10 th ISE 2014, Trondheim, Norway PREDICTING ECOLOGICAL RESPONSES TO ENVIRONMENTAL FLOWS: A REVEW IN HINDSIGHT OF A NOVEL APPROACH TO SYNTHESIZE LITERATURE EVIDENCE, EXPERT OPINION AND MONITORING DATA J. ANGUS WEBB Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia MICHAEL J. STEWARDSON Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia KIMBERLY A. MILLER Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia SIOBHAN C. DE LITTLE Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia In a world of increasing water scarcity, environmental flows programs need to be underpinned by robust quantitative predictions of the ecological benefits expected to result from returning water to the environment. However, many environmental flow recommendations have been qualitative and based upon expert opinion. We developed a process designed to make maximal use of all the information that can be brought to bear on the problem of modelling ecological responses to flow variation. It employs literature analysis, expert elicitation, and Bayesian hierarchical analysis of data from purpose-built monitoring programs. The process has been implemented through research associated with the Victorian Environmental Flows Monitoring and Assessment Program, in the Australian state of Victoria. While proving very successful in the derivation of general flow- response relationships that can be used in future to predict the ecological benefits of environmental flows programs, we encountered unforeseen difficulties with implementing the process within a science-management partnership. Our experience may assist future users to implement similar approaches successfully elsewhere in the world. 1 INTRODUCTION Governments around the world are developing policies to return water to regulated rivers in the form of environmental flows [1], and huge sums of public money are being invested in implementation [2]. Environmental flows programs can be controversial when they divert water from consumptive (e.g. agricultural) to environmental uses amid uncertain predictions of the likely ecological benefits [3]. Such controversy is exacerbated because predictions of ecological benefits of environmental flows are usually qualitative [e.g. 4], and based upon expert opinion rather than empirically-based quantitative models [5]. Such predictions have been necessary because, while case studies on the ecological effects of flow alteration are common [6], they are mostly conducted over short time periods and small spatial scales [7]. Attempts to synthesize multiple case studies to derive general flow-response relationships have been unsuccessful [8]. If environmental flows are to move into an era of evidence-based management, then new approaches are required. In earlier research, we provided an overview of a monitoring and evaluation process being used in study of the ecological effects of environmental flows in the Australian state of Victoria [9]. The framework makes best use of all the information that can be used in the derivation of general flow-response models (Figure 1). It uses systematic review of the rapidly-expanding literature to derive evidence-based conceptual models. The links in these conceptual models are then initially quantified using expert elicitation as a robust means of employing expert opinion. After this, data from a purpose-designed, large-scale monitoring program are combined with these expert quantifications using Bayesian hierarchical statistical analysis of process-based numerical models. The approach relies on strong partnerships between researchers and managers to design monitoring programs, collect and collate the data, and to synthesize the results. In this paper, we look back at the first major application of this approach, providing indications of where it was most successful, where it was weak, and where improvements could be made. Overall, we found that a strong basis in the literature, use of expert opinions to provide prior estimates, and the use of hierarchical models
Transcript
10th ISE 2014, Trondheim, Norway
PREDICTING ECOLOGICAL RESPONSES TO ENVIRONMENTAL FLOWS: A REVEW IN HINDSIGHT OF A NOVEL APPROACH TO SYNTHESIZE
LITERATURE EVIDENCE, EXPERT OPINION AND MONITORING DATA
J. ANGUS WEBB Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
MICHAEL J. STEWARDSON
Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
KIMBERLY A. MILLER Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
SIOBHAN C. DE LITTLE
Department of Infrastructure Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia
In a world of increasing water scarcity, environmental flows programs need to be underpinned by robust quantitative predictions of the ecological benefits expected to result from returning water to the environment. However, many environmental flow recommendations have been qualitative and based upon expert opinion. We developed a process designed to make maximal use of all the information that can be brought to bear on the problem of modelling ecological responses to flow variation. It employs literature analysis, expert elicitation, and Bayesian hierarchical analysis of data from purpose-built monitoring programs. The process has been implemented through research associated with the Victorian Environmental Flows Monitoring and Assessment Program, in the Australian state of Victoria. While proving very successful in the derivation of general flow-response relationships that can be used in future to predict the ecological benefits of environmental flows programs, we encountered unforeseen difficulties with implementing the process within a science-management partnership. Our experience may assist future users to implement similar approaches successfully elsewhere in the world.
1 INTRODUCTION
Governments around the world are developing policies to return water to regulated rivers in the form of environmental flows [1], and huge sums of public money are being invested in implementation [2]. Environmental flows programs can be controversial when they divert water from consumptive (e.g. agricultural) to environmental uses amid uncertain predictions of the likely ecological benefits [3].
