- Groundwater is a critical resource for food security, providing 40% of the world’s irrigation.
- Millions of farmers depend on groundwater irrigation to help produce 40% of the world’s agricultural production, including a large proportion of staple crops like rice and wheat.
- Yet, groundwater reserves are becoming rapidly depleted in many important agricultural regions across the globe
- The geographical conditions coupled with nature of monsoon rainfall in India make irrigation indispensable for sustainable agricultural development.
- Rainfall in India is uncertain, unreliable, irregular, variable, seasonal and unevenly distributed because of seasonal and erratic nature the main rain bringing south-west monsoon which often fails to keep its date.
- While the extent of current and projected groundwater depletion is well documented, the potential impact of this depletion on food production remains poorly quantified.
Thus, it is especially critical to quantify the impacts of groundwater depletion on crop production in India—the world’s largest consumer of groundwater.
The need for irrigation in India
- Regional and spatial variation: The north-western parts of the country which consists of states such as Punjab, Haryana. Rajasthan and western parts of Uttar Pradesh often suffer from high variability of rainfall.
- There are large variations in the spatial distribution of rainfall. On the one end of the scale, there are areas in Meghalaya which receive more than 1000 cm of annual rainfall while on the other end there are parts of the Thar Desert which receive less than 10 cm of rain in a year.
- Insufficient rainfall: Only 30.2 percent of the cultivated area in India receives sufficient rainfall where the annual rainfall exceeds 100 cm.
- About 7 percent of the cultivated area receives 75 to 100 cm of annual rainfall and 34.1 percent of the cultivated area receives less than 75 cm of annual rainfall. Hence, about two thirds of the total cropped area needs irrigation facilities.
- Monsoon gaps: Even in areas of high rainfall, irrigation is necessary to increase farm productivity because Indian rainfall is characterized by monsoon gaps.
- The gap in rainfall pattern when rainfall does not occur for two or more weeks during the rainy season and the crops may be badly damaged in the absence of irrigation facilities.
- Seasonal nature of Indian Monsoon: The chief characteristic of the Indian monsoon is that it is seasonal as about 75 percent of the rainfall in India is caused by the south-west monsoons which are active only for 3-4 months in a year.
- The remaining 8-9 months are marked by dry season when irrigation is surely needed for successful growing of the crops.
- The duration of dry season varies from 5 months in Kerala to over 9 months in north-west India.
- Torrential rainfall: Rainfall in most parts of India is torrential due to which soil is unable to absorb water and much of the surface water goes waste. This loss of water due to wasteful flow is usually compensated by irrigation.
- Culture of growing water intensive crops: India has a culture of growing water intensive crops such as paddy, Sugarcanet.c.
- Sometimes, such crops are grown in water scarce drier regions of the country supported fully by irrigation facilities.
Case Study: Cultivation of water-intensive crops in dry regions
- Paddy cultivation in Punjab is fully dependent on canal irrigation while Sugarcane cultivation in Marathawada region of Maharashtra is fully supported by ground water irrigation.
- Similarly, Sugar Cane cultivation in Ananthpur district of Andhra Pradesh is supported by groundwater irrigation.
- These unethical agricultural practices in these drier regions have caused scarcity of water resources coupled with problems of soil salinity and alkalinity.
Types of irrigation
- Surface Irrigation: In this system of irrigation, water moves over and across the land by simple gravity flow in order to wet it and to infiltrate into the soil.
- It can be subdivided into furrow, border strip or basin irrigation.
- It is often called flood irrigation when the irrigation results in flooding or near flooding of the cultivated land.
- Localized Irrigation: Localized irrigation is a system where water is distributed under low pressure through a piped network in a pre-determined pattern, and applied as a small discharge to each plant or adjacent to it.
- Drip irrigation, spray or micro-sprinkler irrigation and bubbler irrigation belong to this category of irrigation methods.
- Drip Irrigation: This type of irrigation is also known as trickle irrigation in which water is delivered at or near the root zone of plants, drop by drop.
- Sprinkler Irrigation: In this type of irrigation technology, water is piped to one or more central locations within the field and distributed by overhead high-pressure sprinklers or guns.
- A system utilizing sprinklers, sprays, or guns mounted overhead on permanently installed risers is often referred to as a solid-set irrigation system.
- Sub-irrigation: This irrigation system is also called seepage irrigation which has been used for many years in field crops in areas with high water tables.
- In this method an artificially raising the water table to allow the soil to be moistened from below the plant root zone.
- Sub-irrigation technique is also used in commercial greenhouse production, usually for potted plants. In this system, water is delivered from below, absorbed upwards, and the excess collected for recycling.
