Five Reasons Why Joshimath Subsidence Is A Man-Made Tragedy, Not A Natural Disaster

The environmental assessment studies by these eight institutions unambiguously concluded that the subsidence in Joshimath was largely man-made. It happened as a result of unplanned development beyond the bearing capacity of the hill town, large-scale construction and over exploitation of natural resources.

Atul Sati, an environment activist based in Joshimath, says the reports broadly suggest two things. First, more research is needed as these studies only tried to find out the reasons for land subsidence in January. Second, there shouldn't be any heavy construction in Joshimath. “Unfortunately, I believe these reports have tried to indirectly give a clean chit to the under-construction Tapovan Vishnugad hydropower project. This project must be stopped. After the subsidence, the work was stopped, but the government is willing to restart it.”

The studies were conducted by Wadia Institute of Himalayan Geology, Dehradun; National Geophysical Research Institute, Hyderabad; National Institute of Hydrology, Roorkee; Department of Earthquake Engineering, IIT Roorkee; Indian Institute of Remote Sensing, Dehradun; Geological Survey of India; Central Ground Water Board; and Central Building Research Institute, Roorkee.

The USDMA had asked these institutions to study the phenomenon in January and they submitted their reports till the end of April. However, the state government made them public only recently after the high courtpulled it up for not disclosing the findings.

Here are five takeaways from these reports:

1.A 100 per cent increase in built-up area footprint in a decade

The Hyderabad-based National Geophysical Research Institute (NGRI), which carried out multi-parametric geological and geophysical investigations, found after a land-cover analysis of satellite data that the percentage of built-up area footprint increased from 1.25 sq km to 2.50 sq km between 2010 and 2020, a 100% increase within a decade.

“It is obvious to expect that the rapid growth of built-up areas would put tremendous pressure and cause an imbalance in demand and supply chain of water potential, large-scale building of sanitation pits and would interrupt the steady-state recharge scenarios,” it said.

2.Possible blockage of underground water flow

On January 2 this year, one of the residential areas of Joshimath, Jaypee Colony, witnessed unprecedented gushing of underground water and cracks in the building floors. The National Institute of Hydrology, Roorkee, studied the cause behind this. In its report, it said a possible blockage of one or more subsurface channels created a temporary water storage which eventually burst out when the hydrostatic pressure exceeded the soil-water bearing capacity of the area.

The experts blamed rampant construction along with the locational disadvantage of Joshimath for these issues. Their report said Joshimath sits on an old landslide deposit, which has excellent recharge area, huge depressions and thick forests (Auli). Water moves from upper to lower reaches in the form of subsurface flow, weakening the soil stability on the steep hill slopes. “This slope instability is exacerbated by unplanned and rampant construction in and around the town and natural calamities (extreme weather events as well as frequent earthquakes),” it added.

3.Wastewater discharge from natural and man-made sources

Two institutions, out of the eight, observed in their reports that the seepage of water to the subsurface could be the possible reason for the recent subsidence.

“The main reason for the subsidence appears to be internal erosion caused by the subsurface drainage, which may be due to infiltration of rainwater/melting of ice/wastewater discharge from household and hotels,” said IIT-Roorkee’s Department of Earthquake Engineering, which studied the shear strength and the bearing capacity of the soil.

The Indian Institute of Remote Sensing, which conducted a satellite-based deformation analysis of Joshimath, too found that one of main reasons for land subsidence could be lateral soil erosion and slope instability as a result of the local drainage water seepage.

4.No subsidence in sparsely populated or no habitation areas

The Geological Survey of India, which deployed its technical workforce to study the preliminary reasons for the subsidence, observed that cracks had developed in and around areas primarily under habitation in Joshimath. “The adjacent areas where there is either scanty or no habitation have so far not been affected by the recent event of ground deformations,” it said.

The deformations were also caused by the construction of multi-storied buildings, which exerted a higher load on the soil having low shear strength. This enhanced the driving forces on the slope, leading to ground distress, it added.

5.Natural flow of springs blocked by haphazard construction

According to the Central Ground Water Board, large-scale construction in the hill town blocked many springs, which ultimately increased the subsurface pore pressure and resulted in a sudden gush of groundwater, for instance, at Jaypee Colony. “The sudden release of groundwater reduces the existing pore pressure and the fluctuation in pore pressure renders the land subsidence in the area. In a nutshell, construction in the spring zone triggered by seismic activities may be the reason for recent land subsidence,” its report said.

The experts from the board observed another interesting thing in Joshimath: the cracks, springs and hand-pumps were present in the same area. “The occurrence of all three in the same zone indicates that strata are saturated with groundwater. Groundwater-saturated zones may accelerate the land subsidence,” they concluded.

“I think, whether it is the Joshimath subsidence or the recent devastation in Shimla due to flash floods and heavy rains, the states should strictly follow construction norms as well as (adhere to) the bearing capacity of the hill towns. Blocking natural springs is inviting natural disasters. Unauthorised construction must be dealt with iron hands. Unfortunately, authorities seem to be oblivious of the crucial aspects of city planning," says Sanjay Parikh, a senior Supreme Court lawyer who takes up cases related to the environment.

(Praveen Mishra is an independent journalist. Views expressed are personal)