New report recommends curbs in Colaba as seawater threatens rise in groundwater salinity in SoBo. The Central Ground Water Board (CGWB) has recommended that the BMC ban groundwater extraction in Dadar and Mulund. It has also suggested curbs on groundwater extraction in the Colaba area.
The CGWB prepared an Aquifer Management Plan for Mumbai and submitted it to the BMC in the second week of August. The report highlights the risk of seawater intrusion into the city’s groundwater, noting that it is more pronounced in areas such as Colaba, Fort, Dadar, Mahim and Mulund East.
According to the report, Fort and Colaba have more than 500 groundwater sources, while Dadar and the eastern part of Mahim have over 400. Mulund East has comparatively fewer groundwater sources. Overall, Mumbai has more than 17,000 groundwater sources, including wells and borewells.
“Saline water has been identified at a relatively shallow depth of 71 metres in Colaba Fort area, towards the southern part of Mumbai City area. In Mulund East, Shivaji Park, Dadar and Mahim, high-salinity zones have been encountered. In Shivaji Park, saline zone has been found at around 18.5-19 metres and 36-37 metres,” the report said.
The CGWB suggested in its report that “groundwater development beyond 60-metre depth should be restricted in Fort area, and completely prohibited in Shivaji Park, Dadar, and creek areas, due to the presence of shallow and highly saline zones.”
Vikram Tambavekar, a structural engineering expert, said, “Fort Colaba, Shivaji Park, Mahim, Mulund East are coastal area. This phenomenon is mainly found in a 2-3-km area along the coastal region. If proper treatment is not undertaken during foundation work, the saline water can harm the full structure. Also, increasing salinity levels can harm old structures.”
On tackling the saline zones, the report said, “In these areas there are many parks and gardens where recharge structures such as recharge pit with filter, recharge shaft, percolation tanks/ponds may be constructed to keep the aquifers saturated and prevent saline water intrusion. Groundwater quality monitoring must be set up around vulnerable areas near coast.”
The CGWB has proposed a Rs 76-crore groundwater recharge and stormwater-management plan for Mumbai.
“I am yet to read the report. We are working on the groundwater recharge project all over the city. Our plan is to start this project till next monsoon,” said Additional Municipal Commissioner Dr Avinash Dhakne.
Following the CGWB’s recommendations, the BMC issued guidelines in 2024 for groundwater extraction for commercial use.
Source: Mumbai Mirror
