Co-development of East African regional water scenarios for 2050

Abstract

•We developed a novel East Africa regional vision scenario for the water sector•Co-development is central to scenario building and analysis•A hydro-economic modeling framework integrates natural and human system trends•We assess links among climate change, water and land use, and environmental water needs Water is critical for leveraging development opportunities in East Africa. Identifying sustainable water-development pathways in the context of climate change and environmental protection is imperative for water security. We co-developed regional water scenarios together with local stakeholders. A hydro-economic assessment of the headwaters of the Nile River revealed the upstream-downstream linkages and interconnections among socio-economic development, climate change, and the environment. Although annual freshwater resources are abundant, in an increasing number of months and sub-basins, advanced water-saving technologies and management are needed to avoid local hotspots of water scarcity. More support is needed to increase access to existing water resources for future sustainable development. We recommend that greater emphasis be put on scenario co-development to build joint research and solution implementation teams with strong ownership by policymakers and practitioners. The development of and access to freshwater resources in East Africa is fundamental to the region's sustainable development goals. Following vision documents for regional development and working with local stakeholders, we developed water scenarios up to 2050 that inform the hydro-economic modeling analysis of the extended Lake Victoria Basin, the headwaters of the Nile River. Water scenarios that take an integrated approach to assessing the combined effects of climate change, land use, and increasing human water use suggest that the flow regime of the Nile may remain relatively stable. However, if this stability is to be achieved, while at the same time sufficient water is preserved for healthy freshwater ecosystems, a large fraction of water infrastructure must rely on advanced, often costly technologies and management. Interconnected analyses of both upstream and downstream water resources over time, guided by co-developed scenarios, are indispensable for planning sustainable water-development pathways. The development of and access to freshwater resources in East Africa is fundamental to the region's sustainable development goals. Following vision documents for regional development and working with local stakeholders, we developed water scenarios up to 2050 that inform the hydro-economic modeling analysis of the extended Lake Victoria Basin, the headwaters of the Nile River. Water scenarios that take an integrated approach to assessing the combined effects of climate change, land use, and increasing human water use suggest that the flow regime of the Nile may remain relatively stable. However, if this stability is to be achieved, while at the same time sufficient water is preserved for healthy freshwater ecosystems, a large fraction of water infrastructure must rely on advanced, often costly technologies and management. Interconnected analyses of both upstream and downstream water resources over time, guided by co-developed scenarios, are indispensable for planning sustainable water-development pathways. East Africa maintained its lead as Africa's fastest growing region, with estimated growth of 5.0% and above, during the last decade.1African Development Bank East Africa Economic Outlook 2019. Macroeconomic Developments and Prospects. Political Economy of Regional Integration.2019https://www.afdb.org/en/documents/document/regional-economic-outlook-2019-east-africa-108658Google Scholar,2African Development Bank African Economic Outlook 2020: Developing Africa’s Workforce.2020https://www.afdb.org/en/knowledge/publications/african-economic-outlookGoogle Scholar Part of this success is likely linked to the East Africa Vision 2050,3East African Community East African Community Vision 2050. Regional Vision for Socio-Economic Transformation and Development.2016http://repository.eac.int/handle/11671/567Google Scholar which was launched in 2015 by the Heads of States of the East African Community (EAC). It portrays the region's development ambitions and visions of required socio-economic transformations for the coming decades. A key ambition of the EAC Vision 2050 is achieving water security, and reaching this goal will affect security, economic development, and the environment. East Africa's dynamic socio-economic development, which is characterized by rapid economic and population growth, along with a growing rate of urbanization, will lead to increased water demand and increased pressure on water quality. Goal 6 of the Sustainable Development Goals (SDGs), to ensure availability and sustainable management of water and sanitation for all, reflects