Fragile geology of landslide-prone Nainital a recipe for major tragedy
The geological terrain around Nainital Lake has soft sedimentary rocks, which makes it fragile and prone to cave-ins and landslides.Updated: May 28, 2019 14:58 IST
It is not clearly visible during the daylight. But when night falls, the shimmering lights on the steep slopes around Nainital Lake give you some idea about the magnitude of the concretisation that has happened here.
It doesn’t require one to be an expert to see that even a small landslide or an earthquake can trigger a catastrophe someday with significant loss of lives and property, like it had happened way back in 1880 when 151 people were killed in a major landslide in Nainital’s Sher Ka Danda area.
Emerging danger signs
Since August last year, there are clear signs that something is not right with underlying geological features of Nainital. Worried over the emerging dangerous signs, the authorities are still trying to find out what is causing these geological disturbances in the terrain underlying the hill station.
In August last year, the famous Mall Road along one side of the Nainital lake started developing cracks and part of it even caved in and entered the lake, affecting the movement of traffic here.
From January this year, the Upper Mall Road also started developing cracks. Adding to these fears, the Baliyanala mountainside witnessed landslides in September last year, sparking fresh apprehensions and putting spotlight on the possibility of a major tragedy on the steep slopes here. Also in January this year, there were some fresh landslides in the area. The slope treatment done by the irrigation department earlier on Baliyanala mountainside didn’t work as it was washed away in the earlier landslides.
The geological terrain around the Nainital Lake has soft sedimentary rocks, which makes it fragile and prone to cave-ins and landslides. The lake is bound by the high and steep Naina peak on the north-west side, by the Tiffin Top to the south-west and snow view peaks on the north.
Geologist CC Pant of Kumaon University said Nainital’s geology is dominated by Krol group of rocks, comprising slates, marls, sandstones, limestones and dolomites with a few small dyke intrusives. He said a large number of habitations in Nainital are already on the past landslides on the slopes.
“The steep slopes around the Nainital lake, which form its catchment, have highly folded and faulted rocks due to a geological fault line running from Sukhatal through the lake via Baliyanala up to Kathgodam. This fault line results in stress, shearing and pulverising of the rock formations beneath Nainital. So there will be always danger of some major danger from the geological disturbances here,” said Pant, a professor of geology.
Over two years ago, experts from IIT Roorkee had also undertaken a study of the geological terrain around the Nainital lake. The report had pointed out that around 200 metres high and 165 metres long patch on the slope above the Mall Road was highly fragile and vulnerable up to 22 metres depth and as such needs immediate reinforcement through perforated pipes.
What authorities are doing about twin dangers
In case of the caving in and cracks in the Mall Road, the authorities have started deep drilling to looking into the geological disturbances underneath to understand what is causing them.
Yogesh Dobriyal, junior engineer (JE) in PWD who is looking after the issue, said two drilling equipment are taking samples of soil and rock up to 40 meters beneath the surface of the Mall Road surface to check what was leading to geological disturbances. He said the samples of the hard rock strata were being taken out for analysis by geologists as the same would help them in framing a long-term strategy to treat the Mall Road and the hilly terrain around it.
In case of the landslide danger, earlier this month the district administration issued eviction notices to 65 structures including two schools near landslide-prone Baliyanala area for shifting to safer areas at the earliest. The action followed survey and recommendations of the Geological Survey of India (GSI), which had inspected the vulnerable houses and other structures in March this year within 200 metres from the mountainside.
HC monitoring landslide mitigation measures
Stressing that a permanent solution was required to be evolved to protect Baliyanala from further erosion, the high court noted in its order last year: “The Himalayas were the youngest mountain range and still rising. The strata of Nainital town is also fragile. It is prone to landslides, erosions, creeping and sinking. The area adjacent to Baliyanala has human establishments.”
Worried over the dangers from the landslides here, a Nainital-based advocate Sayed Nadim Khurshid filed a PIL in the HC in September last year, urging the court to issue directions to the authorities concerned to take urgent steps for landslide mitigation in Nainital to avoid any major tragedy.
On September 26, 2018, HC constituted a high-power committee of experts for studying and suggesting a treatment plan for landslide-prone Baliyanala. The committee submitted its report to HC on November 30, 2018. Responding to the same, the court directed the chief secretary to study it with officials concerned and present a concrete plan in the form of landslide mitigation at Baliyanala.
Under the directions of HC, many experts including those from Geological Survey of India (GSI) have surveyed the fragile slopes here since August last year.
Piyoosh Rautela, executive director of Disaster Management and Mitigation Centre (DMCC), Uttarakhand, said based on the surveys of Baliyanala site by the experts and geologists over the last six months, the Japan International Cooperation Agency (JICA) will prepare a detailed project report for the treatment of the site.
“JICA will take six to seven months to prepare a DPR, based on which the long-term treatment of the landslide-prone site in Nainital will be undertaken. However, the district administration can initiate the short-term measures suggested by experts, like water channelisation and using different kinds of shrubs, grasses and trees for checking soil erosion,” he said.
Rautela said DMCC is coming with a comprehensive report on geo-environmental issues of Nainital based on surveys of over 3000 households. “This report lists various dangers that could befall Nainital and the damage it can cause. There has been no major earthquake since 1999 in this area. People in Kumoan generally believe that big earthquakes happen in Garhwal region area only. That is not the case,” he said.
“The problem is actually much complex. Mountains are bound to witness landslides periodically. It is the changing demographics and people here are moving away from the traditional way of life that is consolidating the problem. People are leaving the traditional earthquake-resistant architectures and going for concrete structures. This is not in tune with the local ecology of these hills.”
Rautela said any long-term solution has to be holistic, rooted in local ecology and traditions and supported by local people, who need to be made aware of the entangled nature of the whole issue.
“Till my family and I are unaffected, I don’t care what is happening around. This is the general attitude which needs to change here. People have to look into nature-based solutions rooted in local traditions that are holistic and sustainable in the long run,” he said.
First Published: May 28, 2019 14:58 IST