Local Goa News

Wednesday, August 3, 2016

‘Human impacts on Mandovi bank need probe’

PANAJI: While scientists and environmentalists have already been stressing the need to conduct a detailed study to ascertain the health of river Mandovi, considered the state's lifeline, the addition of Goa Coastal Zone Management Authority's (GCZMA) expert member Antonio Mascarenhas's voice to the chorus has provided a fillip to the growing demand. Mascarenhas has also recommended that a few morphological changes in the river system be studied closely too.

"The river banks, on the Panjim side in particular, have under gone systematic and continuous modifications almost on a yearly basis for the last four decades at least," Mascarenhas noted in a report submitted to the GCZMA, which also mentions how the overall impacts of these changes and the anthropogenic interventions the river has been subjected to have not been studied.
Given the number of bridges and jetties built near its mouth, Mandovi is easily the most impacted river in the state.
The ongoing construction of the third Mandovi bridge and a complaint filed before National Green Tribunal (NGT) has recently drawn attention to the possible long-term impacts of additional obstructions in the form of pillars in its channel. The impact of laying the foundations of the third bridge across the river on the existing foundations in close vicinity as a geotechnical issue also needs to be considered.
It was as per an NGT directive that Mascarenhas had conducted a site inspection and placed his initial observations regarding possible impacts of the third bridge before the tribunal.
While the problem of the banks on Panaji as well as Betim side being colonized by mangroves has been overlooked, the reports raises a query whether the piers of both bridges blocking the river's flow could have led to siltation.
"Huge chunks of debris lying in the river even after three decades need to be cleared immediately. The remnants of the bridge which collapsed in 1986 are still lying in the river and their impact on the flow and the river bed have been overlooked all these years," the initial report points out.
A comparison of charts from the naval hydrographic office (NHO) dating back to 1970, 1986, 2007 shows several changes have taken place in the overall river system. The charts point towards increasing silt deposits in the river bed. "A bathymetric survey using an echo-sounder would give the depth profile and a side scan sonar survey would give a complete picture of the river bed, if affected by the three existing bridges," Mascarenhas stated.
Distinct alterations have been noted in the tidal sand and mud flats along the banks at Miramar, Campal, Panaji and Patto-Ribandar. The beach near the children's park at Campal has been progressively growing into the river mouth over the last 45 years and large amounts of silt deposits have also been noticed around the bridges in some locations.
"The bed of River Mandovi is deeper towards Ribandar and Reis Magos whereas it is shallower around the bridges. More severe shoaling takes place off Aguada while continuous erosion and accretion is observed at Miramar," Mascarenhas says, summing up the changes.

TOI Goa News

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