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Environmental Flow Assessment: Methods and Applications

Environmental Flow Assessment: Methods and Applications

John G. Williams (Editor), G. Mathias Kondolf (Editor), Peter B. Moyle (Editor)

ISBN: 978-1-119-21738-1

Apr 2019, Wiley-Blackwell

240 pages


Product not available for purchase


Provides critiques of current practices for environmental flow assessment and shows how they can be improved, using case studies. 

In Environmental Flow Assessment: Methods and Applications, four leading experts critique methods used to manage flows in regulated streams and rivers to balance environmental (instream) and out-of-stream uses of water. Intended for managers as well as practitioners, the book dissects the shortcomings of commonly used approaches, and offers practical advice for selecting and implementing better ones. 

The authors argue that methods for environmental flow assessment (EFA) can be defensible as well as practicable only if they squarely address uncertainty, and provide guidance for doing so. Introductory chapters describe the scientific and social reasons that EFA is hard, and provide a brief history. Because management of regulated streams starts with understanding freshwater ecosystems, Environmental Flow Assessment: Methods and Applications includes chapters on flow and organisms in streams. The following chapters assess standard and emerging methods, how they should be tested, and how they should (or should not) be applied. The book concludes with practical recommendations for implementing environmental flow assessment.

  • Describes historical and recent trends in environmental flow assessment
  • Directly addresses practical difficulties with applying a scientifically informed approach in contentious circumstances
  • Serves as an effective introduction to the relevant literature, with many references to articles in related scientific fields
  • Pays close attention to statistical issues such as sampling, estimation of statistical uncertainty, and model selection
  • Includes recommendations for methods and approaches
  • Examines how methods have been tested in the past and shows how they should be tested today and in the future

Environmental Flow Assessment: Methods and Applications is an excellent book for biologists and specialists in allied fields such as engineering, ecology, fluvial geomorphology, environmental planning, landscape architecture, along with river managers and decision makers.

About the Editors

Series Foreword


1 An introduction to environmental flows


What are environmental flows

Why EFA Is So Hard; Scientific Issues

Stream ecosystems are dynamic and open

Fish evolve

Streams adjust

Climate changes

Populations vary

Habitat selection is conditional

Spatial and temporal scales matter

Why EFA is So Hard: Social Issues

Social objectives evolve

Science and dispute resolution

Water is valuable

Managers or clients often want the impossible

Why is EFA so hard: problems with the literature

Why is EFA so hard: limitations of models and objective methods

Models and environmental flow assessment

Objective and subjective methods


2 A brief history of environmental flow assessment



The legal basis for environmental flow

The scope of environmental flow assessments

Methods for setting environmental flows


3 A Primer on Flow in Rivers and Streams



Precipitation and runoff

Flow regimes

Describing or depicting flow regimes

Variation in flow regimes across climates and regions

Anthropogenic changes in flow regimes

Hydrologic classifications

Spatial patterns and variability within streams

Spatial complexity of flow within stream channels

The variety of channel forms

Lateral connectivity with floodplain and off-channel water bodies

Bed topography and hyporheic exchange

Managing environmental flows


4 Life in and around streams



Structure of stream ecosystems

Across-channel gradients

Upstream-downstream gradient

Adaptations of stream organisms

Morphological Adaptations

Physiological adaptations

Behavioral adaptations

Adapting to extreme flows.


Environmental flows and fish assemblages


5 Tools for environmental flow assessment



Descriptive tools

Graphical tools and images

Stream Classifications

Habitat classifications

Species classifications

Methods classifications

Literature reviews


Flow experiments

Laboratory experiments

Thought experiments

Professional opinion

Causal criteria



Sampling methods

Hypothesis testing

Model selection and averaging

Resampling algorithms


Environment‐abundance relations

Habitat association models

Drift–foraging models

Capability models

Bayesian networks

Hierarchical Bayesian models

Dynamic occupancy models

State‐dependent life‐history models and dynamic energy budget models

Hydraulic models

Hydrological models

Temperature models

Sediment transport models

Other uses of models in EFA

Hydraulic habitat indies

Hydrological indices


6 Environmental flow methods



Hydrologic, habitat rating, habitat simulation, and holistic methods

Top–down and bottom–up approaches

Sample–based methods and whole system methods

Standard–setting and incremental approaches

Micro–, meso–, and river–scale methods

Opinion–based and model–based methods

Hydrological methods

The Tennant Method and its relatives

Indicators of Hydraulic Alteration (IHA)

Hydraulic rating methods

Habitat simulation methods

Habitat Association Models

Bioenergetic or drift foraging models

Frameworks for EFA

Instream Flow Incremental Methodology (IFIM)

Downstream response to imposed flow transformation (DRIFT)

Ecological limits of hydraulic alteration (ELOHA)

Adaptive management


7 Good modeling practice for EFA



Modeling practice

What are the purposes of the modeling?

How should you think about the natural system being assessed?

How will the available budget be distributed over modeling efforts, or between modeling and data collection, or between the assessment and subsequent monitoring?

How will the uncertainty in the results of the modeling be estimated and communicated?

How will the model and model development be documented?

How will the models be tested?

How good is good enough to be useful?

Who will use the results of the modeling, and how will they be used?

Do you really need a model?

Behavioral issues in modeling for EFA

Data-dependent activities in developing models


General Considerations

Spatial scale issues in sampling

Cleaning data sets

On testing models

The purpose of testing models

Why testing models can be hard

The problem with validation

The limited utility of significance tests

Tests should depend on the nature of the method being applied

Models should be tested multiple ways

The importance of plausibility

The importance of testing models with independent data

The quality of the data limits the quality of the tests

The importance of replication

Models should be tested against other models

Experimental tests of models

Flow experiments

Behavioral carrying capacity tests

Virtual ecosystem experiments

Testing models with knowledge

Testing hydraulic models

Testing EFMs based on projessional judgement

Testing species distribution models

Goodness of fit


Imperfect detection

Spatial scale and other complications


8 Dams and Channel Morphology



Diagnosing the problem and setting objectives

Managing sediment load

Existing dams

Proposed dams

Obsolete dams

Specifying morphogenic flows

Three common approaches to setting morphogenic flows

Clear objectives needed



The hydrograph



Flows for managing vegetation in channels


Minimizing cost of foregone power production and other uses of water

Preserving spawning gravels

Preventing flooding and bank erosion


9 Improving the use of existing evidence and expert opinion in environmental flow assessments



Overview of proposed method

Basic principles and background to steps

Literature as a basis of an evidence-based conceptual model

Translate the conceptual model into the structure of a Bayesian Belief Network

Quantify causal relationships in the BBN using formal expert elicitation

Update causal relationships using empirical data

Case study: golden perch (Macquaria ambigua) in the regulated Goulburn River, south-eastern Australia

Evidence based conceptual model of golden perch responses to flow variation

Bayesian Belief Network structure of the golden perch model

Expert-based quantification of effects of flow and non-flow drivers on golden perch

Inclusion of monitoring data to update the golden perch BBN


Hierarchical Bayesian methods as best-practice

Piggy-backing on existing knowledge

Resourcing improved practice

Accessibility of methods


10 Summary conclusions and recommendations

Conclusions and recommendations

A checklist for EFA