CHAPTER
2
METHODOLOGY
FOR MINOR IRRIGATION CENSUS
2.1.1
For effective implementation of irrigation policy and planning, sound database
regarding Minor Irrigation Sector is a must. The inadequacy of data has been
considered as a serious constraint at
various forums of irrigation planning. The National Commission on Agriculture had recommended that “Census of
irrigation sources should be undertaken alongwith the agricultural census once
in 5 years, Special irrigation surveys on the number of wells and their
utilisation may be undertaken by the States” (recommendation 24/page 141
Volume-XIV). Planning Commission also
recommended for a detailed census of minor irrigation works in 1970. A meeting of the Technical Committee for
agriculture census 1980-81 considered the inclusion of list of items relating
to minor irrigation in the primary enumeration schedules, but it could not be
agreed. The main reason for
non-inclusion of items relating to minor irrigation was that the agriculture
census data was to be compiled from the existing data of land records of
various States. The data do not have
the information relating to minor irrigation works as desired.
2.2 DEPARTMENTS/ORGANISATIONS DEALING WITH MINOR IRRIGATION PROGRAMME
2.2.1
Installation of minor irrigation works in the States is being taken up by
various departments and organisations under different developmental
sectors. Generally dugwells, shallow
tubewells and pump-sets are installed by individual farmers. Ministry
of Agriculture, Government of India is operating a centrally sponsored
scheme of assistance to small and marginal farmers for increasing agriculture
production under which 70 percent of the outlay has been earmarked for minor
irrigation works. It covers gully
plugging, nala bunding, construction of small surface storage structures
including ponds, tanks, deepening of village ponds, percolation tanks, dugwells,
shallow tubewells, filter points, boring and deepening of wells, renovation of
old wells, rahat, pump-set with appropriate water conveyance and distribution
systems, pump houses, etc. The plugging
cross-bunding of natural streams, nalas, rivulets, gullies and water harvesting
structures are also covered under minor irrigation.
2.2.2 Under rural development programme, the minor irrigation works
are installed with a view to raise the standard of living of rural people. Since these schemes are quick maturing and
rural employment oriented, more and more emphasis is being given for lifting up
the poor people above the poverty line.
The Department of Rural Development, Government of India is operating a
centrally sponsored scheme titled “Integrated Rural Development Programme” (IRDP) under which subsidies are being made available to the farmers for
installation of minor irrigation works.
The renovation of tanks and construction of ponds/tanks, gully, plugging
and nala bunding, etc. are also taken up under various employment generation
programmes such as Jawahar Rozgar Yojna Employment Assurance Scheme. The Million Wells Scheme helps the
beneficiaries to acquire asset for their sustained self employment on land
based activities. Under the Drought
Prone Area Programme, which is operative in 947 blocks of 155 districts in 13
States, about 7.45 lakh square kilometre of area is being benefited. Similarly, under Social Welfare Programme
minor irrigation works are installed as a component of Tribal Development
Programme.
2.3 CENSUS OF MINOR IRRIGATION WORKS
2.3.1 The finance for private minor irrigation works flow as subsidy from the government departments and loans from banks. The monitoring of the programmes by different departments does not consider the minor irrigation schemes separately and there is no single department in the State for compiling the minor irrigation data for the entire State. It results into incomplete compilation of data. Based on the objectives of various programmes, monitoring is not given due importance for the generation and compilation of minor irrigation data. A separate department such as minor irrigation has to keep a close coordination with all such departments for compilation of minor irrigation data which was lacking in almost all the States/UTs. The Minor Irrigation Division of the Ministry of Water Resources and the Planning Commission, Government of India compile data on minor irrigation through annual plan discussions in Planning Commission. Due to the lack of the generation of data, a firm database was not available for minor irrigation sector. Keeping this in view, the scheme Rationalisation of Minor Irrigation Statistics (RMIS), funded by the Centre was launched in 1987-88. One of the objectives of the scheme was to conduct census of minor irrigation works on quinquennial basis. Under the scheme, statistical cells consisting of requisite number of staff were also proposed to be created in each State/UT for compilation of minor irrigation statistics. Up to 1998-99, only 21 States/UTs implemented this scheme and appointed staff for the purpose. These statistical cells are collecting data relating to number of minor irrigation schemes constructed and potential created/utilised through these schemes and communicated to the Ministry of Water Resources. Efforts are being made to set up such cells in the remaining States/UTs also.
