How satellite technology can support life-saving flash flood alerts for African cities

In 2006, a night-time rainstorm triggered a devastating flood in the Ethiopian city of Dire Dawa. Water up to four meters high surged through residential areas, claiming 260 lives and displacing thousands. With no warning system, residents were completely unprepared. These flash floods are a growing problem in African cities, where rapid urbanisation and inadequate infrastructure leave residents vulnerable.

A Dutch-African consortium, led by HKV is addressing this challenge through an innovative warning system, funded by the Partners for Water programme. The approach uses satellite data to generate crucial information for flood management and emergency responses. Dorien Lugt, Water and Climate Consultant at HKV, shares insights on this promising solution.

Floods without warning

“Many urban areas in Africa are not prepared for heavy rainfall”, says project leader Dorien Lugt. “This creates situations that are not only disruptive, but can also be life-threatening.”

“One of the major causes of the problem is the lack of reliable precipitation information,” Lugt explains. “In the Netherlands, we have rain radar; we can see where it’s raining at any moment. In many African countries, this information does not exist. There are often no radars and the ground stations that do exist only measure rainfall at one particular point and often do not automatically transmit data.”

Satellites as a solution

To address this problem, the consortium, consisting of HKV, Deltares, the Red Cross, TAHMO and ICPAC, are focusing on an early warning system for urban areas. Lugt explains how the consortium was brought together: “HKV and Deltares, are strong in flood risk management, “TAHMO measures rainfall throughout Africa, the Red Cross knows how to communicate effectively during disasters, ICPAC is a regional organisation, supporting 11 east African countries with weather and climate information.” The consortium uses satellites that look at Africa every 15 minutes and can detect rain. “This provides a comprehensive map – comparable to rain radar – of where and how much rain is falling.”

“We integrate this satellite data into a computer simulation to generate detailed flood forecasts with a six-hour lead time,” says Lugt. “Our team then translates these technical predictions into actionable information for the city: Which neighbourhoods face imminent danger? When is the flood expected? And most critically, how can we ensure residents not only receive these warnings in time but also understand how to respond effectively?”

This timing is critical. In Dire Dawa, sometimes only a few hours separate mountain rainfall from flooding in the city. “When you know it’s raining in the mountains, you must act quickly,” says Lugt. “For example, evacuating a busy market with hundreds of vendors in a dry riverbed before the water arrives.”

Local cooperation is the key

Dire Dawa was chosen as a pilot location due to the tangible risks and the existing involvement of local parties. “We initially contacted the Ministry of Water, the disaster management organisation and the municipality. They were immediately enthusiastic,” Lugt recalls.

The local community plays an important role: “People from the city took photos of bridges and drainage points. Based on this, we developed a model of the city and simulated the 2006 flood,” says Lugt. Local knowledge was also used to fill in the gaps on historical water level measurements. “Normally, you compare models with measured water levels. Instead, we asked the residents how high the water level was in different years. That provided surprisingly useful information.”

Innovations on multiple fronts

The project innovates at three levels. “First, we use satellite data that until now were underutilised. Second, we model the city in unprecedented detail using Deltares’ rapid modelling tool. And third, we’re working with the Red Cross on new protocols. Unlike traditional disaster plans, which often look days ahead, urban protocols must anticipate sudden events. That requires a different way of working and communicating,” Lugt adds

A model for the future

The collaboration is going well, despite challenges in finding the right approach. “Ethiopia was new terrain for most of us. But, the enthusiasm from the local partners has been contagious. They even indicated that they want to learn modelling themselves, so now we offer an online training every two weeks.”

“The project runs until the end of 2025. Now that the rainy season is starting, we agreed that we will run the system and that the Ethiopian team will monitor what happens. This way, we can see how well it works and what we can still improve.”

According to Lugt, the goal is clear: “With this project, we not only want to make Dire Dawa safer, but also demonstrate that this approach works for other African cities facing similar flood risks. Because the problem is widespread and the need for solutions is urgent.”

Continue the conversation: join the Meet-up 29 January

Dorien Lugt is also featured in the podcast episode #9 Early Warning! released on 22 January. On 29 January we will continue the conversation live in-person at Bar Beton at Utrecht Central. The meet-up on 29 January builds on the insights from the Waterproof podcast episode 9.