the attention paid to water and sanitation issues in the global political agenda.4UN Water Sustainable Development Goal 6 Synthesis Report on Water and Sanitation.2018https://www.unwater.org/publication_categories/sdg-6-synthesis-report-2018-on-water-and-sanitation/Google Scholar The integrated, indivisible, and universally accepted 2030 Agenda for Sustainable Development5United Nations Transforming Our World: The 2030 Agenda for Sustainable Development.2015Google Scholar balances three dimensions of sustainable development (social, economic, and environmental). The identification of sustainable water-development pathways can leverage East Africa's development opportunities and contribute to development across the entire continent of Africa. Scenarios can be used to explore possible development pathways against the background of uncertain futures. They help make the long-term consequences of near-term decisions understandable and therefore are an essential part of sustainability research. By using scenarios to develop forecasts, we can pursue sustainable, long-term water security. We endorse the broad definition of water security given by the United Nations: “The capacity of a population to safeguard sustainable access to adequate quantities of and acceptable quality water for sustaining livelihoods, human well-being, and socio-economic development, for ensuring protection against water-borne pollution and water-related disasters, and for preserving ecosystems in a climate of peace and political stability.”6UN Water Water Security and the Global Water Agenda: A UN-water Analytical Brief.2013https://www.unwater.org/publications/water-security-global-water-agenda/Google Scholar This study focused in particular on the quantity of available water. Water scenarios have been presented at different spatial scales, from global to subnational regions, and in a variety of applications. Rapidly changing populations, accelerated urbanization, uneven economic growth patterns, degraded water infrastructure, rapid changes in land use, and climate change all have had impacts on freshwater flows in ways that have knock-on effects across spatial scales. The ongoing regional integration of East Africa requires that harmonization of water policy be a priority in the urgently needed development of water infrastructure. Analyses of water systems must therefore bridge the gap from the local to the regional and global scales. Several multi-scale scenarios have been developed through the application of the widely used global scenario-development process of the Intergovernmental Panel on Climate Change (IPCC), as characterized by scenario matrix architecture.7Van Vuuren D.P. Kriegler E. O’Neill B.C. Ebi K.L. Riahi K. Carter T.R. Edmonds J. Hallegatte S. Kram T. Mathur R. A new scenario framework for climate change research: scenario matrix architecture.Clim. Change. 2014; 122: 373-386Crossref Scopus (362) Google Scholar In this method, one axis represents community-developed shared socio-economic pathways (SSPs), in the form of five plausible and possible trajectories of global socio-economic development, including broadly preferred values related to the environment, institutions, and geopolitics.8O’Neill B.C. Kriegler E. Ebi K.L. Kemp-Benedict E. Riahi K. Rothman D.S. van Ruijven B.J. van Vuuren D.P. Birkmann J. Kok K. et al.The roads ahead: narratives for shared socioeconomic pathways describing world futures in the 21st century.Glob. Environ. Change. 2017; 42: 169-180Crossref Scopus (993) Google Scholar The other axis provides four representative concentration pathways (RCPs) that characterize climate change.9Van Vuuren D.P. Edmonds J. Kainuma M. Riahi K. Thomson A. Hibbard K. Hurtt G.C. Kram T. Krey V. Lamarque J.-F. The representative concentration pathways: an overview.Clim. Change. 2011; 109: 5Crossref Scopus (4546) Google Scholar Although the global SSPs were originally developed to improve the understanding of the determinants of challenges to the mitigation of and adaptation to climate change, these SSPs were designed with their extension to regional and sectoral scenarios in mind.8O’Neill B.C. Kriegler E. Ebi K.L. Kemp-Benedict E. Riahi K. Rothman D.S. van Ruijven B.J. van Vuuren D.P. Birkmann J. Kok K. et al.The roads ahead: narratives for shared socioeconomic pathways describing world futures in the 21st century.Glob. Environ. Change. 2017; 42: 169-180Crossref Scopus (993) Google Scholar,10O’Neill B.C. Kriegler E. Riahi K. Ebi K.L. Hallegatte S. Carter T.R. Mathur R. van Vuuren D.P. A new scenario framework for climate change research: the concept of shared socioeconomic pathways.Clim. Change. 2014; 122: 387-400Crossref Scopus (1151) Google Scholar The foremost use of the SSP scenarios has been for comprehensive water-resource assessment at the global11Arnell N.W. Lloyd-Hughes B. The global-scale impacts of climate change on water resources and flooding under new climate and socio-economic scenarios.Clim. Change. 