Sir,
It was reported that one more landslide has struck the Nandi Statue Road atop Chamundi Hill (SOM dated Oct. 21). Repeated slides seem to have given rise to the perception that this isolated escarpment has grown weak and become landslide-prone, possibly because of human intervention beyond the carrying capacity of the region.
In the background of my experience with the landslides of Kodagu and extensive studies pertaining to them, I have visited and tried to understand the causes for slides in Chamundi Hill.
I am convinced that the slides on the Nandi Statue Road are all a failure of the structure of the road and are not movement of the land per-se.
It is found that the present road surface in many parts is formed on 15 to 20 ft deep earth fills over the original formation — a couple of culverts built across the original road have also been exposed by the excavation now done for repairing the road.
With the growth of exceptionally dense shrubby vegetation on the slopes during the last decade and excessive rainfall, the quantity of water infiltrating into the ground has enhanced extensively during the last three years.
Because the land is basically rocky with little scope for percolation below the soil layer, the infiltrating water has flown in the lateral direction as seepage. This subsurface flow has led to removal of the loose material in the filling, leading to the slides being witnessed.
In fact, no ‘true landslide’, of the kind that occurred in 1994, has been experienced these days. Hence, there seems to be no threat of the Hill having become unstable.
However, the current series of slides has brought to light the dangers involved in undue development works on the slopes and the new event goes to raise questions on the reliability and adequacy of the restoration work being taken up.
It is observed that a good part of this stretch of the road is in filling and quite a length is on the verge of caving in. Hence, the restoration work underway is bound to go to waste, unless the whole stretch is engineered properly. Restoring the road to the original formation level or a bit above it with properly designed earth filling seems to be the only way out.
– Yadupathi Putty, Mysuru, 25.10.2022
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This post was published on October 27, 2022 5:55 pm