Various organisations are working on rejuvenating ancient systems of water harvesting as an alternative "mega-project" like dams.
Rain water harvesting is a technique of increasing the recharge of ground water by capturing and storing rain water by the construction of special water-harvesting structures.
Need for Rain water harvesting. Ground water is a precious natural resource. It plays a significant role in our national economy and in our daily life. It is the primary source of water for domestic, industrial as well as irrigation sectors. To cope with the growing demand, there has been rapid development of ground water supply. But increasing demand, especially in urban areas, has led to depletion of ground water and associated problems. With growing human population, the gap between demand and supply of water has widened. About 85 percent of rural water supply and more than 50 percent of urban and industrial supply is mined. So ground water is sinking to new depths in most of Delhi, all of Daman and Deu, nearly three-fifth of Punjab, about two-fifth of Haryana and Mehsana area of Gujarat. Hence conserving the surplus water during the monsoons by water harvesting and recharge techiques must be adopted as the water management agenda.
Significance of Rain water harvesting :
(i) It reduces run off loss and avoids flooding.
(ii) It meets the increasing demand of water.
(iii) It reduces contamination of ground water and raises the water table.
(iv) It supplements ground water supplies during lean period.
(v) Reduces power consumption.
(vi) It arrests sea water-ingress as during ground water deficiency in coastal areas, there is landward movement of fresh water-sea water interface and contamination of fresh water sources.
(vii) It improves soil moisture and decreases soil erosion.
Methods of Rain water harvesting:
(i) Traditional methods :
(a) In high rainfall areas, rainwater from roof tops shown in figure is collected into water storage tanks from where water is diverted to some abandoned well or lifted by using a hand pump.
(b) In foot hill areas, spring water is collected into water storage embankments.
(c) In the ancient times, rain water was collected in talabs, baawaris, johars, hauz, etc. to be used in dry period.
KULHS IN HIMACHAL PRADESH
About four hundred years, Himachal Pradesh people had developed a novel local system for water requirements like irrigation etc. Water from streams was diverted towards villages called Kulhs. These canals were made down the hillside. A common management of villagers worked with the agreement of all. Two or three managers looking after the Kulhs were paid by the villagers. Water flowing downwards in these Kulhs was first used by the village farthest away from source. Water from these Kulhs also percolated in the soil and became the source of springs at various points.
After the irrigation department took over the charge of such kulhs, the following changes were noticed
(a) Most of the kulhs have become defunct. [No longer in use]
(b) Amicable sharing of this water between different villages is also lacking.
(ii) Modern techniques of Rain water harvesting :
These are employed in arid and semi-arid regions :
(a) Rainwater from large catchment areas is collected in check dams. This techiques was nicely used in Rajasthan by Magasaysay Award winner Rajender Singh, commonly called "Water man".
(b) By building ground water dams for storing water underground. These are more advantageous than surface dams due to minimum loss by evaporation and low chances of contamination.
Government of India has established a Central Groundwater Authority under the Ministry of Water Resources. Main theme of this authority is :
"Replete Groundwater Before it Depletes"
According to its authority, Rain water harvesting is the only option for the 21st Millennium. It has successfully completed the artificial recharge experiments in the following areas resulting in the rise in water level:
1. Mehsana Project (Gujarat) : Water level increased from 1.84 to 15 metres by spreading channel techniques.
2. Amaravati Project (Maharashtra) : Rise in water level by 3 metres through percolation tanks.
3. Kolar Project (Kerala) : Rise of 5-10 metres of ground water level through watershed management.
Characteristics of watershed
(i) It is an area of high land from where water flows under gravity into river or sea.
(ii) It has a natural unit of water.
(iii) It has a well defined topographic boundary and has only one water outlet.
(iv) It includes complex interactions of water, soil vegetation, animals and human beings.
(v) Watersheds vary in size from few sq. km. to few thousand sq. km.
Watersheds supply water for irrigation, hydro-power generation, transportation, vegetation growth and reducing the chances of floods and droughts. So watersheds improve the economy of the region.
Water harvesting is an age old concept in India like :
(i) Khadins, tanks and nadis in Rajasthan.
(ii) Bandharas and talc in Maharashtra.
(iii) Bundhis in M.P. and U.P.
(iv) Ahars and Pynes in Bihar
(v) Kulhs in H.P.
(vi) Ponds in Kandi belts of Jammu.
(vii) Eris (Tanks) in Tamil Nadu.
(viii) Surangams in Kerala.
(ix) Kattas in Karnataka.
Water can be retained throughout the year only in large structures. In most of the structures water depletes within few months after monsoons. Main aim of storing water should not be to hold the surface water but to recharge the ground water.
Ground water is useful in :
(a) It provides soil moisture for plant growth.
(b) It is commonly used for human consumption.
(c) It supplements water in streams.
(d) This water is used by human beings for drinking, cooking, bathing, cleaning, etc. It is relatively protected from contamination by human and animal waste.
(e) Fresh water is also required for various types of industries.
(f) It is required for irrigation purpose (agriculture).
