Holistic methodologies currently represent around 8 percent of the global total, with at least 16 extant methodologies based on the holistic principles described above having been developed over the last ten years Tharme Although predominantly developed and used in South Africa and Australia, recently such methods have begun to attract growing international interest in both developed and developing regions of the world, with strong expressions of interest from in excess of 12 countries in Europe, Latin America, Asia and Africa Tharme These approaches have been described see Arthington et al.
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For comparative purposes, selected holistic methodologies are summarised in Table 1, in terms of their origins, key features, strengths, limitations and present stage of development and application adapted from Tharme Further details of the various methodologies are available in the source references provided in Table 1, as well as in the review papers listed herein. Examples of top-down methods are the Benchmarking Methodology Brizga et al. These methodologies make such predictions in different ways, as outlined in Table 1 and the background literature cited for each method therein.
The Flow Restoration Methodology Arthington et al. The Flow Events Method Stewardson and Cottingham seems to be a rather similar approach, usually linked to a scientific panel method Table 1.
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Summary of holistic environmental flow methodologies presented in approximate sequence of development, highlighting salient features, strengths and limitations, as well as their current status in terms of development and application adapted from Tharme Further information on the strengths and deficiencies of individual holistic methodologies is provided in Tharme ; Arthington ; Cottingham et al.
Represents conceptual and theoretical basis of most other holistic EFMs; developed and applied in various forms in Australia, e. Developed in South Africa by local researchers and DWAF, through application in numerous water resource development projects to address EFRs for entire riverine ecosystems under conditions of variable resources; adapted for intermediate and comprehensive determinations of the ecological Reserve under the new SA Water Law.
Bottom-up, reconnaissance-level approach for initial assessment of proposed WRDs with many conceptual features and methodological procedures in common with the Holistic Approach and BBM; rapid and inexpensive, with limited field data collection; site-specific focus; applicable primarily for sites where dam releases are possible; relies on field-based ecological interpretation, by a panel of experts, of different multiple trial flow releases ranked in terms of scored ecological suitability from dams, at one or a few sites, to determine EFR typically expressed as flow percentiles ; low resource intensity; limited resolution of EF output; aims to address river ecosystem health using fish communities as indicators , rather than to assess multiple ecosystem components; strongly reliant on professional judgement; limited subset of expertise represented by panel e.
Bottom-up field multiple sites and desktop approach appropriate for provision of interim or intermediate level EFAs with many conceptual features and methodological procedures in common with the Holistic Approach and BBM; evolved from EPAM as more sophisticated and transparent expert-panel approach; aims to determine a modified flow regime that will maintain ecosystem health; differs from EPAM in that key features of the ecosystem and hydrological regime and their interactions at multiple sites are used as basis for EFA; EFR process includes: Appears limited to a single application in Australia in its original form; general approach variously modified for other expert-panel based EFAs.
Relatively rapid, inexpensive, basin-wide reconnaissance method for determining preliminary EFRs at multiple points in catchment rather than at a few critical sites ; superior to simple hydrological EFMs, but inadequate for comprehensive EFAs; field data limited or absent; bottom-up process of 4 stages using TAP: Developed in Queensland, Australia, by local researchers and DNR, to provide a framework for assessing risk of environmental impacts due to WRDs, at basin scale.
Rigorous and comprehensive, scenario-based, top-down approach for application at basin scale; using field and desktop data for multiple river sites; same conceptual basis as BBM and Holistic Approach, EFM has 4 main stages: Sole holistic EFM for basin-scale assessment and assessing risk of environmental impacts due to WRD; adopted for routine application in Queensland with applications in 15 basins; under consideration for use in Western Australia; only applied in Australia to date.
Developed in South Africa by the Institute for Water Research, for use for intensively regulated river systems. Simplified bottom-up approach, applicable in highly regulated and managed systems with considerable operational limitations; considered for use within South Africa Reserve determination process only where BBM or equivalent approach cannot be followed; workshop-based, multidisciplinary assessment including ecologists and system operators; 3-step process: Limited to 3 applications; only used in South Africa to date; uncertain status within the national Reserve framework.
