speech on rainwater harvesting for asl
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This is most advantageous in constructing large storage tanks which are expensive. Another way of using rooftop rainwater harvesting is to collect it so that it percolates into the ground to recharge wells instead of flowing over the ground into rivers. Thus, by recharging the groundwater by water harvesting from rooftops, the table rises and the surrounding wells retain water throughout the year.
For centuries, people have relied on rainwater harvesting to supply water for household, landscape, livestock, and agricultural uses. Before large centralized water supply systems were developed, rainwater was collected from roofs and stored on site in tanks known as cisterns.
With the development of large, reliable water treatment and distribution systems and more affordable well drilling equipment, rain harvesting systems have been all but forgotten, even though they offer a source of pure, soft water.
A renewed interest in this time-honoured technique/ approach emerged in recent decades due to following reasons:
ADVERTISEMENTS:
a. The problem of water shortage in arid and semi-arid regions
b. The escalating environmental and economic costs of providing water by centralized water systems or by well drilling
c. Health benefits of rainwater
d. Potential cost savings associated with rainwater collection systems.
Rainwater harvesting is defined as a method for inducing, collecting, storing and conserving local surface runoff for later use.
Three types of water harvesting are covered by rainwater harvesting:
1. Water collected from roof tops, courtyards and similar compacted or treated surfaces is used for domestic purpose or garden crops, or for groundwater recharge.
2. Micro-catchments water harvesting is a method of collecting surface runoff from a small catchments area and storing it in the root zone of an adjacent infiltration basin. The basin is planted with trees, bushes or with annual crops.
3. Macro-catchments water harvesting, also called harvesting from external catchments is the case where runoff from hill-slope catchments is conveyed to the cropping area located at hill foot on flat terrain.
Rain Water Harvesting is collecting and using precipitation from a catchments surface. The rainwater collected can be stored for direct use or used for hydrant purpose on emergency or can be recharged into the groundwater. Rain Water harvesting is thus becoming essential as it helps to meet our demand for the water either directly as rain water is stored and put to different uses or indirectly via replenishing the ground water.
There are two main techniques of Rain Water Harvesting (RWH):
(i) Storage of rainwater on surface for further use
(ii) Recharge to groundwater
For RWH, the rainwater thus as it falls on a catchment (The surface that receives rainfall directly. It can be a paved area like a roof, terrace or courtyard of a building, or an unpaved area like a lawn or open ground) is carried through conduits (The pipelines or drains that carry exclusive rainwater from the catchment) for Storage or Recharge.
In general, runoff (It is the term applied to the water that flows away from a catchment after falling on its surface in the form of rain) from only paved surfaces (for example rooftop) is used for storing since it will be relatively less ‘contaminated. Drainpipes that collect water from the rooftop are diverted to the storage container. Rainwater collected from rooftops is free of mineral pollutants like fluoride and calcium salts which may be found in groundwater.