Different types of irrigation and irrigation systems storage

Irrigation is the artificial application of water to the soil or agricultural field. It is the replacement or supplementation of rainwater with another source of water. It is used in dry areas and during periods of inadequate rainfall. 

• Applications:
  • to assist in the growth of agricultural crops and plants by maintaining with the minimum amount of water required.
  • suppressing weed growth in grain fields.
  • preventing soil consolidation.
  • Protecting plants against frost
  • for dust suppression
  • Disposal of sewage, and in mining
  • Maintenance of landscape
• Methods: Every irrigation method has advantages and disadvantages. Therefore before choosing a specific technique, the irrigation engineer must evaluate all the factors and choose method which is most suited for local condition.
  • Surface irrigation:  In this technique water flows and spreads over the surface of the land. 
    • Surface irrigation technique is broadly classified as basin irrigation; border irrigation; furrow irrigation and uncontrolled flooding
  • Sprinkler irrigation: It is a method of applying irrigation water which is similar to rainfall. Water is sprayed into the air and irrigate entire soil surface. Water is distributed through a system of pipes usually by pumping.
  • Sub-surface irrigation method: It involves irrigation to crops by applying water from beneath the soil surface either by constructing trenches or installing underground perforated pipe lines or tile lines.
    • Subsurface irrigation is a highly-efficient watering technique.
    • It reduces outdoor water use by 30 to 40 percent.
• Irrigation in India:
  • In India, the irrigated area consists of about 36 per cent of the net sown area. Presently, the agriculture sector accounts for about 83% of all water uses.
  • There are various techniques of irrigation practices in different parts of India. These methods of irrigation differ in how the water obtained from the source is distributed within the field. In general, the goal of irrigation is to supply the entire field homogeneously with water, so that each plant has the amount of water it needs, neither too much nor too little.
  • Irrigation in India is done through wells, tanks, canals, perennial canal, and multi-purpose river valley projects.
• Types of Irrigation in India:
  • Well and Tube Well Irrigation:
    • Wells are mainly found in U.P., Bihar, Tamil Nadu, etc. There are various types of wells – shallow wells, deep wells, tube wells, artesian wells, etc.  
      • Deep wells are more suitable for the purpose of irrigation as water from them is available throughout the year.
    • At places where ground water is available, a tube-well can be installed near the agricultural area.
      • A deep tube well worked by electricity, can irrigate a much larger area (about 400 hectares) than a surface well (half hectares). Tube wells are mostly used in U.P., Haryana, Punjab, Bihar and Gujarat.
    • Merits:
      • Well is simplest, cheapest and independent source of irrigation and can be used as and when the necessity arises. Several chemicals such as nitrate, chloride, sulphate, etc. found in well water add to the fertility of soil. More reliable during periods of drought when surface water dries up.
    • Demerits: 
      • Only limited area can be irrigated.
      • In the event of a drought, the ground water level falls and enough water is not available.
      • Tubewells can draw a lot of groundwater from its neighbouring areas and make the ground dry and unfit for agriculture.
  • Canal Irrigation:
    • Canals can be an effective source of irrigation in areas of low level relief, deep fertile soils, perennial source of water and extensive command area. Therefore, the main concentration of canal irrigation is in the northern plain of India, especially the areas comprising Uttar Pradesh, Haryana and Punjab.
    • The digging of canals in rocky and uneven areas is difficult and uneconomic. Thus, canals are practically absent from the Peninsular plateau area. However, the coastal and the delta regions in South India do have some canals for irrigation.
    • Two types:
      • Inundation canals, which are taken out from the rivers without any regulating system like weirs etc. at their head. Such canals provide irrigation mainly in the rainy season when the river is in flood and there is excess water.
      • Perennial Canals are those which are taken off from perennial rivers by constructing a barrage across the river. Most of the canals in India are perennial.
    • Merits: 
      • Most of the canals provide perennial irrigation and supply water as and when needed.
      • This saves the crops from drought conditions and helps in increasing the farm production.
