Agriculture Reference
In-Depth Information
8.6 M
ANAGING TRADEOFFS BETWEEN UPSCALING
I
RRIGATION AND
H
YDROPOWER
P
RODUCTION
The results of this study compares to a similar study conducted by De
Condappa et al. (2008) and Leemhuis et al. (2009) on the Volta Basin. Both
studies provide insight into possible consequences of climate change and
development of upstream small reservoirs on water allocated to the
downstream Akosombo hydropower scheme. The study by De Condappa et
al. (2008) defined a scenario of rapid increase in number of small reservoirs
at a growth rate of 10% per year and simulated it over a study period of
2000-2020. The results showed that, the mean inflow to Volta Lake is
reduced by about 0.8 x 10
9
m
3
/a, which is about 2.1% of the mean inflow.
The study area considered the entire upstream section of the Volta Lake and
included both small and large reservoirs in Ghana and Burkina Faso of all
sub-basins of the Volta basin.
In the present study, small reservoir irrigation development was assumed to
grow at 5%/a, reaching its maximum in 2025. The maximum small reservoir
irrigation attained in 2025 is simulated over 20 years and results in a
reduction in streamflow of 1.17 x 10
9
m
3
/a, which is about 3.1% of the total
inflows into the Volta Lake. Even though this study covers only the White
Volta sub-basin, it includes the impact of groundwater exploitation for
irrigation on the Volta Lake. The overall water loss for hydropower
generation is 3.31 x 10
9
m
3
km
3
/a, which is significant and has consequences
on hydropower generation at the Akosombo dam. Thus co-ordinated
management of all water uses in the sub-basin should address the
consequences and the possible trade-offs between upstream and downstream
water uses. The benefits of irrigation development upstream and of
hydropower production downstream will be estimated and compared.
8.6.1 Benefits of Irrigation Development in the
White Volta sub-basin
The increase in irrigated agriculture in the White Volta sub-basin has
provided labour opportunities for the youth and women during the dry
season who work on irrigation farms for daily wages. Owners of land close to
river channels also seasonally rent/lease out their land to prospective
irrigators at a fee and also obtain irrigated products from their tenants at
the end of the season. The landowners also gain from these arrangements as
irrigators plough the land at the end of the irrigation for the landlord
making it ready for rainy season farming. There are other job opportunities
created from dry-season irrigation in the White Volta sub-basin. This
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