Slope instability assessment in the Karmi area of Central Himalaya, India

Summary

In July 1983, the Karmi region of Central Himalaya witnessed a calamitous landslide which was destructive not only for the human inhabitants but also was an incident of immense significance relating to environmental degradation. Karmi village is situated on the debris of an old landslide. The toe of the slope of the landslide, filled with debris, on the flanks of a stream has developed slip zones dipping towards the channel at various angles. These slip zones are the most likely to become active during heavy rains. On the steep slopes and ridges, which consist of a thick sequence of chlorite and talc schists interbedded with soapstones and thin quartzites, sliding and movement of the rock-mass is quite evident during excessive rains. Chemical solution of the rocks is also a common phenomenon in this region. Higher slopes and ridges are comprised of thick sequences of quartzite and slate which also have steep dip angles.

Seven types of slope instability have been recorded in the Karmi area, these are: surficial erosion, rock falls, collapsed terraces, slides, flows, slumps and complex mixtures. It is argued that a full assessment of the terrain should be both rational and mandatory prior to any form of construction or development in the area.