Lake Nyos 
Hill shade modelling of Katsina-Ala area 
showing streams, Benue river and Lake Nyos. 
    
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A 
   
Lake Nyos 
-low direction modelling of Katsina-Ala watershed 
showing streams, Benue River and Lake Nyos 
  
  
' Flow height modelling of Katsina-Ala watershed 
showing streams, Benue river and Lake Nyos. 
  
Digital Elevation mode! of Katsina-Ala area 
showing high and low landforms 
Lake Nyos 
  
  
Figure 2: Digital elevation models showing the fracture and drainage patterns, altitude and land use/cover type in Katsina-Ala drainage basin 
4.0 RESULTS AND DISCUSSION 
The study showed generally a strong correlation between the use 
of Earth Observation products and field measurements to 
determine the possibilities of emplacing effective 
monitoring/early warning systems in an event of the collapse of 
the Lake Nyos dam. Field and satellite observations revealed the 
occurrence of numerous fractures and widening of potholes 
created by the process of erosion on the pyroclastic dam 
materials. The digital elevation model, flow direction and flow 
10 
height models revealed that in the event of the dam failure, 
which could be caused by disturbances within the Earth crust, 
about 3 billion m3 of water will flow down the Katsina-Ala and 
Benue drainage valleys; to be aided by distinctly marked fracture 
zones controlling the stream flow direction and may serve as 
conduits/channels to the gas and water transport. Fourteen Local 
Government Areas in Benue State of Nigeria and Cameroun are 
prone to the immediate impact of the collapse of the lake because 
of their proximity to the flood plains and contiguity and tangency 
with other LGAs directly bordering the floodplains (Figure 2). 
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