Relatively limited application to date; general approach appears to have been extended to other EFA studies in the UK. Developed in southern Africa by Southern Waters and Metsi Consultants with inputs from Australian and southern African researchers as an interactive scenario-based holistic EFM with explicit socio-economic component. Rigorous and well-documented top-down, scenario-based process with interactive scenario development; same conceptual basis as BBM and Holistic Approach; appropriate for comprehensive EFAs years based on several sites within representative and critical river reaches; comprised of 4 modules: EFM with most developed capabilities for scenario analysis and explicit consideration of social and economic effects of changing river condition on subsistence users; limited application to date, within southern Africa.
Developed in a study of the Brisbane River, Queensland, Australia, specifically addressing EFRs in river systems exhibiting a long history of flow regulation and requiring flow restoration. Primarily bottom-up, field and desktop approach appropriate for comprehensive or intermediate EFAs; EFM represents hybrid of Holistic Approach and BBM; designed for use in intensively regulated rivers with emphasis on identification of the essential features that need to be built back into the hydrological regime to shift the regulated river system towards the pre-regulation state; EFM uses an step process in 2 stages, in which the following are achieved: Ord River study, Western Australia.
Top-down method for regulated rivers; considers the maximum change in river hydrology from natural or key ecologically relevant flow events, based on empirical data or expert judgement; considered a method of integrating existing analytical techniques and expert opinion to identify important aspects of the flow regime; EFM comprises 4 steps: Recent approach with few applications in Australia to date; often linked to expert-panel approaches. Additional holistic methodologies developed and applied elsewhere include the River Babingley Method Petts et al. In applications of holistic methodologies to date, the focus has almost entirely been on river systems, with most effort addressed to the main river channel and its tributaries and it is only relatively recently that specialist methods have been proposed to address the freshwater flow requirements of downstream receiving waterbodies e.
Loneragan and Bunn Further, methodologies to integrate the dynamic interactions of surface and groundwater systems into existing holistic methodologies are at a fairly immature stage of development, with none routinely applied as part of holistic assessments King et al. In a review of the use and utility of Australian expert panel methods, Cottingham et al. Their shortcomings are judged to fall into two categories: To offset these shortcomings, Cottingham et al. Clear processes for selecting panel members and protocols to guide the conduct of panels and the interactions between members;.
Guidelines for developing a "vision statement" and explicit ecological objectives, so that any ecosystem response to environmental flow provisions can be measured against the desired outcomes in an adaptive management framework;. More explicit guidelines regarding the selection of field sites and the collection of new field data;. Procedures for recording the strengths and limitations of evidence used to make environmental flow recommendations;.
An opportunity to make recommendations on the additional information required to support or improve decisions relating to water management and particularly, to strengthen the scientific basis of environmental flow assessments. It is worth noting that a "Best Practice Framework" see Figure 1 for the conduct of holistic environmental flow assessments is already available in Australia Arthington et al.
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In the following sections of this paper, we show how the more sophisticated and structured holistic methodologies share common features that address the best practices recommended above points and the common and additional features proposed by Arthington et al. We focus particularly on the BBM, DRIFT and the Benchmarking and Flow Restoration methodologies, as these represent the most recent developments in holistic methodologies familiar to us and were not included in the appraisal of Cottingham et al.
Best Practice Framework for assessing environmental flows in regulated and unregulated river systems from Arthington et al. Guidelines for selecting scientific or technical panel members were established as part of the BBM King et al. Each assessment using the BBM, DRIFT, Benchmarking and Flow Restoration methodologies involves one or more scientists in the fields of hydrology and occasionally, geohydrology , hydraulics, geomorphology, water quality and aquatic ecology algae and aquatic plants, riparian vegetation, invertebrates, fish, and wildlife and occasionally, estuarine ecology.
The roles, responsibilities and interactions of panel members during EFA studies and associated workshops are governed by the particular step-by-step procedures built into each methodology. These procedures generally circumvent outright dominance of workshops and discussions by any one member of the team.
Each member has equal opportunity to contribute as fully as they wish and it is usually not possible for any one member to dominate the workshops or bias the outcomes of the evaluations of environmental flow evaluations. Furthermore, workshops forming part of the BBM, DRIFT, Benchmarking and Flow Restoration methodologies are structured and facilitated in such a way that there are frequent comparisons of results and EFA evaluations and results among the participating scientists.
If such issues can be identified early in the workshop process, they can usually be resolved before any consistent patterns of bias affect the entire EFA process. Sensitivity analysis can also be used to identify the influence of particular components of the overall outcome of an EFA. The BBM, DRIFT, Benchmarking and Flow Restoration methodologies all address clear working objectives established as part of the study design, and formalized in design and the contracts signed between the client and each scientific or technical panel member.
