Hydropower

Two Case Studies

Two case studies are provided to first show what the impact on a hydropwer system is after a major storm in the Himalayas. The second case study features the hydropower impact and treaty issues in an international river basin between Canada and the USA.

Kulekhani Hydropower Project in Nepal

A 114 m high dam was built in Nepal in 1982 with a capacity of 92 MW. At that time , wit produced 45% of the hydropower capacity of Nepal. It was to have a life-time of 100 years.

Storm Event and Impacts

In 1993 a major monsoon storm produced a 540 mm rainfall event over 24 hours with intensities of up to 70 mm/hour. This resulted in more than 300 landslides and produced massive amounts of sediment that was deposited on the agricultural and into the  hydropower reservoir. Images of the erosion, quantification of the rainstorm and data on the sedimentation are provided below.

Impact on the reservoir

The sediment accumulated in the reservoir amounted to a 15% loss in dead storage and because so much sediment was deposited within the watershed it was estimated that  without major sediment control, the lifetime of the reservoir would be reduced by 20+ years. Major dredging and construction of check-dams were initiated at a cost of $3.2 million to prevent further losses of operating power.

What is interesting is that the estimated erosion rate used during the design of the project was 18 m3/ha/year. For the 10 year before the major event it averaged 45 m3/ha/year and reach 410 m3/ha/year during the 1993 event. It took about 10 years of conservation efforts to finally reach the pre-storm levels.

Lessons Learned

After this flood event it was estimated that this storm was a 1 in 100 year event. However, with increasing climatic variability, re-occurrence of such event are likely to become more frequent. 

This case shows how difficult it is to a) determine the lifetime of reservoirs in steep and fragile mountain environment, and b) how costs of maintaining a fully functioning systems over time are always underestimated.

The Columbia Basin Case Study

The Columbia Basin is the 4th largest river basin in North America. It originates in the Purcell & Rocky Mountains of Canada and discharges into the Pacific Ocean in Oregon. The Canadian portion is only 15% of the basin size but produces about 40% of the annual discharge. It is the largest hydropower producing basin in North America and generated 50% of the electricity for B.C. and about 40% for the Pacific North-West in the USA. There are more that 300 hydro-systems within the basin and some dams and reservoirs are among the largest in North America. The reason for featuring this case study is that it has a unique international treaty on how the manage an international river basins

The Columbia River Treaty

Two factors were responsible for negotiating a treaty between Canada and the USA on how to manage this international river: 1. The re-occurrence of major flood events in the lower portion of the basin in 1894, 1948 and 1964, and 2. The high potential to produce hydropower (the river has the highest vertical gradient in North-America).

The treaty which was signed in 1964 is one of the most unique agreement on how to manage a trans-boundary river, for two reasons: 1. The downstream nation agreed to compensate the upstream nation for some of the benefits received for flood control and for being able to produce more electricity downstream, and 2. The treaty was to last for 50 years.

By storing water in three very large reservoirs in the Canadian high mountain headwaters allowed the USA to produce far more hydropower that would have been possible without it. They agreed that they would share the benefits of this additional energy on a 50:50 basis. This compensation amounted to a payment of around $200-300 million/year depending on the yearly water flow.

At the time the treaty was signed only two issues were of concern: Flooding & Power generation. The treaty will expire in 2024 and it was agreed at the time that the re-negotiation should take place over a 10 year period between 2014-2024.

Columbia Basin Trust

The people in charge of the Columbia River Treaty (in 1964) in B.C. did do little to compensate many land owners that lost their land as a result of construction of the reservoir and in the early days most of the compensation money from the USA went to supporting the cost of building the dams and power stations. Once the construction was completed the revenues flowed directly to the Provincial Government with little direct contribution to the region. After many complaints, the Provincial Government in 1994 allocated a one time compensation of some $ 300 million to the region primarily for economic development. The Columbia Basin Trust (CBT) was created to manage these funds. It invested most of this compensation money in hydropower and used the profits for economic development and community based initiative to stimulate economic development, improve social problems and reduce some of the environmental risk these mountain communities face.

Because of the lack of basic information on climatic and environmental conditions, the CBT sponsored a number of very creative community based initiative that have become very successful. Some of the successful initiatives can be adapted and used in  many other mountain communities around the world.

The Examples are:   

1. Community based Watershed Monitoring. 2. Developed Adaptation Plans for Climate Change in Mountain Communities. 3. Initiated Municipal Water Conservation Programs in all communities. 4. Supported a Glacier and Lake Monitoring program. 4. Initiated fire Risk Assessment in key communities. 5. Supported a Wetland Rehabilitation and Wetland Expansion program. 6. Initiated a Farm Program to increase local food production.

Community Environmental Programs

The community based Watershed Monitoring Program was one of the first to engage volunteers to monitor the water quality and aquatic organisms in local watersheds. Due to the rapid development of water quality sensor equipment it is now possible for citizens to produce scientific data at a much more widespread basis that would have been possible with traditional government monitored programs.

The engagement of a locally based University GIS programs enabled 15 communities groups to place all this information into a geo-spatial data base that is publicly accessible.

Treaty Re-negotiations

The challenges for a new agreement by 2024 are of course far more complex than before, because climate change, endangered species, fish and aquatic life, and impacts on the river system were not considered in the initial negotiation. Also, additional benefits from storing water in reservoirs for irrigation were also not considered. Some 6% of the water on the US -side is used for irrigating 3 million ha of agricultural land. Trying to project future conditions given all these concerns together with climate change is a formidable task that will make the development of a new treaty much more challenging.