When lakes were tanks

Bengaluru's lakes were actually tanks created in the absence of a big river

 
By Rohan D'souza
Last Updated: Thursday 11 June 2015

When lakes were tanks

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Bengaluru is on the global map for a variety of reasons. It is an information technology hub. It is also known for its salubrious climate, the result of being located 920 metres above sea level. The presence of several parks, neighbourhood and central, has led people to refer to it as the garden city. A lesser known fact is that Bengaluru also has a number of lakes. According to the city corporation, Bruhat Bangalore Mahanagara Palike (BBMP), the city has 198 lakes.

Bengaluru’s lakes are not natural lakes, but human-made tanks created by damming the flow of water at various points. Three valleys in Bengaluru—Koramangala and Challagatha in the southeast, Hebbal in the northeast and Vrushabhavati in the west—determine the flow of water in the city. A series of interconnected cascading tanks were created over centuries along the inclines of these valleys. One tank’s overflow was carried to the next tank through a wetland system, which included rajakaluves, or canals. In this manner, six chains of tanks came into being. The water flow in the tanks was regulated through a community-operated sluice mechanism. The absence of a major river in Bengaluru led to the need for such a system. There was a need to harvest rainwater which could then be used for irrigation and household needs and livelihood activities such as fishing. The tanks served this purpose.

The overflow of one tank was carried to another tank through a wetland system involving canals

Inscriptions found near some of the tanks suggest that many of these water bodies preceded the mud fort settlement of Bengaluru created by Kempegowda, a local chieftain, in 1537, which sprawled into the city of Bengaluru as we now know it. One such inscription found near Agara tank dates to 9th century AD.

Other tanks such as Kudlu and Begur in south Bengaluru also trace their history to this period. The region in the southern part of Bengaluru came under the Western Ganga dynasty around 350 AD. The dynasty ruled till 1,000 AD. Kempegowda, his successors and the British continued this system of creating and maintaining tanks.

A complex maintenance system also came into being. Collective memory of residents who have lived close to the tanks, or keres in Kannada, offer insights into the maintenance system. Villages near the kere shared the responsibility of maintaining them. The system ensured bund maintenance, de-silting of the tank bed and maintenance of the rajakaluves. The Neergunti community was among those involved in this. The community maintained the rajakaluves and its work was rewarded through a land tenure system.

These canals were maintained by the community whose members were rewarded through a land tenure system

There is reference to this system in the Mysore Gazette compiled by B L Rice, director of the department of archaeology of the then Mysore state in 1897. He notes, “Kodigi Inams represent land granted free of tax, or on a light assessment, in consideration of services rendered in the construction or restoration of tanks, or on condition of their being maintained in good repair. Kerebandi and Kerekulaga Inams were granted for the annual petty repair of tanks.” The land granted as part of the Inam tenure system usually included the “wetlands” located downstream of the tanks, which were ideal for growing water-intense crops such as rice and sugarcane. However, who obtained which land depended on the caste hierarchy and in many instances dominant castes got the more fertile wetlands.

Post-Independence, the government started dismantling the system to replace it with more centralised systems of maintenance. The Mysore (Personal and Miscellaneous) Inam Abolition Laws Act came into force in 1954, possibly to counter the feudal land tenure system. However, the Act also impacted the tank maintenance system. Various government departments which were carried forward from the colonial times such as the minor irrigation department started playing a larger role in the maintenance of tanks, especially the larger ones. Currently, BBMP maintains tanks in Bengaluru. At various points, government departments such as the forest department played a role. The department was brought into the picture with the recommendation of the Laxman Rau Committee, which was set up in 1986 to look into the issues related to the tanks of Bengaluru.

The water flow in the tanks was also regulated through a communityoperated sluice mechanism

The forest department viewed these water bodies purely as ecological spaces. This also led to a change in the discourse around these systems. Tanks increasingly started to be referred to as lakes. In the urbanised environs of Bengaluru, the now renamed lakes were being seen as ecological and social spaces that catered to naturalists and recreation seekers. This also started increasingly dictating how they were to be maintained.

