City Matters | Madurai

Will construction of check dams be a boon or bane?

Construction of a check dam across Vaigai under way near the AV Bridge in Madurai.

Construction of a check dam across Vaigai under way near the AV Bridge in Madurai.   | Photo Credit: G_Moorthy

Civic body says project will provide water for the float and Chithirai festivals

Madurai Corporation is constructing two check dams across the Vaigai under the Smart City Mission.

Though it has earmarked ₹21 crore for the dams coming up near AV Bridge, urban planners and researchers question usefulness of the project.

The two check dams would be built 1.4 metres above the riverbed and can hold water on the riverbed for up to 1.5 km, an engineer from the City Corporation said.

While Public Works Department (PWD) is executing the project, the Corporation is undertaking work like developing a park along the river under the ₹85 crore-Vaigai Riverfront Development Project.

The latter includes works related to the beautification along the banks of the check dams through construction of parks, pathways and lightings.

Status of the project

The construction of check dams, which commenced in February this year, is expected to be completed by February 2020, officials say.

“After the construction of these check dams, the groundwater level will improve for around 2 km radius,” says T. Subramanian, Executive Engineer-Periyar Vaigai Division.

A Corporation official said that the new check dam near A.V. Bridge will help raise the water level in the Vaigai river so that it can flow from the river to Mariamman Teppakulam through the Panaiyur channel.

As of now, the water has to be pumped into the temple tank using huge motors for the annual 12-day float festival.

“Once this project is completed, excess water from the Vaigai river can continue to be diverted into the Teppakulam and it can have water throughout the year,” says the engineer.

However, construction of a sluice gate is essential to channelise water from the check dam to the Paniyur channel.

“The PWD has submitted a proposal seeking funds totalling ₹90 lakh for the construction of the sluice.

But the Corporation is unable to allocate funds through the Smart City Mission.

The local body is exploring possibilities to see if Corporate Social Responsibility (CSR) funds can be raised for the project,’ says an official.

Apart from the float festival, the check dams are set to provide water during the Chithirai festival when Lord Kallazhagar enters Vaigai, the official adds.

“The construction of the check dams will also ensure some amount of sedimentation on the riverbed, which will enrich the soil,” says the engineer.

Disadvantages

Researchers and urban planners state that spending a total of ₹21 crore to ensure groundwater recharge along the stretch may have an adverse effect on the environment through contamination of groundwater.

S. Praveen Kumar, Project Executive, Water Knowledge Centre, Tata-Dhan Academy, states that the current flow into the river is primarily sewage water.

“When it rains and there is flow in the river, the sewage water automatically gets washed out. However, if there is marginal flow of sewage into the specified site through the channels connecting to the river, it could turn into a large mosquito breeding ground,” he says.

Apart from the several health hazards associated with vectors like mosquitoes, Praveen states that sewage water could percolate into the ground and spoil the groundwater quality.

“The main reason for concretisation of the inlet channels and stormwater drains was to prevent sewage percolating into the groundwater. This project may end up facilitating such a situation,” he adds.

G. Balaji, Professor and Conservation Architect, Thiagarajar College of Engineering, states that check dams are usually established near freshwater sources.

With sewage in the river and dumping of garbage, their main purpose may not be solved, he says.

He adds that silt deposit will rise between the check dams, leading to accumulation of chemicals at one spot.

Mr. Praveen says that if floating wetlands with tall reeds are established near the junction of each inlet channel into the river, it may prevent some level of sewage percolation.

Only if there is freshwater flow into the check dam for over 60 days a year, will the project be useful, they add.

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Printable version | Feb 25, 2020 8:18:03 AM | https://www.thehindu.com/news/cities/Madurai/will-construction-of-check-dams-be-a-boon-or-bane/article28236722.ece

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