Diverse technologies: a treasure trove

Diverse technologies: a treasure trove

Our traditional water harvesting structures demonstrate the people's ingenuity at its best. Using unique modes and basic engineering skills, Indians have developed a wide array of techniques for satisfying their thirstIndia has an extraordinary diversity of agro-ecological systems, ranging from the hot desert of Rajasthan to the cold desert of trans-Himalayan Ladakh, from the sub-temperate Himalayan mountains to the high tropical mountains in the south; interspersed are various hill and mountain ranges, plateaus and the unique Indo-Gangetic plains which are more flood-prone than any other part in the world.

Hill areas: convenient modes
Traditionally, wherever there were streams, especially in the hill and mountain regions of India, people diverted the water with the help of simple engineering structures, into artificial channels that would take the water to agricultural fields. In arid and semi-arid regions, where streams were more seasonal, the diversion channels were first directed into a storage structure -- variously called a zing in Ladakh, an ahar in south Bihar or a kere in Karnataka -- so that the water could be used in the dry period for human and animal consumption and for agriculture. Stream flow in the desert of Ladakh, as it is dependent on glacier melt, is almost non-existent in the morning but heavy in the evening -- a time when cultivators cannot use it. Therefore, Ladakhis traditionally divert the evening flows into a small reservoir to use it next morning. In certain villages of the eastern Himalayan states of Nagaland and Arunachal Pradesh, the villagers take the diverted channel through a cattleshed so that the water can pick up rich nutrients before it reaches their fields. The Angami Naga tribals ensure that forests above the main stream are never cut so that the streamwater remains full of nutrient-rich forest humus.

In fact, in terms of carrying water over a difficult terrain, the indigenous people of north-eastern India, traditionally expert in the use of bamboo, have developed some of the most interesting and artistic systems. All over eastern Himalaya and the north-eastern hill ranges, people continue to build bamboo pipelines to carry water from natural springs to a convenient point, where it can be used for drinking. But this art has been raised to a sublime level by the people of southern Meghalaya, living near the border of Bangladesh, who have used intricate networks of bamboo pipelines to deliver water to betel leaf plantations in rocky areas; it is impossible to build channels in such areas. The entire system literally works like a modern drip irrigation network which delivers measured quantities of water straight to the roots of the plants. Some 18-20 l of water enter the bamboo irrigation systems every minute and after getting transported over several hundred metres, finally get reduced to 20-80 drops per minute at the site of the plant.

Tamil Nadu: tank culture
Not all storage structures are riverfed or streamfed. Many of them simply collect water running off a catchment area to be stored for later use. But in the southern state of Tamil Nadu, a big stream is often diverted to feed a chain of 25-30 tanks in sequence. As this chain of tanks -- called 'system tanks' -- is served by a stream collecting water over a large catchment, it is traditionally considered much more desirable than a tank with a single, small catchment. Because of the wide variability in rainfall in both space and time, agricultural lands served by system tanks have always been more expensive and prized than lands served by stand-alone tanks. The Palar anicut (dam) system, for example, supplies water to 317 tanks, irrigating about 32,000 ha in North Arcot and Chengalpattu districts. Some tanks are supplied directly by channels coming from the Palar river, but several others depend mainly on the surplus flows of upstream tanks. The profusion of tanks in Ramnathapuram district of the state can even be seen from a satellite.

In western and central India
In several parts of India, people have been building dams across seasonal channels to capture the runoff. But these structures, unlike normal dams, are used to moisten the soil so that the post-monsoon crop would be assured of the rich soil of the tank bed itself. In the haveli system of Madhya Pradesh, the nature of the soils and traditional crops have forced farmers to store rainwater in the agricultural fields itself. The fields would be embanked and farmers would work out an arrangement amongst themselves to allow rainwater to flow from one field to the other. The collected water would seep into the soil and give it enough moisture for growing a good crop in the following dry period.

The nomadic Maldharis of Gujarat's inhospitable Kutch region have developed an interesting system of procuring potable sweetwater, even in an area where rainwater is scarce and groundwater is saline. They know that density of sweetwater is less than that of saline water and, hence, it is theo retically possible to keep the harvested sweet rainwater stored in a way that it will continue to float over the denser saline water. With this knowledge, they have developed precisely such a system, locally called virda, which is essentially like a well in a tank.

In dry areas of Rajasthan, people have traditionally practised conjunctive use of surface water and groundwater (see box: Jodhpur: providing an example). They invariably built structures like wells and stepwells -- wells with a flight of stairs leading down to the water -- below tanks and other types of water storage structures. Thus, when the tank water dried up, people could at least harvest clean groundwater to meet their drinking water needs. In other places, people would make wells in the tank bed from which they would collect groundwater for drinking. In many places, the surface runoff collected in the tank would not be used for drinking if clean groundwater was available from wells and stepwells. Rajasthan also has an old tradition of using rooftops as a catchment area to collect rainwater. In the town of Phalodi, if one household does not want to collect water from its rooftop, the neighbours borrow the roof to collect water for their purposes.

