Landslide at Talacauvery caused due to multiple contour trenches and cutting of slopes 

Madikeri:  The Geological Survey of India (GSI), a Government of India body, has concluded that slope modification without proper precautions is the main reason for recent landslides in parts of Kodagu. The scientists, who have conducted extensive field study and research, have not ruled out the possibility of future landslides in the same places.

‘A note on preliminary post disaster studies in and around Virajpet and Bhagamandala areas, Kodagu’ has been prepared by Geologists from State unit of GSI Sunandan Basu and Kapil Singh after the Kodagu District Administration requested the GSI to inspect the areas hit by landslips. The Geologists visited the areas on Aug. 17 and 18 and were accompanied by State Government officials.

The Geologists examined landslide and land-crack patterns at Ayyappa Betta of Virajpet, Nehru Nagar in Virajpet, Virajpet – Heggala road (opposite rock quarry) at Thora in Virajpet, Kedamulloor Village, Virajpet, Brahmagiri Hills, Talacauvery Temple and Korangala near Bhagamandala.

In the preliminary report, the Geologists observed that the Ayyappa Hill area falls under highly susceptibility class. Construction of houses by cutting and benching of the hill slope without proper support has destabilised the slope. As this area is already highly susceptible to landslides, this kind of slope modifications without proper precautions is likely to trigger landslides in the future also, the scientists observed.

Likewise, Nehru Nagar, Thora, Talacauvery Temple and Korangala areas fall under moderate to highly susceptibility class when it comes to landslides. Here too, unbridled construction of houses by carving hill slope has resulted in land destabilisation. At Talacauvery, unsupported slope cut for road widening has destabilised the entire slope and future landslides cannot be ruled out. “There are multiple contour trenches made by Department of Forest at the mid slope for conservation of water and prevention of soil erosion. These trenches are aligned parallel to the crack and situated near the upslope of the cracks. It cannot be ruled out that the trenches with standing water may have allowed infiltration into the overburden material. Slope cut for road expansion and the cut slope is left unsupported,” the report stated on the geo-scientific causes of surface cracks at Talacauvery.

The Geologists have suggested certain remedial measures like slope grading, construction of retaining wall with weep holes and plantation on the slope. This will increase the toe support to the unstable slope. Cracks observed atop the hilly areas should be filled preferably with impervious material to reduce chances of water infiltration into the overburden material. Filled cracks must be monitored regularly and in case of any movement, authorities must be informed immediately.

These landslides were also caused due to excessive rains. Up to Aug. 11 this year, Kodagu has experienced slightly deficient rainfall compared to normal monsoon. The rainfall data shows that the district received heavy rainfall from Aug. 5 to Aug. 11, the report mentions.

Speaking to Star of Mysore, K.V. Maruthi, Director, GSI, said that the GSI team has prepared and submitted a preliminary report. “The field results carried out in 2018 after the massive devastation is yet to be finalised and the report will be submitted soon to Kodagu DC and will also be published in the GSI official website,” he said.

On the latest cracks being observed at Brahmagiri Hill and Gajarajagiri Hill, he said that if the Kodagu Administration requests a survey and analysis, the team will study the cracks.