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Environmental Flows: Saving Rivers in the Third Millennium

Angela H. Arthington
Copyright Date: 2012
Edition: 1
Pages: 424
https://www.jstor.org/stable/10.1525/j.ctt1ppw56
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  • Book Info
    Environmental Flows
    Book Description:

    Environmental Flowsdescribes the timing, quality, and quantity of water flows required to sustain freshwater and estuarine ecosystems and the human well-being and livelihoods that depend upon them. It answers crucial questions about the flow of water within and between different kinds of ecosystems. What happens when the flow or the availability of water is curtailed or diverted, either naturally or by human activity? How will climate change alter the availability of water and impact aquatic ecosystems? Methodological developments from the simplest hydrological formulas to large-scale frameworks that inform water management make this book a must-read for water managers and freshwater and estuarine ecologists contending with ever-changing conditions influencing the flow of water.

    eISBN: 978-0-520-95345-1
    Subjects: Ecology & Evolutionary Biology

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. PREFACE AND ACKNOWLEDGMENTS
    (pp. ix-xii)
    Angela H. Arthington
  4. 1 RIVER VALUES AND THREATS
    (pp. 1-12)

    Rivers and their associated floodplains, groundwater, and wetlands are in crisis. Globally they are the world’s most damaged ecosystems, losing species at a rate that far outstrips the decline of biodiversity in terrestrial and marine systems (Dudgeon et al. 2006). A new synthesis of threats to the world’s rivers (Vörösmarty et al. 2010) has found that over 83% of the land surface surrounding aquatic systems has been significantly influenced by the “human footprint.” The stamp of human activities is manifest as widespread catchment disturbance, deforestation, water pollution, river corridor engineering, impoundments and water diversions, irrigation, extensive wetland drainage, groundwater depletion,...

  5. 2 GLOBAL HYDROLOGY, CLIMATE, AND RIVER FLOW REGIMES
    (pp. 13-34)

    The natural fluctuations of freshwater ecosystems and water supplies are governed by the climatic regime of the region and the prevailing hydrologic cycle—the dynamic mechanism connecting all forms of water in its liquid, solid, and vapor phases and in the cells and tissues of living organisms (Fig. 1). In a perpetual cycle driven by solar energy, the global hydrological cycle delivers an estimated 110,000 km³ of water to the land annually as precipitation. About two-thirds of this precipitation is water recycled from plants and the soil as evapotranspiration (70,000 km³ per year), while one-third is water evaporated from the...

  6. 3 CATCHMENTS, DRAINAGE NETWORKS, AND RESOURCE REGIMES
    (pp. 35-48)

    Rivers and other freshwater systems receive their water from rain, hail, sleet, and snow in the endless flow of evaporation, transpiration, precipitation, infiltration, and runoff processes of the hydrologic cycle. Water is delivered to each freshwater system from its catchment or drainage basin (watershed)—an area of land that collects precipitation and drains that water to a common point in the landscape or into another freshwater body. Larger catchments are made up of smaller subcatchments, and the familiar treelike branches of streams join to form larger tributaries and then major river channels, all of which form the drainage network of the catchment...

  7. 4 RIVER ECOLOGY, THE NATURAL FLOW REGIME PARADIGM, AND HYDROECOLOGICAL PRINCIPLES
    (pp. 49-74)

    The directionality of flowing water is so vital to running waters that physical system structure and ecological linkages within a river system are generally divided into longitudinal, lateral, and vertical vectors (Poole 2002). River ecosystems have also been visualized as four-dimensional systems made up of longitudinal, lateral, and vertical components, relationships, and processes, with temporal vectors adding the fourth dimension (Ward 1989; Ward and Stanford 1995). The differentiation of rivers into major geomorphological zones (see Chapter 3) led to biologically based schemes of longitudinal zonation. Early schemes classified rivers into three or four zones along the upland-floodplain transition, each characterized...

