Link between Dam and Natural disasters – Explained Pointwise
Table of contents:
Rishiganga dam in Uttarakhand was recently destroyed by the Glacial Lake Outburst Flood and intensified the GLOF in the region. This is not the first time a Dam is aiding and intensifying the disaster in India. It can be a potential hazard to both human life and the environment. This raises a larger question on the net benefit of big dams.
What is Dam?
It is a structure built across a stream or river to hold back water. There are many reasons to build a dam. Such as,
How dams are aiding disasters?
Dams were built to provide benefits to human. But many times instead of providing benefits, dams are harming the region by aiding a disaster. The reasons are:
- Dams as a hydropower plant: Construction of hydro-power plant requires diversion of rivers through tunnels to generate power. The construction of these tunnels unsettles the mountainous terrain by displacing the supportive sediment. It results in the slipping down of rocks due to the removal of their support system (Landslides).
- Dams as a reason for frequent floods: Due to poor maintenance, siltation, etc. dams are not able to hold adequate water. This is responsible for the increasing frequency of floods in India.
- Dam as a solution to prevent/divert large run-off water: To protect the river run-off, many bigger dams have been constructed in highly vulnerable locations, like the Himalayas. For example, the entire state of Uttarakhand is vulnerable to earthquakes, but there are large dams planned in the fragile region that disturb the ecosystem. Dams in these locations aggravate the natural disaster.
- Dams as a reason for an earthquake: When a large quantity of water is loaded and unloaded frequently in the region, it might lead to reservoir induced seismicity. For example, Koyna earthquake of December 1967.
All these reasons lead to dam failure. This is then followed by a large-scale release of water, downstream of the river and creating floods. This will create economical, infrastructural, environmental, and livelihood losses.
Dams aided disasters in the past:
- The worst dam disaster in India was the Machu dam failure (Gujarat) in 1979. The torrential rainfall in the area created a large scale flood and a failure in the dam. According to the official estimates, around 2000 people had lost their lives.
- In August 2018 Kerala witnessed its worst floods since 1924 due to the torrential rainfall. Too much water stored in the dam aggravated the disaster. At least 35 of 50 large dams had been opened for releasing water in to the already flooded areas. The flood took the lives of around 503 people in the state.
- Similarly, in 2019 heavy rain caused a breach in Tiware dam (Maharastra). This led to the flooding of seven villages and 20 people swept away.
- Most recently, a Glacial Lake Outburst Flood destroyed the Rishiganga dam. This led to a large surge of water downstream which breached the Tapovan Hydropower Plant.
Vulnerability of Indian dams:
- India has more old dams. India in total has 5,745 reservoirs in the country, of which, 293 are more than 100 years old. The age of 25% of the dams is between 50 and 100 years and the remaining 80% are over 25 years old. Ageing dams face the following issues,
- Differential settlement of foundation in the dam,
- Clogging of filters, increase of uplift pressures,
- Cracks in the dam core,
- Loss of bond between the concrete structure and embankment,
- Reduction in slope stability in earthen and rockfill dams,
- Erosion of earthen slopes,
- Deformation of the dam body itself.
All these aids the intensification of any disaster.
- Many dams have structural deficiencies and shortcomings in operation and monitoring facilities. Few dams not even meet the present safety standards on structural and hydrological conditions.
- Many states are not providing sufficient budgets for the maintenance and repair of the dam. There is also a lack of institutional and technical capacities for addressing dam safety issues. For example, According to Central Water Commission data, “Not even a single dam in Kerala was inspected before monsoon during Kerala floods”.
- The current legal framework does not have any provision for penalizing the person/trust/state responsible for dam failure.
- Real-time inflow forecasting systems are not in place even in important reservoirs. This creates vulnerability to dam safety and dam operation.
Government Initiatives to improve dam safety:
- Dam Rehabilitation and Improvement Project (DRIP)
- It is a World Bank assisted project. The project aims to improve the safety and operational performance of selected existing dams and associated appurtenances sustainably.
- Ministry of Water Resources, River Development & Ganga Rejuvenation through the Central Water Commission, is implementing the project.
- Dam Safety Bill, 2019.
- The Bill provides for proper surveillance, operation, inspection, and maintenance of all specified dams in the country.
- The Bill aims to constitute the National Committee on Dam Safety. The committee shall suggest dam safety policies and also recommend any necessary regulations.
- The Bill also establishes the National Dam Safety Authority. The NDSA is a regulatory body that discharges functions to implement the policy, guidelines, and standards in the country.
- The Bill also provides for the constitution of a State-level Committee on Dam Safety by State Governments.
- Dam Health And Rehabilitation Monitoring Application (DHARMA)
- It is a web-based software package. It supports the effective collection and management of Dam Safety data in all large dams of India.
- The major aim of DHARMA is to digitize all dam related data.
- Seismic Hazard Assessment Information System (SHAISYS) for mapping Seismic Hazards.
Suggestions to make dams disaster-resilient:
- State governments should strictly follow the dam safety manual.
- Creation of the buffer zone: States have to ensure that there is no encroachment in the nearby area.
- Need to integrate urban-rural planning with dam safety. Since India is a populous country, it is impossible to shift people during calamities. Proper dissemination of information on a real-time basis and regular flushing of water has to be carried out downstream to keep the river beds dry. This can be done only through an integrated approach.
- A Standing Committee recommended a penal provision for dam failures on authorities. The government has to incorporate this into law. Along with that, the government has to increase the capacity building of locals and associated institutions.
- The government has to create a well-planned monitoring system using modern instruments. This is the key to the early detection of defects and averts disasters.
The government must consider the issue holistically and avoid building large dams for political gains in fragile regions. The construction of a dam is not a disaster, but the mismanagement and poor planning of the dam is a disaster which affects all of us in a severe manner. It is a high time for the government to understand this.