2.3.2 The first census with reference to 1986-87 was conducted by all the States/UTs, except Rajasthan and the all India census report published in November,1993. The second census has been delayed for few years and has been taken up with reference to 1993-94. This is a step ahead in preparation of a sound database for minor irrigation sector. In consultation with the State Governments and the concerned central organisations slight modifications have been introduced over the previous census. The additional important information on area actually being irrigated by major and medium schemes, saline/alkaline area and water logged area at village level in the village schedule has also been collected. The information in respect of adoption of newly developed and technologically advanced water and energy conserving devices such as sprinkler and drip irrigation systems and use of non-conventional energy sources such as solar pumps and wind mills have also been obtained.
2.4 FORMULATION OF PROPOSAL FOR CENTRAL GRANT-IN-AID
2.4.1 The Chief Secretaries of the States were requested by the Ministry of Water Resources to declare the Head of the nodal department as Minor Irrigation Census Commissioner. They were also requested to submit their proposal for Central grant to conduct the second census under the aegis of the centrally sponsored scheme of Rationalisation of Minor Irrigation Statistics.
2.4.2
Cost Estimates
It is proposed to pay an honorarium as a token of appreciation of work entrusted to various officials in addition to their normal duties and not as compensation or re-numeration for additional work. An honorarium of Rs. 2000/- each to the Minor Irrigation Census Commissioner in case of major States, and Rs. 1500/- each for others (namely Arunachal Pradesh, Nagaland, Manipur, Meghalaya, Mizoram, Sikkim, Tripura etc. and Union Territories, was paid. The District Level Officer in charge of Census was paid an honorarium of Rs. 1000/- each and at the Block Level an honorarium of Rs. 500/- each was paid to the Block Level Officer. The rate of honorarium for the primary enumerator was Rs. 100/- per village. The estimated cost of contingent expenditure for printing schedules and other miscellaneous expenditure was Rs. 25/- per village. The cost of computerisation of Census data was at the rate of Rs. 1.20 per Minor Irrigation Scheme. The entire cost for conducting the Census was born by the Centre.
2.4.3. Time Schedule
The time schedule for completing the Minor irrigation Census operation is as follows:-
(i) Submission of proposal by the States - December 1994
(ii) Training Programme - January 1995
(iii) Field work - March 1995
(iv) Sample check - April 1995
(v) Computerisation of Census data - June 1995
(vi) Submission of data floppies to theCentre - August 1995
2.5.1 The Census data was collected through canvassing six different enumeration schedules. One of the schedules is the village schedule which was canvassed by the enumerators through enquiries from patwaries/village level workers/gram pradhans, and the revenue or land records maintained in the government records. The other five schedules were to be canvassed by enumerators through enquiries from the owners of the schemes. These five schedules relate to five different types of minor irrigation schemes. The various schedules alongwith instructions for filling up are given as annex. The fieldwork of the census was either undertaken by the nodal department itself or entrusted to some other agency which the State/UT government considered fit in respect of infrastructures available with it. However, for the entire census operation, Minor Irrigation Census Commissioner, was the pivotal point. The primary work of collection of data was carried out by the enumerators. They were village level workers or village accountants or lekhpals or patwaries or a combination of these as the case may be. The work of supervision was entrusted to the next superior officer of the field agency by the State/UT. They were Block Level Officers or Sub-Divisional Officers who in order to ensure the correctness of data recorded by an enumerator conducted frequent site visits of the schemes.
2.5.2 In order to increase the reliability of data a sample check was conducted in addition to the enumeration and supervision of data collection as mentioned above. Systematic sampling technique was adopted for 5 percent sample check at the district level. It helped in detecting under enumeration/over enumeration and hence a correction factor, wherever necessary, was applied to the main census results. The following methodology was adopted for drawing the sample.