  8. 5 EFFECTS OF CATCHMENT CHANGE AND RIVER-CORRIDOR ENGINEERING
    (pp. 75-86)

    Every environmental flow assessment has a catchment context with a particular “human footprint” (Sanderson et al. 2002). Environmental flow assessments are most often focused on the geomorphic and ecological implications of flow alterations below large dams, but many other human interventions at the catchment scale intercept or exacerbate overland flows and influence the hydrology of streams and rivers, wetlands, and estuaries. Not only do catchment activities alter surface and groundwater hydrology, they also alter the dynamics of other catchment resource regimes—sediments, nutrients and organic matter, temperature, and light. Alterations to these regimes have many consequences for aquatic and riparian ecosystems, and...

  9. 6 HISTORY OF WATER CONTROL AND DAM IMPACTS
    (pp. 87-98)

    Human activities have modified the natural hydrologic and ecological processes of catchments and rivers, wetlands, floodplains, and estuaries for thousands of years (Boon et al. 1992). Early hunter-gatherer societies drew upon the natural resources of rivers and floodplains, their riparian corridors, and the surrounding areas for water, food, and shelter (Freitag et al. 2009). Fishing and hunting activities were closely attuned to the seasonal cycles of climate and river flows and to the plants and animals adapted to those natural cycles. various devices were used to catch fish (nets, stone traps, fish wheels, spears, and hooks) and to capture wildlife...

  10. 7 EFFECTS OF DAMS ON SEDIMENT, THERMAL, AND CHEMICAL REGIMES
    (pp. 99-112)

    Dams are the most obvious direct modifiers of river flow because they capture both low and high flows and can alter the entire flow regime in many different ways. Modification of the natural flow regime dramatically affects sediment dynamics and channel morphology, nutrient transformations and other chemical conditions, thermal regime, habitat structure, and recruitment of both aquatic and riparian species in streams and rivers worldwide (Poff et al. 1997; Naiman et al. 2008). Ecological responses to altered flow regimes in a specific stream or river depend on how the five basic components of a flow regime have changed relative to...

  11. 8 EFFECTS OF DAMS ON HABITAT AND AQUATIC BIODIVERSITY
    (pp. 113-124)

    Flowing water creates and maintains a variety of habitats, reflecting channel planform and variation in hydraulic conditions across the stream, modified by habitat elements such as fallen timber, fine vegetable litter, overhanging and in-stream vegetation, rocky outcrops, undercut banks, and root masses (Pusey et al. 1993). These elements and the distribution patterns of flow velocities and depths create diverse hydraulic habitat patches across and along streams and rivers. This diversity of habitat (and associated chemical conditions) is important for maintaining various ecological functions: resting and refuge, foraging, spawning and nesting, seedling establishment, plant germination, local movement patterns of invertebrates and...

  12. 9 INTRODUCTION TO ENVIRONMENTAL FLOW METHODS
    (pp. 125-138)

    Environmental flow assessments (EFAs) take place in many different management contexts, at various spatial scales, within different biophysical systems, and in contrasting socioeconomic contexts and political settings. These settings and circumstances have a strong bearing on the methods most suited to achieving desired ecological outcomes. As many reviews of methods have noted, there is no single best approach to determining an environmental flow regime. Nevertheless, it is possible to set out some parameters for selecting a suitable method. More than 200 methods are available, and variations continue to be developed to accommodate particular issues and special circumstances (Tharme 2003; Acreman and Dunbar...

  13. 10 HYDRAULIC RATING AND HABITAT SIMULATION METHODS
    (pp. 139-148)

    Both the Montana Method (Tennant 1976) and the FDC approach (Stalnaker and Arnette 1976) are based on the premise that the amount and quality of habitat in a stream is related to the amount of water transported down its channel. Hydraulic rating methods seek to define the relationship between flow volume (discharge) and the amount and type of habitat provided during the passage of flow along a stream channel. Once this relationship is known, a modified flow regime can be defined that either maintains that habitat at maximum suitability or at lesser levels of suitability (Pusey 1998). More than 20...

