Newsletter and Technical Publications
<Sourcebook of Alternative Technologies for Freshwater Augumentation
1.1.12 Lagoon-front Hand-dug Wells
|The land adjacent to a lagoon is called the lagoon front. This land is
commonly divided into family- or individually-owned plots. Farm
development starts by making row beds of approximately 1.5 m in width and
6 m in length on which vegetables are grown. Hand-dug wells are then
constructed in between the rows of beds (Figure 19). One metre diameter
well rings are constructed by trained masons. The rings for the well are
left for at least a week to dry.
Figure 19. Vegetable beds among a well field
In order to sink a well a suitable place is chosen among the rows of bed and
a hole of about one metre diameter is dug in soil with a shovel. The first ring
for the well is lowered into the hole. The well digger goes into the well and
digs the soil out from under the ring with a hoe. As the soil is removed the
ring moves downwards until the top edge of the ring is flush with the ground
surface. A new ring is added on top of the old one, and the well digger
continues digging. New layers are added until the groundwater table is reached,
at which time water flows into the bottom of the well. Usually the groundwater
table on the lagoon-front is at a very shallow depth. Having struck water,
digging continues for about one metre below the groundwater table. When the well
reaches the desired depth, a 0.5 m ring is added at the surface so that the well
stands above the ground level. A bucket with an attached rope is commonly used
as the mechanism for lifting water from the hand-dug wells.
Operation and Maintenance
After the system has been installed, ongoing maintenance costs range from $10
to $40 annually. There is no need for power and spares.
Level of Involvement
This technology is traditional and farmer-managed. Construction is done by
local masons and workers with simple hand tools (e.g., shovels, etc.). Because
the scheme is entirely privately-owned and farmer-managed, there are fewer
potential organizational problems.
Effectiveness of the Technology
The technology of lagoon-front hand-dug wells yields quality of water good
enough quality for vegetable crop irrigation in an area filled with salty water.
Without this technology, commercial farming would be impossible in the densely
populated sand bar region of southeastern Ghana.
1995 cost of constructing a well is approximately $20. The operation and
maintenance costs range from $4 to $10, annually.
This type of irrigation scheme is suitable for irrigation of small rural
farms, ranging in area from 0.1 ha. to 0.5 ha, in coastal areas .
The materials for making the wells are obtained locally, and local skills are
employed. These skills are traditionally passed on for generations. Once
installed, the wells can be used for many years. Interviews with local farmers
revealed that income from irrigated farming activities constitutes up to between
90% and 100% of family income. The viability of the farming activities helps to
curb the drift of youths from the rural areas to the cities. It is labour-based
and provides employment for the youths, thereby providing a vibrant economic
activity in an otherwise poor rural area.
This technology requires no pumps or power-driven tools.
The shallow depth of the well sometimes makes it dry up during the growing
season. It also makes the well susceptible to contamination from the surface.
The rural life style of the coastal dwellers makes it easy for them to accept
Further Development of the Technology
Geophysical surveys to determine the freshwater - seawater interface will
improve the technology. This will enable the depth of the well, the pumping
rate, etc. to be determined. Such determinations will improve overall water
management in the coastal zone.
Dr C.S Kpordze, UST, Kumasi, Ghana.