25 Aug 2023

Anticipating floods in Sudan: the power of secondary data

Since 2022, the Sudanese Red Crescent Society, with technical support from the German Red Cross and the Red Cross Red Crescent Climate Centre, has been working hard to improve its capacity to implement anticipatory action in areas at high risk of riverine flooding. Unfortunately, due to the current conflict in Sudan, project activities cannot be carried out as planned and are currently paused. But while the focus on the ground is now on emergency support, floods and other weather extremes remain one of the major risks for the population.

Outside of Sudan, a small team continues to analyse the risks and potential impacts of riverine flooding, and how to forecast this for parts of the River Nile Basin. Much of this is being done by sifting through secondary data. This includes historical data on rainfall and riverine flood forecasts, as well as on the previous impacts of severe riverine flood events. The Heidelberg Institute for Geoinformation Technology (HeiGIT) has stepped in to support this process and together, the project partners are working behind the scenes to improve the predictability of riverine flood impacts and risk.

Wait – what does “anticipating floods” actually mean?

Anticipatory action refers to a proactive approach taken to prevent or mitigate the potential consequences of a forecast hazard before it occurs, or before its most acute impacts are felt, based on forecasts or predictive analyses of when and where the hazard will occur. The idea is to shift away from mainly reactive, ad hoc measures after a disaster and, instead to act early.

Meet the secondary data team

Hello, I am Sheikh Khairul Rahaman and I work for German Red Cross as an anticipatory action project delegate. Until recently I was based in Sudan, but due to the current situation, I moved to Nairobi, Kenya, where I support the emergency response to the humanitarian crisis in Sudan.

In parallel, I’m gathering and analysing secondary information from various reputable sources. For instance, according to EM-DAT (an international disasters database), between 2003 and 2022 there were 30 meteorological, hydrological and climatological disaster events in Sudan – and 46 per cent of these were riverine floods. This is the main reason why the Sudanese Red Crescent Society decided to address this hazard first.

Other data sources include the Intergovernmental Panel on Climate Change’s reports, ACAPS reports, numerous needs assessments, and research conducted by different agencies and academic institutes. Together with HeiGIT, we aim to enhance the quality and depth of the risk analysis required to understand where to act early, based on the population’s exposure and vulnerability to riverine flooding.

Hi, we are Anne Schauss and Alec Schulze-Eckel and we are both research associates at HeiGIT. This institute supports humanitarian organizations to boost their geographic information system (GIS) and data analytics capacities, and has been providing sustainable, open-source solutions in GIS and open-source data analysis since 2017.

For Sudan, we just completed risk and historical impact assessments for riverine floods. To do this we used historical flood data and rural area accessibility data, provided by the German Aerospace Center, with which HeiGIT has a strategic partnership. The historical flood data from satellite imagery was necessary to grasp the impact of riverine floods in Sudan, while accessibility analysis was used to estimate how difficult it would be to reach people in the event of floods.

Such analyses are integral to every anticipatory action project because they help us to understand the relationship between climate phenomena and their impact on communities at risk and contribute to identifying the communities most vulnerable and exposed to riverine floods.

I’m David MacLeod, a climate scientist with over a decade of experience in understanding, evaluating and using weather and climate forecasts. I’m a lecturer in climate risk at Cardiff University in the UK, and also work for the Red Cross Red Crescent Climate Centre, supporting National Societies in Somalia and Sudan to develop anticipatory action plans.

For Sudan, I currently work with the Intergovernmental Authority on Development (IGAD), which is a body of eight member states (Djibouti, Ethiopia, Eritrea, Kenya, Somalia, South Sudan, Sudan, and Uganda), and with the IGAD Climate Prediction and Applications Centre (ICPAC) on the evaluation of its new forecasting system for regional riverine floods. Once online, this system will provide forecasts of river heights for major rivers across the region and will be a key piece of the puzzle, being able to look ahead at potential flood risks for a 15-day period. To understand the reliability of this system, I’ve been looking at the rainfall forecasts which feed into the model. This means evaluating a large ‘reforecast’ dataset, comprising 20 years of historical forecasts.

Comparing this reforecast against historical observations of rainfall helps build an understanding of the potential added value of rainfall forecasts in anticipating high-flow events. This work is being carried out across the upstream catchment of the Blue Nile, which is upstream of Khartoum.

So, how does all this help the population avoid or mitigate the impacts of riverine flooding in Sudan? Well, in a nutshell, we can better predict where and when a severe riverine flood event will happen, what the the likely impacts are, and who is most exposed and vulnerable.

The current conflict in Sudan

Since 15 April 2023, the Sudanese army and the paramilitary group Rapid Support Forces have been engaged in heavy fighting in many parts of the country. The fiercest fighting is in Khartoum, the capital city which is home to around 5 million people, and in Darfur.

The humanitarian situation is dire. Intense fighting has been taking place in densely populated urban areas, where essential services have been severely disrupted. Civilians are facing shortages of food, water and medical supplies. More than 3.5 million people have fled their homes, approximately 880,000 of them to neighbouring countries. Many have lost contact with their loved ones.

The Forecast-based Financing in Sudan project is supported by the Deutsche Bank Stiftung. This blog was co-authored by the partners currently supporting Sudanese Red Crescent Society in secondary data analysis: Sheikh Khairul Rahaman and Anita Auerbach (German Red Cross), Alec Schulze-Eckel and Anne Schauss (HeiGIT) and David MacLeod (Red Cross Red Crescent Climate Centre).