The concept of irrigation storage structure refers to a water storage system created by building tanks, cisterns, reservoirs and dams to hold enough water to meet irrigation demand while also minimising seepage and evaporation losses. They are constructed to preserve water during times of low irrigation demand in order to satisfy high irrigation demand in the subsequent period. In places with protracted dry seasons or even dry spells during the monsoon season, a storage facility is extremely important for water distribution supply systems.
The choice of a storage system is based on local topography, geology, cost per unit of water supplied and irrigation demand characteristics. The costs associated with the storage structure are primarily the costs of construction and the costs of maintenance. However, the benefits of a storage structure far outweigh its costs. These benefits help to improve not only the economic parameters but also the food security in the country.
Key storage structures
A well irrigation system involves the usage of groundwater through a dug hole in the ground. Such systems have been in use in India since ancient times. There are different kinds of wells that are used for irrigation such as shallow wells, deep wells and tube wells. Water supply may not always be available from shallow wells because the level of water mostly declines during the dry season. Deep wells are preferred for irrigation requirements because the water supply is maintained throughout the year. Such systems are more prevalent in regions where groundwater is abundant and a few canals are present.
Well irrigation accounts for over 60 per cent of the country’s net irrigated area, compared to 29.2 per cent for canal irrigation and 4.6 per cent for tank irrigation. State-wise, Uttar Pradesh has the most well-irrigated land, accounting for approximately 30 per cent of India’s well-irrigated land. Three-fourths of the country’s total well-irrigated area lies in Uttar Pradesh, Rajasthan, Punjab, Madhya Pradesh, Gujarat, Bihar and Andhra Pradesh.
Meanwhile, the tube well irrigation system involves a deeper well from which water is transferred using a pumping system powered by an electric motor, diesel engine, or solar energy. The availability of sufficient groundwater is the most important factor in tube well construction, as a tube well can generally irrigate 2 hectares per day, as against 0.2 hectares per day irrigated by an ordinary well. Further, there should be a constant supply of electricity at nominal rates. The soil near the tube well should be fertile enough to benefit from the irrigation facility, so that the cost arising from the development and operation of the tube well is offset by increased agricultural production. State-wise, Tamil Nadu has the highest number of tube wells in the country, followed by Maharashtra, Andhra Pradesh, Uttar Pradesh, Madhya Pradesh, Karnataka, Punjab and Haryana.
Canal irrigation entails the use of an artificial channel developed to carry water from the river, tank, or reservoirs to the agricultural land for the purpose of irrigation. Canals are the second most important source of irrigation in India, after wells and tube wells. Canal irrigation is the most efficient technique in areas with low-level relief, deep fertile soils and continuing source of water. As a result, the northern plains of India, particularly the states of Uttar Pradesh, Haryana and Punjab, have a high concentration of canal irrigation. Canal digging in uneven terrain is challenging and uneconomical. Therefore, canals are almost non-existent in the peninsular plateau. However, some canals for irrigation exist in south India’s coastal and delta regions.
Dams are built to store excess water during the monsoon season and this water is then used to irrigate drought-prone lands. One of the primary advantages of dams is that the water supply can be regulated to meet agricultural needs throughout the year. It is projected that dam irrigation will contribute to 80 per cent of the additional food production by 2025. According to India Infrastructure Research, of the 226 upcoming irrigation projects in the country, 40 projects entailing an investment of over Rs 1.43 trillion relate to the construction of dams. These projects are spread across 11 states – Bihar, Chhattisgarh, Gujarat, Haryana, Jharkhand, Maharashtra, Odisha, Rajasthan, Tamil Nadu, Uttar Pradesh and Uttarakhand. Overall, these dam projects have an envisaged irrigation potential of 3.71 million hectares, thus offering huge opportunities for storage system providers.
The way ahead
India has enormous potential for various irrigation storage structures such as wells, tanks, canals and multipurpose dams. However, operations and maintenance of irrigation systems is below par, resulting in significant water loss from storage systems. Efficient water management is fundamental to economical and sustainable water use, which is possible only through the convergence of existing resources of all the ministries and departments. A plan of action needs to be put in place through the combined efforts of the key stakeholders not only at the central level but also at the state level.