Impacts of Climate Extremes and Land Use Land Cover Dynamics on Water Resources in West Africa Salomon Obahoundje (Ph.D) Post-Doctoral Fellow- Spatial Tools for Water Management International Water Management Institute – West Africa Council Cl, CSIR, Airport Residential Area PMB CT 112, Accra, Ghana s.obahoundje@cgiar.org +233 30 278 4752 - 4 (office), +233-533816976 (cell) https://www.linkedin.com/in/salomon-obahoundje-20211588/    Prospective Afrique de l'ouest 2040 / Climat, adaptation, habitabilité, aménagement du territoire et des littoraux Paris, 16 Dec 2024 1 WEST AFRICA REGION Predominantly tropical climate, ranging from arid in the north (Sahel region, one rainy season from Jul-Sep) to humid in the south (coastal areas with two rainy seasons May and Sep to October). Average temperatures range from 25°C to 35°C, with hotter conditions in the Sahara and cooler temperatures in higher altitudes like the Guinea Highlands. Rivers (Niger, Volta, Bandama, Sassandra, Senegal, etc) key driver of socio-economic development of the region Rainfed Agricultural and Hydropower plants (existing and planned) Key Drivers Pressuring Water Resources: Rapid population growth, agriculture dependence, frequent droughts, low adaptive capacity, soil degradation, urbanization, and increasing climate variability. Geographical location of West Africa and countries Climate controlled by the West African Monsoon driven by the movement of Inter Tropical Convergence Zone (ITCZ), 2 CLIMATE EXTREMES IN WEST AFRICA SAHEL Extreme Heat Drought Wildfire Urban flooding River flooding COASTAL Extreme Heat Drought Wildfire Urban flooding Coastal flooding The prominence of climate change related Mult-hazards in West Africa 3 Multiple historical climate trends show that the West African climate became increasingly variable since the beginning of the century. These climatic components include long-term changes in the local temperature, increases in interannual rainfall variability, low-frequency climatic variability, and increasing frequency of extreme weather events in the region. 3 OBSERVED AND PROJECTED CLIMATE VARIABLES Observed projected changes in temperature and precipitation (Jones and Hartley., 2015) Past change in the spatial distribution of precipitation 1981-2018 (Obahoundje and Diedhiou, 2022) 4 Less frequent and more intense rainfall along the coast of the Gulf of Guinea in West and Central Africa (1981−2014). (Bichet and Diedhiou., 2018b) West African Sahel has become wetter during the last 30 years, but dry spells are shorter and more frequent.(Bichet and Diedhiou., 2018a) 2046-2065 2081-2100 seasonal (May–September) mean Tas and Precip. Sylla et al., 2016 SAHEL COASTAL WAF 4 NIAMEY, August 23, 2024 ABIDJAN, JUNE 23, 2024 IMPLICATON OF FLOODING ON WATER RESOURCES MIADUGURI, SeP 12, 2024 Observations show a rise in extreme rainfall events in parts of West Africa, particularly along the Gulf of Guinea and Sahel regions. (IPCC, AR6) More than 5 million people in West and Central Africa have been impacted by floods so far this year, UN OCHA, 2024 Country-based statistics of floods in West Africa during 1966-2017 (EM-DAT, 2017) (Badou et al., 2019) CAUSES These trends are linked to a combination of natural variability and anthropogenic climate change, resulting in heightened flood risks. Rapid urbanization combined with inadequate infrastructure has heightened flood risks in many West African cities. FLOODING Water Quality Water Infrastructure Economic & Livelihood Health (Cholera, Malaria) 5 5 IMPLICATION OF DROUGHT ON WATER RESOURCES 1950-2021 https://public.emdat.be/ Droughts have become more frequent and intense in West Africa due to climate change and variability. These changes are driven by rising global temperatures and associated shifts in precipitation patterns. (AR6) 6 HEATSTRESS AND WATER RESOURCES Observations reveal a significant rise in the frequency and intensity of heatwaves across West Africa, driven by anthropogenic climate change. (AR6) Heat stress events will increase further under future warming scenarios, particularly in the Sahel and coastal regions. Intensifying water scarcity competition over scarce resources Increased Evaporation Reducing water availability, Reduce Water Quality, Decline in Groundwater Recharge Amplifying drought conditions Stress on Water-Dependent Sectors (Domestic, Agriculture and hydropower) IMPLICATION Compounding Risks population growth urbanization infrastructure deficits Changes (2070–2100 minus Ref :2010) In heat stress indicators. (Dajuma et al., 2024) Projected Heat Stress Under 1.5 °C and 2 °C Global Warming Scenarios Creates Unprecedented Discomfort for Humans in West Africa (Sylla et al., 2018a) Exposed population to heat stress will increase in future (Fotso-Nguemo et al., 2023, Dajuma et al., 2024) Heat Index Universal Thermal Climate Index 7 7 climate change and poor management of water resources and services: Africa’s water stress. CURRENT IMPACTS ON WATER RESOURCES Risk=f(vulnerability to floods and droughts, water stress, and seasonal variability) Stress=f(water demand and availability) The Water risk and stress indices vary according to the continent Sahel: from Higher to extremely high risk and stress Gulf of Guinea (Togo, Benin, Nigeria) higher