Study proposes reverse landscaping to restore Munroe Thuruthu’s original geomorphic state

Munroe Thuruth island in Kollam | Photo Credit: C SURESHKUMAR

A study conducted by the National Center for Earth Science Studies (NCESS) has revealed anthropogenic interventions as the main reason affecting the isostatic conditions and land neutrality of Munroe Thuruthu, an island going through drastic environmental degradation.

The multidisciplinary research conducted during the last five years calls for suitable strategies to protect the highly vulnerable estuarine ecosystem and proposes reverse landscaping as an innovative methodology to retrieve the landscape’s original geomorphic state.

According to the study, almost 39% of the land area of ​​the Munroe Thuruthu has been lost with Peringalam and Cheriyakadavu islands recording a land depletion of around 12% and 47%, respectively. “Though the degradation started in 1980s, its severity was felt only in 2000s. Unregulated sand mining and the resulting riverbed pools in the Kallada river have largely contributed to the current degradation. After the construction of Thenmala dam, the sediment supply through the river too was blocked,” says MK Rafeeque, lead author who carried out the study with TR Anoop, MK Sreeraj, R Prasad, L Sheela Nair and A Krishnakumar.

Munroe thuruth island in Kollam | Photo Credit: C. SURESHKUMAR

While the research team used available remote sensing data and land survey records to analyze the island’s morphological changes, electrical resistivity meter surveys were conducted to study the sub-surface geology of the land area.

“We also conducted a bathymetry survey of the Kallada river and found that the depth was around 14 meters. There were many saline pools affecting both soil fertility and groundwater quality. The increased levels of soil salinity had impacted agriculture while the climate change too contributed to the ecological challenges,” he says.

Wetland preservation

Since the Ashtamudi Lake is emerging as an important tourist destination, the study stresses on the need for sustainable management plans to protect the Ramsar-listed wetland. “There should be a well-drafted master plan to minimize land degradation and other environmental issues,” adds Mr. Rafeeque.

The study proposes reverse landscaping, a plan integrating all aspects of earth and social sciences. Apart from strict regulatory measures to control sand mining from Ashtamudi Lake and the Kallada river, the current construction methods in the island should be replaced with well-studied engineering techniques. An artificial sedimentation process to eradicate the saline banks of deep basins is also suggested as a method and the study recommends to use the sediments deposited in the Thenmala reservoir and those removed through dredging navigation channels for the purpose.