Protecting People & Property: The World’s Largest Dam Rehabilitation Program

Throughout history, Indians have stored rainwater for the long dry season, be it in large lake-like ‘tanks’ in the southern peninsula, stepwells in Rajasthan, or small underground storages in Gujarat.

Today, over 6,000 dams play this role, irrigating the land, protecting the people from floods, and meeting India’s soaring demand for power.

Now, however, many of these dams are ageing. Added to that, the erratic nature of present-day precipitation has left them increasingly vulnerable, especially since they were built for the rainfall patterns of an earlier era. Besides, given minimal investment in their maintenance, many of them are unable to perform to their full potential while others have become substantial safety risks.  

India has now become one of the world’s first countries to undertake a large-scale dam rehabilitation program. Since 2012, with World Bank support, it has deployed the latest expertise and technology to upgrade 200 of its large dams in one of the largest such programs in the world.

“It’s simple,” explained Debashree Mukherjee, Secretary in the Government of India’s Ministry of Jal Shakti.  “It is increasingly difficult to find sites to build iconic structures like the Bhakra Nangal Dam,” referring to one of India’s largest dams and the first to be built in independent India.  “So, it’s important to get as much value out of each dam as we can.”  

Strengthening dams with new technology

Every dam faces different challenges. In Karnataka’s century-old Krishna Raja Sagara Dam, for instance, each of the 152 gates had to be lifted manually to allow the excess water to flow through. “This was extremely dangerous,” pointed out K.G Vijaykumar, the engineer in charge, “for when a flood came, water could not be released immediately.”

Although the authorities were reluctant to tamper with the dam’s iconic structure, they managed to replace the old iron gates with new stainless-steel ones, with the help of global experts. Now, computers operate all the dam’s 152 gates and water is discharged in precisely the right volumes to prevent flooding downstream.

On the other hand, Uttarkhand’s Ichaari Dam, was frequently damaged by the large boulders that were carried down by the raging Tons River. However, given the remoteness of the region and the steep mountain terrain, it was difficult to bring in the large equipment needed to repair the damage.

“Logistics was an issue, accessibility was an issue. It was also difficult to ensure that the sharp drop in night temperatures did not alter the properties of the high-strength concrete as we were laying it down.” recalled Ankit Arya, assistant engineer in charge of the dam.

Once again, the authorities devised solutions for these complex challenges with the help of global experts, and a new very high-strength concrete was applied, the first time this was used in the dam sector in India.

The latest technology was also brought in to address other long-standing challenges. For instance, Karnataka’s Krishna Raja Sagara Dam and a few others deployed underwater drones to pinpoint dangerous cracks in the walls of the dams. And Tamil Nadu's Servalar Dam introduced geomembranes to control excessive seepage from the dam walls.  This one-time, long-term solution has reduced seepage by more than 90 percent.

Emphasizing safety

But strengthening a dam’s structure is just one aspect of dam safety. Keeping strict vigil on the dam’s condition is equally important.

The project has thus brought in modern elements of dam safety, including new equipment such as CCTV systems to spot weaknesses in hard-to-reach areas. “We now have proper instruments to do routine checks, especially in the monsoon season when we are on full alert,” said Ms. Supriya S., the chief engineer for dam safety in the Kerala government.

Decision making is also quicker and more precise. As even small mistakes in handling large volumes of water can have catastrophic consequences downstream, dam managers are now equipped to take prompt and informed decisions thanks to instant access to all the dams’ data.  In addition, the sharing of this data with downstream dams makes for coordinated decision making between the various operatives, an especially critical factor for dams operating in a cascading sequence. “Data of 16 dams is now available in our control room,” added Ms. Supriya. “This was not so earlier.”

Preparing for emergencies

Even so, with the increasing onset of unusual weather events, both the authorities and local communities need to be prepared for emergencies, be it a flood, an earthquake, or a glacial lake outburst.

The project has thus enabled each dam under its ambit to develop an Emergency Action Plan, specifying who does what and when in an emergency.  These plans have been devised after extensive consultations with local administrations, disaster management authorities, the police and fire departments, as well as with local communities, enabling a coordinated response to the challenge.

Mapping areas at risk

What’s more, the mapping of areas at risk of flooding has shown how far-reaching the impacts of a breach can be. “Earlier, I thought if the dam fails, the impact will extend to 30-40 kms downstream. But I realized that it would be much larger, extending all the way down to Karnal in Haryana, over 150 kms away,” said Abhishek Kumar, assistant engineer at Uttarkhand’s Ichaari Dam.

Mapping has also helped work out the safest evacuation routes. “We travel daily from Dakpatthar to Ichhari over one particular bridge,” said Bhanu Prakash Joshi, assistant engineer at Ichaari. “When we studied the guidelines, we realized that this bridge would get submerged in a flood. So, we identified at least three alternative routes. Today, I am confident that we are prepared for any untoward incident and know what is to be done.”

Creating a new pool of dam professionals

Since dam management is a complex task, the project has also supported the creation of a new pool of dam professionals. Thus, a new post graduate course in dam safety has been started at the Indian Institutes of Technology (IIT) in Roorkee and Indian Institute of Science (IISc), Bengaluru.

This program covers multiple aspects of dam management, from structural design to safety, sedimentation, geological, seismic and environmental issues, as well as the development of sustainable tourism.

“For the first time, academic institutions have been roped in to study the challenges, conduct research, and devise solutions for a dam’s long-term sustainability,” said Prof N K Goel from IIT Roorkee, India’s oldest engineering college founded to train engineers and surveyors for the construction of the Ganga Canal almost a century ago.

All told, better dam management and stronger safety measures will enable India’s dams perform to their full potential, ensuring better irrigation, controlling floods, helping recharge groundwater, and allowing for more sustainable flow in the rivers.