Real Risk

of Limbe has experienced rapid evolution in terms of human

population and development. With the construction of an oil

refining company in 1978, the status of the city was raised to a

subdivision.

Landslide delineation

Over 30 landslide scarps (landslide swarms) were identified on

the western side of the range of hills bordering Limbe to the

east and northeast. The Mabeta-1 landslide of June 2001 was the

biggest and most disastrous of these.

At each landslide site, the volume of material displaced gives

an estimated level of destruction to human property or envi-

ronment. Layers of air-fall volcanic material which, although

showing signs of chemical weathering, still preserved their orig-

inal graded bedding structure were observed on the exposed

sides of the landslide scarp close to the upper margin.

Flood delineation

Floods are a common occurrence of late in the subdivision. A

literature review of flood history in the area, image interpreta-

tion, analysis, and field observation accentuated the delineation

of flood risk zones.

All settlements along the Djenguele River basin i.e. Animal

Farms, Cassava Farms, Lumpsum areas, Church Street, New

Town and Down Beach have suffered from persistent flooding

over the years. At Maho Bridge during raining seasons, water

usually rises to a height of around 2.6m. The width of the

riverbed that was formerly just a small channel has now

increased to 27m due to a series of flood events.

The number of hours of flash floods causes serious impact in

different localities in the subdivision. In August 2005, a series

of inundations occurred around the city of Limbe lasting for

several hours and disrupting traffic. The rural poor are the most

affected by flood.

Causes of the disasters

Seismicity around the Mount Cameroon region is monitored by

the Unit for Volcanological and Geophysical Research (ARGV)

located at Ekona. Local seismicity for the period preceding the

1999 eruption averaged approximately 15 events per month.

This increased from more than 15 events on 26 March to more

than 200 events on the 27 and 28 of March 1999. An intensity

4 earthquake on 28 March was felt over a 100km radius around

the mountain and destroyed houses in Buea and environs. A

macro-seismic study of earthquake activity in Limbe showed

that it was felt more by people living upslope on the hillside

than by those living in the valleys.

Seismicity played an indi-

rect role resulting from the intense pre-1999 eruption shake

that probably exacerbated the opening of cracks in the hills

around Limbe, which would have facilitated the infiltration rate

of rainwater.

Rainfall data for the past 11–27 years was compiled for four

CDC-run meteorological stations in and around Limbe. Using

this data, a rainfall intensity of approximately 1.1mm/hr is esti-

mated. This is between 10 per cent (Mabeta Bimbia) and 45 per

cent (Bota Head Office) higher than the 15-year mean annual

rainfall intensity for these stations. Much of the June 2001 rain-

fall occurred within a very short time. Questionnaire accounts

indicate that very heavy rains started in Limbe at about 1700

hours local time on 26 June and continued unabated until about

1300 hours on 27 June, when the landslides and floods

occurred. This is confirmed by the daily rainfall data. Of the

total June rainfall recorded at the Bota Head Office station, 70

per cent occurred on 26 and 27 June alone. Field reports suggest

that this was mostly concentrated within about 20 hours (1700

hours on 26 June to 1300 hours on 27 June).

This is evidence of the occurrence of a rainstorm (prolonged

rainfall over days or, as in this case, unusually intense over a

short period) during these two days and suggest that rainstorms

have been an important contributor to both landslide and floods

in this region over the years. All recorded landslides in

Cameroon within the last 18 years have occurred between the

months of June and September, which are the rainiest months

of the year.

Lessons learnt

During the 1970s and early 1980s, the city of Limbe subdivision

was free from natural disasters such as landslides and floods,

other than activities from the Mount Cameroon eruption.

Information gathered from questionnaires points to the fact that

the phenomenon started two decades ago with the setting up of

new infrastructures, construction of roads and expansion of the

city of Limbe without taking into consideration adequate

drainage patterns. Despite the existing water channels, bridges

were constructed without considering the maximum volume of

water expected to flow through them during rainy periods. Thus,

during the most rainy months, settlements along Njegele rivers

and Limbe river suffer from inundation causing the destruction

of properties and human life.

The Limbe Urban Council, working with local partners like

the Limbe Botanical and Zoological Gardens, Bonadikonmbo

Natural Resource Management Committee and other commu-

nity based organizations, are now working on a reforestation

programme aimed at planting trees on the deforested hill slopes

around Limbe. This is aimed at reducing the level of landslides

due to the instability of the deforested slopes.

In 2001, the International Federation of Red Cross and Red

Crescent Societies in central Africa sent a delegation which

financed a mission to evaluate the emergency relief operations

carried out in Limbe when floods and landslide incidence

occurred. This mission gave the local committee the opportu-

nity to meet with volunteers and community leaders (district

leaders and the prefecture leader) to discuss the strengths and

weaknesses of the operation and to ensure that it was prepared

to deal with floods in the future. Stocks of emergency supplies

were established with the support of the DMC, to be used in

these activities and to ensure an effective response to disasters

occurring in the future. Community leaders are aware of the

need to mobilize the population right away on the basis of

community activities, such as the reinforcement of house foun-

dations, water canalization and protective dykes made of sand

and stone. The level of adequate emergency response is still low

in Cameroon and many affected populations are abandoned

and helpless.

Government laxity toward incorporating disaster risk assess-

ments into urban planning and managing disaster-prone human

settlements, especially in highly populated areas and quickly

urbanizing settlements, leads to the great impact of disaster on

the local population and increases the level of poverty.

Each year, natural and man-made disasters around Africa

cause devastation, loss of life, widespread human suffering and

huge economic losses. Images of disaster-stricken areas are often

made available too late to be of real use to relief coordination

agencies on the ground, as current Earth observation satellites

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