water resources & irrigation
TRANSCRIPT
Water Resources & Irrigation
By SudarshanGurjar
Irrigation – Sources and Methods
By SudarshanGurjar
• The main sources of irrigation in India are:
• Canals
• Wells (and tubewells)
• Tanks
• The relative importance of these has been changing from time totime. Let’s look at these in detail:
Canal Irrigation:
By SudarshanGurjar
• A canal is an artificial watercourse constructed for water supply andirrigation.
• There are two types of canals:– Inundation Canals – These are taken out from the rivers without any
regulating system like weirs etc at their head. Such canals are useful only during the rainy season
– Perennial Canals – These are those which are taken off from perennial rivers by constructing a barrage across the river. Most of the canals at present in India are perennial.
Canal Irrigation:
By SudarshanGurjar
• Canals can be an effective source of irrigation in areas of low relief, deep fertile soils, perennial source of water and an extensive command area.
• Therefore the main concentration of canal irrigation is in the northern plains.
By SudarshanGurjar
• The canals are practically absent from the peninsular plateauregion because of rocky terrain. However, the coastal and the deltaregions in South India have some canals for irrigation.
• The percentage of canal irrigation area to total irrigated area in thecountry has fallen from about 40% in 1950-51 to less than 25% atpresent.
• The states UP, Punjab, Haryana, Rajasthan and Bihar account forabout 60% of the canal irrigated area in the country.
By SudarshanGurjar
• Merits of canal irrigation:– Perennial Source
– Provides safety from droughts
– Brings fertile sediments to the fields
– Economical to serve a large area
By SudarshanGurjar
• Demerits:– Canal water soaks into the ground and leads to water logging, increases
salinization, and leads to marshy conditions leading to malaria and flooding
– Wastage of water.
By SudarshanGurjar
Wells and Tube Wells
By SudarshanGurjar
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• This method of irrigation has been used in India from time immemorial. Various methods are used to lift the ground water from the well.
• A tube well is a deeper well (generally over 15 metres deep) from which water is lifted with the help of a pumping set operated by an electric motor or a diesel engine.
• Well irrigation is gradually giving way to energized tube wells.
• But there are many wells still in use where electricity is not available or the farmers are too poor t0 afford diesel oil.
• This method of irrigation is popular in those areas where sufficient sweet ground water is available.
• It is particularly suitable in areas with permeable rock structure which allows accumulation of ground water through percolation.
• Therefore wells are seen more in areas with alluvial soil, regur soil, etc. and less seen in rocky terrain or mountainous regions.
• These areas include a large part of the great northern plains, the deltaic regions of the Mahanadi, the Godavari, the Krishna and the Cauvery, parts of the Narmada and the Tapi valleys and the weathered layers of the Deccan trap and crystalline rocks and the sedimentary zones of the peninsula
By SudarshanGurjar
• However, the greater part of peninsular India is not suitable for well irrigation due to rocky structure, uneven surface and lack of underground water.
• Large dry tracts of Rajasthan, the adjoining parts of Punjab, Haryana and Gujarat and some parts of Up have brackish ground water which is not fit for irrigation and human consumption and hence unsuitable for wellirrigation.
• At present irrigation from wells and tubewells accounts for more than 60% of the net irrigated area in the country.
By SudarshanGurjar
• UP has the largest area under well irrigation which accounts for 28% of the well irrigated area of the country.
• U.P., Rajasthan, Punjab, Madhya Pradesh, Gujarat, Bihar and Andhra Pradesh account for about three-fourths of the total well-irrigated area
By SudarshanGurjar
By SudarshanGurjar
• Merits of well irrigation– Simplest
– Cheapest
– Well is an independent source of irrigation and can be used as and when the necessity arises. Canal irrigation, on the other hand, is controlled by other agencies and cannot be used at will.
– Some ground water salts are useful for crops
– Does not lead to salinization and flooding problems
– There is a limit to the extent of canal irrigation beyond the tail end of the canal while a well can be dug at any convenient place.
By SudarshanGurjar
• Demerits– Only limited area can be irrigated. Normally, a well can irrigate 1 to 8
hectares of land.
– Not suitable for dry regions
– Overuse may lead to lowering of water table
By SudarshanGurjar
Tank irrigation
By SudarshanGurjar
• A tank is a reservoir for irrigation, a small lake or pool made by damming thevalley of a stream to retain the monsoon rain for later use.
• It accounts for approximately 3% of the net irrigated area in India.
• Tank Irrigation is popular in the peninsular plateau area where Andhra Pradesh and Tamil Nadu are the leading states.
• Andhra Pradesh has the largest area (29%) of tank irrigation in Indiafollowed by Tamil nadu (23%).
By SudarshanGurjar
• It is practised mainly in the peninsular region due to the following reasons:
– The undulating relief and hard rocks make it difficult to dig canals andwells
– There is little percolation of water due to hard rock structure and ground water is not available in large quantities.
