Landslides are a part of the
Going by the geological clock, the
Prolonged downpour often reactivates old landslides. "The natural absence of vegetation in the higher reaches of the catchment areas also contributes to frequent landslides," says an expert. Apart from bringing down large quantities of sediments, landslides become a major cause for devastating floods because they block the narrow gorges. They are normally marked by a sudden change in the gradient of a tributary stream, constriction at the point of confluence and weak geological conditions in the catchment of the tributary. The formation of landslide dams is a common sight in the
Large scale deforestation and faulty farming practices have also led to soil erosion, according to local people. Says V Sharma, department of geology,
The increase in human activities along the slopes has changed the existing land use pattern. Experts say that the change in the cultivation patterns is another factor for landslides. A large number of people have shifted to terrace farming. Terrace farming requires vast tracts of denuded land - and also lot of water. The crop pattern has also changed. Villagers now fall prey to the less soil-binding crops such as rice instead of millets, more suited to this area. Local crops like millets and maize have taken a back seat while commercial crops and water intensive crops like paddy are grown.This makes the hills unstable. Earlier, forests would have protected the strength of the soil, but due to excessive deforestation, the protective cover has been drastically reduced. This has resulted in the creation of large number of rivulets in the hilly region.
Source - Down to Earth (14Sep1998)
Photo credit : Suman Tamang (Darjeeling)