Session FT 1.08
The global potential for major water system reoptimisation to restore downstream ecosystems and human livelihoods
Natural Heritage Institute (NHI)
The objectives of this session were to:
1) Launch a global dialogue on the potential for reoptimizing major hydraulic infrastructure systems, of which dams are a part, worldwide. The infrastructure under consideration includes systems built for hydropower generation, flood control, irrigation, water supply or multi-purpose use.
2) Using case examples, present reoptimization tools that will enable the restoration of more natural flow patterns to benefit human production systems in the downstream floodplains as well as aquatic and riparian ecosystems, while retaining the economic benefits that the systems were initially designed to achieve;
3) Gather additional knowledge and feedback from forum participants on existing cases, prospective candidates for reoptimization and on the toolkit presented.
4) Discuss the constraints and opportunities for major water system reoptimization in different settings.
Rivers in the world all face many similar problems in different degrees, such as water scarcity, flooding threat, soil erosion, water pollution, and ecological degradation. Many agencies and stakeholders around the world, and especially in developing countries, are interested in ensuring the sustainable utilization of water and the protection of the environment. The concepts of Maintaining the Healthy Life of the Rivers and integrated river basin management now being developed in China offer a useful example of how to ease these problems.
In transboundary basins such as the Senegal River Basin, the establishment of solid inter-state institutions such as the OMVS and the Water Charter have helped member states to agree on common objectives and priorities;
The optimization experiments in the Senegal Basin were successful beyond the expectations of the donor agencies that funded the program, which provides hope for similar work in other basins;
The analytical methods developed by IRD are transposable to other reoptimization contexts, with appropriate adjustments;
In addition to ensuring the physical feasibility of reoperation, we must ensure that the appropriate legal and institutional frameworks are in place·
The process of designing and implementing major water system reoptimization must include local stakeholders. The water system must be analyzed as a whole that includes people and their livelihoods. Learning how to manage this process will be an important piece of the puzzle.
Small tweaks to the system can result in major beneficial changes;
In addition to action, further research is needed to better understand the links between the social, economic and environmental dimensions of a major water system.
Orientations for action
Document and disseminate the best practices implemented to date to reoperate major water systems built for flood control, irrigation, hydropower generation or for multiple purposes, to achieve environmental and social benefits downstream;
Refine the toolkit of reoptimization strategies to represent a complete set of tools to be used in diverse settings with differing infrastructure characteristics and downstream priorities;
Select a small number of major water systems to carry out demonstration studies, planning and implementation of reoptimization;
Using the above technical inputs and lessons learned, harness the necessary financing at the local, national and international levels that will allow for the reoptimization of larger numbers of major water systems around the world.
Local Actions presented
The Global Initiative on the Reoptimization of Major Dams
Gregory Thomas, NHI
The objective of the Global Initiative is to restore natural ecological functions and environmental services to the downstream floodplains below the major dams of the world. There are today some 49,000 such dams operating in the world, the vast majority built since the Second World War, and two-thirds of them in developing countries. The World Commission on Dams has chronicled both the economic benefits and the pervasive damage that this legacy of large dams has caused to freshwater, riparian, and estuarine ecosystems that support human production systems. Building on that work, the Global Initiative will now assess the feasibility of re-optimizing the major irrigation, power and flood management systems to enable these dams to be reoperated to restore a substantial measure of the formerly productive floodplains, wetlands, deltas and estuaries in ways that do not significantly reduce—and can sometimes even enhance—the irrigation, power generation, and flood control benefits for which the dams were constructed.
The Yellow River Experiments with River Floods and Sedimentation
Xue Songgui, Yellow River Conservancy Commission.
The Xiaolangdi Reservoir is the last storage facility on the Yellow River main stem. Its purposes include flood control, alleviating sediment deposition, water supply, irrigation and hydropower generation. The joint operation of the Xiaolangdi Reservoir together with the Sanmenxia Reservoir right above Xiaolangdi, and the Guanxian and Luhun reservoirs on the major tributaries, is essential for flood control in the Yellow River from Xiaolangdi to the Bohai Sea. The joint re-optimization of these four reservoirs’ operation could significantly improve downstream ecological functions and human livelihoods. The Yellow River Conservancy Commission has conducted four experiments from 2002 through 2005, creating artificial flow through joint reservoir operation to most efficiently flush reservoir and downstream river bed sediment to the Bohai Sea. These four reoperation experiments succeeded in restoring a continuous –but modest and non-variable—flow to the Bohai Sea. Now the challenge is to make those operational features permanent.
Reoptimizing the Operation of Manantali Dam in the Senegal River Basin
Saloum Cisse, Mamédy Sackho and Bouba Camara, OMVS.
The multipurpose Manantali dam built in 1986 in the Senegal River Basin had unintended disruptive effects on the ecosystems and livelihoods downstream that depended on the river's annual flood cycle. Since 2001 the Senegal River Basin Authority (OMVS) and its partners, including the French Institut de Recherche pour le Développement (IRD) have engaged in a focused effort to optimize the dam's operations to satisfy power generation and irrigation objectives while also restoring an annual artificial flood to benefit traditional livelihoods downstream.