TANK IRRIGATION
- Water storage systems known as tanks are created by constructing small bunds made of earth or stones across streams.
- Tank irrigation is commonly practiced in the peninsular plateau region, with Andhra Pradesh, Telangana, and Tamil Nadu being the top states.
- The Godavari river and its tributaries' catchment areas have a significant number of tanks.
- Tank irrigation is mainly concentrated in the Nellore and Warangal districts.
The tank irrigation is practiced mainly in peninsular India due to the following reasons.
- The region's undulating terrain and hard rock make the construction of canals and wells challenging.
- The rock structure of the area causes minimal percolation of rainwater, resulting in a limited supply of groundwater.
- Most rivers in the region are seasonal and do not provide year-round canal water.
- During monsoon season, several streams turn into torrents. Building tanks to impound this water is the only viable solution.
- The dispersed distribution of the population and agricultural lands also supports the use of tank irrigation.
Merits of Tank Irrigation
- Tank construction is often inexpensive, as most tanks are naturally occurring, allowing even individual farmers to have their own tanks without heavy costs.
- Tanks are typically built on rocky beds, giving them a longer lifespan compared to other irrigation systems.
- Many tanks also support fishing, providing additional food resources and income for farmers.
Demerits of Tank Irrigation
- Tank irrigation faces the issue of many tanks drying up during the dry season, failing to provide irrigation when it is most needed.
- The silting of the tank bed poses a significant problem, requiring regular desilting to be carried out.
- A substantial amount of water evaporates from the large expanse of shallow water, rendering it unavailable for irrigation.
- Tanks occupy significant areas of cultivable land, leading to the adoption of alternative sources of irrigation in many regions, and the reclamation of dry tank beds for agriculture.
- Lifting water from tanks and transporting it to fields is a laborious and expensive task, deterring the use of tanks as an irrigation source.
WELLS AND TUBEWELLS
- A well is a dug hole in the ground used to obtain subsoil water. Typically, they are 3-5 meters deep, but can be deeper, up to 15 meters or more.
- Several methods are used for well irrigation, including the Persian wheel, rehr, charas or mor, and dhinghly (lever).
- Well irrigation is popular in areas with sufficient sweet ground water, such as the Great Northern Plain, deltaic regions of the Mahanadi, Godavari, Krishna, and Cauvery, parts of the Narmada and Tapi valleys, and the weathered layers of the Deccan Trap and crystalline rocks and sedimentary zones of the Peninsula.
- However, much of Peninsular India is unsuitable for well irrigation due to rocky structures, uneven surfaces, and lack of underground water.
- Brackish ground water in large dry tracts of Rajasthan, adjoining parts of Punjab, Haryana, and Gujarat, and some parts of Uttar Pradesh is unsuitable for irrigation and human consumption, making it unsuitable for well irrigation.
- A tubewell is a deeper well that uses a pumping set operated by an electric motor or a diesel engine to lift water. The first tubewell in India was sunk in Uttar Pradesh in 1930.
Some of the factors affecting tube well irrigation are as follows-
(i) There should be sufficient quantity of ground water because a tube well can generally irrigate 2 hectares per day against 0.2 hectares per day irrigated by an ordinary well.
(ii) For effective use of a tube well, the water level should be around 15 meters deep. However, if the water table exceeds a depth of 50 meters, the expense of pumping water out from the well becomes impractical.
(ii) There should be regular supply of cheap electricity or diesel so that water from the tube well can be taken out at the hour of need.
(iv) To ensure the economic viability of a tube-well, it is essential to have fertile soil in its immediate vicinity. This would result in a demand for irrigation and ultimately lead to an increase in farm production, which can help to offset the costs associated with constructing and operating the tube-well.
Merits of Well and Tubewell Irrigation
- Well irrigation is an affordable and simple source of irrigation for farmers in India.
- Wells provide an independent source of irrigation that can be used as needed, unlike canal irrigation which is controlled by outside agencies.
- Excessive irrigation from canals can lead to problems such as soil salinity, which is not a concern with well irrigation.
- Wells can be dug at any convenient location, while canal irrigation is limited to the extent of the canal.
- Well water contains beneficial chemicals such as nitrate, chloride, and sulfate that can increase soil fertility.
- Unlike canal irrigation, there is no regular cost associated with well irrigation for farmers.
- The first tubewell in India was installed in Uttar Pradesh in 1930.
Demerits of Well and Tubewell Irrigation
- The area that can be irrigated is limited. Typically, a single well can only irrigate between 1 to 8 hectares of land.
- Overuse of water can cause the well to dry up, rendering it useless for irrigation purposes.
- During periods of drought, the water table may drop, resulting in insufficient water in the well when it is most needed.
- Tubewells can extract excessive groundwater from surrounding areas, causing the soil to become dry and unsuitable for farming.
- Well and tubewell irrigation is not feasible in areas with brackish groundwater.
CANALS
- Areas with low level relief, deep fertile soils, perennial water sources, and extensive command areas can benefit from canal irrigation.
- The northern plain of India, particularly Uttar Pradesh, Haryana, and Punjab, is the primary focus of canal irrigation.
- Due to the challenges of digging canals in rocky and uneven terrain, they are not practical or cost-effective in such areas, such as the Peninsular plateau.
- Despite this, some coastal and delta regions in South India do have canals for irrigation purposes.
Canals in India are of two types
(1) Inundation canals
- Inundation canals are channels that are extracted from rivers without any regulation mechanisms, such as weirs, at their source.
