Fragile Nainital: Hillside survey planned after landslide, house collapse

Authorities are planning a technical survey of the hillside in Nainital where 24 families have been relocated to safer locations in the aftermath of the landslide and house collapse late last month.

Preliminary inspection carried out by the district geologist revealed that the landslide was caused due to seepage of rain and sewerage water, Pramod Kumar, sub-divisional magistrate (SDM) Nainital, said.

“After the incident, we immediately relocated 24 families from the area to safer locations. The district administration has written to the state government to conduct a high-level survey of the affected hillside so that experts can tell what exactly is happening on the affected hillside and suggest short-term and long-term measures to check the reoccurrence of such incidents,” Kumar said.

Given the fragility of the hillside where the incident occurred, engineers have started the process of temporary slope stabilisation by placing bags filled with granular material (geo-bags) in landslide-vulnerable locations.

“We have already put 300 geo-bags there and 500 more bags will be put there to stabilise the slope as a temporary measure,” Ratnesh Kumar Saxena, executive engineer with public works department (PWD), said.

Saxena said the main problem is that construction norms were violated when buildings were built.

“The water seepage due to improper sewerage and rainwater, coupled with the load of concrete, has made the slope vulnerable to landslides. The district administration has written to the state government that the affected area should be studied by experts from IIT Roorkee, Tehri Hydro Development Corporation (THDC) or any other technical institute,” Saxena added.

The recent landslide followed by the house collapse put a spotlight on how Nainital has been showing signs of geological disturbances.

The district administration has shifted 24 families from 22 “unsafe” houses to safer places in Nainital, a geologist who conducted an inspection of the site initially found “poor sewerage network” as one of the key reasons for the landslide.

Earlier this year, Nainital’s famous tourist site Tiffin Top was closed to tourists after it developed cracks. Similarly, the famous Band Stand on Nainital Lake was shut down after it started caving in towards the lake.

Noted environmentalist Ajay Singh said that even though no new construction is allowed in Nainital, residents have increased “concretisation” in the name of renovations over the years.

Also Read: Uttarakhand: Technical committee to survey landslide affected area in Nainital

“After the 1880 landslide in which 151 people were killed, Britishers had developed a 79 km drain network on the hill slopes around Nainital to make them stable. But illegal constructions and encroachments have come upon such drains also, affecting the flow of water. Concretisation has increased stress on slopes, many of which have bulged out, evident from the bending of trees, fences, and poles towards the lake,” Singh said.

According to geologist CC Pant, former head of the geology department at Kumaon University, who has conducted geological studies in and around Nainital, the area has a specific rock-type, which makes the areas vulnerable.

“Slopes here are mainly made of slates (which have a splintery nature) and carbonate rocks (limestone and dolomite which react with water), and these are ridden with large faults. And most of the human habitations are located on ancient landslide fans (spreading out of the landslide area). Also, the rocks on Nainital slopes are dipping and slowly moving. Studies have shown that in the last over 80 years, some rocks have dipped or moved by 80 cms to 1 metre in some areas, which adds to slope instability, bulging and slips in some areas. Nainital Lake itself owes its origin to tectonic movement, which means a large landmass movement created this lake. So geologically the lake area and slopes around it will always remain fragile,” he said

Overall, Nainital is among the most landslide-prone areas in the state.

In 1880, 151 people were killed in a major landslide in Nainital’s Sher Ka Danda area. The Baliyanala area in Nainital has witnessed frequent landslides for the last 20 years.

But from 2018, this small hill station and the areas around it are again witnessing landslides and cracks on the roads with experts terming them as warning signs of geological disturbance in the terrain around the lake area.

The fragility of the Nainital Lake

In 2018, around 25-metre stretch of the famous Mall Road caved into the lake waters.

In 2021 other side of the lake area, known as the “Thandi Sadak”, witnessed a major landslide, with big boulders falling into the lake waters. The same year with parts of Nainital district receiving the highest-ever rainfall in the last 124 years, water from Naini Lake overflowed and excess discharge from the lake was drained into Baliyanala downstream, triggering landslides in the area.

In a separate instance, last year, a landslide on one of the slopes around the lake in the “Saat Number “ area was another sign of trouble in the terrain.

The landslides in the Baliyanala site in Nainital and the geological rumblings in and around the Nainital lake have put a spotlight on the fact that geological disturbances are being witnessed in the hill station which houses over 48000 people living in over 7000 structures on its slopes.

The mango-shaped Nainital lake surrounded by hills is not a big lake. It is situated at an elevation of 1938 metres, with a width of 360 metres and length of 1442 metres.

To gauge the increasing stress on the Nainital Lake and its surroundings, here are some facts: In a small hill station like Nainital, which has an area of just 11.73 sq km, population has swelled from 7,589 in 1881 to 41,377, according to the 2011 census, and to over 48000 at present. The number of buildings in Nainital, most of them built on hill slopes, has increased from 520 in 1901-02 to over 7000 at present, including over 150 hotels and resorts.

After landslides in September 2018, the Uttarakhand high court constituted a high-power committee to study and suggest a plan for to prevent landslides in Nainital.

Over four years ago, the Indian Institute of Technology, Roorkee, conducted a study on the vulnerability of the slopes and roads around Nainital Lake, especially the section of the famous Mall Road adjoining it.

Based on the report, the public works department sent a detailed project report to the state government, asking for a ₹41 crore to address the problem. The report mentioned that a 200-metre high and 165-metre long patch on the slope above Mall Road was highly fragile and vulnerable up to 22 metres depth and needed immediate reinforcement.