouse gases. Another challenge for the energy balances of the MENA countries is the expectation that competition for energy will become more severe, since the energy demand is forecasted to increase due to population growth, urbanization, industrialization and climate change.
Solar energy is considered as a viable renewable energy resource with a significant potential to change the energy balances of the MENA countries by relieving the dependency on non-renewable fossil fuels. When used for in desalination processes, solar energy also offers possibilities for improved water and food security, since the desalinated water can be used to meet the increasing water demands in the domestic, industrial and agricultural sectors. Solar-based desalination systems are particularly attractive for the MENA region, given the high levels of solar radiation as well as the relatively law operation and maintenance costs.
As with other technological innovations, the introduction of the solar energy for desalination into the existing governance systems brings about the need for institutional and social changes. Countries in the MENA region share a common natural and climatic context in terms of the scarcity of freshwater resources, the abundance of solar radiation, and the forecasted adverse effects of climate change. However, these countries differ when it comes to their approaches for realizing the necessary institutional and social changes towards the adoption of solar-based desalination. Currently, many countries in the region use fossil fuels for seawater desalination, whereas recent investments have been made to diversify the energy mixes towards increasing the share of renewable energy resources, including the use of solar energy.
Against this backdrop, the use of solar energy for water desalination is socially and politically relevant for improving the water, energy and food securities in the MENA region. However, the understanding regarding the governance implications of solar-based desalination on water-energy-food nexus is limited. The proposed paper aims to improve this understanding through providing a comparative review of the MENA countries. Particular attention will be paid to identifying the key political, institutional and social factors that influence the diffusion of solar-based desalination in the MENA region. The implications of these factors will be analysed for the water, energy and food securities of MENA countries, and the resulting advancements and/or impediments for the water-energy-food nexus are compared.
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The concept of water-energy-food nexus concept has emerged as a fundamental integrative approach to achieve sustainable development. The increasing pressure over limited resources is forcing to get the best output of the interconnections of water, energy, and land in order not to exacerbate existing problems of food security, water scarcity, and energy poverty. In developing countries, the management of this nexus is crucial to obtain a sustainable development, which satisfies the fast growing demands related to industry and population without degrading the water resources and producing adverse long-term impacts. This work focuses in the Omo River Basin (Ethiopia) where large hydropower dams and commercial irrigation schemes are under development. These projects are aligned with the growth national strategy, but underestimate the impacts on food security and the environment in the region.
In this work, we analyse the complex interconnections between conflicting water uses in the Omo River Basin. Following the Participatory and Integrated Planning (PIP) procedure (Castelletti and Soncini-Sessa 2006), we frame the water resource management problem at the basin level by simulating the effects of the operation of the Gibe cascade scheme (Gibe I, II, and III dams in place) on the water-energy-food nexus. In particular, we take into account the following water-related interests: hydropower production from the Gibe hydropower dams, the commercial irrigation (the Kuraz sugar plantation), the environment in the Lower Omo Valley, and the recession agriculture which is the livelihood for the indigenous population. We model the system by using the fully distributed and physically explicit hydrological model TOPKAPI-ETH. This model accounts for the main physical hydrological process and includes the description of the reservoirs and hydropower plants by means of simple operating rules. We simulate the runoff according to different scenarios of energy production targets and commercial crop schemes. We assess the effects of the scenarios on the water-related interests by computing quantitative indicators expressing the different water uses’ interests. The assessment contributes in understanding the conflicts between current water management practices and the potential trade-offs associated to different management strategies. Results show that the most crucial conflicts take place between commercial agriculture and environment, and between hydropower and recession agriculture. The environment and the recession agriculture indicators are very sensitive to the alteration of the natural flow pattern consequent to the hydropower dams operation. The presence of commercial irrigation contributes to worsen the impacts.
Presentation

The Bale Mountains in South Central Ethiopia provide a range of high-value ecosystem services to communities living in the highlands, but also to pastoralist livelihoods of lowland communities. Water resources generated in the highlands are a fundamental driver to water and food security in downstream areas, extending far beyond the country borders into South Central Somalia and Northern Kenya. However, the Bale Eco-Region is under threat by land degradation caused by overgrazing, changing land use and associated soil erosion. This steadily degrading environment in the upstream water catchment which is likely to increase future water and food insecurity and flood risks in downstream areas already prone to floods and droughts. The SHARE project responds to these issues through tailored research, support to national governments and research institutes and by interventions in natural resources management that include participatory forest management, improved livestock grazing systems, soil and water conservation and assessing suitability and application of schemes on Payment for Ecosystem Services (PES).
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Agricultural transformation and energy transitions are inter-connected, partly competing for the same resources and are driven by an increasing population, a changing climate and a growing economy. Future resource use efficiency and sustainability will strongly depend on the development trajectories for the energy and agriculture sectors, and their ability to collaborate.
In order to attain the national development goals it therefore appears that there is a need for integrated quantitative assessments of future development trajectories for the country, accounting both for cross sector inter-linkages and competing demand for resources. These findings jointly call for informed cross-sector strategic planning and cross-sector linkages. At the moment, there is a window of opportunity in this regard in Zambia since several of the current policies are under revision.
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