(g) Ground water does not evaporate but spreads out to recharge wells and provides moisture for vegetation over a large area.
(h) It does not provide breeding ground for mosquitoes like stagnant water collected in ponds or artificial lakes.
COAL AND PETROLEUM
Most extensively used fossil fuels are coal, petroleum and natural gas. Such fuels are obtained- from underground and sea bed exploratrions. However, due to uncontrolled consumption by the ever increaing population. In the world, such fossil fuels may perish in coming years. Most of the world's energy requirements are met from petroleum and natural gas.
Coal is composed of carbon, oxygen and hydrogen. It is widely used as conventional fossil fuel. It releases enormous heat after burning. Coal is combustible organic rock being used for manufacturing of steel, fertilizers, pesticides, etc. Before plant material is converted into coal, it forms dark brown organic matter called peat. Lignite is formed after deposition of many layers over peat. Anthracite is the last stage of coal formation. It is the hardest form of coal with maximum carbon content. Its heat value is double than that of lignite.
Coal and petroleum have been formed from bio-mass. They contain carbon, hydrogen, nitrogen and sulphur. When burnt, they release CO2, H2O, oxides of nitrogen and oxides of sulphur. In presence of less oxygen, carbon monoxide is released instead of CO2. Oxides of sulphur and nitrogen and CO2 at high concentration (a green house gas) is poisonous. Increase in CO2 concentration in atmosphere will lead to global warming.
Types of Coal
We have learnt that coal is formed by the carbonisation of remains of plants and animals. Depending upon the extent of carbonisation, we get different varieties of coal. These different varieties of coal have different carbon content.
Since the fuel value of coal depends upon the carbon content, Peat is an inferior variety of coal while anthracite is a superior type of coal.
Uses of Coal
The important uses of coal are :
1. Coal is used as a fuel.
2. It can be converted into other useful forms of energy like, coal gas, electricity and oil.
3. Coal is used in the manufacture of synthetic petrol and synthetic natural gas.
4. Coal is used to manufacture many organic compounds like benzene, toluene, phenol, aniline, naphthalene, anthrancene, etc.
5. Coal is used as reducing agent in industries in the extraction of metals.
6. Coal is used to make coke.
World's crude oil reserves are expected to remain up to only 40 years. OPEC (Organization of Petroleum Exporting Countries) with 13 countries have 67% of petroleum reserves. Saudi Arabia has 25% of reserves.
Crude oil is purified and refined by fractional distillation. Several products like petrol, diesel, kerosine, lubricating oil, plastic are obtained during this process.
Advantages of petroleum :
1. Cleaner fuel as compared to coal.
2. It is easier to transport.
The proven reserves for natural gas as on April 1993 works out to be approx. 700 billion cubic meter (BCM). Keeping in future demands and proven gas reserves, it is unlikely that our gas reserves might last more than 25 years.
India is poorly endowed with mineral wealth. If present trend of production continues, we will exhaust most of our reserves soon.
SOME METHODS FOR CONSERVATION OF ENERGY
(i) Use of alternative sources of energy. We should develop the renewable sources of energy like solar energy, wind energy, tidal energy, nuclear energy etc. for our energy requirement.
(ii) Great care in using fuels. We should excercise great care in using fuels for getting energy. The fossil fuels should be used only when no other alternative source is available to us. Thus fossil fuels should be conserved as far as possible.
(iii) Avoid wastage of energy.
(a) As far as possible, we should use the most efficient fuels available.
(b) For burning fuels, most efficient heating devices (stoves, chulhas etc.) should be used.
(c) We have to change our style of living for conservation of energy because energy saved is energy produced.
AN OVERVIEW OF NATURAL RESOURCE MANAGEMENT
Main aims of natural resource management are :
1. To maintain i.e. essential biological processes (like food chains, food webs, and material cycling), to maintain the life-support systems of the earth."
2. To ensure the availability and sustainability of resources, to assure survival of all the species in a healthy and easy manner.
3. To preserve the biodiversity so that evolution and development of life in the long run does not get disturbed.
Individuals and community both play important role in sustainable development by conserving the natural resources e.g.,
1. Conservation of water by closing the water taps when not in use; using less water-consuming toilets; watering of plants in the evening; rain-water harvesting in the houses; using drip irrigation and sprinkling irrigation to water lawns; economic use of water for domestic and industrial purposes.
2. Conservation of energy by avoiding wastage of energy by using most efficient fuels in a judicious manner in efficient heating devices; change of life style to avoid wastage of energy because energy saved is energy produced; development of alternative and renewable sources of energy like solar energy, tidal energy, wind power, nuclear energy, biomass energy, biodiesel, etc. to decrease the demand of fossil fuels like coal, petroleum, etc.
3. Conservation of soil by preventing the soil erosion by crop rotation, terrace-farming on the slopes, contour-farming, regulating grazing, afforestation, reforestation, etc. and restoring the soil fertility by judicious use of fertilizers, green manuring, biofertilizers, etc.
4. To promote environmental education and awareness through our education system and mass media, to develop a feeling of belongingness to earth, called Earth thinking, from the childhood.