Friday, May 9, 2008
Earth is watery planet.
--96.5 percent of the total volume of world,s water is existing in the oceans and only 2.5% is fresh water.
--Nearly 70% of this fresh water is in the form of glaciers, while little less than 30% is stored as ground water in water acquifers.
--India receives nearly 4% of global precipitation and ranks 133 in the world in terms of water availablity per person per annum.
--3/4 of earth,s surface is covered with water, but only small portion of its fresh water can be put to use.
--Fresh water is mainly obtained from surface run-off and ground water and is being continually renewed & recharged through hydrological cycle.
Q..If ¾ of world is covered with water & water is renewable resource, then why do countries of the world suffer from water scarcity?
The availibilty of water resources varies over space and time, mainly due to the variations in seasonal and annual precipitation, but water scarcity is mainly caused due to
–Unequal acess of water among different social groups.
–It can be the outcome of the large growing population and consequent greater demands for water.(for domestic use and for production of food.)
–Ever increasing number of industries exert pressure on existing freshwater resources. As these industries require power to run tem and much of this energy comes from hydroelectric power(approx.22% of the total energy produced.)
–Urbanisation and urban lifestyles require added water and energy resources which has further aggravated the problem.
–This scarcity is also due to the bad quality of water, which is due to domestic and industrial wastes
MULTI PURPOSE RIVER VALLEY PROJECTS
These were launched after the independence with their integrated waer resources management approach.These were thought of as the vehicle that would to national development and progress.
Jawhar lal Nehru called them to be the ‘Temples of modern India’, as it would integrate the development of agriculture and village economy with rapid industrialisation and the growth of the urban economy.
Q.What are Dams and how do they help us?
A. A Dam is a barrier buitl across flowing water that obstructs, directs or retards the flow, often creating a reservoir, lake or impoundment.
Today Dams are built for: irrigation, generation of electricity,flood control, recreation inland navigation and fish breeding.
Example--Bhakara dam,(on sutluj-Beas ), Hira kund on the Mahanadi river.
Q. Why in the recent years multi-purpose projects and the dams are under great scrunity and opposition?
A. There are variety of reasons for this, which are as follows:
1.regulating and damming of rivers affect the flow and excessive sedimentation of at the bottom of the reservoir, resulting in rockier stream beds and poorer habitats for the rivers acquatic life.
2.dams also fragment rivers making it difficult for aquatic fauna to migrate, especially for spawning.
3. the reservoirs that are created on the flood plains also submerge the existing vegetation and soil leading to its decomposition over a period of time.
4. resistance to these projects , recently has also been due to the displacement of local communities.People have to give up their livelihood and their meagre access and control over resources for the greater good of the nation.
5.dams have transformed the social landscape i.e increasing the social gap between the richer landowners and landless poor. As in Gujrat, the Sabarmati basin farmers were agitated and almogst caused a roit over the higher priority given to water supply in the urban areas, particularly during the droughts.
6. Inter-state disputes have also become common with regard to the sharing the cost and benefits of the multi-purpose project.
7.The objections to the projects arose due to their failure to achieve the purpose for which they were built.
as these pojects were built to control floods have triggered floods due to sedimentation in the reservoir, moreover the big dams are extremely unsucessful in the times of excessive rainfall(in 2006 the release of water from dams during the floods aggravated the flood situation )
--sedimentation also meant that the folld plains were deprived of the silt, natural fertiliser, further adding on to the problem of the land degradation.
8. multipurpose projects also induce earthquakes, cause waterborne diseases and pests and pollution resulting from excessive use of water.
NARMADA BACHAO ANDOLAN--OR SAVE NARMADA MOVEMENT.
--It is a non-governmental organisation that mobolised tribal people,farmers, environmentalist and humanrigts activitists against the sardar-sarovar dam being built caross Narmada in Gujrat. --It orginally focussed on environmental issues related to trees that would be submereged under the dam water.
--recently it has re- focussed the aim to enable poor citizens, especially outees(displaced people) to get full rehabilitation facilities from the government.
RAIN WATER HARVESTING
Disadvantages and rising resistance against the multipurpose projects, have diverted us to the water harvesting system as the viable solution, both socially , economically and environmentally. 1. In hills and mountainous regions people built diversion channels like 'guls' and'kuls' of the western Himalayas for agriculture.
2.Roof top rainwater harvesting was earlier commonly practised to store drinking water, particularly in Rajasthan.
3. In flood plains of Bengal, people developed inundation channels to irrigate their fields.
4. In the arid and semi arid regions , agricultural fields were converted into rainfed storage structurs that allowed water to stand and moisten the soil like 'khadins' in Jaisalmer and Johads in the other parts of Rajasthan.
5.In the arid and semi arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, almost all the houses traditionally had tanks or tankas for storing drinking water.
--they could be as large as a big room.
--they are a part of well developed rooftop water harvesting system, built inside main house or courtyard.
-- they are connected to the sloping roof of the houses through the pipe.Rain falling on the rooftops would travel down the pipe and was stored in these underground 'tankas' .
--the first spell of rain was usually not collected as this would clean the roofs and the pipes.
--it is a extremely reliable source of drinking water when all othersources of water are dried up, particularly in summers.
--'Palar pani" or the rain water is the purest form of natural water. Many house constructed undergroung rooms adjoining the tanka to beat the csummer heat as it is would keep the room cool.
Today in Rajasthan sadly this practice is on decline as plenty of water is available due to perennial Rajasthan canal.
ROOF TOP WATER HARVESTING IN SHILONG,MEGHALAYA
It is a most common practice in Shilong and is also very interesting because Cherapunji & Mawsynram situated at a distance of 55km from Shilong receive higest rainfall in the world yet the state capital Shilong faces acute shortage of water.
--nearly every household in the city has rooftop water harvesting structure.
--nearly 15-25%of total water requirement of the house hold comes from the rooftop water harvesting.
--BAMBOO DRIP IRRIGATION SYSTEM IN MEGHALAYA
In Meghalaya, a 200 year old system of tapping stream & spring water by using bamboo pipes is prevalent.
--over 18-20 litres of water enters the pipe system and gets transported over hundreds of metres.
Today in many parts of rural and urban Indiarooftop water harvesting is sucessfully adapted to store and conserve water
1. TAMIL NADU—is the first and the only state in India which has made rooftop rainwater harvesting structure compulsory to all the houses across the stste. There are leagle provisions to punish the defaulters.
2. KARNATAKA: In Gendathur, a remote backward village in Mysore, Karnataka, villagers have installed in their houses rooftop waterharvesting system to meet their water needs.Nearly 200 households have installed this system and the village has earned a distinction of being rich in rain water resources.
--HYDRAULLIC STRUCTURES OF ANCIENT INDIA
Archaeological & historical records show that from anicient times we have been construct1.ing structures like dams built of stone rubble,reserveoirs or lakes, embankments or rivers for irrigation. Some of them are as follows.
1.In the 1st century B.C, Sringaverapura near Allhabad had sophisticated water harvesting system challening the flood water of river Ganga.
2.During the times of Chandragupta Maurya, dams , lakes and irrigation systems were extensively built.
3.Evidences of sophisticated irrigation works have also been found in Kalinga(orrisa)Nagarjunkonda(Andhra Prades), Bennur(Karnataka), Kolapur (Maharashtra) etc.
4.In the 11th the Bhopal lake one of the largest artificial was built.
5.In the 14th the tank in Haus-khas, Delhi was built by Illtutmish for supplying water to Siri Fort area.