Hydrogeology of an urban weathered basement aquifer in Kampala, Uganda

Philip M. Nyenje, Denis Ocoromac, Stephen Tumwesige, Matt J. Ascott, James P. R. Sorensen, Andrew J. Newell, David M. J. Macdonald, Daren C. Gooddy, Callist Tindimugaya, Robinah N. Kulabako, Dan J. Lapworth & Jan Willem Foppen

Weathered basement aquifers are vital sources of drinking water in Africa. In order to better understand their role in the urban water balance, in a weathered basement aquifer in Kampala, Uganda, this study installed a transect of monitoring piezometers, carried out spring flow and high-frequency groundwater level monitoring, slug tests and hydrochemical analyses, including stable isotopes and groundwater residence time indicators. Findings showed a typical weathered basement aquifer with a 20–50-m thickness. Groundwater recharge was 3–50 mm/year, occurring during sustained rainfall. Recharge to a deep groundwater system within the saprock was slow and prolonged, while recharge to the springs on the valley slopes was quick and episodic, responding rapidly to precipitation. Springs discharged shallow groundwater, mixed with wastewater infiltrating from onsite sanitation practices and contributions from the deeper aquifer and were characterised by low flow rates (< 0.001 m³/s), low pH (<5), high nitrate values (61–190 mg/L as NO₃), and residence times of <30 years. The deeper groundwater system occurred in the saprolite/saprock, had low transmissivity (< 1 × 10⁻⁵ m²/s), lower nitrate values (<20 mg/L as NO₃), pH 6–6.5 and longer residence times (40–60 years). Confined groundwater conditions in the valleys were created by the presence of clay-rich alluvium and gave rise to artesian conditions where groundwater had lower nitrate concentrations. The findings provide new insights into weathered basement aquifers in the urban tropics and show that small-scale abstractions are more sustainable in the deeper groundwater system in the valleys, where confined conditions are present.

June 20, 2022
// Cities, Climate information, Climate research, Water

Building the foundation for climate-informed decision-making in Africa: the need for continued investment in African climate research

Roy Bouwer, Moussa Diakhaté, John Marsham, Douglas Parker, Dave Rowell, Catherine Senior, Christopher Taylor, Richard Washington

The FCFA programme aimed to fundamentally improve the scientific understanding of Africa’s climate and pilot new approaches to improve the uptake of medium- to long-term climate information (5–40 years) into decision-making. While much of the real-world impact of the programme emerged from pilot projects, the underpinning science played a critical role in strengthening the knowledge foundation to understand weather and climate processes, and climate change across the continent. The collaborative research approach allowed researchers to work together and build upon each other’s work. This resulted in rapid advances in improving the understanding of Africa’s climate and provides a strong evidence base for future work, as well as decision-making around future climate risks.

This brief aims to encourage further investments from donors in African climate science research. It highlights the advances FCFA has made in advancing the scientific understanding of Africa’s climate, improving climate models, and supporting capacity development. The brief then goes on to emphasise the value of investing in climate science within the FCFA programme and the importance of continued investment, including within existing gaps.

Improving the use of climate change information for adaption in Uganda

Danert K, Lapworth DJ, Macdonald DM, Marsham J, Opwonya D, Rowell D, Tindimugaya C, Kyoburungi G

There is little doubt that climate change is already affecting the lives of people in Uganda. Climate change is a particular challenge for the effective management of the country’s water resources. Reliable information on climate change scenarios and impacts is essential to inform policy and practice. While several climate experiments (e.g. CMIP6) are already available, new experiments such as the 4.5 kilometre-scale convection-permitting regional climate simulations for Africa (CP4A) can now be used alongside the CMIP experiments and allow us to assess the impacts of intense storms in more detail than before. However, if these innovative methods are to influence policy, they first need to be well-understood and accessible. This requires capacity strengthening of the professionals and researchers so that they can analyse such experiments. This workshop provided an opportunity for practitioners in Uganda to learn about a range of climate experiments and see results from case studies focussed on water resources, tea production and urban flooding using the CP4A and CMIP experiments. This was a great opportunity particularly for early career staff at the Ministry of Water and Environment, Ministry of Agriculture Animal and Fisheries and Uganda Electricity Generation Company Limited (UEGCL) as well as researchers at Makerere University.

