pH make them susceptible to erosion (Baboule
et al. 1993). The climate is the sudano-sahelian
type and it is generally characterized by a long
dry season, which lasts seven to nine months
(October to April) and a short rainy season of
three to five months (mid-May to mid-October).
The average rainfall amplitude is around
1,000 mm/year and temperatures oscillate
around 28 °C. This rainfall plays a significant
role in soil erosion, which itself favours the siltation of the lake during intense rainy episodes.
In the watershed of Lake Lagdo, agricultural
activity concerns 85,000 km
2 or almost 18% of
the whole territory. The vegetation is the savannah type to thorny steppe characterised by the
presence of species like Acacia albida (winter
thorn), Balanites aegyptiaca (soapberry), Acacia
spp. and Azadiratcha indica (Neem).
The Lagdo Dam is located on the upstream of
the Benoue River, about 40 km from Garoua.
This dam is of great importance to the northern
region of the country. The benefits of Lake
Lagdo include: electricity generation for users in
Cameroon’s three Northern regions, Adamaoua,
the North and the Far North; agricultural activities within an irrigated area of about 1,000 hectares that have been developed downstream of
the dam for the production of rice and other food
crops; and fishing in the reservoir itself as well as
in fish ponds developed downstream.
The lake is characterized by an elevation of
206 m above sea level (asl), the maximum water
level is 218.18 m and the normal water level is
216 m. The commissioning of the hydroelectric
plant in 1984 has stored approximately 7.7 billion cubic meters of water, covering an area of
700 square kilometres. The map of the SSA
identifies the Lake Lagdo watershed and the
location of the dam (Fig. 1).
Data used for this study are secondary data
from both MEADEN (Mission d’Etudes pour
l’Aménagement et le Développement de la province du Nord Cameroun) and the Lagdo
Hydroelectric Plant. Data collection took place in
February 2008. Data from the Lagdo Hydroelectric Plant include the capacity of dead and
live storage, size and elevation of the storage,
generated power, volume of turbine water, and
prices of the kilowatt hour of electricity. Data
from MEADEN include sedimentation volume in
Lake Lagdo.
2.2 Methodology
2.2.1 The Damage Function Approach
The particular off-site cost of soil erosion and the
sedimentation of dam reservoirs are examined in
detail in this study. According to Pearce and
Markandya (1989), the damage function method
is a method of estimating effects based on
observing actual market behaviour, rather than
observing individuals’ preferences. It aims to
assign monetary values to goods or services
induced by an improvement in the quality of the
environment (or conversely to evaluate the cost
of degradation of the quality of the environment).
It belongs to the methods of monetary evaluation
of the physical effects of the degradation of the
environment and assumes that there is physical
damage to non-market goods and services, for
which the monetary equivalent is sought
(Garrabé 1994).
Its objective is to assess the cost of deteriorating environmental quality. The use of the
damage function method requires knowledge of
the physical and ecological relationships between
the cause and its impact, necessary for the prior
specification of dose–response relationships.
Pearce and Markandya (1989), quoted by
Njomgang (2003) have developed a function
whose simplest form is the following:
R ¼ R P; Z
ð
Þ
ð1Þ
where R denotes impact (effect), P (dose) pollution, and Z other factors (e.g. a palliative to the R
effect). The approach to measuring the monetary
value of physical damage involves two steps.
The first step calculates the variation of R with
respect to P, i.e. the elasticity, or more simply
⊗R / ⊗P. The second step multiplies this
quantity by the unit cost of the damage, denoted
V * (⊗P/P), to obtain V * (⊗R/R), which designates the “avoided damage.” V represents the
value per unit of physical damage borne, which
96
D. Y. Ngondjeb and E. Ayuk
et al. 1993). The climate is the sudano-sahelian
type and it is generally characterized by a long
dry season, which lasts seven to nine months
(October to April) and a short rainy season of
three to five months (mid-May to mid-October).
The average rainfall amplitude is around
1,000 mm/year and temperatures oscillate
around 28 °C. This rainfall plays a significant
role in soil erosion, which itself favours the siltation of the lake during intense rainy episodes.
In the watershed of Lake Lagdo, agricultural
activity concerns 85,000 km
2 or almost 18% of
the whole territory. The vegetation is the savannah type to thorny steppe characterised by the
presence of species like Acacia albida (winter
thorn), Balanites aegyptiaca (soapberry), Acacia
spp. and Azadiratcha indica (Neem).
The Lagdo Dam is located on the upstream of
the Benoue River, about 40 km from Garoua.
This dam is of great importance to the northern
region of the country. The benefits of Lake
Lagdo include: electricity generation for users in
Cameroon’s three Northern regions, Adamaoua,
the North and the Far North; agricultural activities within an irrigated area of about 1,000 hectares that have been developed downstream of
the dam for the production of rice and other food
crops; and fishing in the reservoir itself as well as
in fish ponds developed downstream.
The lake is characterized by an elevation of
206 m above sea level (asl), the maximum water
level is 218.18 m and the normal water level is
216 m. The commissioning of the hydroelectric
plant in 1984 has stored approximately 7.7 billion cubic meters of water, covering an area of
700 square kilometres. The map of the SSA
identifies the Lake Lagdo watershed and the
location of the dam (Fig. 1).
Data used for this study are secondary data
from both MEADEN (Mission d’Etudes pour
l’Aménagement et le Développement de la province du Nord Cameroun) and the Lagdo
Hydroelectric Plant. Data collection took place in
February 2008. Data from the Lagdo Hydroelectric Plant include the capacity of dead and
live storage, size and elevation of the storage,
generated power, volume of turbine water, and
prices of the kilowatt hour of electricity. Data
from MEADEN include sedimentation volume in
Lake Lagdo.
2.2 Methodology
2.2.1 The Damage Function Approach
The particular off-site cost of soil erosion and the
sedimentation of dam reservoirs are examined in
detail in this study. According to Pearce and
Markandya (1989), the damage function method
is a method of estimating effects based on
observing actual market behaviour, rather than
observing individuals’ preferences. It aims to
assign monetary values to goods or services
induced by an improvement in the quality of the
environment (or conversely to evaluate the cost
of degradation of the quality of the environment).
It belongs to the methods of monetary evaluation
of the physical effects of the degradation of the
environment and assumes that there is physical
damage to non-market goods and services, for
which the monetary equivalent is sought
(Garrabé 1994).
Its objective is to assess the cost of deteriorating environmental quality. The use of the
damage function method requires knowledge of
the physical and ecological relationships between
the cause and its impact, necessary for the prior
specification of dose–response relationships.
Pearce and Markandya (1989), quoted by
Njomgang (2003) have developed a function
whose simplest form is the following:
R ¼ R P; Z
ð
Þ
ð1Þ
where R denotes impact (effect), P (dose) pollution, and Z other factors (e.g. a palliative to the R
effect). The approach to measuring the monetary
value of physical damage involves two steps.
The first step calculates the variation of R with
respect to P, i.e. the elasticity, or more simply
⊗R / ⊗P. The second step multiplies this
quantity by the unit cost of the damage, denoted
V * (⊗P/P), to obtain V * (⊗R/R), which designates the “avoided damage.” V represents the
value per unit of physical damage borne, which
96
D. Y. Ngondjeb and E. Ayuk