Rwanda is set to roll out flood sensors countrywide to strengthen the early warning system.

Installing flood sensors (detectors of water levels) on rivers, drainages and lakes, is among the investments that Rwanda is making to manage and control the effects of storm water- surface water in abnormal quantities resulting from heavy falls of rain that result in floods.

The move is based on the fact Rwanda loses over Rwf204 billion due to disasters, such as floods and landslides as a result of lacking effective storm water management.

Disasters, mainly floods and landslides, killed about 100 people and injured 195 from January to mid-October last year.

At least 107 people were killed by disasters from January to April this year alone.

"The flood sensors will be updating us -in between every 5 and 15 minutes- about water levels, quantity, depth and speed of the storm water in rivers and drainages,” Davis Bugingo, the Flood Management and Water Storage Development Division Manager at Rwanda Water Resources Board (RWB) told The New Times.

"With that we will be able to warn people so that they leave a certain place because it might be affected by floods at the moment,” he added.

Bugingo revealed that procurement is going on in Kigali City to install flood sensors on between 10 and 15 places known to have rivers and drainages that are known to be sources of floods in the capital.

"We are targeting areas where storm water converges to cause floods. We have identified catchments such as those of Rwandex, Rugunga, Gikondo, Kinamba, Nyabugogo, Nyamirambo and others,” he said.

By next year, the flood sensors will have been installed in Kigali city, he noted.

"With the sensors we will be alerting the ministry in charge of emergency management and other institutions to do quick evacuation,” he said.

At least US $0.2 million from the Rwanda Urban Development Project, financed by the World Bank, could be spent to procure flood sensors and hydrological stations in Kigali city.

"The system will also help owners of buildings to know the flood status for better decisions and enhance the infrastructure’s resilience,” he said.

Floods sensors in other parts of the country

Bugingo disclosed that flood sensors, in another project apart from Urban Development Project, have been installed on major rivers and lakes across the country.

He said they have been installed on Sebeya River-one of the rivers when inundated usually causes floods in western province.

The government has also been constructing Rwf7.5 billion dams to contain flooding caused by this river under the support of Embassy of the Kingdom of Netherlands

The flood sensors, he added, have again been installed on Rivers; Muvumba, Akanyaru, Rusizi, Mukungwa, and Nyabarongo, that are usually inundated to cause loss of lives and damage of properties.

"We are still installing more in other places,” he said.

Different interventions to manage stormwater

Last week, the City of Kigali announced that over $1 million (over Rwf1 billion) is set to be invested in developing the Kigali ‘Stormwater Management Master Plan’ that is expected to be complete by 2024 so as to mitigate floods in the city.

Bugingo explained that managing storm water requires different interventions at different levels.

"Storm water management is wide. It starts with home, land and building owners. When it rains, they must make sure they harvest rainwater using different techniques. They should also avoid a lot of pavements on the ground in their homes but also have lawns, gardens to ensure they curb runoff water speed,” he said.

However, harvesting rainwater, according to Rwanda Water Resources Board (RWB), is just 17 per cent across the country. Only two per cent of the households use rainwater tanks.

It would also take an investment outlay of $40 million to equip all identified public buildings with rainwater storage systems.

"After rainwater harvesting, the runoff water needs proper channels and drainage networks so that they do not cause flooding.

"When detailing a physical plan for settlement in a village, the issue of storm water should be considered. Then we need big drainage networks with capacity to convey storm water across the whole city,” Bugingo said.

He said centralised sewerage system in the City of Kigali starts from managing stormwater in neighbourhoods.

Natural based solutions

To manage stormwater, he added that nature-based solutions are also needed.

"These include planting trees and vegetation on hills, along rivers and drainages to help reduce speed of runoff water to avoid flooding,” he said.

In addition, he said, rehabilitating and conserving wetlands is needed since they retain and curb floods.

"The infrastructure such as roads and bridges among others should also be built in a way that they are resilient to floods,” he added.