The tanks or keres in their earlier form had cultural connotations. Many had a deity assigned to it and a temple in which the deity was located. These were largely local deities, such as Muneeswara, Duggalamma, Gangamma. There were annual festivals at some of the keres such as Bellandur in South Bengaluru—one of the largest which spread over 350 hectares. However, with increasing urbanisation and increased pollution, such practices have been discontinued in most of the urban lakes.

An attempt to privatise the management of the lakes by the Lake Development Authority, which was set up in 2002, was thwarted by a public campaign by a local NGO, Environment Support Group. The authority, which was mandated to work for the regeneration and conservation of lakes in Bengaluru district as well as other municipalities and corporations in Karnataka, claimed a paucity of resources, human and financial, and therefore invited the private sector to undertake the maintenance of these water bodies and in return use these spaces to carry out commercial activities to generate revenue for themselves. The Karnataka High Court has since directed a cancellation of this scheme, which brought the city corporation back to the role of maintaining the lakes of Bengaluru.

Rohan D’Souza is a researcher with the National Institute of Advanced Studies, Bengaluru

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  • Excellent. In fact

    Excellent. In fact traditional water storage methods need to be revived. CSE has done great service by documenting the tradtional methods.
    Ground catchments systems channel water from a prepared catchment area into storage. Generally they are only considered in areas where rainwater is very scarce and other sources of water are not available. They are more suited to small communities than individual families. If properly designed, ground catchments can collect large quantities of rainwater.
    Roof catchment systems channel rainwater that falls onto a roof into storage via a system of gutters and pipes. The first flush of rainwater after a dry season should be allowed to run to waste as it will be contaminated with dust, bird droppings etc. Roof gutters should have sufficient incline to avoid standing water. They must be strong enough, and large enough to carry peak flows. Storage tanks should be covered to prevent mosquito breeding and to reduce evaporation losses, contamination and algal growth. Rainwater harvesting systems require regular maintenance and cleaning to keep the system hygienic and in good working order.
    Subsurface dyke
    A subsurface dyke is built in an aquifer to obstruct the natural flow of groundwater, thereby raising the groundwaterlevel and increasing the amount of water stored in the aquifer.
    The subsurface dyke at Krishi Vigyan Kendra, Kannur under Kerala Agricultural University with the support of ICAR, has become an effective method for ground water conservation by means of rain water harvesting technologies. The sub-surface dyke has demonstrated that it is a feasible method for conserving and exploiting the groundwater resources of the Kerala state of India. The dyke is now the largest rainwater harvesting system in that region.
    Groundwater recharge
    Rainwater may also be used for groundwater recharge, where the runoff on the ground is collected and allowed to be absorbed, adding to the groundwater. In the US, rooftop rainwater is collected and stored in sump. In India this includes Bawdis and johads, or ponds which collect the run-off from small streams in wide area.
    In India, reservoirs called tankas were used to store water; typically they were shallow with mud walls. Ancient tankas still exist in some places.
    Advantages in urban areas
    Rainwater harvesting can be adopted in cities are to provide supplemental water for the city's requirements, to increase soil moisture levels for urban greenery, to increase the ground water table through artificial recharge, to mitigate urban flooding and to improve the quality of groundwater. In urban areas of the developed world, at a household level, harvested rainwater can be used for flushing toilets and washing laundry. Indeed in hard water areas it is superior to mains water for this. It can also be used for showering or bathing. It may require treatment prior to use for drinking
    In New Zealand, many houses away from the larger towns and cities routinely rely on rainwater collected from roofs as the only source of water for all household activities. This is almost inevitably the case for many holiday homes.
    Quality
    As rainwater may be contaminated, it is often not considered suitable for drinking without treatment. However, there are many examples of rainwater being used for all purposes ÔÇö including drinking ÔÇö following suitable treatment.
    Rainwater harvested from roofs can contain animal and bird faeces, mosses and lichens, windblown dust, particulates from urban pollution, pesticides, and inorganic ions from the sea (Ca, Mg, Na, K, Cl, 4SO), and dissolved gases (2CO, xNO,xSO). High levels of pesticide have been found in rainwater in Europe with the highest concentrations occurring in the first rain immediately after a dry spell; the concentration of these and other contaminants are reduced significantly by diverting the initial flow of water to waste as described above. The water may need to be analysed properly, and used in a way appropriate to its safety. In the Gansu province for example, harvested rainwater is boiled in parabolic solar cookers before being used for drinking. In Brazil alum and chlorine is added to disinfect water before consumption. So-called "appropriate technology" methods, such as solar water disinfection, provide low-cost disinfection options for treatment of stored rainwater for drinking.
    System sizing
    It is important that the system is sized to meet the water demand throughout the dry season. Generally speaking, the size of the storage tank should be big enough to meet the daily water requirement throughout the dry season. In addition, the size of the catchment area or roof should be large enough to fill the tank.
    Around the world
    Currently in China and Brazil, rooftop rainwater harvesting is being practiced for providing drinking water, domestic water, water for livestock, water for small irrigation and a way to replenish ground water levels. Gansuprovince inh China and semi-arid north east Brazil have the largest rooftop rainwater harvesting projects ongoing.
    In Rajasthan, India rainwater harvesting has traditionally been practiced by the people of the Thar Desert.
    In Bermuda, the law requires all new construction to include rainwater harvesting adequate for the residents.
    The U.S. Virgin Islands have a similar law.
    In the Indus Valley Civilization, Elephanta Caves and Kanheri Caves in Mumbai rainwater harvesting alone has been used to supply in their water requirements.
    In Senegal/Guinea-Bissau, the houses of the Diola-people are frequently equipped with homebrew rainwater harvesters made from local, organic material.
    In the United Kingdom water butts are oft-found in domestic gardens to collect rainwater which is then used to water the garden, though the use of larger commercial systems is becoming more common (as seen in Germany and Australia).
    In the Ayerwaddy Delta of Myanmar, the groundwater is saline and communities rely on mud lined rainwater ponds to meet their drinking water needs throughout the dry season. Some of these ponds are centuries old and are treated with great reverence and respect.
    Until 2009 in Colorado, water rights laws restricted rainwater harvesting; a property owner who captured rainwater was deemed to be stealing it from those who have rights to take water from the watershed. The main factor in persuading the Colorado Legislature to change the law was a 2007 study that found that in an average year, 97% of the precipitation that fell in Douglas County, in the southern suburbs of Denver, never reached a streamÔÇöit was used by plants or evaporated on the ground. In Utah and Washington State, collecting rainwater from the roof is illegal unless the roof owner also owns water rights on the ground. In New Mexico, rainwater catchment is mandatory for new dwellings in Santa Fe(Source:IWA Water Wiki).