2.5.3 The District Level Officer concerned with the census operation prepared a list of villages in alphabetical order for the district after receiving the completed schedule relating to field enumeration. The total number of villages was divided by 20 and the remainder obtained was serial number of the village first selected. Thereafter every 20th village was selected for the sample. If the remainder was zero, the villages at the 20th serial was first selected village. For example, if there were 226 villages in a district-dividing the number by 20, the remainder works out to be 6. Therefore, the first village selected for the sample would be at serial numbers 6 and thereafter every 20th village. Thus the village at serial number 6,26,46,66,86,106,126,146,166,186,206 and 226 would be included in the sample.
2.5.4 The village enumeration schedules of the selected villages was checked by the district level authority. The Heading of the schedule was marked by putting letter(s) in red ink in front of the schedule number, say, schedule A.1(S). The information obtained during the sample check was recorded in the respective columns by red ink wherever there was a change. The data so obtained was separately computerised for finding out correction factor.
2.6 TRAINING PROGRAMME FOR DATA COLLECTION
2.6.1 Training cum workshops were organised by the Minor Irrigation Census Commissioners at the State Headquarters in which the District Level Officers participated. A representative from the Centre was invariably an Observer in such workshops. The details of the methodology adopted for the census, its procedure, concepts and definitions were discussed thoroughly and necessary clarifications were given. The instructions for filling up the primary enumeration schedules were also discussed during the workshops. In turn, the District Level Officers organised training programmes at district headquarters where the primary enumerators participated. They were explained thoroughly the instructions for filling up the primary enumeration schedules.
2.7 COMPUTERISATION OF CENSUS DATA:
2.7.1 The National Informatics Centre (NIC), Planning Commission was requested to develop necessary software for computerising the Census data. Such softwares in floppy were provided to Minor Irrigation Census Commissioners for computerising the Census data. Wherever necessary, private consultants/agencies were hired by the Minor Irrigation Census Commissioners to computerise the primary enumeration schedules, according to software provided by NIC. The work was taken up at the district headquarters to avoid transportation difficulty and misplacement of enumeration schedules. It also minimised the delays in computerisation. The validated high density floppies containing data collected during the census on primary enumeration schedules were prepared and after duly ascertaining the correctness of data two copies were passed on to the Minor Irrigation Census Commissioner at the state level. A copy of the data floppy was sent to the centre by the State Minor Irrigation Census Commissioners. Based on the primary data floppies at the State headquarters, a State Minor Irrigation Census Report was brought out for which a tabulation plan was supplied by the Centre. The census data received from the States at the Centre in floppies were utilised for compiling a National Level Minor Irrigation Census Report. The processing of the report was taken up with the help of National Informatics Centre.
2.8 CLASSIFICATION OF SCHEMES:
2.8.1 Minor irrigation schemes involving either ground water or surface water use, having culturable command area up to 2000 hectare individually fall under the category of minor irrigation schemes. For the purposes of this, these schemes were classified into five broad categories:-
(a) Dug-well: It covers ordinary open wells of varying dimension dug or sunk from the ground surface into water bearing stratum to extract water for irrigation purposes. These are broadly masonary wells, kuchcha wells and dug-cum-bore wells. All such schemes are of private nature belonging to individual cultivator.
(b) Private shallow tube-well: It consists of a bore hole built into ground with the purpose of tapping ground water from porous zones. In sedimentary formations depth of a shallow tube well does not exceed 60-70 metres. These tube wells are either cavity tube-wells or strainer tube-wells. These are usually drilled by percussion method using hand boring sets and sometimes percussion rigs. Success and popularity of the scheme depends on how cheap they are. Coir structures formed by binding coir strings over an iron frame is being used as strainer. In shallow water table areas, bamboo frames are also used. Sometimes steel pipe casing are replaced by pipes constructed by rapping bituminised gunny bags over the bamboo frame. These are called bore wells, in which bore-hole is stable without a lining in the bottom portion and a tube is inserted only in the upper zone. The tube wells are generally operated for 6 to 8 hours during irrigation season and give yield of 100-300 cubic metre per day, which is roughly 2 to 3 times that of a dug well.