In areas where land is not a limiting factor, people have even developed customised rainwater harvesting structures called kundis. These amazing structures -- apparently unique to the region -- dot the landscape of Churu district in the Thar desert. Kundis are artificial wells which store runoff from an artificially prepared catchment surrounding them so that rainwater that falls on the catchment rapidly runs into the well and gets stored. They can be made anywhere if adequate land is available. Their potential can be understood by the following fact: If an area receives only 100 mm of rainfall -- which would make it an extremely arid environment -- this rain harvested over one ha of land would provide one million litre (l) of water a year. As a family of five would not need more than 10-15 l a day for drinking and cooking -- or 3,650-5,475 l a year -- 180-270 families could meet their most critical water needs by building a one-ha kundi. Management: of the people, by the people

Elaborate community-based water management systems, including ingenious property rights systems, have been in vogue in the country for ages

Water harvesting systems are fragile creations. They have to be continuously monitored, maintained and repaired. Even more difficult is sharing the scarce water amongst its consumers, particularly farmers. Popular ingenuity has found a way out even here: Across the country, people have devised a variety of property rights systems to share water and to maintain their water harvesting networks.

Himalaya and the north-east: right methods
To ensure equity in distribution of the scarce water, villagers in Ladakh elect a water official every year, known as churpun. This is done at the start of each agricultural season. The churpun ensures that each farmer gets adequate water in proportion to the area of land he owns without leaving any field unirrigated. Hence, disputes over the use of water are very rare. Canals are repaired by community effort. The position of churpun rotates amongst all households to ensure that no household monopolises this critical post.

Villagers in Nagaland have also developed a variety of practices in order to share the available water for their terraced rice plots. While water sources are common property, land is a private acquisition. There are cases where water is transported over channels several kilometres long to reach crop-fields. In some Naga villages, local chiefs stand on a rock on a particular day in the months of May, June and July, and exhort villagers to offer prayers for good water and to clean the traditional water sources. Among the Angamis, Chakhesangs and Zeliang tribes, traditional water rights are held very rigidly by individuals, clans or khels (villages). In Khonoma village of Kohima district, for instance, the person whose field is closest to the water source is responsible for conserving the source. But the individual whose field is at the bottom of the canal is its owner; he,she has a major share of water and also regulates the flow of the water. He,she is also responsible for keeping the canal clean. While every one has the right to take water from the stream, nobody can take more than the demarcated share.

In Kikruma, a Chakhesang village located in Phek district, a curious combination of water rights is in vogue. If a spring exists on a particular terrace which is not yet cultivated, the person below it is entitled to use it to develop his terrace. But in case the owner of the uncultivated terrace decides to develop his terrace at some later date, then the two will share the water equally. In general, the rights over runoff between different terraces is respected. The person at the top end of the terrace cannot harness what is legitimately the runoff right of those below. The maintenance of all channels and catchment areas of ponds is done once every year, usually before the onset of the monsoon. The responsibility of mobilising people to clean the channels rests with the last person tapping the channel, locally referred to as the neipu, which literally means the lord.

Inhabitants of the central Himalayan villages of Uttar Pradesh have adopted a simple device to avoid excess water being drawn by a channel at the head, thereby leaving less water for downstream users. A small boulder is placed at the mouth of each turnout. The size of the stone at successive water turnouts gets progressively smaller. Some measure of equity is thus ensured in water distribution. Water distribution in Ladyura village, for instance, is carried out by an irrigation committee which has 10 members, including a chowkidar (guard). Many non-elected members who are familiar with water distribution arrangements are co-opted as members. Major decisions are taken in a general body meeting which is open to all residents of the village. There is a mechanism to resolve disputes, under which the irrigation committee members of the upstream and downstream villages sharing the same channel meet to discuss the matter.

Maharashtra's phad system
The community-managed phad irrigation system, prevalent in Dhule and Nasik districts of north-western Maharashtra, probably came into existence some 300-400 years ago. A series of bandharas (dams) were built on the local rivers to divert water. In the phad system, variations in water availability from one year to another were managed by demarcating the command area into two categories: one with assured and another with unassured irrigation. In the years of good rain, the unassured area, which is invariably at the tail-end, also gets irrigation benefits.

Only one crop can be grown in one phad; the variety of crops to be grown in different phads is decided by an assembly of irrigators, depending on water availability. Crops are rotated among the phads so that over a period of two to three years every phad gets to grow sugarcane, the main cash crop. In Daterti village, for instance, the total cultivated land is divided into four phads (see figure). Every landowner has a plot of land in each of the four phads. In a year of plentiful water the community may decide to grow sugarcane in three and millet in one. Conversely, in a year which has seen an average rainfall, the farmers may grow two phads of sugarcane and two of millet. In a bad year, the community may allow sugarcane in only one, grow millet in two and even keep one fallow.