Do Not Cite, Quote or Distribute 4-1 Total pages: 139 1 Chapter 4: Sea Level Rise and Implications for Low Lying Islands, Coasts and Communities 2 3 Coordinating Lead Authors: Michael Oppenheimer (USA), Bruce Glavovic (New Zealand), Tuhin Ghosh 4 (India) 5 6 Lead Authors: Amro Abd-Elgawad (Egypt), Rongshuo Cai (China), Miguel Cifuentes-Jara (Costa Rica), 7 Rob Deconto (USA), John Hay (Cook Islands), Jochen Hinkel (Germany), Federico Isla (Argentina), 8 Alexandre K. Magnan (France), Ben Marzeion (Germany), Benoit Meyssignac (France), Zita Sebesvari 9 (Hungary), AJ Smit (South Africa), Roderik van de Wal (Netherlands) 10 11 Contributing Authors: Maya Buchanan (USA), Gonéri Le Cozannet (France), Catia Domingues 12 (Australia), Virginie Duvat (France), Tamsin Edwards (UK), Miguel D. Fortes (Philippines), Thomas 13 Frederikse (Netherlands), Jean-Pierre Gattuso (France), Robert Kopp (USA), Erwin Lambert (Netherlands), 14 Elizabeth McLeod (USA), Mark Merrifield (USA), Siddharth Narayan (US), Robert J. Nicholls (UK), 15 Fabrice Renaud (UK), Jonathan Simm (UK), Jon Woodruff (USA), Poh Poh Wong (Singapore), Siyuan Xian 16 (USA) 17 18 Review Editors: Ayako Abe-Ouchi (Japan), Kapil Gupta (India), Joy Pereira (Malaysia) 19 20 Chapter Scientist Maya Buchanan (USA) 21 22 Date of Draft: 20 April 2018 23 24 Notes: TSU Compiled Version 25 26

/pdf/sea-level-rise-and-implications-for-low-lying-islands-coasts-1ptd3trc7d.pdf

Sea Level Rise and Implications for Low Lying Islands, Coasts and Communities

Climate change: Protect the world's deltas

River restoration is one of the most prominent areas of applied water-resources science. From an initial focus on enhancing fish habitat or river appearance, primarily through structural modification of channel form, restoration has expanded to incorporate a wide variety of management activities designed to enhance river process and form. Restoration is conducted on headwater streams, large lowland rivers, and entire river networks in urban, agricultural, and less intensively human-altered environments. We critically examine how contemporary practitioners approach river restoration and challenges for implementing restoration, which include clearly identified objectives, holistic understanding of rivers as ecosystems, and the role of restoration as a social process. We also examine challenges for scientific understanding in river restoration. These include: how physical complexity supports biogeochemical function, stream metabolism, and stream ecosystem productivity; characterizing response curves of different river components; understanding sediment dynamics; and increasing appreciation of the importance of incorporating climate change considerations and resiliency into restoration planning. Finally, we examine changes in river restoration within the past decade, such as increasing use of stream mitigation banking; development of new tools and technologies; different types of process-based restoration; growing recognition of the importance of biological-physical feedbacks in rivers; increasing expectations of water quality improvements from restoration; and more effective communication between practitioners and river scientists.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2014WR016874

The science and practice of river restoration

Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize flow regime at the expense of sediment regime. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural flow regime concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment regimes have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment regimes to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.

https://www.engr.colostate.edu/~bbledsoe/pubs/2015/Wohl_etal_2015_natsed.pdf

The Natural Sediment Regime in Rivers: Broadening the Foundation for Ecosystem Management

Source-to-sink transport processes of fluvial sediments in the South China Sea

By trapping sediment in reservoirs, dams interrupt the continuity of sediment transport through rivers, resulting in loss of reservoir storage and reduced usable life, and depriving downstream reaches of sediments essential for channel form and aquatic habitats. With the acceleration of new dam construction globally, these impacts are increasingly widespread. There are proven techniques to pass sediment through or around reservoirs, to preserve reservoir capacity and to minimize downstream impacts, but they are not applied in many situations where they would be effective. This paper summarizes collective experience from five continents in managing reservoir sediments and mitigating downstream sediment starvation. Where geometry is favorable it is often possible to bypass sediment around the reservoir, which avoids reservoir sedimentation and supplies sediment to downstream reaches with rates and timing similar to pre-dam conditions. Sluicing (or drawdown routing) permits sediment to be transported through the reservoir rapidly to avoid sedimentation during high flows; it requires relatively large capacity outlets. Drawdown flushing involves scouring and re-suspending sediment deposited in the reservoir and transporting it downstream through low-level gates in the dam; it works best in narrow reservoirs with steep longitudinal gradients and with flow velocities maintained above the threshold to transport sediment. Turbidity currents can often be vented through the dam, with the advantage that the reservoir need not be drawn down to pass sediment. In planning dams, we recommend that these sediment management approaches be utilized where possible to sustain reservoir capacity and minimize environmental impacts of dams.