  14. 11 FLOW PROTECTION METHODS
    (pp. 149-164)

    A major shift in thinking about environmental flows emerged in the early 1990s, when river scientists concerned about the limitations of existing water-allocation methods (then termed “in-stream flow methods”) increasingly made the case for a broader approach to sustain and conserve river ecosystems rather than just a few target species. Conceptual foundations were laid by several contributors, for example Hill et al. (1991) outlined ecological and geomorphological concepts for in-stream and out-of-channel flow requirements. Holistic approaches incorporating ecologically relevant features of the natural hydrologic regime to protect the entire riverine ecosystem emerged through parallel developments and collaboration in Australia and...

  15. 12 FLOW RESTORATION METHODS
    (pp. 165-180)

    River fragmentation and flow regulation by dams are the most pervasive and destructive changes wrought by humans in rivers worldwide (Dynesius and Nilsson 1994; Vörösmarty et al. 2010). Dams sever dynamic, interconnected surface-water and groundwater pathways of the river continuum, and they disrupt the natural flow regimes that create environmental heterogeneity and maintain biodiversity. Typically, biodiversity and biological productivity are reduced or altered in regulated rivers, and nonnative species proliferate (Poff et al. 1997; Bunn and Arthington 2002). Awareness of these impacts has generated practical efforts to recover the ecological properties of rivers by adjusting flow regimes (e.g., Petts 1989;...

  16. 13 ECOLOGICAL LIMITS OF HYDROLOGIC ALTERATION (ELOHA)
    (pp. 181-198)

    All existing environmental flow assessment (EFA) methods—from hydrological to habitat simulation and ecosystem approaches—necessarily involve significant use of risk assessment, professional judgment, and expert opinion. How can environmental flow methods and the underlying science be enhanced to shift away from expert advice and risk assessment toward more quantitative and predictive methods?

    The Natural Flow Regime Paradigm, the River Continuum Concept, the Flood Pulse Concept, and other hydroecological principles confirm that numerous hydroecological processes are common to unregulated rivers. However, these concepts do not provide immediately applicable quantitative models from which to predict how regulated rivers or any of their component...

  17. 14 ENVIRONMENTAL FLOW RELATIONSHIPS, MODELS, AND APPLICATIONS
    (pp. 199-212)

    Environmental flow assessment (EFA) and effective management require the capacity to predict the future ecological condition of a river ecosystem after its flow regime has been altered. Proactive (river protection) methods aim to predict ecological consequences after proposed dams are constructed and formerly “natural” flow regimes are changed in ways that reflect dam characteristics such as water storage and release procedures (see Chapter 11). Reactive (river restoration) methods aim to predict ecological outcomes after a regulated flow regime is restored to some degree, although flow manipulations are rarely expected to completely restore former pre-dam ecological characteristics (see Chapter 12). This...

  18. 15 GROUNDWATER-DEPENDENT ECOSYSTEMS AND THREATS
    (pp. 213-228)

    All water that occurs beneath the earth’s surface can be termed “subsurface” (or underground) water. Precipitation, flowing surface water, ice, wind, and tectonic forces create opportunities for surface water to penetrate into underground materials. This downward movement of water (termed “groundwater recharge” or “percolation”) through soils and the root zone of plants may continue until the water meets an impenetrable layer of clay, shale, rock, or other impervious or semiwatertight barrier, such as organically cemented sand. once such a barrier is encountered, subsurface water can accumulate and completely saturate the underground materials. The top of the saturated zone is known...

  19. 16 SUSTAINING GROUNDWATER-DEPENDENT ECOSYSTEMS
    (pp. 229-242)

    Providing water for the environment is more than just allocating water for the maintenance of surface water flows in rivers. It must also consider the water regimes that maintain terrestrial, riparian, wetland, and stygian (groundwater-inhabiting organisms) systems that require groundwater for their survival (Murray et al. 2003). The global literature on environmental flow methods for rivers has little to offer in relation to the integration of groundwater-dependent ecosystems into riverine assessments (Tharme 2003), even though many countries have committed to protecting the ecological integrity of both surface water and groundwater ecosystems. Although international literature on stream and river ecology has...

