Part 5: The Roorkee institute has advised making channels for the flow of water in cities situated in mountains
The reason for the water coming out in JP Colony located just below Joshimath is not clearly known. Photo: Sunny Gautam / CSE Restriction in the flow of water in Joshimath, Uttarakhand may have led to the major land subsidence in the region early in January this year, according to a report by the National Institute of Hydrology (NIH), Roorkee. The NIH is among the eight institutes that conducted an in-depth study into the landslides in the region.
The reports by these institutes recently came into the public domain after the Uttarakhand High Court objected to the government’s decision not to make expert reports on Joshimath land subsidence public. This series by Down To Earth (DTE) examines these papers one by one.
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When landslides in Joshimath suddenly intensified that night, a thick stream of water began to emerge on the roadside near JP Colony, which is located just below the city. The NIH was tasked with investigating where this water was coming from.
Water leakage was thought to be a major cause of landslides in Joshimath, which is why this paper is so important. Similarly, the cause of landslides or landslides in mountain hill stations is thought to be water leakage and a lack of drainage arrangements.
As water flows from top to bottom, restrictions in the path of the flow can mean water will go into the ground, weaken the soil and lead to landslides, the NIH has said. Joshimath has its own local weaknesses, as it is situated on an old landslide reservoir in the middle of the hill slope, with fragile slopes in the upper reaches (Auli area), the report said.
The region’s thick forests also serve as a water recharge area. As a result, the water flows downward. Under such circumstances, large-scale, unforeseen construction as well as natural disasters in cities situated on hills have led to an increase in incidents such as landslides.
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According to discharge data from the Jaypee Company, the recharge area held an estimated 10.66 million litres of water, which was emptied in approximately one month, according to the NIH report. To gather this much water, it might take approximately 12 to 15 months.
While the reason for the water flow is not known, there is a possibility that it may have collected due to the blockage of a sub-surface channel and burst from a weak spot. It then gushed out near JP Colony, as witnessed, the report said.
Although not specifically stated in the NIH document, it has been reported that Joshimath had experienced heavy rainfall, which was measured at 190 mm in 24 hours in October 2021, about 15 months before the torrential flow of water started in JP Colony. There was also flooding in the area on this day. That is, it is feared that rainwater may have collected underground. Water in JP Colony comes from the upper areas (Sunil Forest and Auli area).
The report explained through maps that the water channels flowing from the upper areas have disappeared in the middle. Therefore, permanent surface channels will have to be built to dispose of water coming from the upper areas. The water requirements of local people and flora and fauna should be kept in mind before the channelisation of water. Water coming from upper areas and city waste should be disposed of safely.
The NIH made note of the necessity to pinpoint both cities with geological settings and specific geographic locations, such as Joshimath. These towns ought to have the tools required so that preemptive actions can be done well in advance.
Natural springs serve as excellent indicators of groundwater in mountainous regions and function as natural piezometers, according to the institute. As a result, it is imperative to enumerate every waterfall surrounding Joshimath, just as there are cities throughout the Indian Himalayan Region. Their routine observation will be an effective means of anticipating any such incidents in hilly regions.
Read the first part of the series here, the second part, the third part and the fourth part.
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