(c) Deep tube wells: It usually extends to the depth of 100 metre and more and is designed to give a discharge of 100 to 200 cubic meter per hour. The deep tubewell are drilled by rotary percussion or rotary cum percussion rigs. These tube wells operate round the clock during the irrigation season, depending upon the availability of power. Their annual out put is roughly 15 times that of an average shallow tube well and are usually constructed as public scheme which are owned and operated by government departments or corporations.
(d) Surface flow
irrigation scheme: These schemes use rainwater for irrigation purposes
either by storing it or by diverting it from a stream, nala or river. Some times, permanent diversions are
constructed for utilising the flowing water of a stream or river. Temporary diversions are also constructed
in many areas which are usually washed away during the rainy season. The small storage tanks are called ponds or
bundhis which are mostly community owned.
The command areas of such schemes are 20 hectares or less. The large storage tanks whose command varies
from 20 to 2000 hectares are generally constructed by government departments or
local bodies. These are the biggest
items of surface minor irrigation works.
Various types of such schemes are as follows:-
Storage schemes
Storage schemes include tanks and reservoirs which impound water of streams and rivers for irrigation purposes. After wells, tanks occupy a very important place under the minor irrigation programme. They provide nearly two-third of the total irrigation from minor sources in the states of Andhra Pradesh, Karnataka, Kerala, Maharashtra, Orissa and Tamilnadu. Tracts with undulating topography and rocky sub-strata are eminently suitable for tank irrigation. Besides, there exists scope for further construction of tanks in many areas. A large number of existing tanks in southern States have gone into disuse due to long neglect of repairs. Renovation of these tanks so as to restore the lost irrigation potential is being accorded priority under the minor irrigation programme.
The essential features of these schemes are (i) a bund or a dam which is generally of earth, but is also sometimes partly or fully masonary, (ii) anicut and feeder channels to divert water from adjoining catchments, (iii) a waste weir to dispose of surplus flood water, (iv) sluice or sluices to let out water for irrigation, and (v) conveyance and distribution system. The size of the storage is determined by the run-off expected on the basis of dependable monsoon rainfall in the catchment and by the fact whether the rainfall and cropping pattern would permit more than one filling of the tank. The best and direct method to calculate the runoff would be to gauge the stream flow at the proposed site for a number of years. However, as the observed data over a long number of years is normally not available, the run-off is computed on the basis of empirical formula found applicable from past experience for the region. When tanks are constructed in a series by bunding up the same valley at several points, some spill-over yield from the bunded catchment is also accounted for. In the gross storage provided some percentage provision is allowed for dead storage to be consumed by silting in course of time.
The irrigable command of the scheme is fixed on the basis of certain standard duties in terms of crop area irrigated per unit of water. The proposed cropping pattern is decided on the basis of past experience in the region. The flood discharge to be escaped over a waste weir is computed by empirical formula which from experience is found to generally hold good for the region. The design of the various component parts of the tank usually requires specialised engineering knowledge.
The tanks fail mainly due to two reasons: (i) silting of bed, and (ii) breach due to inadequate surplussing arrangement or bad maintenance of the bund. Renovation of derelict tanks so as to restore the lost irrigation potential is being accorded priority under the minor irrigation programme. The work of restoration generally consists of (i) strengthening or raising of bund, (ii) improving the surplussing capacity and (iii) occasional de-silting of bed. De-silting is costly but in some cases this is being rendered economical by utililsing the excavated earth for reclaiming part of the previously submerged land. The work of restoration is usually carried out by the State Public Works Department. After renovation, irrigation works below a specified acreage are handed over to the panchayats for maintenance. Works having higher irrigation capacity are maintained by the Public Works Department. The new works are usually taken up as State works by the State Public Works Department.
