Environmental Flows: Saving Rivers for the Third Millennium (2012). University of California Press, Berkeley. Freshwater Ecology Series. 424 pp. ISBN 9780520273696, Price $75.00, £52.00 (Hardback).
Fresh water – our most precious resource – has never been in greater demand or in more need of management, legislation and policy strategies to protect aquatic ecosystems and the goods and services they provide. Such is the importance and timeliness of Angela Arthington's excellent book, Environmental Flows: Saving Rivers for the Third Millennium, which further consolidates the emerging science of environmental flows, defined in the book as ‘the quantity, timing and quality of waters required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend upon these ecosystems’.
The book, which has 22 chapters, initially provides an introduction to the key concepts in river hydrology and ecology that underpin the environmental flow approach. The first three chapters focus, respectively, on river values and threats, global hydrology, climate and river flow regimes, and the hydromorphology of catchments. The fourth chapter describes essential concepts of river ecology, most notably the natural flow regime paradigm, which underpins environmental flow management. With the basics covered, the narrative progresses to consider how humans threaten the natural character of our river systems (chapter 5) and describes how dams and flow regulation alter natural flow regimes, with consequences for river physicochemistry, habitats and biodiversity (chapters 6–8).
Having set the scene, the author turns to the question at the heart of the book: how much change from the natural flow regime rivers can tolerate before these ecosystems, and their goods and services become degraded? Chapters 9–14 chart the development of the various methods, frameworks, modelling techniques and decision support systems that address this issue and which constitute modern environmental flow assessment. These chapters cover hydrological, hydraulic rating, habitat simulation and holistic (or ecosystem) methodologies. Thankfully, we are spared the minutiae of modelling; as the author states, ‘readers looking for manuals setting out the details of each method will be disappointed’ and should use this book as a springboard to the more technical echelons. Instead, these chapters set out how the field evolved through time, from species-to-ecosystem, and source-to-sea perspectives – an approach which is also helpful in highlighting the strengths and weaknesses of each type of method. Thereafter, recent developments in modelling ecological responses to flow change are reviewed (chapter 14), and subsequent chapters focus on the threats to, and flow requirements of, groundwater-dominated ecosystems, wetlands and estuaries (chapters 15–18), and on the legislation, policy and water management strategies established to protect freshwater resources and ecosystems (chapters 19–21). The book's final chapter (22) turns to climate change and the role of environmental flows as a means to sustain ecosystem resilience and biodiversity.
Overall, the book is well produced, with appropriate use of illustrations and tabulation. The text is very readable, being refreshingly non-technical, although perhaps some of the chapters are little light on citations for some tastes. I like the structure of the book too – lots of short chapters propel the reader forward.
In the concluding remarks, Arthington notes that whilst many countries now recognise the importance of flow regimes and have legislated to protect water needs of rivers and floodplains, ‘a vigorous global river and catchment restoration effort is needed if societies wish to enjoy the benefits of freshwater biodiversity and the ecological goods and services of healthy ecosystems’. I think this book stands as a considerable achievement and will make an important contribution towards that effort, by equipping students, researchers and managers with the broad, interdisciplinary knowledge base required to turn the emerging science of environmental flows into practice.