risk and medium stress Western coastal medium risk and from low to medium stress UNEP., 2020 8 Potential water availability for each river basin (Sylla et al., 2018b) Ref: 1976–2005 Both RCP4.5 and RCP8.5 scenarios show significant reductions in water availability across all river basins (Senegal, Gambia, Niger, Volta, Chad) relative to historical periods. The impacts are more severe under RCP8.5, reflecting the higher greenhouse gas emissions and associated climate stress. The decline intensifies in the latter period, particularly under RCP8.5, suggesting worsening conditions over time. FUTURE IMPACTS ON WATER RESOURCES Water availability 9 General Decline in Basin Irrigation Potential: All basins experience a decline in Basin Irrigation Potential (BIP), with the magnitude increasing as global warming intensifies. Higher Impact in Coastal Basins: Coastal basins such as Volta, Sassandra, and Bandama face more significant declines and greater variability in BIP under higher warming scenarios. Lower Impact in Sahelian Basins: Sahelian basins like Senegal, Gambia, Niger, and Chad show relatively lower declines in BIP, with less variability compared to coastal regions. This indicates that West African river basins will likely face severe freshwater shortages thus limiting sustainable agriculture FUTURE IMPACTS ON WATER RESOURCES Basin irrigation potential for each river basin (Sylla et al., 2018c) Basin irrigation Potential (BIP) 10 FUTURE IMPACTS ON WATER RESOURCES: HYDROPOWER GENERATION Climate change and variability could also affect the inflow of water to the reservoir as well as the energy generation, The changes depend on the basin, the size of the hydropower plant, the emission scenario The energy generation will decline for both Nangbeto and Taabo Akafou et al., 2024 11 DEFORESTATION Around 1.9 million hectares/year of forest were lost in the 2015-2020 (Saifaddin Galal, 2024). Key Drivers of LULCC: Agriculture, mining, and infrastructure development, unsustainable logging practices, and charcoal production (Obahoundje et al.,2018). Coastal West Africa forest loss Implication on water resources Disrupts the water cycle Reducing evapotranspiration& rainfall recycling Reduce regional precipitation Water Availability Soil Erosion & Siltation reduces reservoir capacity and affects water quality Reduces infiltration rates, leading to less groundwater availability for agriculture and drinking water Groundwater Recharge Flooding and Hydrological Imbalance more vulnerable to flash floods during heavy rainfall events Temperature and Drought Amplification Small-scale cropland Large-scale cropland Pasture Tea Plantation Settlement Cashew Oil-Palm Coffee Rubber Forest Other-land with tree cover Roads Cocoa Mining Water Bodies Mapping the diversity of land uses following deforestation across Africa; (Masolele et al. 2024) 12 CLIMATE-LAND-ENERGY-WATER NEXUS Adjarala Nangbeto Bui Dry conditions due to climate change could reduce hydropower generation, while wet conditions may boost it. Land-use and land-cover changes can help mitigate the impacts of climate change on hydropower production. (Obahoundje et al., 2018) Climate change impacts on hydropower will intensify with higher GHG emissions and over future periods. Projected development conditions could further decrease energy production from hydropower. Land-use and land-cover changes (LULCC) can mitigate climate change impacts on dams, with effectiveness varying by dam (Obahoundje et al., 2021) 13 SENSITIVE TO CLIMATE EXTREMES & LULCC The Water-Energy-Food (WEF) Nexus is deeply influenced by land use practices and climate extremes, requiring a holistic, integrated approach to address climate change impacts. Effective management of climate change impacts on livelihoods depends on considering the interconnectedness of water, energy, food, and health sectors, as changes in one sector can affect others. A systems-based approach is critical for developing adaptive strategies that strengthen resilience and sustainability, particularly in regions vulnerable to climate-related challenges. CLIMATE-LAND-ENERGY-WATER NEXUS https://geographycasestudy.com/the-water-food-energy-nexus/ 14 KEY CHALLENGES Despite the growing risks, adaptation efforts in the region face significant barriers, including : limited financial resources, weak governance, and insufficient access to technology. Lack of Infrastructure (non-operational and/or low coverage weather stations, management issue), Data gap, lack of existing methods, and technologies for river discharge estimation in Africa (Apkoti et al., 2024) Data accessibility, Data uncertainties (observed, satellite, reanalysis, models etc.) Mistrust among stakeholders (Researchers, Decision makers and end users), Misunderstanding of the data sharing policy Data commercialization concerns Historical data digitalization 15 CONCLUSION Climate Extremes in West Africa: Climate extremes are significantly impacting water-dependent sectors in West Africa, and these effects are expected to worsen in the future, potentially leading to greater loss and damage. Vulnerability of Local Communities: Local communities in the region have low adaptive capacity and are highly vulnerable due to fragile infrastructure, making them especially susceptible to the increasing risks posed by climate change. 