Given India’s renewed thrust on hydropower sector, there is an urgent need to invest time and resources on reservoir sediment management in order to preserve the efficiency of all these projects and extend their life
Hydropower projects have since long been the backbone of India’s economic growth and it is critical to maintain the infrastructural efficiency of these projects in order to ensure longevity and ecological conformity. The absence of due diligence and crucial upkeep of the dams and hydropower facilities, especially on the sedimentation front, can impact the productivity of the project, besides making it a threat for the environment. In order to ensure long-term resilience of these critical infrastructure facilities, attention needs to be paid to the process of reservoir sedimentation removal management.
Increasing amount of reservoir sedimentation can lead to unexpected repercussions for the project by reducing the storage capacity of reservoirs besides damaging the hydro-mechanical equipment. The accumulated sedimentation in the reservoir bed can also pose a threat to the sustainability of hydropower, water supply and irrigation services. Though solar and other forms of renewable energy generation are fast gaining ground, hydropower projects still remain a compelling option of sustainable energy generation.
This is evident by the fact that India is the seventh largest producer of hydroelectric power with a potential of 84,000 MW at 60 per cent load factor, making it one of the largest in the world. The present installed capacity as on March 31 is 42,783 MW, that is 14.35 per cent of total utility electricity generation capacity in India. Additionally, a 4,274 MW hydropower unit was added till March 31.
India’s reliance on hydropower is set to grow in future. At a recent energy conclave, Piyush Goel, the Minister for Coal, Power, New and Renewable Energy and Mines said that the Government intends to remove the roadblocks in the path of wind and hydropower sectors to fuel growth.
Given India’s renewed thrust on hydropower sector, there is an urgent need to invest time and resources on reservoir sediment management in order to preserve the efficiency of these projects and extend their life. An effective strategy for sediment management for dams and run-of-river hydropower can provide guidance on adopting sediment management practices, especially during the early planning phase of hydropower and dam projects and during the subsequent stages of actual operation. Sediment management strategy can help safeguard important services of the hydel projects, including water supply, irrigation and renewable electricity.
Executed effectively, sediment management strategy can become a robust adaptation plan to support sustainable hydropower and supply of water for domestic use, agriculture and industry. The strategy also assumes critical important as it can effectively counter the impacts of climate change by increasing power generation capacity of hydel projects, bringing down maintenance, thereby cutting back on the use of fossil fuel that contribute to green house gas emissions.
As the hydropower projects receive impetus, the Government must concentrate on enabling measures to reduce sedimentation in reservoirs. This can be done through erosion control and upstream sediment trapping. Management of water flows can also be resorted to during periods of high sediment yield in order to minimise sediment trapping in reservoirs.
Sediments can also be bypassed by constructing an off stream reservoir outside the natural river channel, either by impounding a side tributary or by constructing the impoundment on an upland area. This helps clear water to be diverted to an off stream reservoir by a river intake, whereas large sediment-laden floods are passed beyond intake and are not diverted into storage area of the reservoirs. The Government can also focus on other methods such reservoir sediment redistribution and dredging.
New hydropower projects must have checklists made available to them that account for the sedimentation management. This will assist in the implementation of a programmatic approach using selected scientific methods for screening climate change and disaster risks, and integrating appropriate resilience measures into water, hydropower, and dam investment projects.
As the Government steps up its hydropower activities, the risks of climate change need to be understood and managed to ensure sustainable, resilient, and cost-effective outcomes.
Increased awareness is essential for hydropower, water supply reservoir and dam projects, given that climate change is projected to significantly affect water resources by changing mean annual river flows and hydrologic variability, thereby causing extreme droughts and floods.
Even though sedimentation poses the greatest threat to the sustainability of hydropower, most guidelines on water supply and dam projects provide virtually no direction on how to deal with the problem. Current guidelines tend to focus on mitigating changes in flows associated with climate change and do not address sedimentation. India must change that in the favour of robust hydropower scenario.
(The writer is an environmental journalist)