2014; 122: 127-140Crossref Scopus (161) Google Scholar, 12Hanasaki N. Fujimori S. Yamamoto T. Yoshikawa S. Masaki Y. Hijioka Y. Kainuma M. Kanamori Y. Masui T. Takahashi K. A global water scarcity assessment under shared socio-economic pathways—part 2: water availability and scarcity.Hydrol. Earth Syst. Sci. 2012; 17: 2393-2413Crossref Scopus (173) Google Scholar, 13Hanasaki N. Fujimori S. Yamamoto T. Yoshikawa S. Masaki Y. Hijioka Y. Kainuma M. Kanamori Y. Masui T. Takahashi K. A global water scarcity assessment under Shared socio-economic pathways—part 1: water use.Hydrol. Earth Syst. Sci. 2013; 17: 2375-2391Crossref Scopus (115) Google Scholar, 14Wada Y. Flörke M. Hanasaki N. Eisner S. Fischer G. Tramberend S. Satoh Y. Van Vliet M. Yillia P. Ringler C. Modeling global water use for the 21st century: the Water Futures and Solutions (WFaS) initiative and its approaches.Geosci. Model. Dev. 2016; 9: 175-222Crossref Scopus (205) Google Scholar and broadly regional scales, e.g., for Europe15Alfieri L. Feyen L. Dottori F. Bianchi A. Ensemble flood risk assessment in Europe under high end climate scenarios.Glob. Environ. Change. 2015; 35: 199-212Crossref Scopus (149) Google Scholar and for Asia.16Satoh Y. Kahil T. Byers E. Burek P. Fischer G. Tramberend S. Greve P. Flörke M. Eisner S. Hanasaki N. Multi-model and multi-scenario assessments of Asian water futures: the Water Futures and Solutions (WFaS) initiative.Earth's Future. 2017; 5: 823-852Crossref Scopus (35) Google Scholar A few studies have used these tools for local watersheds, such as in the Pearl River Delta.17Yao M. Tramberend S. Kabat P. Hutjes R.W. Werners S.E. Building regional water-use scenarios consistent with global shared socioeconomic pathways.Environ. Process. 2017; 4: 15-31Crossref Scopus (11) Google Scholar When SSPs are adapted to the regional or national level, participatory methods are often employed to develop multi-scale scenarios together with stakeholders, such as in New Zealand,18Frame B. Lawrence J. Ausseil A.-G. Reisinger A. Daigneault A. Adapting global shared socio-economic pathways for national and local scenarios.Clim. Risk Manage. 2018; 21: 39-51Crossref Scopus (54) Google Scholar West Africa,19Palazzo A. Vervoort J.M. Mason-D’Croz D. Rutting L. Havlík P. Islam S. Bayala J. Valin H. Kadi H.A.K. Thornton P. Linking regional stakeholder scenarios and shared socioeconomic pathways: quantified west African food and climate futures in a global context.Glob. Environ. Change. 2017; 45: 227-242Crossref PubMed Scopus (71) Google Scholar and Austria.20Steininger K.W. Bednar-Friedl B. Formayer H. König M. Consistent economic cross-sectoral climate change impact scenario analysis: method and application to Austria.Clim. Serv. 2016; 1: 39-52Crossref Scopus (22) Google Scholar However, these studies have taken a broader perspective as well, and freshwater resources are only one aspect of their analyses. In the African context, the management of water resources is increasingly being seen as pivotal to development goals. Africa Water Vision 202521UN Water/Africa The Africa Water Vision for 2025: Equitable and Sustainable Use of Water for Socioeconomic Development.2003http://hdl.handle.net/10855/40449Google Scholar clearly articulates the particular challenge and need for Africa's water development to overcome extreme poverty and enable progress in socio-economic development. Its holistic vision statement marshals the three dimensions of sustainable development in the case of water for the achievement of “an Africa where there is an equitable and sustainable use and management of water resources for poverty alleviation, socio-economic development, regional cooperation and the environment.” The same document indicates the need for more research on how sustainable water use can be achieved in Africa. The EAC includes the source of the Nile River. Socio-economic development and climate change may affect the future water balance of the region with potential interactions between upstream and downstream countries. The Protocol for Sustainable Development of Lake Victoria Basin22East African Community (2003). Protocol for Sustatinable Development of Lake Victoria Basin.Google Scholar recognizes the importance of sustainable development for the region and beyond. To pursue this end, this study developed water scenarios for the member states of the EAC to produce a deeper understanding of the critical parameters that will enable their achievement of water security. Guided by the basin approach, a key principle in integrated water-resource management, we produced quantitative modeling analyses for the transboundary headwater of the Nile, namely, the extended Lake Victoria Basin (eLVB). This area incorporates parts of seven countries and the basins of all inflows into Lake Victoria, the third-largest freshwater lake in the world by area, as well as the basins of the Victoria and Albert Niles. Our approach to scenario co-development