After the Sikki tragedy, CEA develops rules for hydro projects

 After the Sikki tragedy, CEA develops rules for hydro projects

NEW DELHI: Following damage to a dam in Sikkim caused by severe rains and glacial lake floods, India's top power planning organization, the Central Electricity Authority (CEA), has developed rules for slope stability—inclines that can resist movement—in hydropower projects.

According to the rules, in the event of "vulnerable" projects, the project authority or developer would be in charge of inspecting the higher reaches, including the reservoir, pinpointing fault locations, and taking corrective action for stabilization.

The term "vulnerable projects" refers to those with capacities of 400MW or more.

"The examination of higher portions may include study of hazards related to avalanche, GLOF (glacier lake outburst flood), including landslide hazard analysis of slopes above the reservoir rim area, many others," it stated.

In the recent past, the Himalayan nations have seen several catastrophes, including floods, landslides, and dam collapses. The most recent of these was the collapse of the Chungthang dam in Sikkim, which came after a GLOF in northern Sikkim.

Slope stabilization techniques, including procedures to be followed both before and after the project is commissioned, are described in the recommendations by CEA. Additionally, it recommended collecting data on all significant slope failures, including satellite images of the project region dating back more than 20 years.

The notice stated: "Vulnerable zones in these places may be detected using Remote Sensing and Geographic Information System (GIS) methods with minimum field effort. Physical access to glaciated, significant landslide zones, or avalanche-prone areas in the Alps is usually challenging. Using technologies like drones and Light Detection and Ranging (LiDAR) technology, possible slide zones may have their dimensions (length, breadth, and depth), slope angle and altitude, volume, etc. evaluated accurately and fast.

It claimed that the Indian Space Research Organisation's (Isro) satellite data is useful for this purpose.

It advised hydropower developers to retain archival copies of periodic satellite images.

"Records of periodic satellite images should be retained. These photographs should be taken over a three- to six-month period, with the first one being taken immediately before the reservoir is initially filled. The reservoir rim area and homes must also be appropriately photographed and filmed, it said.

In addition to creating geological maps, geomorphological maps, rock outcrop maps, overburden maps, and slope classification maps, CEA has advised using cutting-edge technologies like remote sensing, drones, and LiDAR to measure and monitor vulnerable zones like glacial lakes, landslide, and avalanche prone areas.

RK Singh, the union minister for power, gave CEA the go-ahead to create a technical handbook or set of rules for considerations to be made prior to and during the building of hydro projects in January of this year. Post the direction, an expert group was created comprising of representatives from CEA, Central Water Commission, Geological Survey of India (GSI) and the public sector hydro power corporations for writing the guidelines.

The standards also included geometric, hydrological, chemical, and mechanical strategies for slope stability.

The rules take on more importance in light of the recent catastrophic flooding, landslides, and dam damage that occurred in Himalayan states with a lot of hydropower projects, including Uttarakhand, Himachal Pradesh, and Sikkim.

Over 30 people are said to have died when the Teesta III hydroelectric plant in Sikkim collapsed last week as a result of a glacial lake outburst flood (GLOF). Similar GLOF incidents and catastrophes occurred in Uttarakhand in 2013 and 2021. This year, landslides and floods have also affected Himachal Pradesh and Uttarakhand, causing multiple fatalities.

The CEA decided late last month to establish a standing technical committee to study the issues in the event of any geological surprises faced in the hydroelectric projects and to investigate and recommend the extra delay and cost involved as such geological instances have developed momentum and India also has significant plans to add hydro power capacity.