NEED OF MINOR IRRIGATION (Why M.I. ?)
An “Irrigation Project” comprising of dam, head works, main irrigation canals and complete network of distribution system with field channel takes a long time (generally in decades) to complete. Cost of such projects is also huge, often requiring foreign aid and loans. Such projects generally submerge a large area of habitation and forest which in turn give birth to problems of rehabilitation and environmental destruction respectively. Even completion of major irrigation projects leads to typical problems in its command area, like water logging and salinity. Seepage of water from irrigation canals and distributaries coupled with instinctive over irrigation provided by the farmers results in gradual increase in the ground water level which culminates in the problem of water logging and salinity. Even completion of a major irrigation project is not the end of woes for the people. Every irrigation project has definite life span, how much long it may be. We can't even imagine the magnitude of chaos, destruction and upheaval which will be caused by a defunct major irrigation project. Due to the above mentioned problems people started giving second thoughts to the “Utility” of major irrigation projects. This resulted in creating a need of Minor Irrigation Projects.
HISTORY OF MINOR WATER RESOURCES DEPARTMENTInitially Minor Irrigation started functioning as a wing of Agriculture Department in 1960. At that time a post of Agriculture Director (Engineering) in the scale of Superintending Engineer was created. Under him eight divisions of M. I. were also created. In order to facilitate implementation of M. I. Schemes throughout Bihar, the post of C.E., M.I., Bihar,
OBJECTIVE & ADVANTAGES OF MINOR IRRIGATION: ( What for M.I.?)
The department is functioning with the objective of providing irrigation by executing and maintaining small schemes having command area up to 2000 hectares by utilising available ground water & surface water.
Minor Irrigation Projects have great utility in
Ø Minor Irrigation Projects provide irrigation in comparatively very short duration on very small investment.
Ø Minor Irrigation Projects are suitable in exploiting abundantly available small catchments with their network of natural drains, in the State.
Ø A Minor Irrigation Project gets completed in as short a period as within three construction season.
Ø A Minor Irrigation Project doesn't involve problems of rehabilitation and environmental degradation.
Ø Construction of a Minor Irrigation Project requires very small area; hence the land to be acquired by the Government for Minor Irrigation Projects is also not a problem.
Ø High patches of land in the command of a Major Irrigation Project don't get irrigated. Such patches of land could be provided irrigation with the help of a suitable type of Minor Irrigation Project. Thus a Minor Irrigation Project works as complimentary as well as supplementary project to a Major Irrigation Project.
Ø "Conjunctive Irrigation", which is nothing but exploitation of G/W in the command of Irrigation Project, does not allow the G/W to rise. This keeps at bay the problems of “Water-Logging” and “Salinity”.
The above illustrated points underline the importance as well as utility of Minor Irrigation in overall efficient and optimum management of water as an invaluable natural resource.
TYPE OF MINOR IRRIGATION SCHEMES
Minor Irrigation Schemes could broadly be divided in following categories:-
1. Surface Water Flow Irrigation Schemes
2. Surface Water Lift Irrigation Schemes
3. Ground Water Irrigation Schemes
1. Surface Water Flow Irrigation Schemes :- As the name suggests in this type of scheme, surface water under gravity flow is utilised for irrigation purpose. Surface water flow irrigation projects comprising storage and diversion works occupy a conspicuous place in the complex hierarchy of irrigated agriculture in the country particularly in the undulating areas and the hilly regions. These are the only means of irrigation available in major part of the chronically drought affected areas. Such schemes are labour intensive and offer extensive opportunities for rural employment. These are also of considerable help in recharging the resource of ground water in the hard rock areas. Construction period of such schemes is rather long in comparison to other categories of Minor Irrigation schemes. Construction cost is also more in comparison to other Minor Irrigation schemes, but there is no recurring cost involved in providing irrigation once scheme is complete. Surface water Flow Irrigation Schemes could further be classified in following two categories:-
A. Surface Water Storage Irrigation Schemes:- In such schemes, water brought in by seasonal rivers, rivulets, drains etc. during rainy season is stored by constructing small earthen dams at appropriate place. In lean season such stored water is provided for irrigation through a network of distribution channels. Ponds, Check dams, traditional Ahar & Pynes etc. are examples of this type of scheme.
B. Surface Water Diversion Schemes:- In this type of scheme an "obstacle" or "barrier" is constructed across the small seasonal river, rivulet, drain etc. at an appropriate place. This results in increasing the water level of the water body at that place and flow of water is diverted into irrigation channels. Depending upon requirement, cost involved, terrain & topography of the site the "obstacle" or "barrier" constructed could be of "permanent" or "temporary" nature. Weir is an example of such type of scheme.
2. Surface Water Lift Irrigation Schemes are playing a very useful role on sites where available surface water cannot be used for irrigation through construction of flow irrigation schemes due to topographical limitations. In such type of schemes surface water available in flowing water body is lifted by means of pumps and is made available for irrigation. The pumps are either electricity or diesel driven. Investment on these schemes is comparatively less and these can be completed very quickly but recurring cost of providing irrigation is quite high due to high energy costs. Besides this, as the structures like Intake well, Pump house are constructed at any one bank of flowing water body, fields on only that side can be irrigated. Some times due to shifting or change in water course of river, intake well becomes defunct. Very often "Intake Well" gets filled with sand & silt. To overcome these problems of Lift Irrigation Scheme an innovative lift irrigation scheme by the name "Barge" has been launched...
"Barge" Lift Irrigation Scheme:- In this scheme a diesel pump is fitted on a floating platform made up of large hallow iron cylinders (Pontoon). Due to floating platform this scheme achieves the much required "mobility" rendering it very useful. As the Barge can be towed it can be moved to either of the two banks of river and fields on both sides of river can be irrigated. There is no risk of scheme becoming defunct due to siltation or shifting of river course.
3. Ground Water Irrigation Schemes:- As the name suggests, in this type of irrigation scheme "ground water" is lifted by means of electricity or diesel driven pumps and is provided for irrigation. Ground water exploitation forms the major part of the minor irrigation programme and includes construction of dug wells, dug-cum-bore wells, filter points, private shallow tube wells and deep public or state tube wells. It is essentially a people's programme implemented primarily through individual and cooperative efforts with finance obtained mainly from institutional sources. The programme thus, imposes very little burden on the public exchequer.
The programme of ground water exploitation has become a vital factor in promoting modern agriculture through high yielding crops. Ground water is abundantly available in most part of the state and hence provides instant and assured sources of irrigation in the hands of the cultivators. It provides critical help in improving the status of irrigation supply and in controlling water logging and salinity in the canal commands. The programme also provides abundant opportunities for rural employment.