Environmental Engineering Reference
In-Depth Information
Figure 27.7
Traditional water-lifting systems. For each
method the lift in metres, energy source and approximate
area irrigated per day in hectares are indicated.
Source: After Heathcote (1983).
DAMS
In the above examples of water use the supply of water was dependent upon the river
level; levels too high or too low could cause disaster for different reasons. The ideal
would be control of the water level through damming so that it became more stable and
the annual fluctuations were removed. During wet years surplus water could be stored
until the capacity of the dam was reached and in dry years the surplus could be drained
off to sustain the river at the optimum level.
Dams have been constructed for at least 5000 years in order to control river flow.
Recently dams have acquired a dual purpose, with power generation being an important
feature. As technology has improved so the scale of dam building has increased and now
there are many examples
