WRD begins work to drill exploratory wells in Minjur belt for a pilot study on groundwater mapping

The Danish team recently visited the site in Minjur for a field investigation along with officials of the Water Resources Department of Tamil Nadu.
| Photo Credit: SPECIAL ARRANGEMENT

The Water Resources Department has started work to drill exploratory borewells in three villages in Minjur belt to help validate findings of a pilot study on groundwater mapping using Danish technology.

Following the State government’s nod, three wells would be sunk at depths varying from 50 metre to 100 metre in Siruvakkam, Murichambedu and Akkarambedu villages to facilitate better understanding of the hydrogeological formations of the study area.

Officials from WRD’s State Ground and Surface Water Resources Data Centre, along with Danish team, would validate data obtained through the pilot study using s-Tem profiler with real-time data from the wells. The s-Tem profiler is a geoscanner tool designed to acquire subsurface data and ideal for mapping groundwater aquifers.

The Danish team had recently visited the site for a field investigation along with WRD team. Officials of WRD said the coastal stretch of Minjur, which has been severely affected by seawater intrusion and groundwater over-extraction, was chosen to implement the demonstration project on ‘Managed Aquifer Recharge’, which aims to provide solutions for groundwater recharge.

Of the total 1,202 revenue blocks in Tamil Nadu, nearly 395 revenue blocks are over-exploited and 64 others fall in the critical category, in terms of groundwater extraction. Chennai, Dindigul, Salem, and Thanjavur are among the districts that have many over-exploited revenue blocks as per the dynamic groundwater resources assessment of Tamil Nadu.

Besides sharing their technology for optimal groundwater infiltration in a short span, the Danish team from Geological Survey of Denmark and Greenland would also organise capacity-building programmes for field officers on groundwater management.

Officials of the WRD noted that seawater had intruded up to 16 km inland in Minjur – Ponneri belt. It was found that patches of paleo channels, which are remnants of former river systems that have changed direction over several decades, still exist in Minjur belt. The area still has sand formation that is capable of holding groundwater.

The Danish technology would help identify lithology of a site and potential pockets for groundwater recharge. One of the solutions is to inject freshwater into the wells or recharge shafts to replenish groundwater and create a barrier against saltwater incursion.

Following the project’s success, the pilot study on aquifer mapping and solutions for artificial recharge would be extended to other districts, including Cuddalore and Thoothukudi along the Tamil Nadu coastline, officials said. The borewells would be converted into recharge wells and groundwater monitoring wells, once the study is completed.