Hazard Vulnerability and Risk Profile of Himachal Pradesh
Himachal Pradesh is highly vulnerable State to a large number of natural as well as man- made disasters. Earthquake and floods has jolted this hilly State many times and caused great losses to the State. Flood, cloudburst, landslide and cloud burst are other common natural calamities of the State.
Earthquake
Himachal Pradesh is located in the northwestern part of Himalaya. Himalaya came into being due to inter-continental collision between Indian Plate and Eurasian Plate. The inter-continental collision caused volcanism, folding, faulting, under thrusting, uplift, crustal shortening and accumulation of seismic energy. There are a number of faults viz. Himalayan Frontal Thrust (HFT), Jawalamukhi Thrust (JT), Barsar Back Thrust (BBT), Muree Thrust MT; Main Boundry Thrust MBT; Panjal Thrust; Main Central Thruct (MCT), Kulu Thrust (KT), Vaikrita Thrust (VT) etc. Release of accumulated energy along these fault lines has resulted into some devastating earthquakes and great losses to the State. Every year state is experiencing a number of earthquakes. Whole of the state is either in seismic zone IV of high risk zone or in seismic zone V of very high risk zone.
Floods
All the major rivers of the State have their sources in glaciers. One common feature of glacier area is the presence of glacier lakes. When these lakes burst causes flash floods. Sudden discharge of huge volume of water from glacial lake is known as Glacial Lake Outburst Floods (GLOFs).The frequency of GLOFs increases with the climate change and deforestation. Cloud bursting is another cause of flash floods during monsoon period. State has harnessed its hydroelectric potential owing to perennial rivers. This has produced a number of hydroelectric dams. These dams and natural lakes may get damaged especially during earthquake. Sudden release of water by opening floodgates of hydroelectric power project also increases the volume of water in the downstream. This poses a great threat due to floods in the downstream.
Cloudburst
Cloudbursts are associated with convective clouds. Vertical Development of clouds in Himalayan region is associated with its topography and southwestern monsoon wind direction. Himalaya is arch shape mountain located in east-west direction in the northernmost part of India. Average elevation of Himalaya is about 6100 meters above mean sea level. Himalayan river valleys are open towards south and are closed in the north. Summer monsoon winds enter in the river valleys and are forced to rise vertically along the valley slopes. Vertical development of clouds can extend up to 15 kilometers above the earth surface. Sometimes a very heavy rainfall occurs of equal to or greater than 10 centimeters per hour which is called cloudbursts. Cloudbursts are usually associated with landslides and flash floods.
Landslide
Downward movement of rocks primarily under the influence of gravity is called landslide. Besides gravity there are factors that build a specific subsurface condition to make area prone to slope failure. However, the actual landscape often requires a trigger before the event. Earthquake and rainfall trigger the rocks downward movement. It is both natural and manmade phenomena and varies spatially with variation in altitude, geology and topography. The controlling factors of landslide are steepness of slope, type of rocks, change in vegetation and developmental activities like C/o roads, tunnels, Hydropower projects etc.
Avalanche
Sudden slide of large mass of snow along the slopes of mountain is called avalanche. They occur in high altitude area with steep valley slopes and are common in Kinnaur, Lahul and Spiti, Kullu, Chamba and Kangra districts.
Road Accidents
Roads in the state are along the former river beds or by cutting the mountains and are curving. Common causes of accidents are poor visibility due to fog, non use of horns especially on curves, use of alcohol, over speeding, overtaking on curves and poor maintain of the vehicles.
Risk analysis
Earthquake (Very High Risk)
In Himachal Pradesh 60% population lives in very high risk zone; 38 % population lives in high risk zone and the rest of population lives in moderate to low risk zone. Limited awareness, Preparedness, structural weaknesses of the buildings, Flouting of bye laws by public and high population density in various institutions reveal very high vulnerability to day time earthquake and low capacity. This suggests very high risk.
Flood (High Risk)
Topography of Himalayan river valleys, glacial fed rivers, damage or sudden release of water from power project dams and densely populated former river beds poses high risk.
Cloudburst (High Risk)
Impact of cloud burst is dual. It leads to landslides and flashfloods. Settlements on river terraces are at high risk.
Landslide (High Risk)
landslides pose risk to buildings and disruption in road and communication network. Landslides also choke rivulets and form temporarily lakes. When these lakes burst it causes flash foods.
Avalanche (Low Risk)
Six districts viz. Hamirpur, Una, Bilaspur, Mandi, Sirmour, and Solan have no risk of avalanche. Further Kangra, Chamba and Shimla have medium risk. Kullu falls in High risk zone, whereas Kinnaur and LahulSpiti are in Very High Risk zone. Further there is small proportion of population living in High and very Avalanche risk prone districts. Low vulnerability suggests Low risk.
Road accident (High Risk)
Steep slopes, Sharp bends in roads, narrow roads, overloaded buses & reckless driving, negligence, unskilled drivers, causes accidents.