was to extend the commonly used stakeholder engagement approach by scrutinizing existing regional vision documents for water-relevant topics. In this way, we developed the East Africa regional vision scenario (EA-RVS), which will enable a higher degree of collaboration because its regional documents are the result of multi-year efforts, including many more stakeholders than we would have been able to work with for a single study. Because regional visions assume optimistic development pathways, for comparison, to provide a contrast to stakeholder views, and to assess the impacts of more challenging conditions, we analyzed a second scenario as well. This was based on the global middle-of-the-road scenario (SSP2), which is often used as a baseline. Water systems depend on interconnected variables that extend across spatial scales, ranging from global (climate change and trade) to regional (country-level demographic and economic growth) and local (irrigation patterns, water reservoirs, and land use) conditions. We adopted a spatially nested scenario approach, informed by co-developed narratives and data (Figure 1). In its global dimension, the study of water systems considers characteristics that extend beyond national borders, including climate change, trade, and technological progress. On the regional scale, this study explored the water-development target space of the five founding countries of the EAC (Burundi, Kenya, Rwanda, Tanzania, and Uganda), a group that is developing into an increasingly influential regional constituency. In our quantitative scenario modeling, we selected the eLVB, a transboundary basin that includes large freshwater resources that are vital for the development aspirations of East Africa. Socio-economic uncertainties were addressed with two plausible scenarios for pathways of future development toward the 2050s (Table 1). The reference scenario (REF) takes the storyline and quantification of SSP2, as developed by a key constituency operating at a global scale, the IPCC,23Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change.in: Core Writing Team Pachauri Intergovernmental Panel on Climate Change, 2014Google Scholar reflecting business as usual in the absence of any major expression of development ambitions from countries in the study area.Table 1Development scenarios for East AfricaScenarioAcronymSocio-economic developmentClimate changeReference scenarioREFSSP2 of the shared socio-economic pathwaysensemble of two GCMs (MIROC5 and HadGEM2-ES) calculated for the emissions pathways of RCP6.0 (i.e., medium climate change)East Africa regional vision scenarioEA-RVSbased on regional vision documents and co-developed with stakeholders (Box 1); many aspects such as SSP1 Open table in a new tab To portray the vision for the region, we co-developed the novel EA-RVS through several regional vision studies, completed together with stakeholders. The EA-RVS was informed by a detailed review of regional documents and enriched by participants in two regional workshops24Burtscher, R., Langan, S., Tramberend, S., and Burek, P. (2018). Solutions for a water secure East Africa in 2050. Workshop on mid- to long-term water resources management and planning in Eastern Africa. December 4–6, 2017, Entebbe, Uganda. IIASA Working Paper.Google Scholar,25Burtscher, R., Lanzi, E., Tramberend, S., and Burek, P. (2019). East Africa Future Water Scenarios to 2050. Consultation and Joint Learning Workshop. December 4–6, 2018, Entebbe, Uganda. IIASA Working Paper.Google Scholar in which more than 50 stakeholders and experts from government, academia, civil society, and the private sector participated (also see the experimental procedures). The EA-RVS was initiated in the first stakeholder workshop on the issue of achieving a water-secure East Africa. Further consultations with participants followed the workshop to seek feedback on the storyline and quantification of key input variables for modeling the future water balance (Box 1).Box 1East Africa regional vision scenarioMotivating forces: Stimulated by the UN Conference on Environment and Development (UNCED, 1992), the world has begun to move toward a more sustainable path that sets a greater priority on inclusive human development that respects perceived environmental limits. After certain landmark events26United Nations Johannesburg Declaration on Sustainable Development.2002https://undocs.org/pdf?symbol=en/A/Conf.199/20Google Scholar,27United Nations (2012). The future we want. Outcome document of the United Nations Conference on Sustainable Development, Rio de Janeiro, Brazil, June 20–22, 2012.Google Scholar and taking into account consultations with tens of thousands of institutional and individual participants to define “The World We Want,” the SDGs were unanimously adopted by the UN General Assembly.5United Nations Transforming Our World: The 2030 Agenda for Sustainable Development.2015Google Scholar The international community is thus