Indigenous is the byword in the water harvesting techniques followed in India's northeast. In Meghalaya, an intricate network of bamboo pipes is used to irrigate betel leaf or black pepper crops in rocky areas where no channels can be built, a practice which has been raised to a sublime level. Similarly, Mizoram has perfected the art of rooftop harvesting of rainwater
carrying water over difficult terrain has never been easier. Whether it is rainwater, streamwater, floodwater or groundwater, people have developed indigenous ways to harvest and deliver the precious resource for irrigation and for human and animal consumption. In the northeastern state of Meghalaya, for instance, a vast and intricate network of bamboo pipes functions like a modern drip irrigation system; the state has raised this system to the level of a fine art.
About 18 to 20 litres of water may enter the bamboo network every minute, but it is equitably distributed at the rate of 20 to 80 drops per minute at the site of the plant after being carried hundreds of metres through pipelines. The bamboo pipes divert perennial springs on hilltops to the lower reaches with the help of gravity. The channel sections made up of bamboo convey water to the plot site, where it is further distributed into sections which branch off from the main pipe laid out with different forms of bamboo. It is also possible to control the inflow of water if the intake pipe position is manipulated. Reduced channel sections and diversion units are used at the last stage where the water is to be dropped at the roots of the plant.
Bamboos of varying diameters are used for laying the channels. The fabrication of the system requires the removal of about a third of the outer casing of the bamboo and the internodes of bamboo pieces. The bamboo channel is then smoothened by using a dao, a type of local axe that is a round chisel fitted with a long handle. Other components of the system include small pipes and channels of varying sizes used for diversion and distribution of water from the main channel. There are about four to five stages of distribution from the point of water diversion to that of application.
A Singh, principal scientist at the Water Technology Centre of the Indian Agricultural Research Institute in New Delhi, says in his book, Bamboo Drip Irrigation System, "Water diversion from one channel to the other is the key to the success of the system." It is estimated that it takes an average of 15 days for two labourers to install a system in a hectare of land. The time varies depending on the distance of the water source from the crops and the number of plants to be irrigated. Once installed, most of the materials last long.
The land used for cultivation is owned by the clan, and is allocated by the clan elders on payment of a one-time rent. The clan elders have the prerogative to decide who should get which and how much land. Once the rent has been paid and the land taken on lease for cultivation, the lease period operates as long as the plants live. In case of betel leaf cultivation, the lease can last for a very long time as the plants are not lopped off after one harvest. But once the plants die, the land reverts back to the clan and can only be leased out again after rent is paid.
The water for the betel leaf plants is brought from streams by temporary diversions into intricate bamboo canal systems. Betel leaf is planted in March before the monsoon. It is only during winter that irrigation water is required and the use of the bamboo pipe system becomes necessary. Hence, these bamboo systems are prepared before the onset of winter; no water is diverted into them during the monsoon season. Maintenance of the pipes and their supports is done by the farmers themselves.A cooperative has been formed and each farmer provides his skill and labour to maintain the system. Repair work is undertaken as and when required. Water is distributed by diverting it from one field to another at fixed timings. To divert the water, a short bamboo with a hole at the bottom is placed across the main lines. This blocks the main water pipe and diverts the water.
Attempts have been made to introduce modern pipe systems, but farmers prefer using their indigenous form of irrigation. The new systems have met with ill-concealed suspicion; local farmers trust neither the new materials nor the people who supply them.
Down To Earth will carry more on traditional water harvesting systems in its forthcoming issues. Readers are invited to send in their comments and contributions
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