Improving Our Understanding of Climate Change Impacts in East Africa // by David Macdonald

David Macdonald is a senior hydrogeologist in the Groundwater Directorate in BGS. He is currently coordinating the BGS contribution to an exciting four-year project that is improving the understanding of the climate in East Africa and using this to assess impacts of climate change on urban water and sanitation, rural livelihoods and water management.

Five years ago, the Future Climate for Africa Programme, funded by NERC and DFID, set out to generate fundamentally new climate science focussing on Africa, and to ensure that this science has an impact on human development across the continent. Within the programme, the IMPALA project - led by the Met Office - is tackling the major scientific hurdle that limits the use of climate information: that current climate models have only a modest ability to capture African climate systems. Four further projects are focussing on specific regions of the continent. The project involving the British Geological Survey is in East Africa - 'HyCRISTAL:Integrating Hydro-Climate Science Into Policy Decisions For Climate-ResilientInfrastructure And Livelihoods In East Africa', with a budget of £4M. It is led by Leeds University and in the UK, in addition to BGS, involves the Met Office, the Walker Institute at Reading University, the Centre for Ecology and Hydrology, Evidence for Development and Loughborough University. In East Africa there are many institutions and NGOs involved including Makerere University, Maseno University, Jomo Kenyatta University, Practical Action and the national Met Agencies. From the USA, research teams in Connecticut, Stonybrook and North Carolina State Universities are also involved.

HyCRISTAL showcase event - an expert panel gives its views on
the challenges facing East Africa as a result of climate change 
The first Annual Meeting was opened by the Ugandan Prime Minister four years ago, partners and stakeholders met for the final showcase event at the Fairway Hotel in Kampala to share some of the exciting climate science and impact studies that have taken place during the project (although thanks to an extension until March 2020, or perhaps even longer, there is still work ongoing).

An automatic weather station installed at one of Kampala's water
treatment works, as part of the new meteorological network
The HyCRISTAL project has taken advantage of the new pan-Africa high-resolution (4.5 km) climate model developed in the IMPALA project which, crucially, explicitly simulates the rainfall-generating convection processes in the atmosphere. This has been used to show that there is likely to be a greater and more widespread increase in extreme rainfall in East Africa than indicated by models in the CMIP suite that feeds into the IPCC assessment reports - these take a more simplistic approach to simulating convection. Research has also shown that in East Africa, where there are two wet seasons, climate change may lead to later and longer Short Rains (September to December), with a larger rainfall increase than in the Long Rains (March to May), and with an earlier end to the Long Rains. The project has also shown that aerosol emissions may induce climate changes not currently included in CMIP, and that the model that generates the greatest rainfall increase for East Africa is likely implausible due to its rainfall increase being driven by unrealistic processes in the Southern Ocean.

Kampala residents gathering water from one of the springs being monitored
by the HyCRISTAL project
In terms of impact studies, the HyCRISTAL project has examined the implications of climate change on Lake Victoria levels and on tea production. BGS has developed river flow models for 27 catchments across East Africa and examined how flows might change by the 2050s by driving the models with rainfall and temperature outputs from the CMIP models. The range of projected flows in each catchment is wide. In some of the catchments there is general consensus in the direction of change of the modelled future flows, however, across all the catchments this is neither consistently an increase nor decrease in flow. What is consistent is that when the output from the IMPALA high-resolution convection-permitting climate model is used to drive the river flow models, the flows are higher than with the CMIP models. This shows that use of the CMIP models may lead to underestimation of future river flows. BGS is working closely with the Uganda Ministry of Water and Environment to assess what these model results mean for water resource planning.
BGS is also involved in a number of other aspects of the project. It is collaborating with flood modellers and water and sanitation engineers to examine flood risk under future climates, what impact this has on the low income urban population in the region, and how infrastructure can be made more resilient. BGS is also working with Makerere University in Kampala to better understand the resilience of spring water supplies and has helped to set up a hydrometeorological network in the city which has provided essential data to allow high intensity rainfall datasets to be produced to drive the flood models.

Impacts that may be felt in Urban East Africa under three different possible climate
futures. More information here
Informing decision makers is a key element of the HyCRISTAL project. It is challenging for decisions to be made given the uncertainties in the future climate, as well as other future land use and socio-economic conditions. As a means to help decision-makers assess the possible impacts of climate change a series of simplified urban and rural future scenarios have been developed on the project.

The HyCRISTAL project continues to be an excellent opportunity for interdisciplinary science and the BGS team that also includes Matt Ascott, Vasileios Christelis and Dan Lapworth are looking forward to working with the wider project team in the final months ahead.

To find out more about the project please contact David Macdonald.

A list of HyCRISTAL publications to-date. 

All photography copyright BGS / David Macdonald