increasing its support for the development ambitions of less-developed regions as part of a concerted effort toward achieving the SDGs.Political integration: Recognizing the value of cooperation and economic scope in development and negotiations, East Africa is embarking on a period of economic and political integration. This unification is driven by the countries of the EAC, all of which are in the watershed of Lake Victoria. The importance of this common watershed has made Lake Victoria a point of reference for an integrated East Africa. The principles of sustainable development here both drive and intertwine with political integration, as reflected in the 2016 founding of the SDG Center for Africa in Kigali, Rwanda. Several memoranda of cooperation and understanding that have been signed between institutions in East Africa and those in more developed countries are facilitating the promotion of innovation, knowledge co-creation, and investment.Socio-economics: In close cooperation with the more developed nations and countries across Africa, investment in education is accelerating. Teacher training that is targeted to address local challenges, the goals of completion of at least a secondary level of schooling for all, small class sizes, and well-equipped schools will provide a solid foundation for achieving a higher educational attainment for entire populations. Women's high educational attainment is expected to lead to significantly lower population growth than was seen in the first two decades of the 21st century. Ongoing urbanization, planned and carefully managed by the local authorities, will stimulate education and vocational training. The close integration and cooperation of educational initiatives with regionally important economic sectors can become a highly effective means of increasing the population of skilled labor. The sluggish growth in standards of living in East Africa over the two decades before 2015 has begun to accelerate due to the double thrust of the construction and strengthening of national and trans-national institutions, together with the development of human capital and research and development that is internationally well connected. The resulting political stability and trust in governance and institutions is triggering increasing capital investment in the region from both domestic and international sources.Infrastructure: Coordinated trans-national development is planned for electricity, critical internet infrastructure, and road-railway connections among major markets to develop a reliable infrastructure that can attract domestic, regional, and foreign direct investment. The resulting inter-connectivity is providing further contributions to the political stability of East Africa, producing trust, boosting economic development, and triggering further investment.Furthermore, the EA-RVS narrative includes water-specific elements, such as a shared understanding of water security, raising awareness of the water sector, and creating strategies for surface and groundwater resources and the main water-use sectors of agriculture, domestic use, and industry (details in Note S1). Motivating forces: Stimulated by the UN Conference on Environment and Development (UNCED, 1992), the world has begun to move toward a more sustainable path that sets a greater priority on inclusive human development that respects perceived environmental limits. After certain landmark events26United Nations Johannesburg Declaration on Sustainable Development.2002https://undocs.org/pdf?symbol=en/A/Conf.199/20Google Scholar,27United Nations (2012). The future we want. Outcome document of the United Nations Conference on Sustainable Development, Rio de Janeiro, Brazil, June 20–22, 2012.Google Scholar and taking into account consultations with tens of thousands of institutional and individual participants to define “The World We Want,” the SDGs were unanimously adopted by the UN General Assembly.5United Nations Transforming Our World: The 2030 Agenda for Sustainable Development.2015Google Scholar The international community is thus increasing its support for the development ambitions of less-developed regions as part of a concerted effort toward achieving the SDGs. Political integration: Recognizing the value of cooperation and economic scope in development and negotiations, East Africa is embarking on a period of economic and political integration. This unification is driven by the countries of the EAC, all of which are in the watershed of Lake Victoria. The importance of this common watershed has made Lake Victoria a point of reference for an integrated East Africa. The principles of sustainable development here both drive and intertwine with political integration, as reflected in the 2016 founding of the SDG Center for Africa in Kigali, Rwanda. Several memoranda of cooperation and understanding that have been signed between institutions in East Africa and those in more developed countries are