Agriculture Reference
In-Depth Information
includes the youth who load trucks for market women from southern Ghana
who travel to buy vegetables and the middle-men who act as the mediators
between market women and the farmers.
In the 2007/2008 dry season, income made by farm labourers on tomato
irrigation farms ranged from 0.06-0.19 US$/m
3
of water consumed, while
tomato farmers made a profit of 0.13-0.85 US$/m
3
of water consumed
(Chapter 6 above). The gross profit margin of farmers ranged from 45-70%.
Using vegetable production as the main crops produced in these irrigated
areas and assuming that the water consumption and profit obtained for
vegetables are the same as that of tomatoes (using the lower bound income
and profit figures to cater for all vegetable crops), total water use of 3.31 x
10
9
m
3
/a would translate into a profit of 429 million US$/a for farmers and
198 million US$/a as wages for farm labourers. It should be noted that the
profit margin is very sensitive to market variations (Ofosu et al., 2010).
Inhabitants of the White Volta sub-basin are mainly subsistence farmers
(85%). Due to the semi-arid nature of the sub-basin, there are few
employment opportunities for the inhabitants during the dry-season. This
accounts for the high rural-urban migration during the dry season to do
menial jobs in the urban centers (Ofosu et al., 2010). Therefore the creation
of job opportunities through irrigation is a major socio-economic benefit for
the inhabitants of the sub-basin.
8.6.2 Benefits of Hydro-power production at
Akosombo
The Akosombo dam was created in 1961, with the first phase completed in
1968 and the second in 1972. The dam has created the Volta Lake, which is
the largest man-made lake in the world with a maximum surface area of
8,500km
2
and a maximum storage volume of 148 x 10
9
m
3
. It has six turbine
units with a total plant capacity of 1020MW. The maximum operating level
of the dam is 84.73m and the minimum is 73.15m. The height above
tailwater of the Akosombo dam is 73.20m. Based on a combined turbine
efficiency of 0.93, and the maximum height, the power production is
0.186kWh/m
3
(Obeng and Fiagbe, 2005).
The Volta River Authority (VRA), a state-owned entity, is responsible for
generation and transmission of electricity in Ghana. The Akosombo dam is
the largest producer of electricity in Ghana. Electricity accounts for about
11% of the nation's total energy consumption. It is estimated that about half
of this amount is consumed by residential consumers for household uses,
while commercial and industrial users account for the rest. Deregulated
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