The Public Works Department (PWD) of Uttarakhand has identified 294 chronic slide zones on the road network of the State. These slide zones are the areas where the landslides are a regular phenomenon; due to these landslides, the road network in the State invariably gets disrupted.
The landslides are a regular phenomenon, especially in the mountainous terrain. landslides become particularly severe in the rainy season as the loose top soil prompts slides. Slides normally occur when the stability of the slope changes from a stable to an unstable condition. A change in the stability of a slope can be caused by a number of factors, acting together or alone.
The Senior Geologist of PWD Vijay Dangwal told The Pioneer that the department identified these chronic slide zones on the basis of reports sent by its various field divisions. He said that on the basis of factors like Traffic load, morphology of the slide, dimension of slide prone area, history of slides, frequency of slides and rainfall patterns the department has categorized these chronic slide zone in four categories (A, B, C, D). In A category which groups' acute cases have 43 slide zones, B category has 49, C-30 and D category has 172 slide zones which are least dangerous. Dangwal said that traffic load is the most important criteria as it caters to roads with high traffic flow and the department gives top priority to these roads.
The PWD has signed a Memorandum of Understanding (MOU) with Tehri Hydro Development Corporation (THDC) a mini Ratna Public Sector Undertaking for stabilization of 43 slide zones which fall in A category. It is pertinent to mention here that THDC was involved in a massive and successful stabilization of Varnawat Mountain in Uttarkashi district. THDC was also involved in a project to stabilize the slide zones in the Vaishno Devi shrine area of Jammu and Kashmir.
The stabilization work on a chronic slide zone involves a detailed planning and plenty of resources. The process to stabilize a slope involves conventional methods like removal of material around slide zone and construction of Gabbian walls. Dangwal said that nowadays the slopes are stabilised by modern methods like soil Nailing, soil netting, rock bolting, surface drainage, sub surface drainage, geo jute technique and geo grid techniques. In additions to the above mentioned methods plantations on the slide zones are also helpful. The THDC has sent a Detailed Project Report (DPR) for
treatment of four slide zones, the work on which would
soon start.