Wayanad Landslide: Why Kerala & Uttarakhand are more Vulnerable to Landslides?
The catastrophic landslide in Wayanad district, occurred in the wee hours of 30th July claimed at least 199 lives.
This death toll is likely to go up as 150 persons are still missing. As per the last update from SEOC Kerala, this landslide has injured 278 people. The agencies, running relief and rescue operations, have rescued 214 persons alive.
This, being the worst incident of landslide in the history of Kerala, has affected more than 10,000 people and destroyed 200 shops/houses.
Indian Meteorological Department had issued a red alert for 8 out of 14 districts. Wayanad, where this massive landslide took place is among them.
This was not the first landslide Kerala has witnessed this season. There have been a couple of events including one in Kozhikode and one in Varkala Hills.
As per a news report, between 1961 and 2016, landslide killed 295 people in Kerala. The frequency and severity of such events have gone up dramatically since 2018.
From Kerala to Uttarakhand
Kerala and Uttarakhand are two states in India which are facing an increasing vulnerability to landslides than the rest of India.
Uttarakhand has witnessed more than 186 landslides in 10 districts during this monsoon season.
This includes a massive landslide in Chamauli district and many others. Apart from these two states, the rest of the Indian states are also witnessing several landslides in this season.
Why does a Landslide Occur?
Landslide is a hazard of a mountainous terrain. It is the movement of a mass of rock, earth or debris down a slope.
This is caused by natural and anthropogenic (human activities) reasons. Its natural causes include earthquakes, rainfall, snowmelt etc.
The anthropogenic causes include excessive development, terrain cutting & filling, and overgrazing by cattle.
Let me explain the natural causes first - when an earthquake shakes a mountainous region, it displaces a mass of rock, earth, and debris on mountains.
This displacement results in freefall down the slope movement of these things
If we talk about rainfall which is considered one of the major reasons for landslides in India then it is because of its extreme events.
A period of extremely heavy rainfall can cause a landslide for mainly four reasons -
water loading of the slope
reduction in soil strength
removal of soil particles
other material changes in the slope
Amongst all anthropogenic reasons, excessive development in unstable mountainous terrain is considered one of the leading reasons for landslides.
Activities like road and tunnel construction can reduce the soil strength which in turn can lead to a landslide during rainfall events.
It is necessary to understand that each landslide incident is not a disaster. It is a hazard of a mountainous region.
However, as per the UN Disaster Risk Reduction Agency, a hazard can turn into a disaster when vulnerability and exposure are involved.
What Makes a Place Vulnerable?
The vulnerability of a place to any hazardous event like a landslide is decided upon that place’s likelihood of experiencing the harmful effects of the hazard.
And, exposure is simply the place’s proximity to the hazardous location.
Let’s suppose, you live in a village which is situated near the slope of a mountain.
Now, if this mountain is declared landslide-prone by the authorities and your village is in the path of the debris then your village may become vulnerable to a landslide.
The closer you live to such a location, the higher your exposure to the risk associated with such an event.
But if there is no risk then there would be no vulnerability.
Which Parts of India are most Vulnerable?
India ranks first in terms of fatal landslides across the world. In the last three decades from 1988 - 2022, there have been more than 80,000 landslides in India.
That’s more than 2,380 landslides each year in above mentioned duration. And, half of these landslides occurred in the northeastern states of India with Mizoram topping the list.
Now, you may ask if more landslides are happening in the northeastern region then why Uttarakhand which lies in the Western Himalayas and Kerala which lies on Western Ghats are more vulnerable.
National Remote Sensing Centre has answered this question in its Landslide Atlas of India which was released in 2023.
It has created a list of districts which are more vulnerable to landslides.
The top five most vulnerable districts in India include two from Kerala and two from Uttarakhand.
Rudraprayag from Uttarakhand tops the list and is followed by another Uttarakhand district Tehri Garhwal, and Thrissur in Kerala.
How Many People have Died?
As per the data compiled by NRSC, India has witnessed more than 10,305 landslide deaths in just two decades from 1988 to 2018.
However, the national crime records bureau’s figures say that in India one person dies everyday in landslide related incidents.
What Makes these States More Vulnerable?
If you look deeper into this dataset then you would see that this includes all the districts of Kerala and Uttarakhand.
This is not it Uttarakhand’s 5 and Kerala’s 8 districts are in the top 25 most vulnerable districts.
But this data doesn’t give us the full picture. It tells us that Uttarakhand and Kerala are vulnerable but it doesn’t tell us why.
The one reason that increases the vulnerability of any region is its population of humans, livestock, and infrastructure.
So, the more people are living in a landslide-prone area, the more would be its vulnerability.
And, this area is happens to be larger in the Western Himalaya then Eastern Himalaya.
Dr Tapas Rajan Martha, head of NRSC’s Geodynamics and Geohazards division has explained this issue in one of his seminar.
The extremely heavy rainfall events coupled with ongoing construction activities play a major role in causing landslides.
As per a research paper authored by Tapas Ranjan Martha and his colleagues, landslides in the northeastern region occur in gentler slopes than in northwest Himayala and Western Ghats.
This research paper also tells us that in western ghats landslides occur due to less rainfall in comparison to the Himalayan region.
Dr Martha has also explained in one of his lecture that the area of landslide in north western himalaya is about three times than north eastern Himalaya.
Climate Change is Responsible?
Climate change can not be directly linked to landslides. However, it has been established that the events of extremely heavy rainfall are linked with climate change.
So, if an unstable mountainous region is getting short periods of extremely heavy rainfall along with anthropogenic disturbances then it is more likely to create the perfect conditions for a landslide.
Speaking to The Hindu, Roxy Mathew Koll, the leading Climate Scientist says, “The total monsoon rainfall India gets has over the years from 1970 to 2010 has decreased but at the same time extreme rainfall events has steadily increased in India.”
Dr Koll’s study says -
Widespread extreme rain events across central India have tripled since 1950. These severe weather events result in large floods and catastrophic loss of life and property across central and northern India – Gujarat, Maharashtra, Madhya Pradesh, Chhattisgarh, Telangana, Odisha, Jharkhand, Assam, Meghalaya and parts of Western Ghats – Goa, north Karnataka and central Kerala.
Why Mitigation is a Challenge?
In past few decades, India has developed its capability in dealing with major natural disasters like flood etc.
But landslide has remained a challenge for disaster management agencies.
Dr Tapas Rajan Martha, head of NRSC’s Geodynamics and Geohazards division has spoken about this issue.
He says -
The factors responsible for landslide occurrence in different parts of India are different which makes dealing with landslides challenging. Like how to create early warning system etc. As I said, rainfall is the main culprit but the occurrence of rainfall is also different in different provinces of India. Intensity of the rainfall is also not the same.
Landslide FAQ - What to do - What not to do?
India’s disaster management agency, NDMA periodically issues advisories for landslide prone areas.
As per this advisory, you should stay calm and don’t panic during such an accident. You shoul also try to reduce the spread of rumors.
Additional Readings:
India tops the world in landslide deaths
Western Himalayas more “risk prone” than the East, according to new index