Can insurance catalyse government planning on climate? Emergent evidence from Sub-Saharan Africa

Swenja Surminski, Jonathan Barnes, Katharine Vincent

This paper explores how climate risk information produced in the context of insurance-related activities can support public climate adaptation planning. The central contribution is to outline how relevant climate risk information can translate into behaviour change, and the drivers and barriers that influence this in Sub-Saharan Africa. The insurance industry has the potential to catalyse greater use of climate information, either through existing insurance transactions or through capacity building and investment in data sharing and collaboration. We investigate the interplay of climate risk information and insurance processes from two angles: the use of climate risk data by those who provide insurance – with information as an input to the underwriting process; and the catalyst role of insurance for governments to move towards anticipatory climate risk management. We apply a multi-method approach, combining insights from a survey of 40 insurance experts with key informant interviews and document analysis from three complementary case studies: indemnity-based insurance of private assets in South Africa; parametric sovereign risk pool in Malawi; and collaboration on risk analytics and risk management advice (no insurance) in Tanzania. The analysis offers a new perspective on the catalyst role of insurance by focusing on the ways in which political economy factors, particularly incentives and relationships, influence this process. Overall, there appears to be clear scope for a dynamic interaction between insurers and governments where symbiotic use and generation of climate risk information can advance mutual goals. However, that ambition faces many challenges that go beyond availability and suitability of data. Limited trust, unclear risk ownership and/or lack of incentives are key barriers, even if there is risk awareness and overall motivation to manage climate risks. The three cases show the importance of sustained cross-sectoral collaboration and capacity building to increase awareness and utilization of insurance-related climate risk information.

Water conservation can reduce future water-energy-food-environment trade-offs in a medium-sized African river basin

C. Siderius, H. Biemans, J. Kashaigili, D. Conway

The need for achieving efficient and sustainable use of water resources is pressing, however, this often requires better understanding of the potential of water conservation, taking into account the impact on return flows, and the costs in relation to sectoral benefits. Using modelling and limited observational data we explore the costs and potential water savings of 24 combinations of water conservation measures in the Rufiji basin, Tanzania. We compare these costs with estimates of the value such water savings could generate from water use in three important economic sectors; agriculture, energy and downstream ecosystems with high tourism potential. The cost of water conservation measures (median: 0.07 USD m⁻³) is found to be: higher than the value of most uses of water for agriculture (growing crops in expanded irrigation sites) and the median value for hydropower generation (from a new mega dam currently under construction); and lower than the ecosystem value. Nevertheless, under our modelling assumptions, the volume of additional water required to supply planned irrigation expansion in the basin could be reduced by 1.5 BCM using water conservation methods that would be financially viable, given the value of competing uses of water. Water savings of this magnitude would reduce potential trade-offs between use of water for hydropower and ecosystem services, by allowing peak environmental flow releases even in dry years, and without reducing firm energy generation. This methodology is transferable and relevant for producing realistic assessments of the financial incentives for long-term sustainable water use in agriculture, given incentives for other uses. With most reservoirs now being built for multiple purposes improved understanding of trade-offs between different sectors and functions is needed.

Stress-testing development pathways under a changing climate: water-energy-food security in the lake Malawi-Shire river system

Ajay G. Bhave, Declan Conway, Suraje Dessai, Andrew J. Dougill and David Mkwambisi

