DREF (KzG: Disaster Response Emergency Fund) timeline according to the evolution of the situation:

On 26 and 27 October 2023, the first intense rainfall and high winds caused important flooding in Cibitoke affecting 1,590 people. Based on the needs reported by the NS, a DREF operation was launched in Cibitoke on 15 November 2023 to assist 265 HH.
From 26 to 27 December 2023, other heavy rain occurred in Bujumbura town (Kinama, Buterere, Musaga and Kanyosha) and Bubanza Provinces (Gihanga and Mpanda), with 371 houses totally or partially destroyed and 7,278 people affected. BRC extended the DREF to assist 150 more affected HH in Ntahangwa and Muha.
In April 2024, as the situation worsened, the NS requested a 3rd allocation to assist 200 more affected HH. That third allocation was triggered by an unprecedented rise of Lake Tanganyika waters as a result from the continuous rains. On 12 March 2024, the waters of Lake Tanganyika had risen by 776.76 m, i.e. 1,76 m above the normal, their worst for sixty years. According to data collected by the CRB volunteer network, the damages were:
66,391 persons affected and in need in 10 communes of 4 provinces. Local residents had been forced to suspend their activities, and some were forced to move, as the lake waters continued to gain ground. At this time 162,356 people are at high risk of being affected by the floods.
1,344 flooded houses and 300 immediately houses threatened; main roads markets, ports, schools, more than 365 Ha of fields were flooded, and the road from Bujumbura to DRC via Mutimbuzi commune is already flooded since 2nd March 2024 and the road along Tanganyika Lac in Bujumbura Town (Avenue du Large).
The humanitarian situation has been worsened by the rising of the level of the Lac Tanganyika which was at 777.30 m on 17 May. To date, 54 Collines are flooded where live 492,825 people of Bujumbura (Communes Mutimbuzi and Kabezi), Province Marie (Commune Muha, Mukaza and Ntahangwa), Province Rumonge (Muhuta, Bugarama and Rumonge) and Province Makamba (Commune NyanzaLac). Burundi Government has officially declared the humanitarian crisis and a holistic humanitarian response developed. Burundi is almost at the beginning of the dry season, and flooding should normally decrease. However, cases of cholera have begun to increase exponentially, and landslides could continue on unstable ground that has accumulated a lot of rainwater.

IFRC has recategorized of the crisis as orange based on the humanitarian situation, which allows BRCS to extend this operation more months to alleviate the burden of the crisis on the most vulnerable affected families.

Scope and Scale

The rise of the Lake Tangayinka waters from 775 m of altitude to 777.3m on 17 May has aggravated to humanitarian situation and 7,796 more houses are now flooded, for an overall 10,648 since the beginning of the operation. Since March, more and more residents are forced to suspend their activities, and to move, as the lake continues to gain ground with 47,547 displaced people at the moment. These families lost their homes, their means of subsistence, and the underground passages are flooded, bringing up sewage and toilet waste, with a high probability of the appearance of epidemics. The flood and landslide are causing the outbreak of the cholera epidemic in Bujumbura, Marie. The sitrep published on 17 May by the MoH showed 1,783 cumulative cases with 34 actives cases. The 18 new cases came from Mukaza and Ntahangwa Commune in Mairie of Bujumbura and Mutimbuzi in Bujumbura. Due to the flood, the risk of landsidles has drastically increased in Rumonge (Muhuta especially), Bujumbura (Kabezi commune), Marie of Bujumbura (Mukaza exactly at Mugoboka) and represents an additional threat for those families already made vulnerable by the floods.

Data collected by the BRC volunteer network on 17 May show the following cumulated damages:

54 Collines flooded where lives of 492,825 people were affected.
10,648 houses are flooded
2,914 houses are totally destroyed
3,017 are partially destroyed.
47,547 people are displaced as their houses are flooded or totally destroyed.
498 HH from Gabaniro Colline in Muhuta Commune have been affected by the landslide and have been relocated in a new site at Gitaza
600 HH from Gatumba are to be relocated to Gisagara Site in Mubimbi commune, 392 HH of whom have already been relocated
Public infrastructure: 2 Makamba markets flooded, Mukungu Communal High School and 15 primary schools destroyed
Damaged fields: 67 Ha in Nyanza, 43 Ha in Makamba, more than 300 Ha in Bujumbura Rural. In Rumonge 12 Ha of palm tree fields, 2.5 ha of rice fields, 1.5 ha of cassava fields.
The main challenges are the lack of evacuation sites for affected populations, the reluctance of some affected households to leave flooded areas because they have nowhere else to gO and the lack of people on the ground to monitor the situation and prepare for any assistance that may be required.