Diversion schemes, including hilly channels
These schemes aim at providing gravity flow irrigation by mere diversion of stream water supply without creating any storage. As compared to storage schemes they are economical but their feasibility is dependent on the presence of flow in the stream at the time of actual irrigation requirements. Essentially such schemes consist of (i) an obstruction (weir) or bund constructed across the stream for raising and diverting water; the weir being called anicut in the South, bandhara in Maharashtra and Gujarat, and thingal in the Assam region, and (ii) an artificial channel, known as kuhl in the hilly areas, pyne in Chhota Nagpur and Bihar and dong and ilhowkong in the Assam region. In case of small schemes which have prominent scope in the hilly tracts and foot hill plains, the water is usually diverted by constructing temporary bunds across the streams, made up of earth, stones or even bamboos. The discharge handled being of small order, the bund on the head of the channel is not provided with any gated structure for controlling and regulating the flow. Construction of work, is, therefore, simple and cheap and can be handled to a large extent by the people themselves. However, these constructions being temporary, require frequent renovation. The bunds are liable to be washed away by every major flood. The channels also get silted up and scoured frequently. It is essential that whenever such schemes aim at diverting higher discharges, say more than 5 to 10 cusecs, or tackle streams having high intensity of flood discharge, proper regulation structures equipped with suitable types of gates are provided. Weir has to be provided with scouring sluices in order to regulate the flow of silt in the off-taking channels. The construction of masonary weir is comparatively simpler and cheaper where rocky foundation is available beneath the streambed. The design of the weir on permeable and erodable foundation is more complicated and requires specialised engineering knowledge.
The irrigation capacity of the diversion schemes is dependent on the actual flow in the stream at the time the irrigation is required. The cold weather and the hot weather flow, therefore, need to be ascertained carefully before deciding the feasibility and economics of these schemes. This is particularly important in the case of non-snowfed flashy streams that spurt to lift suddenly in the rainy season after which the discharge in them dwindles down to appreciable quantity. Some diversion schemes are also constructed as kharif or monsoon channels supplying water only during the monsoon season. Such schemes are useful for providing supplemental irrigation for paddy and preliminary watering for sowing of rabi.
In most of the hilly tracts, small irrigation channels called ‘kuhls’ are the only means of irrigation. These channels carry water diverted from streams by constructing temporary or pucca bunds across the streams. These channels are often constructed in hazardous hilly terrain under very difficult conditions. To avoid seepage of water and for the sake of stability, these channels are lined in most of the reaches.
Water conservation-cum-ground-water recharging Schemes:
Under this head are included schemes which serve primarily one or more of the following purposes: (i) submerging agricultural land during monsoon for sowing post-monsoon crops, (ii) improving moisture regime of the adjoining fields down stream for raising of post-monsoon crops without irrigation and replenishing the ground water. An additional advantage of these schemes is that they help to conserve the soil. When constructed in the head water region serving catchment area of tanks down below, they serve the important purpose of retarding the silting rate of these tanks.
The system of water conservation through field embankments is peculiar to central Indian tracts and is commonly in vogue in the northern Madhya Pradesh, Bundhelkhand region of Uttar Pradesh and eastern Rajasthan. In the Bundhelkhand region, these works are popularly known as ‘bundhies’,which consist of earthen embankments thrown across gently sloping ground. During the rainy season, water is stored upstream and the land gets submerged. If the land slope is gradual, often large areas get submerged even by low embankments. Ordinarily, no direct irrigation is carried out and benefit is mostly due to submergence. In nearly all these areas, the soil is generally black which is retentive of moisture. After remaining submerged under water during the rainy season, the soil retains sufficient moisture to grow good rabi crops. The remaining water is let out and the submerged land released for cultivation. The other advantage of submerging land in this manner is that the first flood brings a lot of silt which acts as rich manure. By preventing free flow of water across steep gradient, the soil of the land is also conserved.
Ahars in Bihar, which store water for irrigation of paddy fields also function somewhat in a similar manner. Water is let out in October for irrigating the rice fields and the drained out fields in the bed of the ahars are cultivated with rabi crops. The head water tanks popularly in vogue in Orissa have a similar role to perform. These consist of bunds put up across slope at the head of gullies with the objective of impounding and diverting the cumulative run-off into the wider valley area down stream of the bunds by percolation, seepage and surface flow. Surface channels are provided in the flanks to carry floodwater received in excess of the storage capacity of the bunds during the monsoon season.
