Rainwater Harvesting for Reconstruction
Practical Action
Large-Scale Solutions
Run-off Rainwater Harvesting
Run-off rainwater harvesting involves collecting rainwater flowing along the ground into
underground storage tanks. The solution is particularly suited to areas which see concentrated,
heavy rainfall for a short period annually; large volumes (up to 12,000 litres) can be held for
irrigation purposes during extensive dry seasons.
A large brick pit is dug to house am underground brick tank, which is lined with cement and fed
by an inlet, placed in the direction of surface water flow. Construction of the large brick tank
requires significant construction and materials, and the workmanship must be of a high quality to
withstand the pressure of such large volumes of water.
Whilst being able to hold significant amounts of water, there are several limitations with this
technology; it requires certain geological conditions, rainfall patterns and skill sets that may not
be present in emergency situations; the time and investment required are long term
considerations. Consequently, it is generally suited to permanent reconstruction stages.
Practical Action South Asia has produced a
technical brief Runoff Rainwater Harvesting
on the subject.
Figure 14: Runoff rainwater harvest tank
Photo: Practical Action South Asia
Harvesting Dams
The concept of harvesting rainwater isn’t limited to using dwelling roofs; in many arid and semi-
arid areas the local rivers are trickles for much of the year, yet experience high water flows during
intense periods of rainfall.
The inability of local populations to irrigate their lands leads to shortages in fertile soil and hence
food supplies. The large volumes of water that pass in flooding season are not utilised, instead
often causing damage to communities.
Constructing dams is one way to capture and use large quantities of water for irrigation and
consumption. Water can be directed through the use of canals and channelling pipes to provide
adequate amounts of floodwater for agricultural land. Alternatively, water can simply be stored
and then collected for various uses.
Practical Action has worked in several areas of Western Sudan to construct water harvesting
dams, and a detailed overview of these projects is available in the manual Building Small-Scale
Water Harvesting Dams. The figure below is taken from the report, and shows a landscape plan for
the Shangili Tobaya dam installation, including diversion canals and water courses.
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