Restoration of Physical Integrity of Rivers

by

Lina E. Polvi, Daniel W. Baker

• LAST REVIEWED: 28 November 2016
• LAST MODIFIED: 28 November 2016
• DOI: 10.1093/obo/9780199363445-0059

Introduction

Physical integrity for rivers refers to a set of active fluvial processes and landforms wherein the channel, floodplain, sediment, and overall spatial configuration maintain a dynamic equilibrium, according to Graf 2001 (cited under Components of Physical Integrity). Physical integrity is achieved when river processes and forms maintain active connections with each other in the present hydrologic regime. The term “physical integrity” was first used in an important piece of legislation in the United States of America, the Clean Water Act of 1977, in which it is stipulated that the nation must restore and maintain the chemical, physical, and biological integrity of the nation’s water. Within the Environmental Protection Agency, the governmental agency charged with carrying out and enforcing the Clean Water Act, and the scientific literature, much of the focus has been on the chemical and biological integrity, with less direct focus on how to restore physical integrity. However, in the late 20th and early 21st centuries, there has been a greater scientific focus on restoration of physical forms and processes in rivers. Restoration of physical integrity encompasses several aspects: reducing fragmentation, ensuring functional physical processes and equilibrium, allowing dynamic processes, and matching restoration to geographic large-scale controls. In practice, restoration of physical integrity can be divided into two main categories—those focused on restoring form by increasing physical heterogeneity or creating a specific planform (e.g., meandering) or bedform (e.g., pool-riffles), and those focused on restoring processes, including sediment transport, flow retention, and flooding in order to maintain forms. Form-based restoration is usually rooted in the assumption that a reference condition can elucidate the forms that best match the processes under similar hydrologic and sediment regimes. Reference conditions can either be historical (i.e., where there is sufficient data on previous channel conditions before the degradation occurred) or geographical—where there is an undisturbed stream reach within the same region with similar climatic, hydrological, geological, and land-use conditions and the reference and degraded reaches have similar drainage areas and valley characteristics (in terms of valley slope and with and hillslope conditions). In addition, process-based restoration goals based on ecosystem functioning or channel classification schemes can be used in designing channel restoration. In areas where the flow regime is heavily altered, by for example dams, flow diversions or land-use conditions, environmental or functional flows have been used to determine which flows (e.g., five-year flood) are necessary to maintain certain physical processes or forms.

Textbooks and Edited Collections

Restoration of physical integrity is a fairly new field within fluvial geomorphology, and most published work is either in the form of scientific articles or management-focused reports and manuals. However, the need for edited volumes and textbooks with a scientific backing has been recognized and is slowly emerging. Many textbooks on general fluvial geomorphology and river science include a section on river management and restoration as in Knighton 1998, Wohl 2010, and Wohl 2014. Although river restoration is not the main focus of these aforementioned textbooks, they provide a solid basis in understanding the factors contributing to physical integrity in streams, which is crucial to properly design or even just understand how a restoration project should be carried out in order to ensure high physical integrity. Similarly, Fryirs and Brierley 2005 introduces key concepts in fluvial geomorphology in the context of river management by using a river classification scheme, the River Styles Framework, to determine the physical controls on a river section and thereby how a river should look. One of the first edited volumes, combining several disciplines pertinent to river restoration, is Brookes and Shields 1996. One of the first textbooks that gives a holistic view of river and watershed restoration is Roni and Beechie 2013, which goes through the planning and organizing stages (with, for example, stakeholders and other members of society) of a restoration project as well as the background for understanding processes and choosing restoration methods. Simon, et al. 2011 compiled state-of-the-art stream restoration science in an edited volume. Similar papers can be found in journals, but this volume provides a thorough overview from respected experts in the field: it will be most useful for those who already have a solid background in the field.

• Brookes, Andrew, and F. Douglas Shields, eds. 1996. River channel restoration: Guiding principles for sustainable projects. Chichester, UK: John Wiley.

  This volume combines several disciplines, including hydrology, hydraulics, geomorphology, and ecology, to guide managers in designing appropriate restoration projects. Case studies show state-of-the-art river restoration and highlight principles for sustainable restoration; however, new methods have been developed since this volume was published.

• Fryirs, Kirstie, and Gary J. Brierley. 2005. Geomorphology and river management: Applications of the river styles framework. Oxford: Blackwell.

  This easy-to-read textbook introduces students to a method for characterizing river form and behavior: the river styles framework. A thorough section on geomorphic considerations for river management provides students of river management with tools needed to put geomorphic theory into practice.

• Knighton, David. 1998. Fluvial forms and processes: A new perspective. London: Arnold.

  This textbook introduces the field of fluvial geomorphology through processes and forms created at the catchment down to the channel scale. Although only a short section deals with channel change and human activity, a solid background of processes necessary for restoring physical integrity are given.

• Roni, Philip, and Tim Beechie, eds. 2013. Stream and watershed restoration: A guide to restoring riverine processes and habitats. Oxford: John Wiley.

  This book with multiple contributors is organized to give the reader a holistic view of watershed and stream processes in order to design process-based restoration techniques. This book serves as a guide for planning, selection of techniques, implementing projects, and monitoring restoration results.

• Simon, Andrew, Sean J. Bennett, and Janine M. Castro, eds. 2011. Stream restoration in dynamic fluvial systems: Scientific approaches, analyses, and tools. Washington, DC: American Geophysical Union.

  This edited volume contains overview papers of multiple aspects of stream restoration directed at academics and experienced practitioners about the current state of knowledge of hydrology and hydraulics, habitat, sediment transport, structural approaches, and models.

• Wohl, Ellen. 2010. Mountain rivers revisited. Washington, DC: American Geophysical Union.

  DOI: 10.1029/WM019

  Provides a comprehensive review of concepts and literature related to the geomorphology of mountain rivers. The “River Management” section thoroughly discusses types of river restoration, principles of restoration, and challenges that face restoration projects. The remainder of the book provides a foundation for understanding river processes.

• Wohl, Ellen. 2014. Rivers in the landscape: Science and management. Chichester, UK: Wiley-Blackwell

  This comprehensive introduction to rivers focuses on sediment dynamics and channel forms with overviews of hydraulic and hydrologic processes and extra-channel environments (e.g., floodplains and deltas). River restoration is briefly discussed, but this book is most valuable for understanding how rivers fundamentally work—mandatory knowledge prior to commencing restoration.