Authorities at Ranganathittu Bird Sanctuary in Mandya district have initiated the construction of eco-friendly gabion structures to protect vulnerable river islands from flood-induced erosion. The sanctuary, located on the Cauvery River, comprises 25 islands that serve as crucial nesting and breeding grounds for both resident and migratory birds.
First Phase of Protection
In the initial phase, five of the most flood-prone islands are being fortified with gabion walls engineered to withstand strong currents. For years, the forest department relied on temporary sandbag barriers. However, during large water releases from the Krishna Raja Sagar (KRS) dam, these sandbags were often washed away, leading to severe erosion. This erosion reduced island size and destroyed nests, eggs, and chicks, threatening bird populations, particularly migratory species, officials said.
Long-Term Solution with Gabion Technology
Officials have now adopted gabion technology as a permanent solution. The system uses boulders and stones enclosed in corrosion-resistant galvanised iron wire mesh to form retaining walls that remain stable during floods while blending with the riverine ecosystem. Syed Nadeem, Range Forest Officer at Ranganathittu Bird Sanctuary, explained that earlier soil-based protective structures frequently failed during high water releases from KRS. “Whenever large quantities of water were released from KRS, the islands protected by sandbags suffered erosion and damage. After consulting experts, we decided to implement the gabion shield system as a permanent solution.”
He added that five major islands have been prioritised, and work is nearing completion. The protection system will be extended to the remaining islands in phases. Constructed using stones within corrosion-resistant mesh, the gabion walls are expected to provide long-lasting protection to the islands and the bird population.
