INTRODUCTION:

Water is a social, economic and environmental good because of its multiple uses. At global level, demand for water is increasing steadily with general trend toward diversification of use away from agricultural activities. Even though earth is covered with water on two thirds of its surface area, 97% forms the ocean with salt water and 2.3% exists as ice and snow in Polar Regions and mountain tops. Only about a meager percent of global water is available for domestic, industrial and agricultural purposes. This quantity can neither be increased nor reduced. According to² world uses now around four times as much fresh water as it did in 1940 and a huge increase in use is forecasted for the developing countries that are already short of water. Hence, securing water amidst scarcity has, thus, become a part of everyday life, though it is scarce and costly but essential for survival and for food production. India’s water resources potential and the Country’s agricultural economy hinge on the monsoon rains and its spatial and temporal variations. Water resources of a country constitute one of its vital assets.

India receives annual precipitation of about 4000 km³. Nearly 40% of India’s land mass falls under semi-arid conditions with annual rainfall of 500 to 1000 mm facing high spatial and temporal variability. Since time immemorial, India’s rural communities have followed a policy of conserving rain water for subsequent use through innumerable tanks or small storage structures like ponds built, owned and managed by the local people through community organisations.

Tank systems, developed ingeniously and maintained over the centuries, have provided insulation from recurring droughts, floods due to vagaries of the monsoon and offered the much-needed livelihood security to the poor living in fragile semi-arid regions^8. Almost all monsoon countries in the semi-arid tropics have small water bodies like tanks¹²

As one of the oldest man-made ecosystems, the tank system consists of water bodies, tank structures, feeder canals, supply channels, wells, wetlands, semi dry tank fed lands, soil and plants, animals and birds, aquatic plants and fishes. As an agricultural system, tank fed agriculture is distinct in cropping practices, varieties and water management. As an engineering system, it is historically one of the oldest in irrigation engineering design. As a management system, tanks had institutions built around them. As a social system, a tank serves and benefits various sections of the village community such as farmers, fisher folk, artisans, animal rearers and especially women. The pre-eminence of tanks as a source of water storage and supply for multiple uses was lost after independence due to a variety of factors: chiefly, the development of large-scale gravity irrigation systems, rapid spread of tube well technology and decline in traditions of community management. As a result, a large majority of the tanks in the southern and eastern parts of India started declining from inadequate management and maintenance. Some have become dysfunctional while others are even obliterated. In fact, even the exact number of tanks existing as of now and their status is not known ^4.The decline in tanks is evident both in terms of the relative importance of tanks vis-à-vis, other sources of irrigation, as well as the decrease in the actual area irrigated by tanks. While at the all India level, the area under tank irrigation declined from 4.6 M ha to 3.3 M ha. The total area under tank irrigation in the three predominant states like Tamil Nadu, Andhra Pradesh and Karnataka together has declined from 2.4 M ha in 1960-61 to 1.7 M ha in 1996-97, a reduction of about 30% ^3.Number of studies attributed many reasons for the decline in tank irrigated areas like silting of feeder channels, encroachments, interruption in the catchment, poor maintenance and the development of well irrigation in tank commands ⁶. Various reasons have been spotted for the decline in the area under tank irrigation. Poor management of the tanks is primarily responsible for their decline. This is evident in the non participation of farmers in cleaning channels, encroachment of the tank bed, inadequate repairs, weed infestation and siltation. Having surveyed 32 tanks in Andhra Pradesh and Maharashtra, ¹³ indicate that increases in population density resulted in deforestation in catchment areas leading to soil

erosion and siltation.

REVIEW OF LITERATURE:

According to⁹ tank bed cultivation and the lack of an administrative structure to provide timely repair and maintenance contributed to the decline of tank irrigation. An econometric analysis of the factors responsible for tank degradation¹found that variables such as encroachments in catchments, water spread areas and the increase in canal and well-irrigation had significantly increased the degradation of tanks. Increasing importance given to modern irrigation systems, larger reservoirs and river valley projects and the spread of private irrigation wells also have a considerable negative impact on traditional community irrigation systems. The State of Tamil Nadu is also a world by itself in which millions of farmers who are small and marginal depend on the tank systems for their livelihoods. The numerous benefits of tank ecosystems across the undulating topography of the state are so vital for them in times to come and forever. Finally, it is a world where tank systems are used and managed in a fair and sustainable manner for economic security. Due to negligence of the tank by the villagers in general and the farmers in particular, the decay of the tank has slowly set in and finally is in a bad state. The feeder channel got silted up, heavily encroached and ploughed for cultivation. Tanks lost receiving any water and its ecosystem was completely vanished. Increased soil erosion, decreased bio-diversity, reduced soil moisture regime, diminished vegetative growth, decreased fodder production, decreased bio-mass production etc. are the environmental problems faced by degradation of tank eco-system. Due to insufficient surface and ground water availability, there was a reduction in both total area and number of seasons of crop cultivation in command area. The water level in the wells under the tank has gone down year by year and the farmers have tried to extract ground water by increasing the depth of wells. Realising the importance of tanks, the south Indian states have started rehabilitating the tanks in mid 1980’s under state funds as well as external assistance. The general belief is that tanks are in vicious cycle of “Poor maintenance – decline in performance – Rehabilitation – Poor maintenance. In a strict sense, ‘rehabilitation’ has traditionally meant technical interventions aimed at restoring a system to its originally designed potential for performance (FAO 1997). The accumulating evidences globally (especially after 1980) indicate that restoration and rehabilitation of existing irrigation tanks by adopting appropriate methodology and institutional mechanism (community based participatory irrigation management, water user associations, tank association) will generate rural economy and promote sustainable development, through empowerment and self reliance. Tank rehabilitation not only helps farmers but also improves the livelihoods of landless poor, women and other vulnerable groups⁷. Water resource development is a strategy to optimise the use of soil, water and vegetation subject to local agro climatic and topographic conditions, all for the purpose of strengthening the natural resource base, supporting more productive agriculture and improving livelihoods. Initial focus of tank rehabilitation was to maximise the productivity per unit area, per unit time and per unit of water. On the other hand, there are proponents who argue that tank rehabilitation is a must around which livelihood options of the poor are to be built in view of the multiple use of tank water. With limited water resources, vagaries of the monsoon and looming water scarcity in many parts of India, the need for rehabilitating and restoring the tanks assumes significance. In recent years, a variety of efforts has been made to improve the performance of tanks. In Tamil Nadu, 569 Public Works Department (PWD) tanks and 80 Ex-Zamin tanks (out of total 39,200 tanks) were rehabilitated and modernised under European Union assistance, with a financial outlay of Rs 179.39 crores. These tanks were supposed to benefit a command area of 73,161 ha and the cost of rehabilitation worked out to be Rs 25,000/ha ⁷. Potential socio-economic benefits of tank rehabilitation are, it reduces risk of crop failure, improved production and higher incomes, equitable distribution of water for command farmers, improved nourishment (through fisheries development), increased opportunities for gainful employment, reduction in seasonal migration by landless and poor households, increased family income, improved quality of life, improved interaction among different communities, improved livestock and milk production through increased biomass production, minimise tank flooding and increased availability of water for livestock and human.

ANALYSIS AND INTERPRETATION:

Water is being treated as a revered divine gift. Tanks are important means to conserve precious water resources in semi-arid areas. A tank is a natural or a manmade reservoir created by simple earthen construction that captures surface runoff. Tank systems are an important traditional decentralised form of irrigation. Tanks environmental importance lies not only in its functions of collecting and impounding water for irrigation but also in enabling percolation and recharging the ground water. And it is also a mechanism to cope up with water scarcity and flood control. In addition to ground water recharge, tanks provide water resources for fish culture, silt for fertilising, livestock, duck rearing, washing, bathing, drinking, collection of fodder, fuel wood, vegetable cultivation, tree planting, clay for brick and pot making. The tank never existed as isolated from the lifestyle of people who used it whole day long for a variety of purposes. The tank systems of South India are both a technology and a resource and need to be treated in terms of a wide complex of natural resources, physical facilities, land use patterns and managerial institutions. Equally, they imply a particular system of social relations which defines a set of rights, entitlements and obligations which make cooperation, conflicts resolution and collective action for maintenance and repair within villages and because of nature of drainage among villages. The location of the tank and its physical conditions were a matter of much significance to people, particularly to women, to carry out their respective economic activities. Many agricultural and irrigation experts have begun to emphasise the importance of tanks and believe that tanks are important for water management and stress the need for a most efficient strategy to ensure water supply for crop production in drought years.

Tanks are generally classified based on the source of augmenting water and size of command area. They are normally classified into system and non-system tanks. System tanks are those which receive water from nearby major streams or reservoirs in addition to water from their own catchment. Many a time, they enable the farmers to raise more than one crop. Non-system tanks depend on the rainfall in their own catchment area and are not connected to the river system and usually single crop is raised under these tanks. Non-system tanks are often linked with the other tanks thus forming upper and lower tanks in a cascade form. During times of heavy rainfall, the surplus water from upper tanks will flow to the lower tanks. In the non-system tanks, the command to catchment area ratio will vary anywhere between 1:8 and 1:15 depending on whether the area comes under high rainfall or low rainfall, whereas for system tanks, the ratio will be smaller from, 1:2 to 1:5 due to their additional sources of water. Tanks are also classified based on the size of command area and the nature of control. Normally, the tanks after standardisation are classified as major and minor tanks. Major tanks irrigate more than 80 ha of land and minor tanks irrigate less than 80 ha. However, the maintenance responsibility is based on a different size classification. Tanks irrigating more than 40 ha are the responsibility of the PWD and the tanks irrigating less than 40 ha are the responsibility of the Panchayat (local office) Unions. The Ex-Zamin tanks generally are the non-standardisation tanks irrespective of the size of the command area. After standardisation, the Ex-Zamin tanks will be either PWD or Panchayat Union tanks based on the size of the command area. Among the total, about 7,300 tanks have irrigation area of more than 40 ha and about 31,900 tanks have less than 40 ha. Thus in numbers, the small tanks matter more for augmenting the water resource base.

