Guidelines for use: Risk assessment and decision making framework for managing groundwater dependent ecosystems with declining water levels

Media type: 
Reports
Author/s: 
Jane Chambers
Gaia Nugent
Bea Sommer
Peter Speldewinde
Simon Neville
Stephen Beatty
Stacey Chilcott
Stefan Eberhard
and others
Institution/s: 
Murdoch University
Edith Cowan University
University of Western Australia
State: 
Western Australia
Year: 
2013

Executive summary

This document provides guidance on how to use a risk assessment and decision making framework (referred to hereafter as ‘the framework’) to manage groundwater dependent ecosystems (GDEs) with declining groundwater levels due to climate change, anthropogenic extraction, land use and land management. 

The framework integrates a standard risk assessment protocol enabling the approach to be easily transferred to sites within Australia and internationally. The framework is based around the construction of a conceptual model which identifies the interrelationships between climate, hydrology, water quality and/or biotic resources and the biota in an ecosystem. It is a problem solving framework that provides a transparent outline of the cause and effects of change to an ecosystem, highlighting key drivers that provide the focus for management and climate change adaptation. The framework is designed for declining water levels within the ecosystem, so it can readily be adapted to address surface water ecosystems by substituting, or adding, surface water inputs into the conceptual model. 

An example of a conceptual model designed for the Blackwood River groundwater intrusion zone, showing top down and bottom up management approaches. 

The document is in two parts. In Part 1) Identifying your Management Issue and the Nature of your Ecosystem we outline steps to identify the management issue of concern, determine if your ecosystem is groundwater dependent, construct a hydrogeological model that identifies the inputs and outputs of water in the GDE, determine the spatial boundaries of the system and prioritise assets within these boundaries. In Part 2) the Risk Assessment and Decision-Making Framework we outline how to incorporate information in a series of five steps that creates a model relevant to your ecosystem and management/adaptation needs.The five steps are:

Step 1: Identify the hazard  - the framework is designed to manage the hazard of declining groundwater levels. This step identifies the primary and secondary hazards and the cause of declining groundwater levels.

Step 2: Determine exposure and vulnerability - the magnitude and rate of groundwater decline is determined spatially and temporally (historically, currently and projected to the future). The dynamics of hydrological change, such as changes in seasonality and/or the number and frequency of dry periods, are also considered.

Step 3: Assess effects - a conceptual model of ecosystem function is developed describing the cause and effect interrelationships between climate, hydrology, water quality, required biotic resources and biotic response. The key drivers that cause ecosystem change are identified.

Step 4: Characterise risk – A number of techniques (expert opinion, using presence/absence data and statistical analysis) are described to determine the tolerance limits or thresholds of the key drivers that drive change in the biota. The conceptual model, with key drivers now quantified by thresholds, are now incorporated into Bayesian Belief Networks (BBNs) that can be easily modified to show changes in probability of risk resulting from these interactions. The outputs of the BBNs or other risk models can then be mapped spatially using geographic information systems (GIS).

Step 5: Manage risk - The use of a conceptual model provides the framework with a high degree of adaptability. The framework can be used to determine the effects of groundwater decline (whether through climate change, groundwater extraction, other cause, or a combination of these) on GDEs. This would be a top down approach using the conceptual model (Figure A) to test a number of scenarios of differing levels of groundwater decline. It can equally be used to determine the tolerance limits of GDEs or specific biota within them. This ‘bottom up’ approach would define the limits of unacceptable change that could inform management targets.

The framework was developed by a multidisciplinary team of ecologists, modellers and hydrogeologists in south-western Australia, a biodiversity hotspot that has already suffered three decades of below average rainfall and consequently declining groundwater levels due to increased groundwater abstraction and land use change. This has provided a ‘living experiment’ providing validation of the framework against observed changes (not just modeled projections). The combination of this research together with input from a suite of end-users, other scientists and experts from across Australia has provided a robust and adaptable framework.

Please cite this report as:
Chambers, J, Nugent, G, Sommer, B, Speldewinde, P, Neville, S, Beatty, S, Chilcott, S, Eberhard, S, Mitchell, N, D’Souza, F, Barron, O, McFarlane, D, Braimbridge, M, Robson, B, Close, P, Morgan, D, Pinder, A, Froend, R, Horwitz, P, Cook, B & Davies, P 2013, Adapting to climate change: A risk assessment and decision making framework for managing groundwater dependent ecosystems with declining water levels. Guidelines for use, National Climate Change Adaptation Research Facility, Gold Coast, 59 pp. 

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This photo is copyright © Blackwood River, Western Australia (Stephen Beatty, Murdoch University, Freshwater Fish group).

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