- 1 The Importance of water in Our Daily Lives and Conscious use of Water
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The Importance of water in Our Daily Lives and Conscious use of Water
Water is the basic necessity for all forms of life, human beings, other animals as well as plants. Some parts of our country have good resources of water whereas other parts suffer from chronic water shortage. The regions having good availability of water are flourishing because they have good crops but the regions having shortage of water are in the thick of poverty because of poor crop growth.
It is, therefore, necessary to have proper management of available water resources so that there is an equitable distribution of water for all the people in all the parts of the country. The various sources of water which are available to us are: Rains, Rivers, Lakes, Ponds, Wells, Oceans and Glaciers (Snow mountains). We will discuss the management of water from some of these sources of water in detail. Let us start with rains.
Rain is a very important source of water. Rains in India are largely due to monsoon which lasts for a few months. This means that most of the rainwater falls on the earth in a few months of the year. This rainwater fills the lakes and ponds, and also flows into rivers. Some rainwater also seeps into the ground and becomes available as ground water (or rather underground water).
Though most of the parts of our country get a good rainfall during monsoon but due to the loss of vegetation cover, much water does not seep into the ground, it rather flows into rivers. Rainwater is stored in lakes for use over a long period of time. There are some natural lakes in our country. Some artificial lakes have also been made at various places to store rainwater to meet the increasing demand for water. In fact, many cities of our country depend on such lakes for their water supply during the year.
Despite good rains, we are not able to meet the demand for water of all the people because :
- our population is increasing rapidly.
- due to lack of sufficient vegetation cover on ground, only a little rain water seeps into the ground and gets stored as ground water.
- the high yielding varieties of crops require much more water for irrigation.
- discharge of untreated sewage and industrial wastes into rivers and lakes reduces the availability of usable water.
- the changing life-style of people, especially in urban areas, is consuming more water.
Rivers are another important source of water. Rivers get their water supply from the melting of snow lying on the peaks of snow mountains (or glaciers) as well as from rains. The management of river-water is done by constructing dams on rivers.
In order to make proper use of river water, dams are constructed across the rivers to regulate the flow of water. In our country dams have been built across many rivers. The large reservoir of a dam stores a huge amount of water (brought in by the flowing river). This stored water is then allowed to flow downstream at the desired rate. Bhakra Dam is one such dam which has been built across the river Satluj in the state of Punjab in our country. Dams built across the rivers are big storehouses of river water.
Dams are useful for the society in the following ways:
1. Water from a dam is used for irrigation in fields through a network of canals. Dams ensure round the year water supply to the crop, fields and help raise agricultural production. For example, Indira Gandhi Canal originating from Bhakra Dam has brought greenery to considerable areas of Rajasthan.
2. Water from a dam is supplied to the people in towns and cities through pipelines after suitable treatment. In this way, construction of dams ensures continuous water supply in the region.
3. The falling water (or flowing water) from the dam is used for generating electricity. The water rushing down the dam turns turbines which run electric generators. The electricity thus produced is called hydroelectricity.
The construction of high-rise dams for the management of river water and generation of electricity has certain problems associated with it. The public opposition to the construction of large dams on rivers is mainly due to the following three problems likely to be created by them :
(i) Social Problems
Due to the construction of high-rise dams, a large number of human settlements (or villages) are submerged in the water of large reservoir formed by the dam and many people are rendered homeless. This creates a social problem. It is, therefore, necessary that all the people who are displaced from the dam site are given adequate compensation by the Government for rehabilitation so as to start their life afresh.
(ii) Environmental Problems
The construction of high-rise dams on the rivers contributes to deforestation and loss of biodiversity. This is because a vast variety of flora and fauna (plants and animals) get submerged in the water of large reservoir formed by the dam and disturb the ecological balance.
(iii) Economic Problems
Some people say that the construction of high-rise dams involves the spending of huge amount of public money without the generation of proportionate benefits. On the other hand, others say that there can be no real progress without building dams because they allow us to manage our water resources properly and at the same time give us much needed electricity (without causing any air pollution). So, whether the construction of dams on rivers is an economic problem or not is a debatable question.
The opposition to the construction of Tehri Dam on the river Ganga and raising the height of Sardar Sarovar Dam on the river Narmada are due to such problems. We have all heard about the protests by the Narmada Bachao Andolan (Save the Narmada Movement) against the raising of height of Sardar Sarovar Dam. So, before taking a decision to construct high-rise dams on rivers, or raising the height of existing dams, it is necessary to consider its long term effects on social life and environment carefully.
Pollution of River Water
The water in most of our rivers is highly polluted. The pollution of river water is caused by the dumping of untreated sewage and industrial wastes into it. For example, the river Ganga which flows for over 2500 kilometres from Gangotri in the Himalayas to Ganga Sagar in the Bay of Bengal is being turned into a dirty water drain by the discharge of untreated sewage and industrial wastes emanating from more than a hundred towns and cities which lie along its way.
In addition to sewage and industrial wastes, the pollution of river Ganga is also caused by other human activities like bathing, washing of clothes, immersion of ashes of the dead and dumping of unburnt corpses in its water. The industries also discharge chemical effluents into the river water. The toxicity of these chemical effluents kills the fish in many parts of the river.