Such controversy is exacerbated because predictions of ecological benefits of environmental flows are usually qualitative [e.g. 4], and based upon expert opinion rather than empirically-based quantitative models [5]. Such predictions have been necessary because, while case studies on the ecological effects of flow alteration are common [6], they are mostly conducted over short time periods and small spatial scales [7]. Attempts to synthesize multiple case studies to derive general flow-response relationships have been unsuccessful [8]. If environmental flows are to move into an era of evidence-based management, then new approaches are required.
In earlier research, we provided an overview of a monitoring and evaluation process being used in study of the ecological effects of environmental flows in the Australian state of Victoria [9]. The framework makes best use of all the information that can be used in the derivation of general flow-response models (Figure 1). It uses systematic review of the rapidly-expanding literature to derive evidence-based conceptual models. The links in these conceptual models are then initially quantified using expert elicitation as a robust means of employing expert opinion. After this, data from a purpose-designed, large-scale monitoring program are combined with these expert quantifications using Bayesian hierarchical statistical analysis of process-based numerical models. The approach relies on strong partnerships between researchers and managers to design monitoring programs, collect and collate the data, and to synthesize the results.
In this paper, we look back at the first major application of this approach, providing indications of where it was most successful, where it was weak, and where improvements could be made. Overall, we found that a strong basis in the literature, use of expert opinions to provide prior estimates, and the use of hierarchical models
for analyzing data from a large-scale coordinated monitoring program, all contributed to the strength of the resulting predictive models. However, several issues arose during the project that were not foreseen at its inception. We feel that the approach has been successful, but we learned much during the process. These lessons will assist future users to implement similar approaches successfully elsewhere in the world.
2 APPLICATION
The monitoring and evaluation process was developed and applied through the Victorian Environmental Flows Monitoring and Assessment Program (VEFMAP) and associated research funded by the Australian Research Council. VEFMAP is an ongoing partnership between researchers from the University of Melbourne , state-level environmental managers from the Victorian Department of Environment and Primary Industries (DEPI), five Catchment Management Authorities (CMAs) responsible for managing the target rivers, and environmental consultants at Sinclair Knight Merz (SKM). The core aim of the program was to greatly improve the power of monitoring to detect beneficial effects of environmental flows compared with previous efforts [7, 10]. The program was first envisaged in 2005 [11]. Monitoring began in 2008 and has been continuing since. Analysis of the data began in 2012 [9]. The structure of VEFMAP means that there is a multitude of interacting partners (Figure 2), necessitating effective lines of communication to make the program work.
3 SELF-ASSESSMENT
Several strengths and weaknesses of the framework have become apparent over the years we have been using it. Here, we highlight several of these, and discuss possible approaches to addressing the weaknesses.
3.1 Strengths
Most importantly, the framework make use of all the information that is available for quantifying ecological responses to change in flow regime – from the literature, the experience of domain experts, and from the monitoring data. By basing statistical analyses on evidence-based conceptual models informed by the literature, the framework lends itself towards a more process-based view of analysis than characterizes many ecological
Figure 1. Work and information flow for the Webb et al. [9] process for modelling the ecological effects of flow variation. Boxes are tasks; circles are outputs from each step. The first four steps’ outputs all feed into the creation of the Bayesian hierarchical model at Step 5, with the final output – predictions of ecological effects of flow restoration – highlighted red. Reproduced from Webb et al. [9].
analyses. The Bayesian approach is completely flexible, and analyses can easily employ non-linear, interactive, or threshold-based responses that more closely emulate the ecological processes taking place [e.g. 12] (Figure 3). Such models quantify continuous responses between flow regime and ecological response, which means they can be used to make predictions of ecological responses to different flow regimes, such as with and without environmental flows [e.g. 12] (Figure 4). This predictive ability provides the ‘counterfactual scenario’ that is often lacking in assessing the ecological benefits of environmental flows.
The hierarchical approach to modelling also allows ecological responses to be quantified at multiple scales. In VEFMAP, predictions can be made at the site, river, and state scale – outputs likely to be of use to different stakeholder groups [13]. This approach also ensures that while predictions will differ for different sites, those predictions will be informed by far more than just the data from those sites.
The partnership-based approach to developing and implementing the monitoring programs has fostered a sense of ownership of the programs among the range of stakeholders involved (state and local managers,
Figure 2. Organizational structure in VEFMAP. Labels on left hand side depict the main responsibility for the party/ies at that level. Arrow types represent the flows of funding, data and the outcomes of analysis and interpretation, as shown in the key. Communication among parties in the partnership is non-structured, with any party able to contact any other (with the exception of the state government) as necessary. Abbreviations: UM = University of Melbourne, W = Wimmera, GH = Glenelg-Hopkins, GB = Goulburn-Broken, NC = North-Central, WG = West Gippsland. Other abbreviations provided in the text. Modified from Webb et al. [10].