/pdf/sustainable-sediment-management-in-reservoirs-and-regulated-14momatd77.pdf

Sustainable sediment management in reservoirs and regulated rivers: Experiences from five continents

This book was developed to facilitate 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 World Bank Group steps up its activities in both the water and energy sectors, the risks of climate change and disasters need to be better understood and managed to ensure sustainable, resilient, and cost-effective outcomes. This increased awareness is particularly important 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 more extreme droughts and floods. For many countries, hydropower is now the largest source of affordable renewable energy . This is especially true in regions like Sub-Saharan Africa, South Asia, and Southeast Asia, which are characterized by significant untapped hydropower potential and water shortages.The remainder of this book is organized into nine chapters and an appendix: Chapter 2: Climate Change, Sediment Management and Sustainable Development discusses the importance of reservoir sediment management for preserving reservoir storage and illustrates how it contributes to satisfying the tenets of sustainable development. Chapter 3: Overview of Sedimentation Issues discusses the importance of reservoir storage and the impacts of reservoir sedimentation up- and downstream of dams. Chapter 4: Sediment Yield provides an overview of sediment yield, describes the important factors that determine the magnitude of sediment yield, and presents ways to estimate sediment yield. Chapter 5: Patterns of Sediment Transport and Deposition describes techniques for estimating the amount of sediment that will be deposited in a reservoir. Chapter 6: Sedimentation Monitoring discusses sedimentation monitoring procedures, bathymetric mapping of sediment, and estimation of sediment bulk density. Chapter 7: Sediment Management Techniques presents an overview of activities of combat reservoir sedimentation. Chapter 8: Sediment Management at Run-of-River Headworks describes basic concepts to consider in the design or rehabilitation of run-of-river headworks with regard to sediment management. Chapter 9: Reservoir Sustainability Best Practices Guidance summarizes sediment management strategies that will provide a higher level of assurance that the project operation can be sustained indefinitely. Appendix A: Checklist for Sediment Management is for use by project proponents to help ensure that projects adhere to the recommendations put forth throughout the book. The checklist is divided into three sections: sediment yield, sustainable sediment management measures, and sediment patterns and impacts.

Extending the Life of Reservoirs: Sustainable Sediment Management for Dams and Run-of-River Hydropower

Sustaining United States reservoir storage capacity: Need for a new paradigm

Economic development relies critically on infrastructure development. Yet, without careful planning, the services provided by hydropower facilities and dams are at risk. Ensuring the long-term resilience of these critical infrastructure facilities requires early and consistent attention to the processes of reservoir sedimentation, which reduce the storage capacity of reservoirs and damages hydromechanical equipment, posing a threat to the sustainability of hydropower, water supply, and irrigation services. Written by two of the world’s leading experts on sediment management, Extending the Life of Reservoirs: Sustainable Sediment Management for Dams and Run-of-River Hydropower provides guidance on adopting sediment management practices for hydropower and dam projects. It stresses the importance of incorporating sediment management into projects in order to safeguard the many important services of these projects, including water supply, irrigation, and renewable electricity. In particular, the book stresses the importance of integrating sediment management into the early planning phases of projects. Importantly, this book provides a new perspective on the importance of sediment management that is not found in earlier work. The authors stress the value of sediment management as a robust adaptation strategy to support sustainable hydropower and supply of water for domestic use, agriculture, and industry. The techniques focus on addressing uncertainties related to future climate changes, and how uncertainty over future hydrological patterns may be addressed. While the primary audience for the book includes policy makers, lending agencies, and general practitioners evaluating dam and hydropower proposals, the level of detail provided in the book should appeal to a wide array of stakeholder groups. The content is neither overly technical nor overly simplistic, and aims to provide practical and useful information.

Gregory L. Morris

Papers

Sustainable sediment management in reservoirs and regulated rivers: Experiences from five continents

Extending the Life of Reservoirs: Sustainable Sediment Management for Dams and Run-of-River Hydropower

Sustaining United States reservoir storage capacity: Need for a new paradigm

Extending the Life of Reservoirs