Jeff Opperman

We know that the world must develop energy systems that support healthy, prosperous lives for people, allow the world to remain within safe climate boundaries, and accomplish those goals without causing unacceptable impacts on ecosystems and their services, vulnerable communities, and irreplaceable natural values. Hydropower is a clear illustration of this central challenge and opportunity.

Abstract: Global hydropower capacity is projected to approximately double in the next several decades, powered by thousands of new dams. Most of this development will take place in South America, Africa, and Asia (China, South Asia, and Southeast Asia). While providing valuable energy to meet growing demands, this expansion of hydropower threatens the diversity and productivity of fish in many tropical rivers, including several river basins where fish provide the primary source of protein to rural communities and larger regional populations. Maintaining the movement of migratory fish within basins undergoing development is a key challenge for governments and those who plan, design, and manage dams. While improving fish passage at dams is critically important, this session will highlight how the spatial arrangement of dams in a river basin impacts fish movement through a channel network. The applied focus of the panel will be maintaining fish passage and migration within river basins that are undergoing development, with an emphasis on tropical rivers. The panel will review current examples of fish passage that illustrate the need for a basin-scale approach, tools for assessing connectivity of different dam configurations, and examine the potential for system-scale planning for dam siting to produced more balanced outcomes between hydroelectric energy and fish migration

Conventional flood control has emphasized structural measures such as levees, reservoirs, and engineered channels—measures that typically simplify river channels and cut them off from their floodplain, both with adverse environmental consequences. Structural measures tend to be rigid and not easily adapted to increased flooding regimes resulting from environmental change. Such actions also limit the natural hydrologic benefits of floodplains such as storing floodwaters, improving water quality, providing habitat for invertebrates and fish during periods of inundation, and supporting a multitude of cultural services. As these benefits are more widely recognized, policies are being adopted to encourage projects that reduce flood risks and restore floodplain ecosystems, while acknowledging the social-ecological context. The number of such projects, however, remains small. We assessed four multi-benefit floodplain projects (two in California, United States, and two in Germany) and chara...

We know that the world must develop energy systems that support healthy, prosperous lives for people, allow the world to remain within safe climate boundaries, and accomplish those goals without causing unacceptable impacts on ecosystems and their services, vulnerable communities, and irreplaceable natural values. Hydropower is a clear illustration of this central challenge and opportunity.

Abstract: Global hydropower capacity is projected to approximately double in the next several decades, powered by thousands of new dams. Most of this development will take place in South America, Africa, and Asia (China, South Asia, and Southeast Asia). While providing valuable energy to meet growing demands, this expansion of hydropower threatens the diversity and productivity of fish in many tropical rivers, including several river basins where fish provide the primary source of protein to rural communities and larger regional populations. Maintaining the movement of migratory fish within basins undergoing development is a key challenge for governments and those who plan, design, and manage dams. While improving fish passage at dams is critically important, this session will highlight how the spatial arrangement of dams in a river basin impacts fish movement through a channel network. The applied focus of the panel will be maintaining fish passage and migration within river basins that are undergoing development, with an emphasis on tropical rivers. The panel will review current examples of fish passage that illustrate the need for a basin-scale approach, tools for assessing connectivity of different dam configurations, and examine the potential for system-scale planning for dam siting to produced more balanced outcomes between hydroelectric energy and fish migration

Though critical to all life – and to most economic activity – water has consistently been undervalued relative to the wide range of uses and benefitsit provides. However, with new valuation methods and frameworks being developed, governments, the private sector and financial institutions are beginning to make progress in recognizing the wider value of water. As these discussions advance, we believe it is important to shine a light on a paralleland equally critical challenge: the consistent failure of economies andsocieties to value rivers for their full spectrum of benefits.

