landslide hazard zones Of India

Landslide hazard zoning of India

Landslide, a frequently occurring natural hazard in the hilly terrains of India, shows preponderance of activity during the monsoon period from July to September and after the snow fall from January to March. The strong earthquakes also cause triggering of landslide, particularly in regions marked by critically disposed and unstable slopes. On a rough estimate, nearly 15% of India’s landmass or 0.49 million sq km area is prone to landslide hazard. This includes 0.098 million sq km of the North Eastern Region, comprising the Arakan Yoma ranges, and 0.392 million sq km of parts of the Himalaya, Nilgiri, Ranchi Plateau and Eastern & Western Ghats. As many as 20 States of India are affected by different degrees of landslide hazard. Of these, the States of Sikkim and Mizoram have been assessed to be falling under very high to severe hazard classes. Most of the districts of the States of Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Arunachal Pradesh, Nagaland and Manipur come under high to very high landslide hazard classes. In the Peninsular Region, the hilly tracts of States like Karnataka, Andhra Pradesh, Tamil Nadu, Maharashtra, Goa, Madhya Pradesh and Kerala constitute low to moderate hazard prone zones.

earthquake hazard zones Of India

Earthquake hazard zoning of India

The Indian subcontinent has a history of devastating earthquakes. The major reason for the high frequency and intensity of the earthquakes is that the Indian plate is driving into Asia at a rate of approximately 47 mm/year.

Geographical statistics of India show that almost 54% of the land is vulnerable to earthquakes. 

A World Bank & United Nations report shows estimates that around 200 million city dwellers in India will be exposed to storms and earthquakes by 2050.

The earthquake zoning map of India divides India into 4 seismic zones (Zone 2, 3, 4 and 5) unlike its previous version which consisted of five or six zones for the country. According to the present zoning map, Zone 5 expects the highest level of seismicity whereas Zone 2 is associated with the lowest level of seismicity.

Zone 5  Covers the areas with the highest risks zone that suffers earthquakes of intensity MSK IX or greater.

It is referred to as the Very High Damage Risk Zone. The state of Kashmir,the western and central Himalayas, the North-East Indian region and the Rann of Kutch fall in this zone.

Zone 4  This zone is called the High Damage Risk Zone and covers areas liable to MSK VIII.The  Indo-Gangetic basin and the capital of the country (Delhi), Jammu and  Kashmir fall in Zone 4.
  

  Zone 3 The Andaman and Nicobar Islands, parts of Kashmir, Western Himalayas fall under this zone. This zone is classified as Moderate Damage Risk Zone which is liable to MSK VII. 
Zone 2 This  region is liable to MSK VI or less and is classified as the Low Damage  Risk Zone. The IS code assigns zone factor of 0.10 (maximum horizontal  acceleration that can be experienced by a structure in this zone is 10%  of gravitational acceleration) for Zone 2. 

MAJOR EARTHQUAKES IN INDIA

flood hazard zones

Floods :

Floods are the most common climate-related disaster in the region and include seasonal floods, flash floods, urban floods due to inadequate drainage facilities and floods associated with tidal events induced by typhoons in coastal areas. In Bangladesh, one of the most flood-prone countries in the region, as many as 80 million people are vulnerable to flooding each year (ESCAP, 1995a). In India, where a total of 40 million hectares is at risk from flooding each year, the average annual direct damage has been estimated at US$ 240 million, although this figure can increase to over US$ 1.5 billion with severe flood events.

About floods in India:

India, being a peninsular country and surrounded by the Arabian Sea, Indian Ocean and the Bay of Bengal, is quite prone to flood. As per the Geological Survey of India (GSI), the major flood prone areas of India cover almost 12.5% area of the country. 

Every year, flood, the most common disaster in India causes immense loss to the country's property and lives.

Five worst floods in India in recent times-

The Uttarakhand flood:

It have been one of the worst disasters that the country has seen so far. Over one thousand people have lost their lives and several hundred rendered homeless after mother nature played havoc in the state.

Floods have been a regular phenomenon in the country especially in the northern and eastern parts of the country. States like Bihar, Uttar Pradesh and Assam every year bear the brunt of floods. Here is a list of floods that have led to widespread destruction in the country in recent times.

Bihar floods 2008:

Bihar is among the most flood prone states of the country. North is the worst affected region in the state where 76% of the population lives under the threat of recurring floods. It was in 2008 when the embankments of Kosi river broke near Indo-Nepal border flooding Supaul, Araria, Madhepura, Saharsa and Purnea. Over 400 people died in this flood and millions were rendered homeless.

Leh floods 2010:

A cloudburst and overnight rainfall on August 6, 2010 triggered flash floods, torrential rains and landslides in Ladakh. Leh-the main town was the worst affected. Over 200 people died in the floods. 71 towns and villages were damaged and over 9,000 people were directly affected by the calamity.

Gujarat floods 2005:

Unprecedented heavy rains in the end of June 2005 resulted in flooding of south Gujarat and Saurashtra. More than eight thousand villages in 19 districts were affected by the floods. Anand, Vadodra, kheda Surat and Valsad were the worst affected areas. Over 200 people are believed to have died in the floodings. It is believed that it rained continuously for more than 100 hours deluging several towns and cities.

Mumbai Floods 2005:

On July 26, 2005 the city of dreams experienced one of the worst floods in its history. The rain that began on July 26 carried on for three consecutive days. It was a case of urban flash flooding. The entire Mumbai was deluged. Traffic and rail services came to a standstill. All the low lying areas were completely flooded and there was no electricity in many parts of the city. Mobile phones had also stopped functioning.

Assam floods 2012:

The 2012 flood in the northeastern state of Assam was the worst since 1998. Over 23 districts including the Kaziranga National Park were affected in the flood. Over 120 people and 540 animals were killed in the floods. 13 rhinos also perished in the floods from the world famous National Park. According to an estimate over 21 lakh people were affected by the floods.

Death Estimates From Indian Floods Vary Wildly- 

NEW DELHI—More than two weeks after India's northern state of Uttarakhand was hit by floods, the death toll from the disaster remains unclear.

Confusion mounted over the weekend after some lawmakers in the state and a national disaster-management official said the death toll could reach 10,000—well above the current official figure of about 800 people.

Tens of thousands of people, mostly pilgrims visiting Hindu sites in the Himalayas, were rescued after the floods hit.

The reason for the disparity of the death-toll estimates isn't clear. In natural disasters, governments typically set up centers and phone lines where relatives can report people missing. If they haven't been heard from in two weeks, those people would most likely be presumed dead. But there is no clarity over the likely number of missing in this case. One government estimate says there are 3,000 people still unaccounted for.

On Saturday, Uttarakhand assembly speaker Govind Singh Kunjwal said he feared more than 10,000 people may have died in floods and landslides triggered by heavy monsoon rains.

After seeing piles of bodies and hearing accounts of people coming down from the mountains and those calling up, I feel the death toll could be well over 10,000."