    • Demerits: 
      • Many canals overflow during the rainy season and flood the surrounding areas.
      • Canal irrigation is suitable in plain areas only.
  • Tank Irrigation:
    • A tank is developed by constructing a small bund of earth or stones built across a stream. The water impounded by the bund is used for irrigation and other purposes. Tank comprises an important source of irrigation in the Karnataka Plateau, MP, Maharashtra, Odisha, Kerala, Bundelkhand area of UP, Rajasthan and Gujarat.
    • Merits: 
      • Most of the tanks are natural and do not involve heavy cost for their construction and have longer life span.
      • In many tanks, fishing is also carried on, which supplements both the food resources and income of the farmer.
    • Demerits: 
      • Many tanks dry up during the dry season and fail to provide irrigation when it is required.
      • Lifting of water from tanks and carrying it to the fields is a strenuous and costly exercise.
  • Drip Irrigation:
    • In drip irrigation, water is applied near the plant root through emitters or drippers, on or below the soil surface, at a low rate varying from 2-20 liters per hour. The soil moisture is kept at an optimum level with frequent irrigations.
    • Among all irrigation methods, drip irrigation is the most efficient and can be practiced for a large variety of crops, especially in vegetables, orchard crops, flowers and plantation crops.
    • Merits: 
      • Fertilizer and nutrient loss is minimized due to localized application and reduced leaching.
      • Field leveling is not necessary.
      • Recycled non-potable water can be used.
      • Water application efficiency increases.
      • Soil erosion and weed growth is lessened.
    • Demerits: 
      • Initial cost can be more,
      • can result in clogging,
      • wastage of water, time and harvest, if not installed properly.
  • Sprinkler Irrigation:
    • In this method, water is sprayed into the air and allowed to fall on the ground surface somewhat resembling rainfall. The spray is developed by the flow of water under pressure through small orifices or nozzles. The sprinkler irrigation system is a very suitable method for irrigation on uneven lands and on shallow soils.
    • Nearly all crops are suitable for sprinkler irrigation systems except crops like paddy, jute, etc. The dry crops, vegetables, flowering crops, orchards, plantation crops like tea, coffee are all suitable and can be irrigated through sprinklers.
    • Merits: 
      • Suitable to all types of soil except heavy clay.
      • Water saving.
      • Increase in yield.
      • Saves land as no bunds etc. are required.
    • Demerits: 
      • Higher initial cost.
      • Under high wind conditions and high temperature distribution and application efficiency is poor.
  • Other Types of Irrigation:
    • Furrow Irrigation: Furrow irrigation is a type of surface irrigation in which trenches or “furrows” are dug between crop rows in a field. Farmers flow water down the furrows and it seeps vertically and horizontally to refill the soil reservoir. Flow to each furrow is individually controlled.
      • One of the difficulties of furrow irrigation is ensuring uniform dispersion of water over a given field.
      • Another difficulty with furrow irrigation is the increased potential for water loss due to runoff.
    • Surge Irrigation: Surge irrigation is a variant of furrow irrigation where the water supply is pulsed on and off in planned time periods. I.e. It is the intermittent application of water used to improve distribution uniformity along a furrow. It works on the principle that dry soil infiltrates water faster than wet soil. When soil is wet is seals because the soil particles at the surface consolidate.
      • The wetting and drying cycles reduce infiltration rates resulting in faster advance rates and higher uniformities than continuous flow.
    • Ditch Irrigation:  A ditch is a small to moderate depression created to channel water.  A ditch can be used for drainage, to drain water from low-lying areas, alongside roadways or fields, or to channel water from a more distant source for irrigation.
    • Sub Irrigation or Seepage Irrigation: It is a method of irrigation where water is delivered to the plant root zone from below the soil surface and absorbed upwards. The excess may be collected for reuse.
      • Advantages: water and nutrient conservation, and labor-saving.
      • Disadvantage: The outfitting cost is relatively high. Potential problems, such as the possibility of increased presence of disease in recycle water.