One or more shared, broad river visions desired future states in the BBM may be established, or several more common water resource development or flow restoration objectives may be set, and EFAs evaluated to achieve these objectives. The common practice is to evaluate the ecological consequences of several well-defined scenarios of change in flow regime either flow reductions, or degrees of flow restoration.
Hydrological statistics generally related to flow quantity, timing, duration, frequency of floods and low flow spells, rates of change e. In contrast, the site selection procedures of the BBM, DRIFT, Flow Restoration and Benchmarking methodologies have a sound, well-documented rationale and they all offer an explicit and transparent framework and methods, for evaluating the ecological implications of many alternative flow scenarios.
A range of quantitative procedures can be applied within any of these methodologies to relate flow changes to ecological responses e. The Benchmarking Methodology, in contrast, relies heavily on the interpretation of data from past field studies, the literature and professional judgement rather than new field studies to relate the ecological condition of fish communities to the level and type of flow modification Brizga et al.
The DRIFT methodology includes an explicit process for evaluating the social consequences of each flow scenario stemming from earlier, less clearly defined procedures applied within the BBM King et al.
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In that study, costs were represented in terms of water yields foregone from a large storage reservoir if particular environmental flow scenarios were to be implemented Arthington et al. The BBM, DRIFT, Flow Restoration and Benchmarking methodologies all produce comprehensive literature reviews and data reports describing the study area and its ecological systems, EFA methods, results and recommendations, thereby providing major reference documents and benchmarks upon which to base the planning and design of any river restoration activities and future assessments or post-implementation monitoring of river condition.
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The collation of historic information and preparation of a sequence of refereed reports is a fundamental aspect of the Best Practice Framework Arthington et al. These principles and rigorous monitoring protocols are built into most other holistic methodologies see Table 1 and the Best Practice Framework Figure 1. For example, all components of DRIFT include a detailed rationale and protocol for monitoring the geomorphological or ecological outcomes of environmental flow allocations and water management scenarios King et al.
With regard to the application of DRIFT in Lesotho rivers, the predictions of fish responses to each environmental flow scenario have formed the basis of hypotheses for testing by monitoring and longer-term research J. Benchmarking Methodology reports always include a section describing key knowledge gaps and research priorities for the catchment under study and the Flow Restoration Methodology devotes a chapter to research and monitoring requirements.
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In considering the recommendations of Cottingham et al. Even so, all such methodologies can be enhanced in many ways and in the next section of this paper we discuss opportunities for the further development of this type of approach to EFAs, particularly in relation to the methods and models used to predict the ecological consequences of flow regime change. These are Level 1: EFA assessments based on detailed studies and predictive flow-ecology models. Clearly, holistic methodologies can be enhanced by integrating modelled responses of river ecosystems to flow change, be it regulation or restoration, that is, by moving towards Level 3 of the EFA hierarchy outlined above.
At this level of resolution, environmental water requirements would be defined and alternative water resource developments or restoration scenarios evaluated, by means of quantitative predictive models describing relationships between hydrology and the flow-related ecological processes governing biological diversity and river ecosystem integrity Arthington et al. Quantitative models that describe associations between flow and geomorphological or ecological parameters are available for some ecosystem components see Arthington and Zalucki and literature cited therein.
For example, hydraulic geometry models can be used to provide an indication of the likely net change in channel dimensions resulting from flow regime change Brizga et al. Sediment transport models can provide an indication of the likely implications of flow regime change for sediment processes. Wetland and riparian water budget analyses have proved useful in environmental flow studies designed to restore regulated stream ecosystems e.
Pettit, Froend and Davies It is useful to briefly review existing techniques and models that predict the responses of fish to changes in river flow regime and the extent of their application in EFAs and river flow management in general. Hydraulic rating and habitat simulation methods and modelling packages e. Hill, Platts and Beschta developed a method linking the timing and magnitude of the low and high flow attributes of annual flow hydrographs to instream and out of channel physical habitat availability and suitability for fish.
In a more ambitious program of studies, Williamson, Bartholow and Stalnaker developed a conceptual framework and a suite of interactive mathematical models of salmon production SALMOD simulating the dynamics of resident and anadromous freshwater populations.