DEPI
WCMA GHCMA GBCMA NCCMA WGCMA
Consultant 1 Consultant 2 Consultant 3 Etc.
SKM
Oversight
Collection
Implem-entation
Facilitation
StateGovernmentFunding
UM
FundsDataReporting
Figure 3. Interactive effects of inundation duration (T) and number of inundation events (f) on the cover of terrestrial vegetation species within regulated river channels. Reproduced from Webb et al. [12]
researchers, consultants). A program that was entirely top-down would achieve consistency over large scales, but would not have the engagement of local expertise necessary to achieve best outcomes. Similarly, a series of programs developed at the local scale could not hope to achieve the consistency necessary to allow large-scale data analyses of the type described above.
The other advantage of the partnership approach to developing the monitoring programs was that it resulted in monitoring of ‘requisite complexity’ [7] – programs that were complex enough to address the challenges of detecting ecological responses to flow variation, yet pragmatic and simple enough to be affordably implemented over large scales.
3.2 Weaknesses and possible responses
The single greatest impediment to successful implementation of the framework has been occasional inconsistencies in the data collected among rivers, and an inability to match data collected for one endpoint to data collected for another. As an example, assessing the effects of inundation on bankside vegetation relies on being able to relate vegetation cover to inundation regime. Vegetation data were collected along the same cross-sectional transects as used to build hydraulic models of the sites. Theoretically, this means that the surveyed cross sections could be related to the chainage (distance from the start of the transect) of the vegetation sample to calculate elevation of the vegetation sample, and hence its inundation history. Unfortunately, this was sometimes not possible. It appears that, on occasions, vegetation contractors unaware of the significance of the previously established transects, did not begin their chainage measurements from the same point on the bank. Consequently, data analysts were unable to unequivocally calculate the elevation of vegetation quadrats, introducing extra uncertainty into data analyses. Problems such as this have meant that data analysts have spent much more time ‘cleaning’ monitoring data than was originally envisaged, greatly reducing the overall number of analyses possible.
Such a problem suggests a lack of coordination at the scale of the contractors collecting the data. Although the CMAs who run the local monitoring programs are a part of the partnership, they contract out actual monitoring to consultants. With these consultants not explicitly being a member of the partnership, it is understandable that they may on occasions fail to see how the data they collect fit into the larger program, or how they may be used in conjunction with other data.
The Commonwealth Environmental Water Office (CEWO) in Australia is attempting to avoid this type of problem in their own large-scale monitoring program by including all data providers in the partnership of managers, researchers and consultants. The program structure of their CEWO’s long-term intervention
Figure 4. Predictions of ecological responses to changes in flow regime. Bars show predicted terrestrial vegetation cover at 7 sites in Victoria under four different inundation regimes as dictated by the key. Reproduced from Webb et al. [12].
monitoring program draws upon VEFMAP, but makes some changes, most specifically in far greater specification of standard methods to be used across the Murray-Darling Basin, and also in engaging directly with the monitoring providers rather than through the local catchment managers responsible for the rivers and wetlands being monitored. These refinements may avoid or reduce the type of problem described above.
One unavoidable disadvantage of the Webb et al. [9] framework is that it is time consuming compared to more standard approaches to data analysis. The systematic synthesis of literature evidence is a small research project in its own right for each endpoint. Expert elicitation to develop prior distributions for Bayesian models takes considerable time and organization, both to recruit experts for the workshop, and then the time to collect and synthesize the information. Bayesian analyses, in general require a greater degree of training and effort compared to ‘standard’ statistical approaches. We argue that the effort is repaid in the quality of outputs, but the additional effort may still deter potential users.
The only way to reduce this effort is by eliminating one or more components of the process. Analyses of terrestrial vegetation encroachment into channels demonstrated that the expert-based prior probability distributions greatly reduced the uncertainty of resulting predictions from the model, and so eliminating this step is not recommended [13]. The systematic literature review may be considered optional for analyses for which there is a strong conceptual model in mind prior to analysis. We are currently undertaking statistical analyses of river channel changes in response to flooding, basing the analysis models on theoretical predictions from geomorphic principles, rather than on an analysis of literature.
The final feature that we believe could have been done better is the engagement between researchers and managers. Although the framework has involved a great deal of successful engagement, this has been the feature of most concern to management stakeholders. For researchers working in an academic environment, it is far too easy to lose sight of the importance of engagement, instead focusing on data analysis and production of academic outputs [14]. It is instructive that the proposal that secured competitive funding to analyze the VEFMAP data did not include any specific budget for engagement. This type of shortcoming can only be improved by sustained and mindful attention to engagement with partners. It may be difficult to specify budget items for this purpose, but its importance cannot be overstated.
