TNN | Apr 23, 2023, 05.49 AM IST, The Time of India
PUNE: The city has permanently lost at least three million cubic metres or three billion litres of groundwater storage capacity due to the construction of buildings and their foundations over the upper portions of shallow and weathered basalt aquifers, revealed a recent report on aquifers by the Advanced Centre for Water Resources Development and Management.
Himanshu Kulkarni, former executive director and current scientist (Emeritus) of the centre, told TOI that the report released this year was based on data collected during four years till 2022. He said, "This loss is based on conservative estimates of buildings
in the city and their foundations. The report selected five major aquifers for the city to illustrate the variety of land-cover and land-use elements on their respective recharge areas. The findings revealed that nearly half of the recharge area (46%) is covered by housing societies, like apartment blocks that are typically multi-storied and often with more than one building."
If collected, three million cubic metres, or one TMC, of groundwater could fill up nearly half of the Khadakwasla dam which has the capacity to store 1.97 TMC of water.
Kulkarni said, "The study revealed that 13% of the recharge areas is overlain by government facilities, while 11% is covered by commercial establishments and institutions each. Private bungalows have come up over 6% of these recharge areas. Besides, an additional volume of groundwater is pumped out into wastewater or stormwater drains from the basements of some constructions."
High-water tables in different seasons or spring discharge imply discharge from aquifers into foundations and basement parking lots. The research team stressed the need to consider the prevention of cutting through productive aquifers during any infrastructure building activity and to take care for avoiding dewatering of such aquifers at the intersection with engineered structures.
Aquifers are natural underground layers of rock, sand, or gravel that contain water and can supply wells and springs with water. They act as storage units for groundwater.
Kulkarni added,
"When excavations are made for parking and other infrastructure, some of the material that stores groundwater are removed. This can cause flooding in the basements during heavy rain. Our study estimated that at least 3 million cubic metre of groundwater storage have been lost due to this excavation in Pune."
He said, "This means that not only the ability to store groundwater is reduced, but the ability to replenish it is also permanently lost."
City loses 3 billion litres of groundwater, says report Himanshu Kulkarni, former executive director and currently scientist (Emeritus) of Advanced Centre for Water Resources Development and Management, said other factors, such as disturbing the areas near river channels, would affect the groundwater recharge and discharge interactions between the river and the aquifers. To manage Pune's groundwater more efficiently, we need to understand this issue more closely."
According to the report, Pune city is underlain by nine main unconfined aquifer systems (see above graphic). In addition to this, there are an additional 19 unconfined aquifers at the higher elevations represented by the hillocks and ridges, particularly in the south and west.
The report stated that protecting the recharge zones would primarily mean a no-compromise protection of the catchments of the three main watershed clusters: Kothrud-Vetal hill-Chatushringi-Pashan-Bavdhan range; Vishrantwadi -Vimannagar highland zone; Dhankawadi-Yewalewadi-Katraj ranges. The study found that some of the natural groundwater recharge and discharge areas for Pune city are situated east of the Dhankawadi area, while the other is in the western part occupying the ridge that lies between Kothrud and Pashan. Significant coherence to the area is occupied by the main ridge in Pune-ARAI hill-Vetal tekdi- Chatushrungi-Bavdhan-MIT college ridge.
"Smaller but significant recharge areas are also noticed in the Aundh-Baner-Pashan ridge line and the Range Hills area," Kulkarni said, adding, "Another indicative groundwater recharge zone is in the uplands as one moves from the river towards Vimannagar, in the direction of the Pune airport in Lohegaon."
The link to the above article is given below
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