Tanks are used for irrigation in peninsular India including Maharashtra and Gujarat. Tank irrigation is useful in Deccan regions where rainfall is seasonal and uncertain.
A tank is an artificial reservoir built across a stream to impound water. Water from the tank is then carried to the fields through narrow channels. Tanks are extensively used in Deccan because of the following reasons:
- The Deccan has many natural depressions where tanks can be easily built.
- The rivers of the region are not perennial and become dry during the summer.
- Wells cannot be dug in the stony regions of the Deccan. Tanks however can be easily built by making small dams of stones in the depressions where rainwater collects. Tank irrigation is largely practised in Andhra Pradesh, Tamil Nadu, West Bengal, south Rajasthan and south Bihar.
Advantages of Tank Irrigation
- Tank irrigation is useful in Deccan regions where rainfall is seasonal and uncertain.
- In the rocky terrain of the Deccan Plateau, it is difficult to build wells and canals. In such regions, tanks are an important source of irrigation.
- Rainwater could be stored in the tanks which otherwise flow out and get wasted. This water is then used for irrigation.
Disadvantages of Tank Irrigation
- Tanks can easily get silted up. Thus, regular desilting of tanks is required.
- In case of failure of rains, tanks also remain dry and hence are not a dependable source of irrigation.
- Because of large area coverage and shallow depth, water from tanks either evaporates or sinks underground.
- Tanks can use a large infertile area which otherwise could be used for growing crops.
- The lifting of water from tanks and bringing it to the fields is a strenuous and costly task.
Major Drawbacks of Conventional Methods of Irrigation
- In the agricultural fields, about 10–15% of land is used for preparing water channels, decreasing the effective area of cultivation.
- In tanks and canals, owing to the evaporation of water, the soil may silt.
- The fields in the low-lying areas always get excess water resulting in waterlogging and subsequently the accumulation of salt which damages the quality of soil.
- In the conventional system of irrigation, a large quantity of water is not properly used and gets wasted.
Also, Read 3 Modern Methods of Irrigation