Nursery Techniques - Afforestation, Reforestation and Forest Restoration in Arid and Semi-arid Tropics - page 22

joints

Joint Section
150 x 50 x 3 mm

Fig. 2.5 Design of an overhead water reservoir (OHR) for a central nursery. c/c Centre to centre,
GL Ground level, RRM Random rubble masonry, and CM Cement mortar

is good enough to fill it more frequently than once per day (e.g. every morning and
evening). It is also possible to drive sprinklers directly from the submersible pump
of the tube well or by using a pressure boosting pump attached to a GLR. In that
case, assured power supply for at least 8 h a day must be available and the additional
costs incurred on the booster pump and the GLR should be less than the cost of an
OHR. In any case, if an OHR is constructed, it should be designed for a pressure
head and a capacity that will serve its purpose well.
Irrigation sprinklers are valuable not only because they save on labour but also
because they economise water use. These should be designed keeping in view the
daily requirement of water and its pressure and the salinity level in water. Perforated
pipes will be suitable only if water salinity is low and the pores do not get clogged
too frequently. Short of this, they are the best choice because of their linear geometry
and efficient irrigation of the beds on both sides. Rotary type sprinklers connected to
hydrants are more suited for irrigating mother beds and other large blocks of plants
growing in field (Fig. 2.6 ).