The lake is also thermally 
ense water near the surface 
yers near the lake bottom. 
gas seeping into the cold 
lissolved in great amounts 
zitation and the collapse of 
rich water may flow down 
h the consequence of a 
lements. This development 
gion around the lake, the 
downstream of rivers that 
er, such as the Katsina-ala 
| into Nigeria. 
HODS OF STUDY 
vernment Areas (LGAs), 
collapse of lake Nyos dam 
bonated water, because of 
atsina-Ala river and other 
nated between latitudes 50 
gitudes 70 47 minutes and 
GAs are located in Benue 
ave some ripple effects in 
nt of the displaced persons 
these local governments. 
nclude the socio-economic 
s in the Katsina-Ala and 
rmers and fishermen with 
1e areas.(Blaike, 1994). 
servations, including field 
tionnaire and hydrological 
1e potential environmental 
include the possibilities of 
ing/early warning systems 
ntrol in an event of the 
The fieldwork was undertaken in September/October, 2007 and a 
mop up exercise was conducted in January 2008, in areas that 
could not be accessed during the wet season. À reconnaissance 
survey was conducted to familiarize with the terrain and prepare 
logistics for the actual field work. Special attention was paid to 
the settlement location, pattern and major economic activities by 
taking the relevant GPS points. À set of strategic data on 
biophysical, administrative, economic and socio-cultural aspects 
of the management of the watersheds at risk were collected. 
Field questionnaires were administered using the existing 
councils/wards. Community mobilization/consultation and 
sensitization were carried out during the field exercise. Relevant 
information on health and socio-economic conditions, such as 
farm size/types, settlement sizes/pattern, livestock and migration 
pattern, etc, in relation to floodplains and riverbanks, were 
collected. Adult respondents were selected from the existing 
communities. Community leaders and focal groups in the LGAs 
were engaged in dialogue to elicit information on issues relating 
to flooding, lake Nyos phenomenon and the susceptibility of the 
area to flood disasters. The focal groups comprised the youth 
organisations, fishermen and herdsmen, farmers and market 
women/men unions. 
Satellite images and field datasets were integrated in a GIS 
(ArcHydro) for hydrologic modelling of Katsina-Ala river basin 
and its vicinity including the Lake Nyos area. The GIS products 
generated include landuse/landcover, digital elevation model, 
hillshade, flow order/height and direction of the Katsina-ala 
watershed as shown in Figure 2.