    Will the new Government at Centre constitute an expert committee to study these methods and adopt them as WATER IS ELIXIR OF LIFE. Just as importance is given to CLEAN UP GANGA RIVER,so also water harvesting and conservation.
    Dr.A.Jagadeesh Nellore(AP),India

    Posted by: Anonymous | 6 years ago | Reply
  • Dear Mr.D'Souza, Your article

    Dear Mr.D'Souza,

    Your article comes at an opportune time for me. We are a small group of citizens interested in participating in the cleaning up of the lake in Kengeri area.

    I would be obliged if you could share any information that you may have about this lake and also the Rajakaluves in this area. A general map of the Rajakaluves in Bangalore would also be very helpful.

    Rgds
    Priti Turakhia

    Posted by: Anonymous | 6 years ago | Reply
  • The important information

    The important information given by this article and by the posters here should be implemented worldwide... Especially in the USA where water conservation is practically unknown.. "Water is everybody's business"..

    Posted by: Anonymous | 5 years ago | Reply
  • Hi Priti, Appreciate your

    Hi Priti,

    Appreciate your concern in wanting to protect a lake in Kengeri. Send me a mail to virtuallyme@gmail.com and I will respond with maps and other information such as other people who could also help with mapping.

    Rohan

    Posted by: Anonymous | 5 years ago | Reply