16 RECOMMANDATIONS Enhance Governance and Infrastructure: Strengthen governance frameworks and invest in robust infrastructure to improve resilience to climate extremes. Strengthen Disaster Risk Reduction (DRR) Capacities: Build capacity for disaster risk reduction (DRR), focusing on anticipatory actions and early warning systems. Invest in Climate Information Services: Expand investments in climate information services, including early warning systems and anticipatory actions to prepare for future climate risks. Develop Harmonized Data Sharing Frameworks: Establish harmonized data-sharing frameworks for better coordination and accessibility of climate-related information. Promote Open Access to Local Data: Support the development of open-access datasets tailored to local contexts to enhance decision-making at all levels. Foster Joint Initiatives and Partnerships: Strengthen cross-border cooperation and build joint initiatives to address shared vulnerabilities, promoting science-policy partnerships for sustainable solutions. 17 IWMI is Part of the CGIAR CGIAR a global research partnership dedicated to reducing poverty, enhancing food and nutrition security, and improving natural resources through global and regional initiatives. Presence in over 75 countries, mostly in developing countries. Network of more than 3000 partners from national governments, academic institutions, global policy bodies, private companies & NGOs. IWMI’s role in the partnership is to deliver evidence-based approaches and water solutions for sustainable climate-resilient development. Water, food & ecosystems Water, climate change & resilience Water, growth & inclusion IWMI Strategic Programs Addresses Global Water Challenges Science for a Transformative Agenda Water data science & digital innovation How can water management decision-making be supported through data science and digital innovation services 18 18 THANK YOU FOR YOUR ATTENTION Dajuma, A., Sylla, M. B., Tall, M., Almazroui, M., Afiesimama, E., Dosio, A., ... & Giorgi, F. (2024). Projected intensification and expansion of heat stress and related population exposure over Africa under future climates. Earth's Future, 12(12), e2024EF004646. Sylla, M. B., Faye, A., Giorgi, F., Diedhiou, A., & Kunstmann, H. (2018a). Projected heat stress under 1.5 C and 2 C global warming scenarios creates unprecedented discomfort for humans in West Africa. Earth's Future, 6(7), 1029-1044. WASCAL, (2024); Migration Under (Multi)Hazards; BULLETIN NO 1, ISSUE 1 Fotso‐Nguemo, T. C., Weber, T., Diedhiou, A., Chouto, S., Vondou, D. A., Rechid, D., & Jacob, D. (2023). Projected impact of increased global warming on heat stress and exposed population over Africa. Earth's Future, 11(1), e2022EF003268. UNEP 2020 Water risk and water stress for Africa ; https://www.grida.no/resources/13697 Badou, F. D., Hounkpè, J., Yira, Y., Ibrahim, M., & Bossa, A. Y. (2019). Increasing devastating flood events in West Africa: who is to blame?. Sylla, M. B., Faye, A., Klutse, N. A. B., & Dimobe, K. (2018b). Projected increased risk of water deficit over major West African river basins under future climates. Climatic Change, 151(2), 247-258. Sylla, M. B., Pal, J. S., Faye, A., Dimobe, K., & Kunstmann, H. (2018c). Climate change to severely impact West African basin scale irrigation in 2 C and 1.5 C global warming scenarios. Scientific reports, 8(1), 14395. Obahoundje, S., & Diedhiou, A. (2022). Potential impacts of climate, land use and land cover changes on hydropower generation in West Africa: a review. Environmental Research Letters, 17(4), 043005. Janes, T., Jones, R. and Hartley, A. 2015. Regional Climate Projections for West Africa. UNEP-WCMC technical report Akafou et al., (2024). Modeling climate change impacts on inflow and hydropower generation in West Africa using ensemble learning with CMIP6. Under Internal Review Masolele, R. N., Marcos, D., De Sy, V., Abu, I. O., Verbesselt, J., Reiche, J., & Herold, M. (2024). Mapping the diversity of land uses following deforestation across Africa. Scientific Reports, 14(1), 1681. Obahoundje, S., Youan Ta, M., Diedhiou, A., Amoussou, E., & Kouadio, K. (2021). Sensitivity of hydropower generation to changes in climate and land use in the Mono Basin (West Africa) using CORDEX dataset and WEAP model. Environmental Processes, 8(3), 1073-1097. Obahoundje, S., Ofosu, E. A., Akpoti, K., & Kabo-bah, A. T. (2017). Land use and land cover changes under climate uncertainty: Modelling the impacts on hydropower production in Western Africa. Hydrology, 4(1), Akpoti, K., Mekonnen, K., Leh, M., Owusu, A., Dembélé, M., Tinonetsana, P., ... & Velpuri, N. M. (2024). State of continental discharge estimation and modelling: challenges and opportunities for Africa. Hydrological Sciences Journal, 1-29. Intergovernmental Panel on Climate Change (IPCC). (2021). Regional Fact Sheet - Africa. In Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Retrieved from https://www.ipcc.ch/report/ar6/wg1/resources/factsheets/ Intergovernmental Panel on Climate Change (IPCC). (2022). Chapter 9: Africa. In Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change (pp. 1285-1366). 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