Introduction to South Africa case study

Author(s): Joy Waddell, Ailsa Holloway, Carinus de Kock (Stellenbosch University)

The FATHUM team in South Africa has selected the Langeberg Municipality in the Western Cape as the case study site for this research. South Africa’s Western Cape, which is home to over five million people, is known as “the Cape of Storms.” Due to the Langeberg Municipality’s extensive disaster history, steep topography, and remoteness of its rural communities, it was identified as a hotspot for high-impact weather events that increase the likelihood of destructive flash flooding. The Langeberg Municipality, which is one of five local municipalities within the Cape Winelands District of the Western Cape, is located about 180 km east of Cape Town.

Location of the Langeberg Municipality in the Western Cape, South Africa

The Langeberg Municipality has a population of 98,000 involved in a diverse economic base that includes mainly agriculture, forestry, and fisheries (15.3% of GDP, 23.1% of workforce in 2014), tourism, and manufacturing (17.5% of GDP in 2015). The Langeberg’s major towns (Montagu, Robertson, Ashton, and Bonnievale) are surrounded by complex mountain topography. The steep gradient of these mountains and the elongated and lobed shapes of the catchments in this area increase the likelihood of flooding, particularly flash flooding.

Mountainous terrain in the Langkloof, Langeberg Municipality

River’s proximity to the Cogmanskloof pass, near Montagu

From 2003 to 2014, the Langeberg Municipality experienced six disasters associated with severe weather events caused by cut-off low pressure weather systems. The resulting disasters were characterised by widespread flooding, with impacts reported across the Western Cape. During that time, the Langeberg reported total financial losses of around ZAR 23.6 million, with 6,424 people affected or requiring assistance.

Flooding in Aston, 2003

Number of people affected in the Langerberg Municipality from disasters associated with cut-off low systems

The town of Montagu, with its population of 15,176, is situated at the confluence of two major rivers. The Cogmanskloof pass through the Langeberg Mountains, near Montagu, is a major road that has flooded, cutting off the northern and southern parts of the Langeberg and causing logistical challenges, especially for response units such as emergency services, disaster management, police, and traffic services during a disaster.
Other contributing factors increasing local flood risk include:
• Changing land-use patterns, which increase surface run-off;
• Location of many towns and critical infrastructure along major rivers and in river valleys;
• Frequent wildfires linked to fire-adapted vegetation (e.g., fynbos, grasslands, Rynosterveld) and alien vegetation (e.g., pine forests), which also increase surface run-off;
• Increasing sediment accumulation (aggradation) in rivers, also linked to increased alien vegetation (e.g., reeds) in riparian zones.

Debris clogging a bridge leading into Montagu, 2015

Damage at Cogmanskloof pass, 2015

There is limited weather radar coverage in the Western Cape, not only because there are not enough instruments in place collecting the data, but the mountainous topography means that accurate inland flash-flood forecasting is blocked by the Langeberg mountain range, As shown in the Figure below, this leaves very little of the Western Cape covered by accurate weather radar, which severely restrains accurate forecasting and warning in the province. The implications were clearly highlighted during the 2011 and 2012 events, when weather warnings disseminated by the South African Weather Service did not specify areas such as the Langeberg Municipality. Heavy rainfall and flooding events in the Langeberg’s towns, such as Ashton, Montagu, and Robertson, claimed several lives, including that of an ambulance attendant. In both instances, preparedness mechanisms that should have been activated were not triggered, as flash flood warnings were not issued for the Langeberg Municipality.

Map of the Western Cape, highlighting the optimal weather radar coverage (green and white circles), compared with actual coverage (red shading) (Taken from Pharoah et al. 2016)

For more information on cut-off low weather systems in the Western Cape and their impact on the Langeberg Municipality, see: Pharoah et al. (2016). “Off the radar: Synthesis report. Severe weather events 2011-2014 and their impacts in the Western Cape Province, South Africa.”

Should seasonal rainfall forecasts be used for flood preparedness?

The first paper from members of the FATHUM team has now been accepted for publication!

