Write an essay on the need for rainwater harvesting in india
Answers
Answer:
Essay # 1. Definition of Rainwater Harvesting:
Rainwater harvesting refers to in general, to the collection and storing of locally available water, mostly from the rains at a place. The main criterion here is the quantum of water involved and the area of influence.
Rainwater harvesting is common in areas having high rainfall intensity well distributed in the year. Such areas include, Himalayan areas, North Eastern States, Andaman and Nicobar Islands, Lakshadweep Islands, Rajasthan and the Southern parts of Kerala and Tamil Nadu.
Rain water harvesting is now being-increasingly used for meeting the drinking water needs of rural areas particularly during the periods of drought.
Many methods are available for harvesting rain water. The choice of a method depends upon the suitability of a particular site.
Essay # 2. Importance of Rainwater Harvesting:
i. Quantity of water available is fixed.
ii. Drastic increase in population in the last four decades.
iii. Increase in the ground water depletion rate.
Essay # 3. Objectives of Rainwater Harvesting:
i. To restore supplies from aquifer due to over explorations.
ii. To improve the physical and chemical properties of ground water.
iii. To reduce storm water runoff and soil erosion.
iv. To prevent salinity of water in coastal areas.
v. To increase the availability of water from wells.
vi. To reduce hazards due to floods.
vii. To reduce power consumption.
viii. To improve soil condition and fertility of soil.
ix. To conserve surface water runoff during monsoons.
x. For up gradation of social and environmental status.
xi. To reduce storm water discharges urban floods and over flooding.
xii. Of sewage treatment plants.
Essay # 4. Methods of Rainwater Harvesting:
The different methods of rainwater harvesting are listed below:
i. Rooftop Rain Water Harvesting,
ii. Paved Surface Rain Water Harvesting, and
iii. Rain Water Harvesting Using Check Dams.
i. Rooftop Rainwater Harvesting:
In this method the first step involves the collection of rainwater from the Rooftops. A network of drain pipes transports the rain water from the rooftops to a designed sump. The sump houses a filter unit. Hence, as soon as the rainwater enters into the sump it first gets filtered and then remains in the sump. Then with the help of a pump the water can be pumped to an overhead tank for future use.
ii. Adaptability:
a. It can be suitability adopted and implemented in new building constructions, houses, factories, schools, etc.
b. It can also be adopted in already constructed buildings.
c. It can be adopted in multistoried buildings and residential apartments.
d. It can be adopted in paved and unpaved areas also.
Method of Collection:
a. Rooftop should be kept clean.
b. Rain water down pipes should be laid to take the rain water down.
c. First wash water should be segregated and should be filtered.
d. Store in a sump, tank or lined pond for later use.
e. Charge the ground water table through percolation pits, open wells or bore-wells.
Rooftops should be designed keeping in mind rain water harvesting. Roof should be given sufficient slope to drain water. Sufficient number of down pipes should be provided. The downpipe should be preferably of P. V.C. as per national building code. In places where rainfall is 50 mm/hr, 75 mm diameter pipes are sufficient for an area of 40 sq. m. and 100 mm pipe for an area of 85 sq. m.
The water should be filtered before collection. A small tank of size 40 cm diameter filled with charcoal and gravel may be used as a filter chamber as shown in the Fig. 14.1.
Method of Storage:
If the conventional building practice is to build a sump, the same sump can be used for harvesting rain water. In Bangalore for example, construction of a sump is a common building practice. Collecting rain water after filtration in the sump would be cost effective. If a well or a bore well is present in the premises then rain water can be used to recharge the ground