Environmental Flows PDF Print E-mail

Developing ecologically meaningful metrics to advance environmental flow ecology


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Project overview


Sustainable management of the world’s freshwaters to provide good quality water for the needs of expanding human populations (water for drinking, food production and electricity generation) without destroying other ecosystem services and values (including biodiversity support, microclimate regulation, carbon accrual and cultural, aesthetic, recreational and recreational amenity) represents a major global challenge in an era of increasing climatic uncertainty (Poff & Zimmerman 2010). In order to conserve future aquatic biodiversity, future management decisions must be made from a firm theoretical and practical understanding of the key drivers of biodiversity that can be actually levered by changes in management.

It is universally accepted that flow regimes underpin the biodiversity and ecological integrity of river systems across the globe (Bunn and Arthington 2002). As such, there is recognition that the management of environmental flow must incorporate a variable flow regime, not just a minimum low flow and that the timing frequency and quality are key (Poff et al, 2010) and flows should reflect the natural flow regime of a river in altered systems (Bunn and Arthington 2002). Human induced alteration of the natural flow regime is one of the major threats to freshwater ecosystems worldwide. In response to the challenge of moving environmental flow ecology forward, a framework for assessing the environmental flow needs of streams and rivers at the regional scale was developed, the ecological limits of hydrologic alteration (ELOHA) (Arthington et al., 2006; Poff et al. 2010). The framework recognises the central role of dynamic flow regimes in maintaining the ecological integrity of flowing water systems and acknowledges the major role that altered flow regimes, often accompanied by other environmental stressors, play in ecological degradation and loss of biodiversity (Bunn and Arthington 2002).

ELOHA is based on the premise that ‘increasing degrees of flow alteration from baseline condition are associated with increasing ecological change’ (Poff et al. 2010). Arthington et al (2006) suggests an initial step of classification of all sites based on some form of reference site hydrological data – to establish natural hydrological differences, the second step is to compare hydrological metrics between these groups, a third step involves exploring how these metrics have changed under hydrological alteration and finally the development of flow – ecosystem response relationships for both reference and flow-modified streams. The ELOHA framework (Poff et al. 2010) extended these ideas to formulate a similar process of hydrological classification, hydrological analysis and comparison of reference and flow-modified sites, and again the development of flow-ecology linkages is an integral step.

These approaches represent a positive way forward for environmental flow management, however, they are still challenging in that they aim to simplify the key relationships between specific flow metrics and the ecological response of aquatic biota. To date there is a general lack of evidence of quantifiable ecological response of biota to alterations of specific flow metrics as suggested in a literature review of 165 flow ecology case studies by Poff & Zimmerman (2010). Finding generalised relationships across varying river types and climatic zones is likely to be problematic due to the confounding nature of embedded environmental gradients across different ecotypes. This workshop aims to focus in on specific climatic zones and river types to investigate whether we can determine specific quantifiable ecological response relationships within different ecotypes and what then are the appropriate flow metrics and ecological response indictors that could be useful for managers. The ultimate aim is to be able to provide managers with the actual flow levers that can be applied to produce specific ecological outcomes for environmental flow management.

Arthington AH, Bunn SE, Poff NL & Naiman RJ (2006) The challenge of providing environmental flow rules to sustain river ecosystems. Ecological Applications 16, 377-395.

Bunn SE & Arthington AH (2002) Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity. Environmental Management 30, 492-507.

Poff NL & Zimmerman JK (2010) Ecological response to altered flow regimes: a literature review to inform the science and management of environmental flows. Freshwater Biology 55, 194-205

Poff NL, Richter BD, Arthington AH, Bunn SE, Naiman RJ, Kendy E, Acreman M, Apse C, B. Bledsoe BP, Freeman MC, Henriksen J, Jacobson RB, Kennen JG, Merritt DM, O'Keeffe JH, Olden JD, Rogers KR. Tharme RE & Warner A (2010). The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards. Freshwater Biology 55, 147-170.


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Harry Balcombe sampling at Moonie.


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Wivenhoe Dam


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Products and outcomes


Final report


Developing ecologically meaningful metrics to advance environmental flow ecology
FINAL REPORT available for download

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Workshop Report (7-9 August 2012)

The provision of water to rivers is vital for the continuance of healthy ecosystems and strong rural economies, and has therefore become a hot political issue and key research area. In August 2012, seventeen invited participants met through ACEAS’s targeted workshops program on beautiful North Stradbroke Island in Queensland to discuss important aspects of environmental flow ecology. The workshop attendees were from both the university and government worlds, thus covering research and management, and come from five Australian states (NSW, NT, QLD, TAS, VIC), as well as South Africa and New Zealand.

The aim of this workshop was to draw knowledge from cross-disciplinary scientists with varied backgrounds to examine whether there are identifiable metrics to assess the success of environmental flows, the ultimate aim of which is to restore or conserve the ecology of river systems. The success of any an environmental flow will be determined in part by exactly what aspects of the flow regime needs to be manipulated and what the predicted response of the target biota will be. At present there is a little evidence of quantifiable flow ecology-biotic response relationships that can be generalised across river systems (climatic zones, river types), as well as the actual relevant flow metrics and biotic indicators that can be measured. These difficulties have been compounded by environmental flow programs that require the grouping of many river types and climatic regimes into smaller sets of flow classes to simplify complex relationships between flow ecology and biotic response.

The group aimed to summarise flow-ecology relationships and to identify any universal relationships/flow metrics, as well as to summarise the statistical methods that underlie these relationships, so as to outline the challenges for development of flow-ecology relationships and a more rigorous scientific basis for environmental flow management.

The workshop was structured around group discussions of background readings and presentations by participants, followed by discussions and synthesis in key focus groups to further explore specific sections for the intended manuscript.

There was a general recognition that there are a number of confounding factors inhibiting our ability to find evidence for a suite of biota and flow metrics that could be widely applied across regions or river types. The main confounding factor was the influence of differing multiple stressors (e.g. catchment land use, alien species) across most regions and rivers.

The group developed a conceptual framework that covered what may influence the likelihood of ecological success from provision of environmental flows in multiple-stressor contexts, and then identified four categories of river settings and examples of environmental flow programs that are suited to these categories based upon our conceptual framework.

We outlined some monitoring designs with appropriate indicators that are likely to detect measureable responses to environmental flows (i.e. cost-effectiveness) within multiple-stressor contexts, and outlined the management utility of our framework.

Our work has identified knowledge gaps and research priorities to advance the science, monitoring and decision-making surrounding environmental flows in multiple-stressor contexts, and our findings are currently being worked into two manuscripts.

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Environmental Flows Workshop 1
Attendees: Back (left to right): Tim Page (Griffith University), Robyn Watts (Charles Sturt Uni), Justin Costello (Uni of Melbourne), Mark Kennard (Griffith University), Alison King (Charles Darwin University), Leah Beesley (Dept of Sustainability and Environment, Vic), Nick Bond (Griffith University) Jon Olley (Griffith University).
Front (left to right): Barbara Downes (University of Melbourne), Angela Arthington (Griffith University), Jay O’Keefe (Rhodes University), Stephen Balcombe (Griffith University), Scott Hardie (Dept of Primary Industries, Parks, Water and Environment, Tas), Stuart Bunn (Griffith University), Christoph Matthaei (Otago University), Danielle Warfe (Uni of Western Australia), Paul Reich (Department of Sustainability and Environment, Vic).


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Developing ecologically meaningful metrics to advance environmental flow ecology
FINAL REPORT available for download

Last Updated on Sunday, 08 February 2015 15:45