TANK REHABILITATION AND ITS COMPONENTS:

A tank comprises the catchment area, feeder channels, water spread area, outlet structures (sluices), flood disposal structure (surplus weir) and the command area. More than 70% of tanks in all the districts of Tamil Nadu need rehabilitation to restore them to their standards. Rehabilitation includes not only restoring these components to their originally designed standard, but more important, facilitating the efficient water management, improved cropping practices and better livelihood options to landless poor, women and other vulnerable groups. The people’s felt needs and priorities shall be given importance in formulating detailed work plans and cost estimates. Tank rehabilitation components can be divided into two major groups viz., tank infrastructure developments like, bund strengthening, tank bed and supply channel cleaning and sluice and weir repairs etc. and command area development like sluice repair, restructuring water distribution channels, junction boxes and lining field channels. The works to be included in the tank rehabilitation follow an order of priority that users perceive as most important. They are generally as mentioned here under.

Acquisition of water:

Encroachment eviction, Cleaning and desilting feeder channels to augment water inflow into to the tanks; and Clearing of weeds and other undesirable vegetation on the tank bed.

System restoration:

Restoration of the tank structures like tank bund to their original design so that they are strengthened adequately to withstand the floods, Repairs or reconstruction of water regulation structures like sluice outlets and surplus weirs to prevent loss of tank water, Involving landless under wage employment; and Planting and preserving fodder, fuel, horticulture or herbal plants in the tank foreshore and on tank bund.

Improvements to water use efficiency:

Replacement of damaged or missing shutters in sluice outlets which prevent wastage and facilitates easy regulation of water to ayacut command area lands, Restructuring the existing water distribution channels, providing additional distribution channels, providing distribution boxes and selective lining in the distribution systems as may be required in the tank command area and to improve the water use efficiency of the system, Avoiding night irrigation which is useful to save water and applying the minimum quantity of water to meet the crop water requirements to supplement rainfall; and Conjunctive use of tank and well water.

Livelihood for landless poor:

The focus is also providing livelihood to all including the landless during off season and during drought.

Components to be rehabilitated, and budget for different components and timing of completion must be flexible enough to meet the requirement of the tank users; and rehabilitation components aiding augmentation of tank water and improved storage of water to cater to the needs of summer season and to recharge the ground water should be given preference over others. Providing livelihood to all including landless during off season and during the dry periods should form part of rehabilitation. Water availability in tank should not only changes the crops and cropping pattern in the command but also the livelihood options of marginal farmers and landless poor¹¹.

SUMMARY AND CONCLUSION:

The tank systems have provided insulation from dependence on rainfall to the people living in the fragile rainfed areas. The farmers in rainfed tanks who are predominantly marginal and small are highly vulnerable to the vagaries of monsoon. The importance of tanks is being realised more and more, as the continued use of ground water and other water resources is proving to be very costly and inadequate to meet their varying demands. The tank ecosystems have to be conserved to provide a safety net to the livelihood of these farmers. While tanks are usually regarded as primarily for irrigation, there are several characteristic of this type of irrigation that makes it eminently suited for multiple uses. Taking other productive uses (excluding domestic and livestock) into account raises the total value of output from tank by approximately 13% and increases the total revenue mobilised from tanks by 213%. The conservation and development of tanks have to be carried out considering the multiple uses such as irrigation, drinking and domestic water for people and animals, for recharging ground water, providing fuel wood and timber, rearing fish, growing fodder, mining silt and sand, sanctuary for birds, animals and bio-diversity complex for flora and fauna. The multiple uses of tanks need to be taken into account in evaluating their performance.

REFERENCES:

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3. Janakarajan. Complexities of agrarian markets and agrarian relations: A study of villages in Northern Tamil Nadu. Paper presented at the Dissemination Workshop for the ODA funded project between Queen Elizabeth House, Oxford, and Madras Institute of Development Studies, Madras, March 27-29, 1996.

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7. Sakthivadivel R. Protocol for tank rehabilitation’, Rehabilitation and Management of Tanks in India, A Study of select states. Asian Development Bank Publication, 2006.

8. Sakthivadivel R., and Gomathinayagam P. Rejuvenating irrigation tanks through local institution. Economic and Political Weekly, July 3, 2004.

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Received on 27.08.2013 Accepted on 01.09.2013

Research J. Engineering and Tech. 4(4): Oct.-Dec., 2013 page 251-254