IITB researchers suggest ways to restore Madurai’s historical water tank system

Researchers conducted a survey of the Vandiyur Tank Cascade System (VTCS), which is suffocating due to negligence, lack of scientific knowledge, and inadequate policy to govern its maintenance.  

Researchers from the Indian Institute of Technology (IIT) Bombay conducted an extensive survey of the Vandiyur Tank Cascade System (VTCS). The Vandiyur tank system is suffocating due to negligence, lack of scientific knowledge, and inadequate policy to govern its maintenance. Further, this traditional water storage system is fast succumbing to the rapid urbanisation of the city  

“The uniqueness of this water system is that, unlike conventional tanks that are filled by channelling water from a flowing river, the VTCS tanks are embedded in the line of river flow. Moreover, they are interconnected. So unless a tank is filled, the river does not progress further downstream,” said Pennan Chinnasamy from the Centre for Technology Alternatives for Rural Areas (CTARA), who led the research group for the study.  

The researchers conducted a water-balance approach study to check the tank system’s present condition. They assessed parameters, including how much water was flowing into the tank from the river and rainfall, the tank volume, and the region’s water demands. They also factored the parameter changes over a two-decade period due to anthropogenic activities and urbanisation measures. The team used both extensive field analysis and Google Earth’s remote sensing database of maps for their assessment. 

The researchers analysed the parameter variations over 20 years. They found a 300 per cent increase in urbanisation leading to 40 per cent of the catchment water lost due to runoff. Reduced agriculture further diminished the chances of slowing down the runoff or recharging the groundwater.  

When they assessed rainfall variations, although there was negligible change in the average rainfall (931mm), runoff increased due to ill-maintained tanks during the flood periods.  Suggesting a few immediate remedial measures, the authors said silt removal, clearing water hyacinth in the tanks, and fortifying the tank embankments could help revive the system.  

In addition, Dr Chinnasamy emphasises that “Primarily, the tanks in the cascade system need to be managed holistically as a single integrated unit for better management and tank efficiency.”  He said policy changes are the need of the hour. Solving an issue at a single tank will not remedy the system but only lead to it percolating down the chain as the tanks are interconnected.  

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