3.3 Summary
Overall, we have great belief in the value of the Webb et al. [9] framework for monitoring and assessment of the ecological effects of flow variation. It has proved that we can gain the type of quantitative predictive ability that will be necessary to move environmental flows into an era of evidence-based management. Nevertheless, throughout the 8 years since VEFMAP was first conceived, we have been learning by doing, and would certainly do some things differently if given the chance again. We believe this type of partnership-based approach to monitoring and evaluation can be of value elsewhere in the world, and also for other types of ecological restoration, where data must be collected across large scales to assess whether the investment of public money in ecological restoration has led to a successful outcome.
ACKNOWLEDGEMENTS
VEFMAP is funded by the Victorian Department of Environment and Primary Industries. We thank the ongoing support of Jane Doolan, Paulo Lay and Louisa Davis for this program. The Environmental Water Reserve Officers from the partner Catchment Management Authorities are also critical to the success of the monitoring programs. Analyses of VEFMAP data are funded by ARC Linkage project LP100200170. We thank Ian Rutherfurd, LeRoy Poff and Andrew Sharpe for their contributions to this project.
REFERENCES
[1] Le Quesne, T., Kendy, E. and Weston, D., "The Implementation Challenge: taking stock of government policies to protect and restore environmental flows", The Nature Conservancy & WWF, (2010).
[2] Skinner, D. and Langford, J., "Legislating for sustainable basin management: the story of Australia's Water Act (2007)", Water Policy, Vol. 15, No. 6, (2013), pp 871-894.
[3] Marohasy, J., "Myth and the Murray: measuring the real state of the river environment", IPA Backgrounder, Vol. 15(5), (2003).
[4] EarthTech, "Thomson River environmental flow requirements & options to manage flow stress", Earth Tech Engineering Pty Ltd, Report to West Gippsland Catchment Management Authority, Dept. of Sustainability and Environment, Melbourne Water Corporation and Southern Rural Water (2003). Available: http://www.water.vic.gov.au/__data/assets/pdf_file/0004/28327/Thomson-River.pdf
[5] Stewardson, M.J. and Webb, J.A., "Modelling ecological responses to flow alteration: making the most of existing data and knowledge", Ecosystem Response Modelling in the Murray-Darling Basin, CSIRO Publishing, (2010), pp 37-49.
[6] Souchon, Y., Sabaton, C., Deibel, R., Reiser, D., Kershner, J., Gard, M., Katopodis, C., Leonard, P., Poff, N.L., Miller, W.J. and Lamb, B.L., "Detecting biological responses to flow management: Missed opportunities; Future directions", River Research and Applications, Vol. 24, No. 5, (2008), pp 506-518.
[7] Webb, J.A., Stewardson, M.J., Chee, Y.E., Schreiber, E.S.G., Sharpe, A.K. and Jensz, M.C., "Negotiating the turbulent boundary: the challenges of building a science-management collaboration for landscape-scale monitoring of environmental flows", Marine and Freshwater Research, Vol. 61, (2010), pp 798-807.
[8] Poff, N.L. and Zimmerman, J.K.H., "Ecological responses to altered flow regimes: a literature review to inform the science and management of regulated rivers", Freshwater Biology, Vol. 55, (2010), pp 194-205.
[9] Webb, J.A., de Little, S.C., Miller, K.A., Stewardson, M.J., Rutherfurd, I.D., Sharpe, A.K., Patulny, L. and Poff, N.L., "Modelling ecological responses to environmental flows: making best use of the literature, expert knowledge, and monitoring data", The 3rd Biennial ISRS Symposium: Achieving Healthy and Viable Rivers, Beijing, China, (2013), pp 221-234.
[10] Webb, J.A., Miller, K.A., de Little, S.C. and Stewardson, M.J., "Overcoming the challenges of monitoring and evaluating environmental flows through science-management partnerships", International Journal of River Basin Management, (in press).
[11] Cottingham, P., Stewardson, M. and Webb, A., "Victorian Environmental Flows Monitoring and Assessment Program. Stage 1: Statewide Framework", Melbourne Water Corporation, D 1 876 810 43 2, (2005). Available: http://tinyurl.com/2feys3
[12] Webb, J.A., de Little, S.C., Miller, K.A., Stewardson, M.J., Rutherfurd, I.D., Sharpe, A.K. and Poff, N.L., "A general approach to predicting ecological responses to environmental flows: making best use of the literature, expert knowledge, and monitoring data", River Research and Applications, (in review).
[13] Webb, J.A., de Little, S.C., Miller, K.A. and Stewardson, M.J., "Quantifying the benefits of environmental flows: combining large-scale monitoring data within hierarchical Bayesian models", Journal of Applied Ecology, (in review).
[14] Cullen, P., "The turbulent boundary between water science and water management", Freshwater Biology, Vol. 24, No. 1, (1990), pp 201-209.
