// // // //
SONGS
ADVERTISE
Advertise with us:
R10 000 pm VAT excl.

Environment articles

BACK
HOME » Wildlife » Environment articles

Harvesting rain

Rain is vital to any farmer and rancher and the wildlife ranchers are no exception although they usually produce natural products. Yet, the rain that is received is often wasted instead of being harvested and stored for optimal use. How many wildlife ranchers, for example, harvest the rain which falls on the roofs of their buildings?

In parts of India that receive 500 mm of rain per year, harvesting the rainfall from the roofs of the houses yields 10 000 litres of water per year from an average roof with a surface area of only 20 m2 where the roof and gutters have been designed for the harvesting of rain. In Kenya, Uganda and Tanzania the harvesting of rain from roofs has been done for many years. Even harvesting and storing waste water can be of use. Rain which is being harvested from the roofs of buildings and parking areas can be stored in underground dams or lakes to augment the ground water and to feed wetlands and waterholes. It can also be used for human consumption provided that it is treated and filtered properly. However, the rain that is collected from grass roofs is not fit for human consumption.

In South Africa, the evaporation of water from open surfaces is usually more than the rainfall that is being received and it is therefore logical to store water underground or in wetlands. Many wetlands in South Africa have, however, over time been drained without thought for the ecological consequences or reflecting on why the soil there is so fertile. In addition, a healthy wetland harbours a rich bird life which is a valuable ecological and tourism commodity. Wetlands should never have been destroyed for short-term cash crop production or grazing. The droppings of the birds enrich the soil and the natural vegetation filters the water to allow a sustained outflow of clean water of excellent quality from a healthy wetland. The restoration of all the old natural wetlands should be a primary objective of all wildlife ranchers and new wetlands can be pivotal in the restoration of eroded areas. In addition, several types of wildlife such as the sable antelope reedbuck and waterbuck prefer to have a wetland in their habitat although this is not an automatic advantage. The restoration and creation of wetlands will, however, be discussed in detail in a later contribution. Wetland restoration; the use of guzzlers, which will be discussed below, and other aspects of habitat restoration are dealt with in detail by Coetzee, Bothma, Van Rooyen and Breedlove (2010) in the references.

The erection of guzzlers is another way in which to harvest and store rainfall. Yet it is surprising how few ranchers in the arid and semi-arid regions of South Africa know about this method. A guzzler system basically consists of an impervious apron of some 1 ha which collects rain and then feeds it to an underground storage dam, from where it can be piped to feed a waterhole or a wetland. A coarse sand filter at the inlet side to the dam is sometimes used to clean the water before it reaches the dam. A guzzler can be erected in any place in the field, in a drainage line or on a slope. The apron can be of raised tin sheets or it can be built on the ground with concrete and rock, especially in a drainage line or on a slope. A sloping concrete, brick or concrete and rock ramp is sometimes built towards an underground waterhole that is being fed from the storage dam and where the inflow is controlled by a ball and valve system. Such a system prevents excessive evaporation of the water. Livestock and wild herbivores can reach the waterhole along the angled ramp but the overhead space must be high enough to allow the horns to pass through. However, when the waterhole is meant for ground-living birds such as a guinea-fowl or a francolin, a grid over the entrance can be built with just enough space to allow them through while preventing possible pollution of the water by livestock or wild herbivores. Such a waterhole will limit the evaporation of the water to not more than 10 per cent of the rainfall that is being received. If it is placed in a drainage line above a patch of soil erosion the outflow can be used to help in re-establishing vegetation there.

The production of water from the apron of a guzzler or the roof of a building in litres is equal to four times the annual rainfall for every 4 m2 of the surface area of the roof or apron. In a region that receives 300 mm of rain per year, for example, such an apron or roof will collect 1200 litres of water per year for every 4 m2 of its surface area. This is a significant bonus and can prevent having to depend on water of possible doubtful quality from boreholes. It is also unobtrusive and ideal for a wildlife ranch, while the water from the underground storage dam can be piped to distant waterholes by gravitation. In South Africa, more details on guzzlers can be obtained from Ben Breedlove in Pretoria at e-mail: ben@bbreedlove-pty-ltd-com.

With the current expectation of future reduced rainfall because of global warming and the erosion of overgrazed areas by the run-off of heavy rain which does not penetrate the soil to augment the underground water sources, harvesting rain and the creation of wetlands is something which every landowner should consider routinely. Its application in urban areas is not relevant here but the possibilities there are huge. Every thinking person already knows that the human race has greatly squandered the abundance of the natural resources with which it was blessed formerly. It is therefore no longer a question of thinking whether it should be done but rather one of how soon can it be done. The reality is that it now concerns the survival of the human race and is no longer something just to keep us busy. For the wildlife producer it is an additional element of achieving success.

 

References:

Bothma, J du P. 2008 . Harvesting and storing water. In J. du P. Bothma and J. G. du Toit (Eds), Game ranch management. Fifth edition. Pretoria: Van Schaik, pp 150 -153.

Coetzee, K, J du P Bothma, N van Rooyen and B Breedlove 2010. Habitat rehabilitation. In J du P Bothma en J G du Toit (Eds), Game ranch management, Fifth edition. Pretoria: Van Schaik, pp 869 - 903.

Waterfall, P. H. 1998. Harvesting rainwater for landscape use. First edition. Tucson, Arizona: Department of Water Resources.

By: Prof J du P Bothma

SONGS
ADVERTISE
Advertise with us:
R10 000 pm VAT excl.