The Temple Tanks of Madras, India: Rehabilitation of an Ancient Technique for Multipurpose Water Storage
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1 Indian Journal of Science and Technology http://www.indjst.org Vol.1 No 7 (Dec. 2008) The temple tanks of Madras, India: rehabilitation of an ancient technique for multipurpose water storage Madhavi Ganesan Centre for Water Resources, College of Engineering Guindy, Chennai, India [email protected] Abstract: There are 39 temple tanks in the city of properly maintained to provide a sublime Madras, most of which have been dry for the past atmosphere. one decade due to rapid urbanization and Apart from the sanctity attached to them, the continuous withdrawal of groundwater. Out 39 tanks help to recharge the wells in and around the temple tanks one tank belongs to Mylapore area. That was one of the reasons for the ancient Temple which is within Madras city and second rulers to allot funds for their maintenance. In India one belongs to Thirupporur Temple which is out of the word "tank" normally refers to a dug-out city have been selected to compare the status of reservoir which has steps on all sides reaching the temple tanks. Thirupporur Tank has been down to the water. The best examples of such taken to find the reason for having water tanks are called kulam in South India. throughout the year. Then the Mylapore tank Traditionally, where the rainfall was relatively low, (within the city) has been taken and studied in every effort was made to retain all the water that detail. The study found the reason for the dryness fell on the ground through appropriate water of urban tanks. It also revealed the methods to retention and conservation strategies such as at rehabilitate and thus to re-establish the the erys, temple tanks and ponds. Traditionally, hydrological role and possible multiple use of the temple tanks seem to have played three hydraulic tanks. The study analysed both the quantity and roles: quality aspects of the tanks. • as a storage, which acted as insurance against Keywords: Temple tanks, rainwater harvesting, low rainfall periods and also recharges groundwater recharge, SCS method & public groundwater in the surrounding area, participation. • as a flood control measure, preventing soil Introduction erosion and wastage of runoff waters during the In India, traditionally settlements are located in period of heavy rainfall, and and around temples. The temple complex includes • as a device which was crucial to the overall a tank which is as an important site for cultural eco-system. actions and the temples and tanks are inseparable. In south India at least one tank is attached to Temple tanks occupy a prime position in the day to every temple. In Madras city alone, there are 39 day living of the people. For instance in temple tanks. The surface area of tanks varies Kancheepuram, there are seven temple tanks from half an acre to seven acres (2000 m2 to corresponding to the days of the week and each 30,000 m2). Most of the temple tanks have been tank has its own significance (Cox, 1894). They dry during recent decades due to urbanization, are still places of socio-religious and cultural continuous withdrawal of groundwater and activity. These temple tanks are located in the very blockage of inlet systems. Most of the temple tanks centre of the village and are the repository of age were served by inlet systems in the olden days. In old rituals. Further the temple tanks are also used recent years, due to mushrooming of commercial for Float Festivals every year. These are normally and residential apartments in the catchment areas, held on a full moon day, and are celebrated at the the inlet systems are totally blocked and precious end of the monsoon. If the locality falls in the rainwater runs into sewers and reaches the sea influence of the south west monsoon, the festival is (Cudworth & Bottorf, 1969). Over-extraction of celebrated in July and August. In regions, which groundwater has occurred due to population get rain from the north east monsoon it is growth in the tanks’ catchment areas. Groundwater celebrated during January and February. The recharge has been reduced due to the increase in people celebrate this festival to thank the Almighty impervious surface from asphalting or concreting of for giving sufficient rain. The festival creates roads and backyards. This has led to a lowering of awareness among people regarding the need to the water table surface and has caused failures in store rainwater. It can be simply summarised that groundwater wells. the temple tanks are meeting places of the social A study has been made to evaluate appropriate and ritual activities. Thus, temple tanks need to be strategies to conserve the rainwater in the existing urban temple tanks. It also deals with the iSee category: Research article “Temple tank: ancient water storage approach” by Madhavi Ganesan Indian Society for Education and Environment Indian J.Sci.Technol. 