By François Edwards, UK Centre for Ecology and Hydrology
Nature-based solutions across Africa have the potential to unlock new tools for successfully incorporating dams into the environmental landscape and optimising the health of river ecosystems and the services humans derive from them. New research providing evidence for the effectiveness of nature-based solutions for water issues in Africa provides a scientific underpinning for policy and planning to realise the multiple benefits nature-based solutions can bring, such as improving water quality and reducing flood risk and pollution. As dams are a key aspect of modern landscapes, nature based solutions provide a useful route for mitigating their effects, and ameliorating ecological outcomes.
Africa is experiencing many serious water issues including floods, droughts, and river pollution, presenting major risks to economies and societies. Furthermore, these issues may worsen in the future as the climate changes. There has been an increasing focus in recent years on the use of nature-based solutions for catchment management, often presenting them as the most sustainable solutions for restoring catchments most altered by human activity. They address a triple challenge of simultaneously minimising climate change, restoring biodiversity and addressing food security and other development priorities.
Nature-based solutions sit in contrast to catchment management techniques that significantly alter the natural baseline, such as the building, operation or removal of dams. However, dams feature highly in water risk scenarios across Africa, thus natural and built infrastructure need to be integrated and their trade-offs understood, for effective water resource management. The implementation of nature-based solutions in African catchments impacted by dams may offer new opportunities for environmental mitigation, restoration and off-setting.
What are nature-based solutions?
A widely acknowledged definition of nature-based solutions, used by IUCN, is ‘Actions to protect, sustainably manage, and restore natural or modified ecosystems, that address societal challenges effectively and adaptively, simultaneously providing
human well-being and biodiversity benefits’
(Cohen-Shacham et al 2019).
New research examining 492 case studies from across Africa sought to answer the questions below relating to the effectiveness of nature-based solutions for downstream water quantity and water quality in Africa:
- Are nature-based solutions effective in mitigating specific water risks to societies and economies in Africa?
- What are the characteristics of nature-based solutions that are effective in mitigating specific water risks?
Consistent evidence was found that nature-based solutions can improve water quality. In contrast, evidence of their effectiveness for improving downstream water resource quantity was inconsistent, with most case studies showing a decline in water yield where forests (particularly plantations of non-native species) and wetlands are present. The evidence further suggests that forests and floodplain wetlands can reduce floods, whilst the presence of headwater wetlands were generally associated with increased floods. Thus potential trade-offs identified include nature-based solutions reducing flood risk and pollution, whilst decreasing downstream water resource quantity.
The evidence provides a scientific underpinning for policy and planning for nature-based solutions to water-related risks in Africa, though implementation will require local knowledge. In particular, it will be important to understand how dams and their operation can be incorporated into an environmental matrix that is underpinned by nature based solutions. For example dams fragment the river continuum into zones of contrasting ecological needs that then need to be matched up to contiguous environmental management measures such as reforestation and wetland creation.
A strategic approach to landscape or catchment management should consider all potential benefits and dis-benefits of nature-based solutions, including water and non-water issues, such as carbon sequestration, food and fuel supply, as well as intrinsic benefits in terms of biodiversity value. Decisions should also be guided by socio-economic, cultural and political considerations as much as by an understanding of the biophysical dynamics of landscapes and catchments. A holistic approach considering nature based interventions successfully integrated with built infrastructure across Africa has the potential to deliver solutions for sustainable development and the climate crisis.
Evidence for the effectiveness of nature-based solutions to water issues in Africa
By M Acreman, A Smith, L Charters, D Tickner, J Opperman, S Acreman, F Edwards, P Sayers and F Chivava
Publsihed in Environmental Research Letters, Volume 16, Number 6, June 2021. Open access.
You may also be interested to watch
‘Integrating natural and built infrastructure in water resource development: what’s stopping us?’. FutureDAMS webinar with Mark Smith, IWMI Director General, discussing how to support the planning and design of integrated natural and built infrastructure and scale up the use of nature based solutions with the effective use of trusted tools.
Note: This article gives the views of the authors featured and does not represent the views of FutureDAMS as a whole.
Image: Zambesian flooded grasslands. By Diego Delso, delso.photo, License CC-BY-SA