The contamination of river water can be usually found from two factors:
(i) the presence of coliform bacteria in river water, and
(ii) measurement of pH of river water. Coliform is a group of bacteria found in human intestines. The presence of coliform in the river water indicates its contamination by disease-causing micro-organisms. This is because though coliform itself is harmless but its presence in river water indicates that other, more harmful, intestinal bacteria might also be present. The pH of river water is measured by using universal indicator paper. If the pH of river water is found to be below 7, then the river water will be acidic and hence polluted. A multicrore ‘Ganga Action Plan’ (GAP) project was launched in 1985 to clean the river Ganga and make its water pollution free.
Wells and tube-wells (bore-wells) are yet another source of water. Some of the rainwater which falls on earth seeps through the soil and goes down under the surface of the earth. Ultimately this water is stopped by some hard rocks and collects there. This underground water is taken out by digging a ‘well’ into the ground.
This is called well water. Such wells are a common sight in village areas. The deep tube- wells called ‘bore-wells’ are also dug into the earth which are much deeper than the ordinary wells and their water is drawn out by using water pumps. This water is used for the irrigation of crops and for drinking purposes.
When too much water is pumped out through deep tube-wells then the water table (level of water below the earth’s surface) gets lowered too much. This lowering of water table decreases the amount of available underground water. In order to maintain the water table at a proper depth; it is necessary to ensure better percolation of rainwater into the soil. A scheme called ‘rainwater harvesting’ is recommended to stop flowing rainwater and make it percolate into the soil more efficiently.
The people in rural India have used a large number of water collecting methods to capture as much rainwater as possible which had fallen on their land. Some of the methods used for water harvesting by the rural people (or farmers) were : Digging of small pits and lakes ; Building of small earthen dams (or embankments); Construction of dykes (long walls of earth to trap water); Construction of sand and limestone reservoirs; and setting up of roof-top water collecting units. All these methods of collecting and saving rain water have recharged the depleting groundwater levels.
Rainwater harvesting is an age-old practice in India. Water-harvesting techniques used depend on the location where it is to be used. Some of the ancient ‘water harvesting structures’ used in different rural regions of our country (which are still in use) are given below :
Region : Ancient water harvesting structure
1. Rajasthan : Khadin, Tanks, Nadis
2. Maharashtra : Bandharas, Tals
3. Madhya Pradesh and Uttar Pradesh : Bhundhis
4. Bihar : Ahars and Pynes
5. Himachal Pradesh : Kulhs
6. Jammu region : Ponds
7. Tamil Nadu : Eris (Tanks)
8. Kerala : Surangams
9. Karnataka : Kattas
We will now describe a traditional rainwater harvesting system for agriculture called khadin which is used in Rajasthan. The main feature of khadin system of rainwater harvesting is a very long (100 m to 300 m long) earthen embankment called ‘bimd’ built across the lower edge of the sloping farmland (see Figure). The rainwater from catchment area flows down the slopes and stopped by the bund to form a
reservoir. The excess water flows across the bund through sluiceways (or pathways) provided for this purpose and goes into shallow wells dug behind the bund. The rainwater which collects in the reservoir formed by the bund, and in the well, seeps slowly into the land (or ground). This water-saturated land is subsequently used for growing crops.
Please note that the main purpose of water harvesting is not to hold rainwater on the surface of the earth but to make rainwater percolate under the ground so as to recharge ‘groundwater’. The various advantages of water stored in the ground are as follows :
- The water stored in ground does not evaporate.
- The water stored in ground spreads out to recharge wells and provides moisture for crops over a wide area.
- The water stored in ground does not promote breeding of mosquitoes (unlike stagnant water collected in ponds or artificial lakes).
- The water stored in ground is protected from contamination by human and animal wastes.
- The water stored in ground is utilised for the benefit of local population.
Rainwater harvesting in rural areas not only increases the agricultural production and income of the farmers but also mitigates (makes less severe) the effect of droughts and floods, and increases the life of downstream dams and reservoirs.
Rainwater Harvesting in Urban Areas (City Areas)
In rural areas (village areas), most of the ground has open soil due to which rainwater can seep into the ground naturally to make up for the loss in groundwater due to excessive use. In urban areas (city areas), however, most of the ground is covered with buildings, concrete pavements and metalled roads due to which only very little rainwater seeps into the ground naturally.
Most of the rainwater which falls in cities flows into dirty water drains and goes away. So, rainwater harvesting is necessary in city areas. Rainwater harvesting by making more water percolate into the ground is usually done in those areas of a city where tube-wells for supplying water are located. This is to make sure that the tube-wells will never go dry.
The rainwater harvesting from open spaces around the buildings in a city is done by constructing percolation pits covered with concrete slabs having holes in them, and connected to a recharge well through
a pipe (see Figure). The recharge well is about 1 metre in diameter and 3 metres deep. The rainwater falling in the open spaces around buildings goes into the percolation pit through the holes in its concrete slab cover. After filtration in percolation pit, rainwater enters the recharge well through the outlet pipe and gradually seeps into the soil.
Please note that the purpose of recharge well is to collect the vast amount of water falling on the ground quickly when it rains and then make it seep into soil gradually. This groundwater can then be taken out through tube-wells as and when required. The advantage of rainwater harvesting is that it increases the availability of groundwater and helps in overcoming water shortage.