– Most of the rivers are seasonal; there are many streams which becometorrential during the rainy season – so the only way to use this water isto impound it by constructing bunds and building tanks.
– Also, it is easy to collect rainwater in natural or artificial pits becauseof impermeable rocks.
– Scattered nature of agricultural fields
By SudarshanGurjar
By SudarshanGurjar
• Merits– Most of the tanks are natural and do not involve cost for their
construction
– Independent source for an individual farmer or a small group of farmers
– longer life span
– can be used for fishing also
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• Demerits• Depends on rain and these tanks may dry up during the dry season
• Silting of their beds
• Require large areas
• Evaporation losses
• Sometimes there might be a need to lift the water to take it to the field
By SudarshanGurjar
Sprinkler and Micro-Sprinkler Application:
By SudarshanGurjar
• Sprinklers:– This system sprinkles water in a manner similar to rainfall so that run-
off and deep percolation losses are avoided and the uniformity of application is quite high.
– The system consists of sprinkler heads or nozzles, which are mounted on risers in lateral lines taken from the main line, which is further connected to a pumping unit.
Sprinklers
By SudarshanGurjar
• This system of irrigation is suitable when:
– The soil is too porous for good distribution by surface irrigation.
– The fields have an uneven surface.
– The soil is easily erodable.
– The water supply is just sufficient for crop growth.
By SudarshanGurjar
• Merits:– Sprinklers can be used on all soil types of any topography.
– It entails increased irrigation frequency which has a positive effect oncrop yield.
– In this method, a water saving of 30% to 50% is reported in comparison to the surface method of irrigation
– Thus by introducing sprinklers, an additional area ~ up to 50% can be brought under irrigation besides increased crop yields.
By SudarshanGurjar
– The overall efficiency of the system is above 80% and no land is wastedon making bunds and channels, and about 40-50% of saving in labour ascompared to surface irrigation.
– Only 2 to 5% water is lost through evaporation.
By SudarshanGurjar
• Demerits:– Expensive
– Requires continuous maintenance and skill for installation and operation
– The high energy requirement for operation as sprinklers operate at water pressure ranging from 1 to 10 kg/sq cm.
– Wind interferes with the distribution pattern.
– It reduces the spreading rate and in turn the efficiency. Under hightemperatures and strong winds heavy evaporation loss takes placethereby offsetting the saving in water.
By SudarshanGurjar
Micro-sprinklers
By SudarshanGurjar
– It sprinkles around the root zone with small sprinklers that work under low pressure.
– In this method, water is applied only to the root zone area unlike to the entire field as in the case of sprinkler irrigation method.
– This method is highly suitable for orchard crops and vegetable crops.
Drip Application
By SudarshanGurjar
• In this method, the application of water is precise but slow as discrete drops, continuous drops, tiny streams or miniature sprays through mechanical devices, called emitters or applicators located at selected points along water delivery lines.
• This is useful in areas with water scarcity and salt problems.
• Drip irrigation system consists of main pipe, sub-mains, lateral valves, drippers or emitters, a riser valve, vacuum breakers, pressure gauges, water metres, filters, fertiliser tanks etc.
• These are designed to supply water at desired rates (1 to 10 litres/hour)directly to the soil.
• Low pressures ranging from 0.35 to kg/sq cm are sufficient for drip system
By SudarshanGurjar
Merits:
By SudarshanGurjar
• Water saving
• Enhanced plant growth and yield
• Saving of labour and energy
• More suited to poor soils
• Controls weed growth
• Easy operations
• Fertilisers or other chemical amendments can be efficiently applied to individual or separate plants using drip irrigation.
• Flexibility in operation
• No soil erosion
• Requires less land preparation
• Minimum disease and pest problems
• This method has been found to be of great value in reclaiming and developing desert and arid areas.
• Demerits:• Expensive
• Technical Limitations
• Requirement of high skills for design, installation andoperation
By SudarshanGurjar
• Availability of safe water is becoming a major challenge, highlight the major reasons
for water scarcity in India. What steps government has initiated in order to control
this situation? Suggest some measures in order to tackle the problem of water crisis in
India.(GS 3)
• The availability of safe water is becoming a major challenge for India. According to a
Water Aid report in 2016 India ranked among the worst countries in the world for the
number of people without safe water.
• An estimated 76 million people in India have no access to a safe water supply .The Asian
Development Bank has forecast that by 2030, India will have a water deficit of 50 per
cent. According to the 2018 edition of the UN World Water Development Report, the
Central India is staring at deepening water scarcity, meaning withdrawal of 40% of the
renewable surface water resources.
Major reasons for water scarcity inIndia:
1. Demand and Supply gap: Rising population has led to increase in demand for water.
However, there persists a gap between demand and supply which has led to water scarce
scenarios in many parts of India.
