Agriculture Reference
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control valves) located behind the embankment. Water from the distribution
point is transported to the irrigation fields by gravity via open canals,
tunnels or pipes.
Grass cover
Catchment area
Dam
wall
Irrigable area
Main drain
Reservoir
Spillway
channel
Main canal
Figure 5.1: Schematic presentation of a small reservoir system
(Source:
Gyasi, 2005).
In the Upper East Region, almost all small reservoir irrigation schemes
observed had irrigation fields developed downstream of the impoundment.
However, at some of these reservoirs (e.g. Dorongo dam) two main methods
of water abstraction and transportation were being employed. Apart from
the normal water abstraction method by means of intake structures in the
impoundment and transportation by gravity via canals to the officially
developed irrigable areas, some irrigators also abstract water directly from
the reservoir by means of motorised pumps and transport the water with
hoses to their farm plots located outside the officially developed irrigable
area (see
Figure 5.2a
). At Dorongo dam these farm plots are larger (0.5-
1.0ha) than farm plots in the developed portions (0.05-0.45ha). Irrigators
using this method explained that the plots in the developed portions were
too small for them. Meanwhile the majority of these farmers cultivated in
the developed portions of the small reservoir and at the same time used
motorized pumps to irrigate outside the developed areas. Therefore the total
irrigated area was 1.5 times the developed irrigable area. The farmers did not
experience any problem with water scarcity; there is the potential that
irrigation will be expanded due to the fact that water is available in the
reservoir at the end of the season.
In Burkina Faso a number of small reservoir irrigation schemes had no
developed irrigation fields downstream of the reservoir as described for
Ghana. This means that there are no water outlets from the canals for water
Laterals
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