Warning Systems and Hazard Mapping Formation zone avalanche control scheme at D-IO avalanche site on National Highway, Jammu-Srinagar (India): A case study

Abstract: The Pir Panjal range in the Indian Himalaya in Jammu and Kashmir state lies in the lower Himalayan region between latitude 33°10 ' and 34°40'N. This region experiences short winters (2-3 months) and moderately high snow precipitation having high moisture content, high temperatures and direct action avalanche activity. The area also experiences very high drift activity. Due to the above conditions which are typical to the lower Himalaya region, the conventional structures for control of avalanches in formation zone are relatively very expensive. Keeping this in view it is desirable to follow a composite scheme having combination of wind control structures, supporting structures, terrain modification and controlled release of avalanches using explosives. The above has been done at an experimental site located on a mountain ridge in Pir Panjal range of Himalayas under which 2.6 kID long tunnel joins the National Highway from south to north. Among 15 avalanche sites on this highway, D-I0 is one of the most important sites with very high frequency of avalanche triggering. The mouth of the tunnel gets blocked frequently due to D-l0 avalanche. Since the catchment is very large and the snow accumulation pattern is quite different in various gullies, a composite scheme to use various types of formation zone control measures was worked out, both from the point of controlling the avalanches as well as understanding the efficacy of this scheme evolved for D-lO experimental site. This paper describes the composite avalanche control scheme, modification made in the design of Snow nets and the effectiveness of structures observed during last four winters from 1998-2002