There is increasing global interest in employing nature-based solutions, such as reforestation and wetland restoration, to help reduce water risks to economies and society, including water pollution, floods, droughts and water scarcity, that are likely to become worse under future climates. Africa is exposed to many such water risks. Nature-based solutions for adaptation should be designed to benefit biodiversity and can also provide multiple co-benefits, such as carbon sequestration. A systematic review of over 10 000 publications revealed 150 containing 492 quantitative case studies related to the effectiveness of nature-based solutions for downstream water quantity and water quality (including sediment load) in Africa. The solutions assessed included landscape-scale interventions and patterns (forests and natural wetlands) and site-specific interventions (constructed wetlands and urban interventions e.g. soakaways). Consistent evidence was found that nature-based solutions can im...

Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one-third of all vertebrate species. This biodiversity is declining dramatically: Globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but coordinated action to reverse the decline is lacking. We present an Emergency Recovery Plan to bend the curve of freshwater biodiversity loss. Priority actions include accelerating implementation of environmental flows; improving water quality; protecting and restoring critical habitats; managing the exploitation of freshwater ecosystem resources, especially species and riverine aggregates; preventing and controlling nonnative species invasions; and safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on B...

Global hydropower capacity is projected to approximately double from the 2010 installed capacity of 1,000 gigawatts (GW). This expansion would require a dramatic increase in the number of hydropower dams in river basins around the world, including many basins that still have natural, free-flowing rivers. Although hydropower can play an important role in a low-carbon energy future, a doubling of hydropower capacity risks many other values that rivers provide, including fisheries and flood-recession agriculture that feed hundreds of millions of people. “The Power of Rivers” explores the potential for achieving more balanced outcomes from hydropower development.

Getting the most out of rivers: Sustainable hydropower development. Henriette (Yetta) Jager 1 , Rebecca Efroymson 1 and Jeff Opperman 2 , (1)Oak Ridge National Laboratory, (2)Global Freshwater Program, The Nature Conservancy, Chagrin Falls, OH ...

A diverse suite of projects will be depicted demonstrating the value of mapping, monitoring, and modeling the North Coast's changing oak woodland landscape. This applied research uses a geographic information system to better integrate biodiversity research and ...

Recent reviews of salmonid habitat restoration programs have recommended that managers emphasize strategies that restore natural habitat-forming processes, such as restoring riparian vegetation, over placement of instream structures. In addition to the direct benefits of shading and providing a source for large woody debris (LWD), riparian restoration is often implemented to improve channel morphology for purposes of restoring fish habitat. However, multiple studies provide equivocal evidence that restored vegetation can lead to improved channel form within a period of years to decades. In this study, we examined the effectiveness of riparian restoration for improving channel morphology and fish habitat in four hardwood-dominated streams in Mendocino County, California. These streams support populations of steelhead Oncorhynchus mykiss and contain reaches with riparian corridors that were restored through exclusionary fencing implemented 10–20 years earlier. We compared channel morphology, LWD, and late-summer water temperature between the restored exclosure reaches and geomorphically similar control reaches within the same properties. Channels within exclosures were significantly narrower and had greater heterogeneity in long profile elevation than control reaches. Frequencies of LWD and debris jams were considerably greater in exclosure reaches than control reaches and were comparable to values from similar streams with mature forests. Late-summer water temperature in exclosures was within the acceptable range for steelhead, whereas water temperature in control reaches was warmer and potentially detrimental to steelhead. Riparian restoration in exclosures has resulted in quantitatively improved habitat characteristics and qualitatively different channel morphologies as compared with control reaches. The ability of vegetation to improve channel morphology in this region is probably due to frequent overbank flooding and high sediment loads. Through a comparative analysis of the cost and performance of exclusionary fencing versus those of instream structures, we propose that riparian restoration can produce instream salmonid habitat benefits that are more comprehensive, sustainable, and cost-effective than the benefits generated by instream structures.

ABSTRACT Floodplains are among the most biologically productive and diverse ecosystems on Earth and they provide significant benefits to society such as attenuation of floodwaters, groundwater recharge, filtration of nutrients and sediments, carbon ...