- These canals are primarily utilized for irrigation during the rainy season when there is a surplus of water due to the river's flood.
- However, once the rainy season concludes, the river's flood recedes, and the water level falls below the canal's source, resulting in the canal drying up.
- Some canals extracted from the Satluj river in Punjab were of this type.
- Due to the uncertainty of irrigation from these types of canals, they have been transformed into perennial canals.
(ii) Perennial canals
- Perennial canals are created by building a barrage across a river to divert water for irrigation purposes.
- In India, the majority of canals are now perennial.
- Canal irrigation is most prevalent in the northern plains of India, including Uttar Pradesh, Punjab, Haryana, Rajasthan, and Bihar.
- Other important states for canal irrigation in India include Andhra Pradesh, Maharashtra, Karnataka, Madhya Pradesh, Chhattisgarh, Odisha, and Tamil Nadu, located in the central and southern parts of the country.
Some of the Important canals in India-
Uttar Pradesh
1. Upper Ganga Canal.
- The Upper Ganga Canal originates from Kankhal (Hardwar) from the river Ganga.
- Approximately 700,000 hectares of land in the upper region of the Ganga-Yamuna Doab are irrigated by this canal.
- At Mainpuri, it meets the Lower Ganga Canal, which significantly increases the water volume.
- Beyond Mainpuri, these two canals continue to flow independently.
2. Lower Ganga Canal.
- This canal was taken from the Ganga near Narora
3. Sharda Canal.
- The Sharda Canal derives its name from the Sharda river located near the Indo-Nepal border at Banbasa.
- Construction of the canal was finished in 1928, and it has become one of the longest canal systems globally.
4. Eastern Yamuna Canal.
- It takes off from the river Yamuna at Faizabad, It was constructed in 1831.
5. Agra Canal.
- This canal is taken from the right bank of the Yamuna at Okhla (Delhi).
6. Betwa Canal
- It was Built in the Third Five Year Plan
- It irrigates some areas of Jhansi, Jalaun and Hamirpur districts.
Apart from the above mentioned major canals, some other camals such as Ken, Chambal, Dharan and Son canal also irrigate some areas in the southern part of Uttar Pradesh.
Punjab
1. Upper Bari. Doab Canal.
- This canal is taken from the Ravi river at Madhopur near Pathankot. Construction of this canal started in 1849 and completed in 1859. It irrigates about 3 lakh hectares in Gurdaspur and Amritsar districts.
2. Sirhind Canal.
- This canal was taken from the Satluj river at Rupnagar (Ropar) in the year 1886-87.
3. Bhakra Canal.
- It draws water from the Bhakra dam buit across the Satluj river. It was completed in 1954.
- It irrigates a vast area of Punjab, Haryana and Rajasthan.
4. Bist Doab Canal.(Beas-Satluj)
- It is a part of the Bhakra Nangal Project.
- It irrigates areas like Jalandhar and Hoshiarpur districts.
Bikaner and Beas are two additional initiatives that offer irrigation services to various regions of Punjab, as well as the adjacent states of Haryana and Rajasthan.
Haryana
1. The Wesern Yamuna Canal.
- It takes off from the right bark of the Yamuna at Tajewala.
- It was built by Feroze Shah Tughlak.
2. Bhakra Canal.
- After irrigating Punjab areas. the Bhakra canal enters Haryana near Tohana and irrigates large parts of Hisar, Fatehabad and Sirsa districts.
3. Jui Canal.
- Jui Canal is a lift irrigation system that has been specifically designed to provide irrigation to the semi-desert area of Bhiwani and the surrounding regions.
4. Gurgaon Canal.
- It takes off from the Yamuna at Okhla in Delhi.
5. Andhra Pradesh
- Canal irrigation in Andhra Pradesh is the highest in South India and next only to Uttar Pradesh.
- The Krishna, Godavari, and Tungabhadra rivers are the primary sources of the major canals in Andhra Pradesh.
- The areas that receive major canal irrigation in Andhra Pradesh are the coastal regions and deltas.
The Godavari delta project comprises of two weirs-
the Dowlaiswaram and the Ralli, which were completed in 1846.
The Krishna delta project comprise
- Vijayawada anicut. Sunkesula anicut across the Krishna and the Tungabhadra
- The Kurnool-Cuddapah canal was taken off from the Tungabhadra in 1816.
- The Nagarjunasagar Project consists of a dam across the Krishna River in Nalgonda district from where two canals have been taken off.
Bihar
1. Sone Canals.
- The Sone river in India has served as the source for two canals: the Eastern Sone Canal and the Western Sone Canal.
- In 1857, the Eastern Sone Canal was constructed by diverting water from the Sone river at Varun.
- Similarly, the Western Sone Canal was developed by taking water from the same river, but at Dehri.
- To increase the irrigation potential of the region, these canals were built to channel water from the Sone river to nearby areas.
- While the Eastern Sone Canal starts from Varun and runs towards the east, the Western Sone Canal originates from Dehri and flows in a westerly direction.
2. Kosi Canals.
- Two canals known as the Eastern and the Western Kosi Canal have been taken from the easter and the western banks of the river respectively by constructing a multipurpose dam near the Indo Nepal border
3. Gandak Canals
West Bengal
- Although most parts of West Bengal receive sufficient rainfall and do not require irrigation, still some parts of the state do feel the necessity of irrigation.
- More than one third of the net irrigated area is irrigated by canals.
The Mayurakshi project
It was completed in 1951 at Tilpara. Two canals have been taken from this project to irrigate large areas in Bir Bhum, Murshidabad and Bardhaman districts.