Mitigation Guidelines for Reconstruction after the 2014 Tonekabon Snowstorm

The 2014 Snowstorm hit the city of Tonekabon and its surroundings in Mazandaran Province, resulting in heavy damage to, and destruction of, both buildings and public facilities. Nearly two meters of snow covered most of the region, blocked roads, and disrupted communication utilities, power lines, and water supplies. The weakness of the response operations, lack of preparedness, and vulnerable buildings created a critical situation. A number of large snowstorms have been experienced in Mazandaran and Gilan in 2005 and 2008. The snowstorms could probably happen again in the future, , which shows the importance of setting mitigation guidelines for this type of disaster. This study examines the process of the reconstruction after the 2014 disaster, while investigating vulnerabilities and providing mitigation guidelines for the reconstruction of the built environment in Tonekabon region.
A qualitative methodology has been used to explore the various aspects of the physical damage. The data are collected through archival and document review, and in-depth interviews with the local authorities. The interviewees were selected using the snowball method. Several field trips were made to the region for careful observations, taking photographs and drawing sketches of the damaged buildings. The collected data were analyzed and compared against the backdrop of the theoretical foundations to better identify the causes of damage to the buildings and the environment, and to propose ways to avoid such damage in the future.
The findings indicate that two dimensions should be considered in planning for mitigation strategies in future disasters. The first dimension concerns the design and implementation of architectural elements, such as installing rows of snow guards on roofs to hold snow; proper roof slope; and construction materials to prevent snow sliding; rehabilitation of buildings against unbalanced snow load resulting from drifting and sliding snow, considering the dynamic force of sliding snow in structural design for lower roofs, applying practicable modifications to avoid overlap of roofs, considering the direction of the prevalent wind in designing roof geometry and building orientation, installing heater cables on roofs and gutters to keep the water running from freezing, ventilation of attic space to keep the temperature similar to the ambient air to prevent the creation of icicles, insulating the ceiling to prevent heat from escaping into the attic space air to prevent the creation of icicles, considering buffer spaces between the main building and secondary buildings (garages, stores, outbuildings), installing canopies with proper orientation for entrance, installing flower box along the eaves to limit the access under the eaves and minimize the risk of the falling of snow and ice, placing the entrance at the gable end where the risk is low, shifting the stairs orientation in regard to the direction of the prevalent wind, designing safe access to the places with the potential of creating unbalanced snow load condition for snow removing, installing single snow guards above rooftop equipment (plumping vent and chimney) to protect them from sliding snow, installing the rooftop equipment near the ridge and not installing them near the eaves to avoid heavier sliding snow loads, and bringing overhead lines at the gable ends and not under eaves.
The second dimension relates to the built environment, which includes determining buffer spaces between buildings and the occupation level based on urban guidelines, avoiding overlap of roofs, considering configuration of adjacent buildings in structural designing, shifting the inappropriate geometry of a sloped roof entrance to avoid the falling of ice and snow on pedestrians and relocating urban furniture located under the eaves to avoid the risk of ice and snow falling on them, and keeping the roofs of buildings from protruding onto the pathways and cable routes.