A little more than a decade ago, a small band of engineers and ecologists came together along the banks of the Green River of Kentucky to discuss a simple idea. The Green River—“where Paradise lay” in the words of John Prine—is in fact a magical place. Although ...

Abstract: Riparian areas (land along river banks) are a natural place for human settlement given the richness of floodplain soils for farming, their proximity to freshwater and the opportunity for transportation and commerce, as seen in antiquity with the settlement of the ...

Abstract: We describe a process and methodology for quantifying the extent of a type of historically prevalent, but now relatively rare, ecologically-valuable floodplains in the Sacramento lowland river system: frequently-activated floodplains. We define a specific ...

Habitat Conservation Plans (HCPs) have become the primary mechanism for resolving conflicts between nonfederal land use and the Endangered Species Act (ESA). In exchange for implementing conservation measures outlined in the HCP, a landowner receives an ...

Résumé/Abstract Recent efforts by nongovernmental organizations (NGOs) to reduce the environmental impacts of water impoundment and diversion have pursued two distinct but interacting strategies in California's complex water resources management system:(1) the ...

Abstract Habitat Conservation Plans (HCPs) have become the primary mechanism by which the Endangered Species Act (ESA) is implemented on private land. Due to the dramatic increase in the number and size of plans, numerous scientists, conservation organizations ...

Getting the most out of rivers: Sustainable hydropower development. Henriette (Yetta) Jager 1 , Rebecca Efroymson 1 and Jeff Opperman 2 , (1)Oak Ridge National Laboratory, (2)Global Freshwater Program, The Nature Conservancy, Chagrin Falls, OH ...

A diverse suite of projects will be depicted demonstrating the value of mapping, monitoring, and modeling the North Coast's changing oak woodland landscape. This applied research uses a geographic information system to better integrate biodiversity research and ...

Abstract: We describe a process and methodology for quantifying the extent of a type of historically prevalent, but now relatively rare, ecologically-valuable floodplains in the Sacramento lowland river system: frequently-activated floodplains. We define a specific ...

Recent reviews of salmonid habitat restoration programs have recommended that managers emphasize strategies that restore natural habitat-forming processes, such as restoring riparian vegetation, over placement of instream structures. In addition to the direct benefits of shading and providing a source for large woody debris (LWD), riparian restoration is often implemented to improve channel morphology for purposes of restoring fish habitat. However, multiple studies provide equivocal evidence that restored vegetation can lead to improved channel form within a period of years to decades. In this study, we examined the effectiveness of riparian restoration for improving channel morphology and fish habitat in four hardwood-dominated streams in Mendocino County, California. These streams support populations of steelhead Oncorhynchus mykiss and contain reaches with riparian corridors that were restored through exclusionary fencing implemented 10–20 years earlier. We compared channel morphology, LWD, and late-summer water temperature between the restored exclosure reaches and geomorphically similar control reaches within the same properties. Channels within exclosures were significantly narrower and had greater heterogeneity in long profile elevation than control reaches. Frequencies of LWD and debris jams were considerably greater in exclosure reaches than control reaches and were comparable to values from similar streams with mature forests. Late-summer water temperature in exclosures was within the acceptable range for steelhead, whereas water temperature in control reaches was warmer and potentially detrimental to steelhead. Riparian restoration in exclosures has resulted in quantitatively improved habitat characteristics and qualitatively different channel morphologies as compared with control reaches. The ability of vegetation to improve channel morphology in this region is probably due to frequent overbank flooding and high sediment loads. Through a comparative analysis of the cost and performance of exclusionary fencing versus those of instream structures, we propose that riparian restoration can produce instream salmonid habitat benefits that are more comprehensive, sustainable, and cost-effective than the benefits generated by instream structures.

ABSTRACT Floodplains are among the most biologically productive and diverse ecosystems on Earth and they provide significant benefits to society such as attenuation of floodwaters, groundwater recharge, filtration of nutrients and sediments, carbon ...