Water use efficiency in most irrigation systems in India – Essay
The water use efficiency in most irrigation systems is low in the range of 30% to 40% against an ideal value of 60%. Many of the irrigation systems have become dilapidated due to silting of canal system, weed growth and breakage of regulatory structures leading to overuse of water.
Introduction of irrigation in any area inevitably results in disturbance of the ground water balance that existed prior to irrigation. Because of seepage from water conveyance systems and deep percolation losses from farms during irrigation, the rate of recharge to the ground water increase, resulting in the progressive rise of the water table, which if unchecked, leads to water logging in irrigated lands.
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Bio-drainage is an effective drainage measures particularly in dry arid regions. Plantation of properly selected species of trees at suitable locations can meet the total drainage requirements without any loss to agricultural produce.
Water Shed Plus:
Watershed is a geo-hydrological area that drains at a common point. The watershed approach is a project based development plan that follows a ridge to valley approach for water harvesting, water conservation and includes afforestation, drainage line treatments, pasture developments and improving agricultural production in rainfed areas. A paradigm shift in the approach to watershed development came in 1995-96, under the guidance of Dr. C.H.H. Hanumantha Rao.
The new paradigm of watershed plus recognises the need to involve the community as a necessary condition for the sustainability of a watershed programme. It seeks to ensure convergence of all other programmes that promote economic activities and generate increased employment opportunities.
Watershed Development:
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Of the 142.6 million hectares of net cultivated area, 57 million hectares (40 per cent) is irrigated. The remainder 85.6 million hectares (60 per cent) is ranifed. Rainfed areas comprise primarily of the arid and semi-arid regions and the drought prone areas.
Going by the past trend, the average expansion of irrigation is around four million hectares every five years. Extrapolating this trend, it is projected that another 20 million additional hectares may be brought under irrigation in the next 25 years. This will still leave 65 million hectares, nearly half of the cultivated area, under rainfed conditions.
Watershed
A watershed (or catchment) is a geographic area that drains to a common point which makes it an ideal planning unit for conservation of soil and water. A watershed may comprise of one or several villages, contain both arable and non-arabel lands, various categories of land-holdings and farmers whose actions may impact on each others’ interest. The watershed approach enables a holistic development of agriculture and allied activities in the area taking into account land=use based on crops, horticulture, agro forestry sick-pastures and forests. Under the ‘Common Approach for Watershed Development’ the watershed development programmes have been reconstructed by retaining the technical strengths of the older programmes and incorporating the lessons learnt from successful projects specially on community participation. it is now mandatory for the ‘Watershed Development’ to be planned, implemented, monitored and maintained by the watershed community.
Rainwater Harvesting:
It is a technique of increasing the recharge of groundwater by capturing and storing rainwater locally in subsurface water reservoirs to meet the household needs. The objectives of the rainwater harvesting are to:
1. Meet the ever increasing demand for water.
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2. Reduce the run-off which chokes drains,
3. Avoid the flooding of roads.
4. Augment the groundwater storage and raise the water table.
5. Reduce groundwater pollution.
6. Improve the quality of groundwater.
7. Reduce the soil erosion, and
8. Supplement domestic water requirement during summer and drought.
Sukhomajri in Haryana
Sukhomajri village in Ambala district of Haryana has earned a nationwide acclaim for the way in which the people of the village have used their forest and water. it has become a model of community participation management. Sitting Silting up of Sukhana lake near Chandigarh led to water shortage in the village. Four check dams were constructed and tress planted in the catchments area of the lake. This raised the water level in the village. The income from cutting of bhabhar grass and harvesting of mungri or forage grass has changed the face of the village.
Several low cost techniques are available to recharge the groundwater aquifers. Among them mention may be made of roof water harvesting, refilling of dug wells, recharging of hand pumps, construction of percolation pits, trenches around fields, and bunds and stop dams on small rivulets. Such techniques are not new to the country. Rainwater has been harvested in India since antiquity.
There are evidences of advanced water harvesting systems like canals, tanks, embankments and wells. In hills and mountains, rainwater harvesting from rooftops and springs was carried over long distances with the help of bamboo pipe.
In arid and semiarid regions, structures like wells and step-wells were built to tap groundwater aquifers. Rainwater harvesting from rooftops used artificially created catchments, which drained water into artificial ‘kunds’ in Rajasthan. Construction of tanks throughout the country has been very popular measure of conserving rainwater. Renovation and modernisation of these structures will not only increase the recharge but also the efficiency of water use of various purposes.