2 Indian Journal of Science and Technology http://www.indjst.org Vol.1 No 7 (Dec. 2008) recharging capacity of the tanks, effects of the Mylapore which is situated in the heavily urbanized surrounding land use pattern and water inlet and densely populated area of the city. It is said to systems. This includes studying the runoff be 330 years old. The Fig.4 shows the location of characteristics of the catchment areas of temple the present study area and Fig. 5 gives the plan of tanks and suggesting methods to improve their the Mylapore Tank. In ancient times the temple and storage potential. tank were surrounded by coconut groves. The Structural features in temple tanks entire average rainfall of 1200 mm soaked into the Temple tanks are either square or rectangular soil and flowed into the tank. The piezometric level in plan, and are truncated trapezoidal in section, then was only 1 metre to 2 metres below the being staggered from top to bottom as shown in ground level. The present urban development of Fig. 1. Often, temples have two tanks: one inside the Mylapore area, namely Mandaveli, and the other outside the temple building. Granite Mandavelibakkam, Alamelumangapuram, slabs are used for constructing the steps on all Ammaniammal Street, Narayana Swamy Garden, sides. Normally, each step has a tread of one foot Abiramapuram, R.A. Puram, were non-existing. and a rise of half a foot (GOI, 1961). At every tenth Now, the groundwater depth is 10 metres or more step there is a landing of two foot width, having the below ground surface. In 1991 groundwater same rise of half a foot as shown in Fig. 1. This withdrawal in this area was estimated to be in the gives stability to the structure. order of 10,000 m3 per day. In Madras (now Chennai) the major inlets are The geology in the locality comprises alternate usually placed in the south west or the north west layers of coastal alluvial sand and clay of recent corner of the tank as shown in Fig. 2. The land formation, deposited over a bed of Archean rock. slopes from west to east. The major inlet is The Adyar river and Buckingham canal are connected to its own catchment area or another drainage channels 10 metres to 12 metres below water resource through storm drains. Apart from the ground level. At this depth there is a potable this inlet there are a few other slots like inlets on all water bearing zone. Below 15 metres the sides of the tank. These help to link the water table groundwater becomes brackish. Areal and the tank laterally. Most of the temple tanks photographic survey of the Mylapore-Mandaveli also have an inlet from the temple area. It has locality shows that the built-up area occupies about been observed from the original layout of tanks in 90 percent and open space occupies some 10 Madras City, there was series of inter linkages percent. The soil group of the open space is among the tanks to allow excess flow of water to classified under Group 'B' known as sandy loam. decant into the neighbouring tank. This design The slope of the paved area from north to south of provided for both inlet and outlet drainage. There is the tank is 1:1875 over a distance of 750 metres. a structure known as a Neerazhi Mandapam The natural catchment of the Mylapore Tank is situated in the centre of the tank. The main intercepted by the Buckingham canal, constructed purpose is to house the deity during the Float in 1901. This reduces the original catchment area Festival. It is constructed with granite stone (Fig. and also takes away rainwater to the sea. The 1). canal also intercepts subsurface flow towards the Most of the tanks are having wells in their bed. tank. The main catchment area of the tank today is Their presence is relevant in the present context a Higher Secondary School and its playground. It and one can visualize a certain functional role for covers nearly 51,000 m2. This area helps to them. The wells link the aquifer and tanks and are provide nearly 1 metre of water to the tank. But the supposed to serve for natural recharge. Wells in runoff from this area was blocked by an the tank are shown in Fig. 3. Thus the design of the unauthorized shopping complex constructed over temple tanks is ideal from the point of view of the storm drain leading to the tank. This blockage harvesting, storing rainwater and recharges the of storm drains was removed in 1972 through a aquifer. tank renovation project. Study area: Mylapore tank Problem inventory of the Mylapore tank After a preliminary survey of the temple tanks in In 1974, rainfall in Madras city, was 900 mm Madras city, the Mylapore Tank has been selected which was below the normal value.