2.Poor water quality: Water is contaminated with bio and chemical pollutants and is unsafe
for drinking.
3.Inefficient agricultural practices and dwindling Groundwater Resources:
Indiscriminate extraction of groundwater has led to declining water table in many parts of
the country.
4.Unequal Access to Water: According to WHO-UNICEF data, as of 2008, about 96 per
cent of the nurban population and 84 per cent of the rural population has access to improved
water sources.
3.Poor storage: In 2015, a report by the Ministry of Water Resources, River Development
and Ganga Rejuvenation stated that though India receives an average annual rainfall of 1170
mm, poor storage infrastructure allows it to store only 6 per cent of rainwater, compared to
250 per cent stored by developed nations.
4.Poor planning and infrastructure: The problem of urban water supply is due to poor
and
leaky distribution networks leading to large amounts of “unaccountedwater.”
Steps initiated by the government in order to control watercrisis:
• The government has taken the following steps in this direction:
1.National Water Policy: National Water Policy has been to govern the planning
and development of water resources and their optimum utilization.
2.National River Linking Project: Interlinking project aims to address the issue of uneven
distribution water but has proved to be contentious between the government and civil
society groups
3.Atal Bhujal Yojna: The Indian Government has formulated the water conservation
scheme
Atal Bhujal Yojana (ABY) to tackle ever-deepening crisis of depleting groundwater.
4.National Rural Drinking Water Programme (NRDWP): It aims at providing every
person in rural India with adequate safe water for drinking, cooking and other domestic
basic needs on a sustainable basis.
Measures• Micro irrigation practices like drip and sprinkler systems have to be promoted in a big way
for efficient use of water for agriculture Both in urban and rural areas, digging of rainwater
harvesting pits must be made mandatory for all types of buildings.
• Sustained measures should be taken to prevent pollution of water bodies, contamination of
groundwater and ensure proper treatment of domestic and industrial waste water.
• The UN World Water Development Report 2018 stresses nature-based solutions (NBS) to
sustainably and economically manage water resources.
• Conscious efforts need to be made at the household level and by communities, institutions
and local bodies to supplement the efforts of governments and non-governmental bodies in
promoting water conservation.
River Linking Project(RLP) or Inter-basin Transfer(IBT) NationalRLP
• There are 3 aspects to water regimes in India.
• i) The monsoon rainfall distribution is not even - Spatial variability.
• ii) The rivers are not all comparable in terms of their discharge and size.
• Himalayas River - 80% of all river discharge, Brahmaputra & ganga alone amount for 60% of all surface drainage.
• iii) Uneven distribution & monsoon variations is the prime reason for floods& droughts related losses.
• Way back in the 19th century, Sir Arthur cotton recommended & operationalized the first IBT in madras Presidency in the Kaveri basin.
By SudarshanGurjar
• In 1960s K. L. Rao fallowed by Captain Dastur recommended a national scale RLP.
• K. L. Rao suggested transferring the water surplus of Ganga & Brahmaputra towards south India using link canals.
• While Captain Dastur suggested garland canal systems
• Two Garlands-
i) Himalayan Garland
ii) The Peninsular Garland
Where in both the systems the water would be transferred from the watersurplus eastern India towards the western & central water deficit area.
By SudarshanGurjar
• Under recommendation of NWDA set up in the 1990s.
• NRLP has been promoted & the feasibility study is at different stages ofthe system.
• NRLP Envisages -
• i) Two components - The Himalayan component & the Peninsula river linkingcomponent.
• ii) A network of around 30 canals with the following 4 sub- components-
• a) Transferring the surplus water of Brahmaputra & Ganga towards western India.
By SudarshanGurjar
• b) Transferring surplus water into Mahanadi to further transfer itto Peninsular River.
• c) Transferring Eastern plateau waters towards the plateau
• d) Transferring the Himalayas waters through series of link canals(Subarnarekha- Mahanadi-Wardha- Penganaga-Wainganga-Godavari-Krishna-Through Tungabhadra into Kaveri system & finally into Vagai system).
By SudarshanGurjar
• Evalution-• i) NRLP with its objective to transfer around 180 bcm of water will be one of the
largest projects ever executed in the history of the world.
• The successful IBT of us on Colorado river transfers less than 1 cubic kms of waterwhereas ambitions Chinese project intend to transfer 40-50 cubic kms of water fromthe change Twang river towards the dry north & North-East.
• ii) The financial feasibility is also much disputed because at 2002 prices the projectwas conservatively estimated at more than 200 billion.
• There are reports which have pegged the cost to more than 1500 billion dollars.
By SudarshanGurjar
• iii) There are serious ecological impacts that need to be studied objectivelysuch as forest depletion because the project will require more than 5000large dams which submerge millions of hectares of forest apart from thisimpacting the ecology downstream of rivers.