facilitating the promotion of innovation, knowledge co-creation, and investment. Socio-economics: In close cooperation with the more developed nations and countries across Africa, investment in education is accelerating. Teacher training that is targeted to address local challenges, the goals of completion of at least a secondary level of schooling for all, small class sizes, and well-equipped schools will provide a solid foundation for achieving a higher educational attainment for entire populations. Women's high educational attainment is expected to lead to significantly lower population growth than was seen in the first two decades of the 21st century. Ongoing urbanization, planned and carefully managed by the local authorities, will stimulate education and vocational training. The close integration and cooperation of educational initiatives with regionally important economic sectors can become a highly effective means of increasing the population of skilled labor. The sluggish growth in standards of living in East Africa over the two decades before 2015 has begun to accelerate due to the double thrust of the construction and strengthening of national and trans-national institutions, together with the development of human capital and research and development that is internationally well connected. The resulting political stability and trust in governance and institutions is triggering increasing capital investment in the region from both domestic and international sources. Infrastructure: Coordinated trans-national development is planned for electricity, critical internet infrastructure, and road-railway connections among major markets to develop a reliable infrastructure that can attract domestic, regional, and foreign direct investment. The resulting inter-connectivity is providing further contributions to the political stability of East Africa, producing trust, boosting economic development, and triggering further investment. Furthermore, the EA-RVS narrative includes water-specific elements, such as a shared understanding of water security, raising awareness of the water sector, and creating strategies for surface and groundwater resources and the main water-use sectors of agriculture, domestic use, and industry (details in Note S1). Each scenario combines socio-economic development with the climate change impact of the greenhouse gas concentration pathway RCP6.0 (moderate climate change), which was selected because runs of the Integrated Assessment Model succeeded in combining the socio-economic development of the sustainability scenario (SSP1) and SSP2 with climate change in RCP6.0.28Rogelj J. Popp A. Calvin K.V. Luderer G. Emmerling J. Gernaat D. Fujimori S. Strefler J. Hasegawa T. Marangoni G. Scenarios towards limiting global mean temperature increase below 1.5 C.Nat. Clim. Change. 2018; 8: 325Crossref Scopus (464) Google Scholar Assessments of climate change impact on hydrology require forcing of meteorological input data that are unbiased in comparison with regional observations. This study uses available bias-corrected data from the Inter-Sectoral Impact Model Intercomparison Project (ISI-MIP),29Hempel S. Frieler K. Warszawski L. Schewe J. Piontek F. A trend-preserving bias correction—the ISI-MIP approach.Earth Syst. Dyn. 2013; 4: 219-236Crossref Scopus (725) Google Scholar,30Warszawski L. Frieler K. Huber V. Piontek F. Serdeczny O. Schewe J. The inter-sectoral impact model intercomparison project (ISI-MIP): project framework.Proc. Natl. Acad. Sci. USA. 2014; 111: 3228-3232Crossref PubMed Scopus (693) Google Scholar based on Global Circulation Models (GCMs) from the Coupled Model Intercomparison Project phase 5 (CMIP5). We adopted the criteria of validity, i.e., that historic runs of ISI-MIP GCMs that fit the observed climatology better will also better represent future climates, and we chose GCMs HadGEM2 and MIROC5 (see Note S2 for details on GCM selection). In both scenarios, critical water dimensions were quantitatively evaluated to force the cost-optimization procedures of the hydro-economic modeling system (see the experimental procedures). Hydrologic variables, e.g., discharge and environmental flow requirements (EFRs), were calculated for both GCMs, and the ensemble mean was chosen to represent future climate conditions. The REF used country-level quantification from the SSP database31Riahi K. Van Vuuren D.P. Kriegler E. Edmonds J. O’neill B.C. Fujimori S. Bauer N. Calvin K. Dellink R. Fricko O. The shared socioeconomic pathways and their energy, land use, and greenhouse gas emissions implications: an overview.Glob. Environ. Change. 2017; 42: 153-168Crossref Scopus (1532) Google Scholar for demography and economic growth for SSP2. For the EA-RVS, we used available quantification from regional documents. Regional projections are often limited to aggregate EAC numbers or individual future years. One global SSP, SSP1, has a narrative and objectives that are similar to those o