Methods of irrigation in India
Government initiatives towards promotion of sustainable agriculture practices in India
Pradhan Mantri Krishi Sinchayee Yojana
Nodal Ministry: Ministry of Water Resources, River Development and Ganga Rejuvenation (MoWR, RD & GR)
- Government has merged previous irrigation and water management programmes such as Accelerated Irrigation Benefit Programme (AIBP), Integrated Watershed Management Programme (IWMP) and On Farm Water Management (OFWM) scheme.
- It aims to create irrigation potential through ground water and assists in any new construction of ground water well based on the data/ knowledge available for the area with the Central/ State Agencies involved in ground water development and management
- Development of ground water Resources: The scheme aims to encourage Groundwater development through Dug wells, Dug Cum Bore wells in hard rock area tapping shallow aquifers and shallow/deep tube wells in alluvium areas tapping prolific aquifers.
- Pump sets and Solar pumps: The scheme proposes for each well to be provided with electric/solar pumps for water lifting.
- It also provides for 75% electric and 25% solar pumps to be considered for a cluster/proposal.
- Adoption of Sustainable water conservation practices: The scheme aims to promote and adopt water use efficiency & conservation practices such as drip/sprinkler, diversification to low water demand crops, promoting on-farm rainwater harvesting etc.
- Scientific studies: In order to minimize the failure of wells, the scheme aims to promote geophysical and hydro-geological investigations may be carried out for proper site selection.
Per Drop More Crop
- It is a component under Pradhan Mantri Sichayi Yojna which aims to promote drip irrigation practices and promote sustainability in the field of irrigation.
- It aims to save water for irrigation as well as check land degradation by checking washing off of key nutrients by flood irrigation and soil salinity caused by it.
Micro Irrigation Fund scheme
- Nodal Agency: National Bank for Agriculture and Rural Development (NABARD)
- Micro Irrigation Fund with a corpus of Rs. 5,000 crore has been created to expand the coverage of micro irrigation facilities by taking up special and innovative projects.
- The fund aims to incentivize micro irrigation beyond the provisions available under PMKSY to encourage farmers to install micro irrigation systems.
Water Productivity Mapping of Major Indian Crops
Nodal Agency: NABARD
- It is a report which has been published by NABARD. Water Productivity mapping is a technique to determine productivity of water in a specific region for a specific type of crop.
- It compares the amount of water used per cubic meter of irrigation for a particular crop with same amount of irrigation’s productivity in other region of a country for same crop.
- For Example: Punjab produces only 0.22 kg of rice for per cubic meter of irrigation while Jharkhand and Chhattisgarh on the other hand produces 0.75 kg and 0.68 kg of rice for same amount of water.
- The report consists of mapping a water atlas for ten major crops such as rice, wheat, maize, red gram or tur, chickpea or channa, sugarcane, cotton, groundnut, rapeseed-mustard and potato.
Soil moisture map
- India has published its first soil moisture map which has been developed using hydrological model.
- Soil moisture is of paramount importance in various applications e.g. hydrology, agriculture and meteorology.
- The mapping of different areas and different types of soil to analyze soil moisture is called soil moisture map.
- It has been prepared by IIT Gandhinagar and the India Meteorological Department (IMD).
- It has taken into consideration soil, vegetation, land use and land cover among other parameters apart from rainfall data.
- It suggest that deficit soil moisture conditions are likely during the winter sowing season in Gujarat, Bihar, Jharkhand, Tamil Nadu and southern Andhra Pradesh.
- It predicts that in western Uttar Pradesh, Bundelkhand, and Chhattisgarh soil moisture is Advanced knowledge about soil moisture is crucial for farmers to plan their crops and the required irrigation in the field.
Following are the advantages of the soil moisture maps:
- Optimal irrigation in farms
- Identify areas being over-irrigated
- Improved flood risk estimation
- Monitor agricultural drought in near real time
- Improved weather forecast
- Analyse the impact of an irrigation project
- Identify the irrigated area by an irrigation source
- Automatic billing of farm based on the actual irrigation
- Estimation of actual evapotranspiration taking place
- Estimation of area getting degraded
- Likely to be normal or surplus in the Rabi season.
Irrigation is one of the important sectors of agriculture in India which has ability to transform drier regions into agriculturally prosperous regions. Further, it has helped agriculture by checking the vagaries of erratic monsoon pattern and phenomenon such as monsoon gaps. By providing sufficient water to commercial and cash crops, the improvement in irrigation sector of India will reflect on India’s urge of doubling the farmer’s income and agricultural export by 2022.