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Understanding the Forest-Water Interactions in the Congo Basin


The development objective of this project is to improve the understanding of forest-water interactions in the Congo Basin across World Bank project teams, client countries and climate scientists in Africa, and to strategize potential application to development programs and policies in the region. The analysis seeks to use emerging data and research to identify links between forest loss and degradation and water resources in the Congo Basin in the context of climate variability, covering impacts both locally and from a regional hydrologic cycle perspective.


The Congo Basin represents roughly 70% of Africa’s forest cover and is the second largest contiguous tropical forest in the world after the Amazon Basin. The Congo Basin provides many ecosystem services (carbon and non-carbon) but the forests are under pressure from economic activity such as logging, agriculture, energy, transport, and mining, and satellite-based data show that annual rates of deforestation have doubled since 1990 (World Bank 2013). Climate change is predicted to impact the Congo Basin significantly: since the 1950's, the region has experienced a 1°C increase in mean annual temperature (Niang et al. 2014; Fuller et al. 2018); by the 2080's, climate models suggest temperatures will increase 3 to 5°C and precipitation will decrease by 40% (Fotso-Nguemo 2016).

Understanding the impacts of forest loss within the Congo Basin and regionally is limited due to limited information on the linkages between forest loss and environmental services in the Congo Basin, particularly of the role of the forest in generating rainfall both locally and regionally. While much of the research related to the impact of tropical forests on rainfall and temperature has been undertaken in the Amazon, the few studies that have been conducted in the Congo Basin indicate that the region is a major source (17%) of moisture for West Africa (Cadet and Nnolli; Gong and Eltahir). One study estimates that the rain forests of West Africa may account for 30-40% of the annual rainfall in the Ethiopian highlands (Ellison 2018). Others suggest that the main source of rainfall in the Congo Basin is evaporation from the Great Lakes and that the Congo forest basin in turn generates much of the rainfall not only in the Congo basin (75-95%) (Brinkman 1983 in Job 1994) but also in the Sahel (van der Ent et al. 2010). At the same time, the drying trend in the Basin suggested by some scientific papers (Zhou et al. 2014) may impact this “water pump” service it provides. Such impacts are well described for the Amazon, where scientists have warned of an “Amazon dieback” or “savanization” of the Amazon (Vergara and Scholz 2011).


This analytic activity will assess the current state of knowledge on forest-water linkages in the Congo Basin in order to identify knowledge gaps. The activity will include a review of literature, datasets, models and development projects (Bank and external) relevant to forest loss and hydrology in the Congo Basin, which would be collated through an online knowledge portal. The team will also flag potential additional impacts, such as health and migration, that may be areas of future inquiry. The research, knowledge, and investment gaps identified through this work will be addressed by appropriate stakeholders and would inform potential future fundraising and partnership needs. This activity will build on similar work completed for other important forest regions, such as the Amazon Basin, and would leverage and connect with relevant Bank projects, both ongoing and proposed, as well as academics and practitioners working within the Congo Basin. The activity and recommendations therein would also align with the Bank’s current Forest Action Plan (FY16-20) and forest-smart approach.
The activity was completed as planned – it helped improve understanding of, and bring attention to, address the data and analytical challenges in the Congo Basin in working on the forest-climate-water nexus, develop a network of professionals interested in these aspects, and improve awareness of emerging data/analytical services and concepts of precipitation-sheds to better understand the regional implications of forest loss in the Congo basin, along with other basin and global implications.
Key outputs include: 
  • The activity expanded the available evidence base through the production of an innovative online, interactive e-book. This e-book/knowledge portal houses both a data and analytics portal for the Congo Basin across numerous social, economic, and environmental themes; and a knowledge portal containing relevant literature, reports, investments, videos and programs in the Congo Basin.
  • Community of Practice Formed. The team held numerous consultations (both in-person and virtually) with Bank teams working within the region, relevant academic experts, donor and other organizations. The CoP distribution list developed had over 200 people and is expected to be useful for the future as well.
  • Two global virtual discussions undertaken. The first discussion session was held in September 2019 with over 50 participants; a smaller, more focused session was held in December 2019 with about 20-25 participants.
This activity compiled information on the forest-climate-water nexus in the Congo Basin; key findings are available in Chapter 2 of the e-book here. The e-book provides collated evidence, such as that suggesting that evapotranspiration in the Congo Basin is high - one study estimated ET at 75% to 85% of annual precipitation in the Congo Basin – and that deforestation in the Congo Basin may increase surface warming by roughly 0.7°C, which is nearly half of all GHG-induced warming in the region. Using a regional climate model, one study estimated that the loss of the Congo Basin rainforest may decrease rainfall by 42% over the western Congo while increasing rainfall by 10% in the eastern part. Further, increased albedo due to deforestation resulted in a cooler and drier climate over the basin as a whole. The e-book presents these findings and more, covering the forest-climate-water nexus both within the Congo Basin as discussed, and within the African continent and globally. The knowledge portal, accessible here, compiles relevant literature on the forest-climate-water nexus in the Congo Basin and beyond in one place, providing an important evidence base that is summarized by the e-book. Further, the data portal aggregates key datasets relevant to this nexus in the Congo Basin into a publicly accessible tool here.
These knowledge products developed and disseminated through the activity have led to an improved understanding of the role of the Congo Basin forests for Bank staff and the larger development community and academia working in this area, and have fostered new connections and dialogue, with the possibility of future collaboration with local and international institutions engaged through the work. The e-book establishes the relevance of the analysis to Africa TTLs in a variety of sectors (e.g. water, energy and agriculture) and provides insight into the potential impacts of forest-water-climate linkages on WBG clients in the region and in other regions, such as the Ethiopian Highlands and the Sahel. The e-book also identifies ways in which technology can be used to close the gap in the understanding and impacts of the linkages identified.

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Last Updated : 06-09-2020