Coughlan de Perez, E.Stephens, E.Bischiniotis, K.van Aalst, M.van den Hurk, B.Mason, S.Nissan, H. and Pappenberger, F. (2017) Should seasonal rainfall forecasts be used for flood preparedness? Hydrology and Earth System Sciences. ISSN 1027-5606 (In Press)


In light of strong encouragement for disaster managers to use climate services for flood preparation, we question whether seasonal rainfall forecasts should indeed be used as indicators of the likelihood of flooding. Here, we investigate the primary drivers of flooding at the seasonal timescale across sub-Saharan Africa. Given the sparsity of hydrological observations, we input bias-corrected reanalysis rainfall into the Global Flood Awareness System to identify seasonal indicators of floodiness. Results demonstrate that in wet climates, even a perfect tercile forecast of seasonal total rainfall would provide little to no indication of the seasonal likelihood of flooding. The number of extreme events within a season shows the highest correlations with floodiness consistently across regions. Otherwise, results vary across climate regimes: floodiness in arid regions in Southern and Eastern Africa shows the strongest correlations with seasonal average soil moisture and seasonal total rainfall. Floodiness in wetter climates of West and Central Africa and Madagascar shows the strongest relationship with measures of the intensity of seasonal rainfall. Measures of rainfall patterns, such as the length of dry spells, are least related to seasonal floodiness across the continent. Ultimately, identifying the drivers of seasonal flooding can be used to improve forecast information for flood preparedness, and avoid misleading decision-makers.

Kick-off Meeting Report

The FATHUM Kick-Off meeting was held from July 3rd to July 5th 2017.

Monday 3rd July

Icebreaker activities and discussion: The FATHUM team had 1-on-1 speed-introductions to each other, trying to find the most interesting / novel thing they had in common. Then they were asked to ‘vote with their feet’, placing themselves in different parts of the room depending on their disciplinary background, applied or theoretical nature of research, and previous history of working with the Red Cross / Red Crescent Movement.

Quiz the Panel: what is Forecast-based Financing? Erin Coughlan de Perez spoke about the history of FbF and why the concept was developed. Irene Amuron spoke about her experience implementing FbF in Uganda. Liz Stephens discussed her view as a scientist advising on the first FbF pilot projects.

Where is Forecast-based Financing now? Erin was quizzed by the group on all the other FbF related activities, including the Dialogue Platform events and the FbF Manual –, to which FATHUM research will contribute.

Presentation from Liz Stephens: Introduction FATHUM

Interdisciplinarity Exercise: The team were invited to think about  what methods we could adopt  as a team to overcome the challenges of interdisciplinary working. We decided on 5 rules to promote interdisciplinary research within FATHUM, along with developing a Glossary of Terms to enable better communication and understanding across our disciplines.

Website exercise: the team were asked for their priorities for the FATHUM website.

FATHUM Advisory Board Meeting: in person & via skype

Tuesday 4th July

Presentation from Hannah ClokeWork Package 1 Overview Probabilistic Forecasts Game: Andrea Ficchi led small teams through a game to highlight the challenges of decision-making from probabilistic forecasts.

Discussion topic: what is needed from a forecast? Andrea Ficchi asked for different perspectives on the required spatial scale of forecasts.

Impact Activity:  Pablo Suarez asked the project team to imagine an important mentor in their life, and what they would tell them about the FATHUM project., then to imagine bumping into a fellow team member in 25 years time; what successes would they like to be reflecting on.

Presentation from Liz Stephens: Project & Impact Deliverables

Work Package 3 Activity: Sara de Wit led groups organised by discipline in a ‘mapping the conversation’ exercise, discussing “What makes a successful implementation of FbF”, and “What are the barriers to FbF being implemented?”

Open Event with other projects from the SHEAR programme and at the University of Reading

Wednesday 5th July

Presentation from Ailsa Holloway: Work Package 2 Overview .

Presentations from Ailsa, Chris and Benedita on the WP2 case studies in South Africa, Uganda and Mozambique. Followed by a fruitful discussion about these case studies.

Presentation from Emily Wilkinson: Work Package 4 Overview. Followed by small group discussions on the how, what and where of upscaling.

Meeting reflections: Erin asked the team for their ‘I like’, ‘I wish’, and ‘I wonder’ feedback on the kick-off meeting. Liz asked for the team to reflect on what they will plan to do ‘on the way home’, ‘in the next month’, and ‘by the next meeting’.

Key Future Activities

*31st August deadline for SHEAR studentship proposals*

*Methodology meeting in Kampala 22nd-26th September 2017*

*Website soon to go live at*

*FbF Dialogue Platform meeting in Nairobi in December / January (to be confirmed)*

*Adaptation Futures conference in Cape Town / FATHUM Year 2 meeting in Stellenbosch from June 18th 2018*