ELOHA in north Australia
ELOHA in north Australia
ELOHA (Ecological Limits of Hydrological Alteration; http://conserveonline.org/workspaces/eloha) is a framework developed by a group of ecologists and water managers to provide a way forward in water resource management in recognition that the pace and intensity of flow alteration in the world's rivers greatly exceeds the ability of scientists to assess the effects of a river by river basis.
None-the-less, existing studies examining the effects of flow regulation offers the opportunity to synthesis the knowledge and experience gained from such studies into a framework that can guide the development of environmental water standards. According to the developers of the ELOHA framework, it provides “ a logical approach that flexibly allows scientists, water resource managers and other stakeholders to analyse and synthesise available scientific information into a coherent, ecologically based and socially acceptable goals and standards for the management of environmental flows” (Poff et al. 2010).
The foundation of the ELOHA approach is based on five general advances in understanding the impacts of water resource development and the way in which management is applied.
- Ecological and evolutionary processes in river ecosystems are heavily influenced by many facets of the historical flow regime (see Poff et al. 1997 – the Natural Flow regime)
- The development of environmental flow methods and ecologically relevant metrics and techniques for quantifying flow and ecological alteration provide a rich toolbox for environmental water science.
- Conceptual frameworks now exist that allow regional environmental flow assessments. By classifying rivers according to meaningful streamflow characteristics, groups of similar rivers can be identified and the range of natural variation in flow regime and ecological characteristics can be identified.
- Hydrologic modelling is now sufficiently advanced to describe stream flow in ecologically relevant ways, to predict streamflow characteristics in ungauged streams and to determine the extent of change from natural wrought by human activities.
- Contemporary scientific understanding of environmental water management recognises the complex coupling of social and ecological systems, which requires collaboration between scientists, managers and other stakeholders to define goals and outcomes that are practicable and socially desirable and acceptable. It further recognises that there is a great deal of uncertainty about the way in which rivers respond to management actions and that monitoring within an adaptive management and learning cycle is needed.
- Poff, N.L., et al. The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards. Freshwater Biology 55, 147-170 (2010).
- Poff, N.L., et al. The natural flow regime: a paradigm for river conservation and restoration. . BioScience 47, 769–784. (1997).
ELOHA framework: as described by Poff, et al 1997. The diagram provides a useful reference for examing the relationship between various water management data and tools.
ELOHA in context
The ELOHA framework consists of a number of steps, feedbacks (through monitoring) and iterations (see figure).
It is broken down into two main processes: the first (scientific) associated with defining the relationship between flow regime and ecology applicable at broad regional scales; and the second (social) concerned with how societal needs and values are accommodated within environmental water management guidelines and with the processes by which scientific information is translated into management guidelines.
These are not separate and independent processes but are linked by feedback relationships loosely termed “monitoring”. See FARWH Report (http://www.track.org.au/publications/registry/941) and Management Strategy Evaluation (MSE) approach (http://www.track.org.au/synthesis-adoption/decision-support).
In the material that follows, we describe the various steps in the ELOHA framework with reference to the northern Australian situation and provide links to resource material relevant to that aspect of the framework.
Environmental water terminology
- A top down environmental water assessment method used in Queensland in which ecological condition is assessed against known deviations from the natural or pre-development flow regime whilst also taking into account the impacts of water infrastructure on ecological condition.
- Bottom–up methods
- Reconstructing an altered flow regime by sequentially adding water needed for specific functions i.e. adding a flushing flow designed to move refine sediment or a maintenance flow designed to provide a minimum amount of wetted area.
- Cultural flows
- Water required to meet the cultural and spiritual needs of Indigenous people. Environmental flows A term that supplanted the term instream flows in recognition that water was needed for more than just the maintenance of habitat quality and quality. Water is needed to provide cues for biota to move and to reproduce, to provide areas for food production, for refuge from temperature extremes, for maintenance of channel form and substrate composition, to create and maintain new habitats such as floodplains and tributaries, and many other needs.
- Environmental water
- A term that supplants the term environmental flows in recognition that flowing water is not the only water critical to the maintenance of ecosystem function. Hyporheic water (water held under the stream bed) and groundwater are also critical compartments of environmental water and groundwater dependent aquatic habitats may never be connected to the riverine environment.
- Holistic flow management
- A conceptual framework first described in 1992 in which water needs are considered more broadly than just those relating to in-stream or in-channel needs e.g. estuaries and the near shore marine environment are dependent on freshwater inputs as are riparian forests and off-channel wetlands.
- Hyporheic water
- (water held under the stream bed) and groundwater are also critical compartments of environmental water and groundwater dependent aquatic habitats may never be connected to the riverine environment.
- Instream flow incremental methodology: a computer driven means of assessing changes in in-channel habitat quantity and quality.
- Instream flows
- The original term for environmental flow management, principally concerned with the maintenance of habitat quantity and quality defined by depth, water velocity and substrate composition. Typically, instream flow investigations of were undertaken at small spatial scales – i.e. at the reach scale.
- Top-down methods
- Environmental water assessment methods in which occurs the simulated sequential removal of volumes of water until an impact of nominated severity occurs, thus defining the limit below which this aspect of the flow regime can be altered.