  20. 17 WETLANDS, THREATS, AND WATER REQUIREMENTS
    (pp. 243-258)

    Wetlands are areas where standing water covers the soil or is present at or near the surface of the soil for some part of the year (Mitsch and Gosselink 2007). Many different types have been recognized, their character depending on climatic and hydrogeomorphic setting, inundation regime, groundwater, water chemistry, and associated factors. The wetland classification scheme proposed by Cowardin et al. (1979) includes riverine, lacustrine, palustrine, and estuarine systems (Table 33). This classification recognizes a small number of essential criteria, namely shallow water, hydric soils, and specialized plant communities. Semeniuk and Semeniuk (1995) extended earlier work to provide a hydrogeomorphic...

  21. 18 ESTUARIES, THREATS, AND FLOW REQUIREMENTS
    (pp. 259-272)

    An estuary is a wide lower course of a river where the freshwater flow meets and is influenced by ocean tides, or it can be visualized as an arm of the sea extending inland to meet the mouth of a river (Maser and Sedell 1994). There are many definitions of estuaries. Fairbridge (1980) defines an estuary as “an inlet of the sea reaching into a river valley as far as the upper limit of tidal rise, usually being divisible into three sectors: (a) a marine or lower estuary, in free connection with the open ocean; (b) a middle estuary, subject...

  22. 19 SETTING LIMITS TO HYDROLOGIC ALTERATION
    (pp. 273-286)

    If indeed the world has now entered the Anthropocene—a new epoch where humans dominate the biosphere and largely determine environmental conditions (Zalasiewicz et al. 2008)—then humans hold the keys to future environmental quality and global prosperity. There is growing agreement that because the risks to freshwater resources and ecosystems are so enormous, a new vision and action agenda for freshwater management should rank foremost among global environmental priorities (Alcamo et al. 2008; Dudgeon 2010; Vörösmarty et al. 2010). Climate change intensifies the urgency of resolving the freshwater crisis because water is the key medium though which the consequences...

  23. 20 IMPLEMENTING AND MONITORING ENVIRONMENTAL FLOWS
    (pp. 287-298)

    Converting the recommendations from environmental flow assessments into management actions that produce the desired river flow regime has lagged behind the actual assessment process in most countries (Le Quesne et al. 2010). Two major forms of regulatory process may be involved in the provision of an environmental flow regime: restrictive and active (Acreman and Ferguson 2010). Restrictive methods involve setting water-abstraction limits (e.g., sustainable diversion limits, “caps” on further abstraction) that maintain a healthy river ecosystem, while active measures involve ecologically appropriate flow releases from reservoirs; there will often be some combination of the two. Both regulatory processes involve rules...

  24. 21 LEGISLATION AND POLICY
    (pp. 299-310)

    Intense interest in the concept and practice of environmental flows at national and international levels has generated significant debate about how to embed environmental water allocations into legislation, policy, and governance (Naiman et al. 2002; Dyson et al. 2003). The Brisbane Declaration (2007; see this book’s appendix) envisions that environmental flow assessment and management should be a basic requirement not only of integrated water resource management (IWRM) but also of environmental impact assessment (EIA); strategic environmental assessment (SEA); infrastructure and industrial development and certification; and land-use, water-use, and energy-production strategies. Consistent integration of environmental flows into land, water, and energy...

  25. 22 ADAPTING TO CLIMATE CHANGE
    (pp. 311-322)

    The decadal drought, floods, cyclones, and firestorms in Australia, flooding and mudslides in Brazil, volcanic activity in Indonesia, earthquakes in New Zealand and Japan, extensive intense snowfalls in North America—the list of catastrophic events goes on, bringing into sharp focus the dynamic nature of planet Earth. People are seeking explanations for what appears to be an increase in the incidence and violence of extreme weather events and their dreadful human and environmental consequences. What is driving them and what is the role of human activities? Opinions vary as to the relationship between such events and climate change and even whether Earth’s...

  26. APPENDIX: THE BRISBANE DECLARATION (2007)
    (pp. 323-328)
  27. LITERATURE CITED
    (pp. 329-382)
  28. INDEX
    (pp. 383-406)
  29. Back Matter
    (pp. 407-407)