Malawi depends on Lake Malawi outflows into the Shire River for its water, energy and food (WEF) security. We explore future WEF security risks under the combined impacts of climate change and ambitious development pathways for water use expansion. We drive a bespoke water resources model developed with stakeholder inputs, with 29 bias-corrected climate model projections, alongside stakeholder elicited development pathways, and examine impacts on stakeholder-elicited WEF sector performance metrics. Using scenario analysis, we stress-test the system, explore uncertainties, assess trade-offs between satisfying WEF metrics, and explore whether planned regulation of outflows could help satisfy metrics. While uncertainty from potential future rainfall change generates a wide range of outcomes (including no lake outflow and higher frequency of major downstream floods), we find that potential irrigation expansion in the Lake Malawi catchments could enhance the risk of very low lake levels and risk to Shire River hydropower and irrigation infrastructure performance. Improved regulation of lake outflows through the upgraded barrage does offer some risk mitigation, but trade-offs emerge between lake level management and downstream WEF sector requirements. These results highlight the need to balance Malawi’s socio-economic development ambitions across sectors and within a lake-river system, alongside enhanced climate resilience.

This article is part of the theme issue ‘Developing resilient energy systems’.

Breaking vicious cycles? A systems perspective on Southern leadership in climate and development research programmes

Blane Harvey, Ying-Syuan Huang, Julio Araujo, Katharine Vincent, Geoffrey Sabitii

South–North research collaborations are now commonly used in the field of climate and development to advance knowledge, inform decision-making and strengthen capacity in the global South. Southern leadership within these collaborations is widely seen as instrumental to their lasting impact. This study examines how Southern leadership and capacity were promoted in the Future Climate for Africa (FCFA) programme, a five-year initiative that sought to enhance resilience to climate change in Africa. Drawing on interview and survey data from programme participants, document analysis and experiential insights from the author team, we examine how Southern leadership was pursued within the programme, and the barriers that constrained action at a range of scales. Most climate and development initiatives, like FCFA, sit at the intersection of multiple social, political and research systems. To disrupt the structures that sustain the power of Northern institutions and obstruct change, funders must go beyond programme-level interventions such as funding and distribution of roles, and consider deeper leverage points of change. We propose how shifts in mindsets and metrics in relation to Southern leadership and capacity can contribute to this change.

“Late-stage” deforestation enhances storm trends in coastal West Africa

Deforestation affects local and regional hydroclimate through changes in heating and moistening of the atmosphere. In the tropics, deforestation leads to warming, but its impact on rainfall is more complex, as it depends on spatial scale and synoptic forcing. Most studies have focused on Amazonia, highlighting that forest edges locally enhance convective rainfall, whereas rainfall decreases over drier, more extensive, deforested regions. Here, we examine Southern West Africa (SWA), an example of “late-stage” deforestation, ongoing since 1900 within a 300-km coastal belt. From three decades of satellite data, we demonstrate that the upward trend in convective activity is strongly modulated by deforestation patterns. The frequency of afternoon storms is enhanced over and downstream of deforested patches on length scales from 16 to 196 km, with greater increases for larger patches. The results are consistent with the triggering of storms by mesoscale circulations due to landscape heterogeneity. Near the coast, where sea breeze convection dominates the diurnal cycle, storm frequency has doubled in deforested areas, attributable to enhanced land–sea thermal contrast. These areas include fast-growing cities such as Freetown and Monrovia, where enhanced storm frequency coincides with high vulnerability to flash flooding. The proximity of the ocean likely explains why ongoing deforestation across SWA continues to increase storminess, as it favors the impact of mesoscale dynamics over moisture availability. The coastal location of deforestation in SWA is typical of many tropical deforestation hotspots, and the processes highlighted here are likely to be of wider global relevance.

Infographic: FCFA at a glance

This infographic provides a brief overview of the Future Climate For Africa programme’s achievements in numbers. This includes key figures from the programme evaluation conducted in 2021. These figures do not represent the full scale of the programme’s long-term impact, rather the outputs and outcomes at the time of the evaluation.

Building climate resilience in Africa through research and development: An evaluation of the Future Climate for Africa programme

Louise Vaughan, Roy Bouwer, Tiffany Chalmers

This brief synthesises the findings from an evaluation of the FCFA programme over the past 6 years of implementation. The evaluation aimed to assess the impacts, outcomes and achievements of the programme in relation to the programme Theory of Change (ToC), with a particular focus on, ‘Improved medium-term (5-40yr) decision making, policies, planning and investments by African stakeholders and donors’.