• iv) Construction of Canals will result in large scale land degradation.
• v) The tribal displacement can be more than 10 million because the systemwill traverse mountainous & forested area of the Central Highlands (ProjectAffected Families (PFA).
By SudarshanGurjar
• The tribal displacement due to Narmada project & due to numerousindustrial projects is yet to be sorted on particularly the challenges relatedto land acquisition for such developmental projects.
• vi) The Himalayan rivers flow along the Northern plains with an averageelevation of around 300-400m.
• At parts at or near the sea level whereas the average elevation of theplateau is 900m.
By SudarshanGurjar
• The river linking will require pumping of water to manage the grade & therelief difference which in tern will require additional energy generation of30-40Gw of power.
• The current installed capacity of power generation in India is 200Gwtherefore an additional 20% of energy generation is required.
• Even if we opt for modern tech and use tunnels to transfer the water acrossMt. ranges the energy generation required will be at least to 10Gw.
By SudarshanGurjar
• Further the political dimension to river linking is another formidable challenge because inter-state river disputes between neighbouring states is yet to be resolved and so it is difficult to imagine how hindi speaking states of Northern India would politically align to interest of southern Indian states.
• vii) Land & water are state subjects in times when these is a increased regional assertiveness
By SudarshanGurjar
• RLP was conceived for 3 objectives primarily-• i) Irrigation & to minimize drought losses.
• ii) To deal with the problems of floods & drought cycles.
• iii) Drinking water.
• The above 3 challenges if analysed objectively are actually not a problem ofwater quantum.
• The problems are more due to faulty infrastructure, invasive interventionsthe compromise natural hydrological cycles or because of misuse of waterLack of drinking water is more due to wastage of rainwater & problemsrelated to water governance, water supply, distribution & equity in accessrights to water.
By SudarshanGurjar
• The problems of water are more rooted in social & admin lacunae.• Historically resource transfer based systems are non sustainable and it is
the decentralised to water problems.
• Eg. Use of Panchayati Raj institutes, Rainwater harvesting, social equity, gender rights which can address water problems more practically.
• Most of the large projects are not only wasteful but are also disruptive-some problems cannot be anticipated before the initiation of projects.
• Hence a crucial life component like water is best managed at local level with the options of self correction & not under centralised systems like RLP.
By SudarshanGurjar
By SudarshanGurjar
By SudarshanGurjar
Ken-Betwa interlinking Project• The Ken-Betwa ILR project aims to transfer surplus water from the Ken
River to the Betwa basin through concrete canal to irrigate India’s worstdrought-prone Bundelkhand region.
• It is India’s first inter-State river interlinking project
• The main feature of the project is a 230-km long canal and a series ofbarrages and dams connecting the Ken and Betwa rivers .
• The key projects are Makodia and Dhaudhan dams.
• On completion, the multipurpose project will benefit Uttar Pradesh andMadhya Pradesh in terms of meeting irrigation, drinking water andelectricity needs of people across 6 districts in the two states.
By SudarshanGurjar
Ken-Betwa interlinking Project• Ken-Betwa river interlinking project will be the first river project that will
be located within a tiger reserve.
• It will submerge about 10% of the Panna Tiger Reserve in Madhya Pradeshwhich has been feted as a model tiger-conservation reserve
By SudarshanGurjar
By SudarshanGurjar
Para-Tapi-Narmada Link
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• Par Tapi Narmada Link proposes to transfer water from the water surplusregions of Western Ghats to the water deficit regions of Saurashtra andKutch.
• The link project includes seven reservoirs proposed in north Maharashtraand south Gujarat.
• The water from the seven proposed reservoirs would be taken through a395 km long canal including the 33km length of the feeder canals to takeover a part of the command of the on-going SardarSarovar Project, whileirrigating small enroute areas.
Para-Tapi-Narmada Link
By SudarshanGurjar
• This would save SardarSarovar water which will be used to extendirrigation in Saurashtra and Kutch region.
• The project of Par-Tapi-Narmada link generally falls in the state ofGujarat except Jheri reservoir which falls in Maharashtra state.
• Jheri dam is located in Nasik district of Maharashtra, while remaining damsviz. Mohankavchali, Paikhed, Chasmandva, Chikkar, Dabdar and Kelwan damsare located in Valsad and Dang districts of Gujarat.
• Par-Tapi reach of canal passes through Valsad, Navsari, Dang and Suratdistricts of South Gujarat whereas Tapi-Narmada reach of canal passesthrough Surat, Bharuch and Vadodara districts of Gujarat.
• The project area is mainly spread in the districts of South Gujarat exceptfor Jheri dam and reservoir.
By SudarshanGurjar
By SudarshanGurjar
By SudarshanGurjar