Percolation tanks primarily constructed for the purpose of recharging ground water are in vogue in Maharashtra, Tamilnadu, Kerala and Rajasthan.
Check-dams or rapats are in vogue in Rajasthan. They consist of bunds constructed across the streams for the purpose of retarding the surface flow and also the sub-surface flow to some extent by making the bed slope of the stream flattened. This results in increased percolation of water in the sub-soil with consequent increase of the ground water supply.
In the case of big embankments impounding large catchments, it is essential that adequate arrangements are made at one or both the flanks or at some other suitable location for passing the floodwater. If no such provision is made, the embankments are liable to be breached.
(e) Surface Lift Irrigation Scheme: In regions where the topography does not permit direct flow irrigation from rivers and streams, water has to be lifted into the irrigation channels. These works are similar to diversion schemes, but in addition pumps are installed and pump houses constructed. These schemes, being costly in operation, are feasible only in areas where (i) gravity flow irrigation is not possible (ii) there is keen demand for irrigation and cultivators are enthusiastic, (iii) water is available in the streams for at least about 200 days in a year, and (iv) cheap electric power is available. Installation of diesel operated pump sets for lifting water makes the operation and maintenance cost of these schemes exorbitantly high. However, for lifting small order of discharge by individual cultivators, portable diesel engine pump sets are feasible as they provide greater flexibility and mobility for installation at different points of the water source or sources.
Culturable Command Area (CCA): It is the area which can be physically irrigated from a scheme and is fit for cultivation.
Gross Irrigated Area: The total irrigated area under various crops during a year, counting the area irrigated under more than one crop during the same year as many times as the number of crops grown and irrigated.
Gross Irrigation Potential Created by a Scheme: The total gross area proposed to be irrigated under different crops during a year by a scheme. The area proposed to be irrigated under more than one crop during the same year is counted as many times as the number of crops grown and irrigated.
Irrigation Potential Utilised: The gross area actually irrigated during 1993-94 out of the gross proposed area to be irrigated by the scheme during the year.
Minor Irrigation Scheme: A Scheme having CCA up to 2,000 hectares individually is classified as minor irrigation scheme.
Medium Irrigation Scheme: A scheme having CCA more than 2,000 hectares and up to 10,000 hectares individually is a medium scheme.
Major Irrigation Scheme:
A scheme
having CCA more than 10,000 hectares is known as major irrigation scheme.
2.10 SELECTION OF PRIMARY ENUMERATORS:
2.10.1 The nodal department of States/UTs had full freedom for selecting a particular agency as primary enumerator. It could be the village level workers/patwari/panchayat inspector/any other agency suitable in a particular region. In selecting such agencies as enumerators the nodal departments were required to ascertain that they should have their associations with the farmers and their operation area be the villages under agricultural development programme. The information required in the primary schedules were to be obtained by personal inquiries from the farmers and physical verification/observation by the enumerators in respect of a particular scheme.
2.11 PROCEDURE FOR CONDUCTING CENSUS OPERATION:
2.11.1 The Primary enumerators while negotiating the schedules were to visit the owner of the minor irrigation scheme or its next neighbour and collect information on the basis of personal enquiry from him. The physical verification of the schemes was also to be done by the enumerators. The purpose of the census was to be explained to the farmers to win over their confidence in revealing the specific information in respect of minor irrigation works. Assurance that the data furnished by them would be kept confidential needed to be given to the farmers. Certain information relating to the schemes were to be collected by the enumerators by physical examination of the scheme.
After filling up the schedules, the enumerators were required to deposit all completed schedules with the Block Development Officer/Officer in-charge at the block level. The block level officer supplied all the schedules to the district level officer concerned who computerised the data contained in the prescribed schedules and passed on the floppy containing data as well as the schedules, to the Minor Irrigation Census Commissioner of the State/UT.