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RISK ANALYSIS AND EARLY ACTION SELECTION
Prioritized hazard and its historical impact.
In Burundi, a country of small rivers and steep (and deforested) watersheds, extreme rainfall often causes riverine flooding with significant impact. These floods constitute a major shock according to the Burundian government's prioritization of potential major risks and the severity criterion (combining probability of occurrence and negative impact). Since 1980, the EM-DAT directory lists more than 28 floods that have caused considerable damage in several of the country's rivers and river basins. For example, the night of 9 January 2014 was a fateful one for the inhabitants of northern Bujumbura. The so-called Gatunguru floods left more than 70 people dead, 182 injured and four missing. 1,100 houses were destroyed, while 900 were partially destroyed. The uwinterekwa floods in the commune of Ntahangwa on 21 December 2019 resulted in 14 deaths and 450 affected households. A site was set up for the displaced and an appropriate response was provided. The flooding was caused by heavy rains and a detour of the Cari River, which ravaged everything in its path.
• Heavy rainfall in the Imbo and Mumirwa regions on 29 March 2015 caused flooding and landslides and around 20 deaths were recorded in Bujumbura Rurale.
• On April 19 and May 1, 2020, the province of Bujumbura Rural, Mutimbuzi commune, Gatumba zone was hit by heavy flooding that affected more than 45,000 people including 17,792 displaced.
• During the months of April and May 2021, the rising waters of Lake Tanganyika affected the provinces of Bujumbura Rural, Rumonge, Bujumbura Mairie and Makamba, resulting in 52,182 people affected in 10,076 households, including 22,580 displaced persons (4,170 households).
More than 10,000 people have been displaced by devastating floods following the heavy rains that have hit Burundi in recent years. In the rural area of Gatumba, in the province of Bujumbura, residents have been forced to seek refuge in schools, churches or sometimes in makeshift shelters set up by the roadside. As well as losing their homes, many have lost their livelihoods as the floods have destroyed crops and damaged businesses. This follows the displacement of 1,000 households in the same area in April 2023, according to IOM's Displacement Tracking Matrix (DTM).
Due to its quasi-tropical climate, Burundi is at enormous risk of flooding all year round, but flooding is particularly concentrated during the two rainy seasons (September to November and February to June). It should be noted that an increase in the risk of extreme rainfall caused by climate change could change this picture and cause the risk of flooding to be considered widespread. It could also have a greater impact if they affect communities with little experience of this kind of disaster.
Riverine and urban flooding, the most common type of flooding in Burundi, is characterized by the overflowing of riverbeds due to heavy (and sometimes long-lasting) rainfall in the various catchment areas. This type of flooding affects the communities that live or carry out their economic and subsistence activities on the banks of these rivers. These floods cause enormous human and material damage. In particular, the Burundi Red Cross has listed the primary impacts as deaths and injuries, the destruction of private and public infrastructures, and the overflowing of latrines. Agricultural and forage fields are often flooded, resulting in crop and livestock losses, and households are often displaced in the short and medium (and sometimes long) term. Secondary impacts cascade down, the most important of which are food insecurity, the outbreak of water-borne diseases, and a host of socio-economic and psychosocial impacts.
These situations impose a clear need for assistance, which can be summed up mainly in the following actions, by the various agencies and organizations (including the Burundi RC (CRB)) involved in disaster management. National and provincial platforms play an important role in coordinating emergency response. Generally, the CRB is responsible for first aid and care, conditional and unconditional cash transfers, setting up evacuation sites and temporary shelters, building houses, supplying drinking water, providing food, medicines, and fuel, and distributing seeds for the following season. For disaster affected people, a range of protection and psychosocial support activities are also offered, tailored to the needs of specific groups.
It should be noted that the period from March to May is an important rainy season in Burundi, with rainfall across the country accounting for up to 60% of total annual precipitation. For the year 2024, the forecasts provided by ICPAC in February are expected to be higher than the climatological normal for Burundi, with probabilities in the order of 55 to 65%, especially in the western part of the country, corresponding to the target region. These forecasts call for urgent action and coordinated preparation, to put in place proactive measures to mitigate the potential impacts and likelihood of flooding during the March to May 2024 (MAM 2024) season in the target region could therefore lead to a deterioration in the socio-economic life of the population.
We must also consider the rising waters of Lake Tanganyika, which is fed by numerous tributaries, the most important of which are the Rusizi and Malagarazi rivers, which have risen significantly (see graph 2). The expected rainfall will also contribute to the rise, especially towards April, when the maximum rainfall is expected (fig.1).
In addition to historically observed cyclical rise in water levels, the rise in water levels is due to multiple rivers flowing into Tanganyika, and localities will be affected according to their elevation levels - see the map of elevation classes from the normal level of Lake Tanganyika below.
According to the analysis of the figure above, the historical threshold of the lake level each time it has overflowed is around 771.2m. This level is a first level of danger in the event of extreme rainfall, as it is sufficient to cause an overflow and soon inflict severe damage to the people and their livelihoods in the minor lakebed. Special monitoring system will be built on this during the peak period (April), to better monitor with meteorologists, extreme rainfall forecasts and the level of Lake Tanganyika.