Infrastructure Engineering - Research Publications

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    Managing risks associated with environmental water delivery: a case study of the Goulburn River, Australia
    Meempatta, L ; Webb, JA ; Horne, AC ; Keogh, LA ; Stewardson, MJ (ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2024-01-01)
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    Exploring the role and decision-making behavior of irrigation water supply authorities in Australia
    Meempatta, L ; Webb, JA ; Keogh, LA ; Horne, AC ; Stewardson, MJ (ROUTLEDGE JOURNALS, TAYLOR & FRANCIS LTD, 2023-03-04)
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    Basin-scale riverine ecosystem services vary with network geometry
    Karki, S ; Webb, JA ; Stewardson, MJ ; Fowler, K ; Kattel, GR (ELSEVIER, 2023-10)
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    The time of emergence of climate-induced hydrologic change in Australian rivers
    John, A ; Nathan, R ; Horne, A ; Fowler, K ; Stewardson, M ; Peel, M ; Webb, JA (ELSEVIER, 2023-04)
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    Modelling Impacts of Environmental Water on Vegetation of a Semi-Arid Floodplain-Lakes System Using 30-Year Landsat Data
    Wu, C ; Webb, JA ; Stewardson, MJ (MDPI, 2022-02)
    River floodplains are among the most dynamic and diverse ecosystems on the planet. They are at risk of degradation due to river regulation and climate change. Environmental water has been delivered to floodplains to maintain environmental health by mimicking natural floods. It is important to understand the long-term effects of environmental water to floodplain vegetation to support its management. This study used Normalized Differences Vegetation index (NDVI) from the 30-year Landsat datasets of the Hattah Lakes floodplain in Australia to investigate the drivers of vegetation dynamics. We developed generalized additive mixed models (GAMM) to model responses of vegetation to environmental water, natural floods, precipitation, temperature, and distance to water across multiple spatial and temporal scales. We found the effect of environmental water on floodplain vegetation to be quite different from that of natural floods in both space and time. Vegetation in most areas of Hattah Lakes will respond to natural floods within one month of flooding, while positive responses to environmental water occur 1 to 3 months after inundation and are more restricted spatially. For environmental water planning, managers need to be aware of these differences. The implementation of new infrastructure to transport or retain environmental water on floodplains needs to be planned carefully, with continuous monitoring of rainfall and natural floods. Whilst environmental floods do not mimic the effect of natural floods, they do provide some positive benefits that can partially offset effects of reduced natural floods.
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    Principles for scientists working at the river science-policy interface
    Thompson, RM ; Barbour, EJ ; Bradshaw, CJA ; Briggs, S ; Byron, N ; Grace, M ; Hart, BT ; King, AJ ; Likens, GE ; Pollino, CA ; Sheldon, F ; Stewardson, MJ ; Thoms, M ; Watts, RJ ; Webb, JA (WILEY, 2022-06)
    Abstract In the face of mounting environmental and political challenges in river management, accurate and timely scientific information is required to inform policy development and guide effective management of waterways. The Murray–Darling Basin is Australia's largest river system by area and is the subject of a heavily contested series of water reforms relying comprehensively on river science. River scientists have specialised knowledge that is an important input into evidence‐based decision‐making for the management of the Murray–Darling Basin, but despite extensive literature on the interface between science and policy, there is little guidance on achieving policy relevance for practicing scientists. Here, we provide a set of important discussion points for water scientists to consider when engaging with policy‐makers and environmental water managers. We place our considerations in the context of a broader literature discussing the role of natural‐resource scientists engaging with policy and management. We then discuss the different roles for river scientists when engaging in this space, and the advantages and pitfalls of each. We illustrate the breadth of modes of engagement at the science‐policy‐management interface using the Murray–Darling Basin as an example. We emphasise the need for effective governance arrangements and data practices to protect scientists from accusations of operating as advocates when working to inform management and policy.
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    Robust Climate Change Adaptation for Environmental Flows in the Goulburn River, Australia
    John, A ; Horne, A ; Nathan, R ; Fowler, K ; Webb, JA ; Stewardson, M (FRONTIERS MEDIA SA, 2021-12-06)
    Climate change presents severe risks for the implementation and success of environmental flows worldwide. Current environmental flow assessments tend to assume climate stationarity, so there is an urgent need for robust environmental flow programs that allow adaptation to changing flow regimes due to climate change. Designing and implementing robust environmental flow programs means ensuring environmental objectives are achieved under a range of uncertain, but plausible climate futures. We apply stress testing concepts previously adopted in water supply management to environmental flows at a catchment scale. We do this by exploring vulnerabilities in different river management metrics for current environmental flow arrangements in the Goulburn River, Australia, under non-stationary climatic conditions. Given the limitations of current environmental flows in supporting ecological outcomes under climate change, we tested three different adaptation options individually and in combination. Stress testing adaptation results showed that increasing environmental entitlements yielded the largest benefits in drier climate futures, whereas relaxing river capacity constraints (allowing more targeted delivery of environmental water) offered more benefits for current and wetter climates. Combining both these options led to greater than additive improvements in allocation reliability and reductions in environmental water shortfalls, and these improvements were achieved across a wider range of climatic conditions than possible with either of the individual options. However, adaptation may present additional risks to some ecological outcomes for wetter climates. Ultimately, there was a degree of plausible climate change beyond which none of the adaptation options considered were effective at improving ecological outcomes. This study demonstrates an important step for environmental flow assessments: evaluating the feasibility of environmental outcomes under climate change, and the intervention options that prove most robust under an uncertain future.
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    The politicisation of science in the Murray-Darling Basin, Australia: discussion of 'Scientific integrity, public policy and water governance'
    Stewardson, MJ ; Bond, N ; Brookes, J ; Capon, S ; Dyer, F ; Grace, M ; Frazier, P ; Hart, B ; Horne, A ; King, A ; Langton, M ; Nathan, R ; Rutherfurd, I ; Sheldon, F ; Thompson, R ; Vertessy, R ; Walker, G ; Wang, QJ ; Wassens, S ; Watts, R ; Webb, A ; Western, AW (Taylor & Francis, 2021-10-30)
    Many water scientists aim for their work to inform water policy and management, and in pursuit of this objective, they often work alongside government water agencies to ensure their research is relevant, timely and communicated effectively. A paper in this issue, examining 'Science integrity, public policy and water governance in the Murray-Darling Basin, Australia’, suggests that a large group of scientists, who work on water management in the Murray-Darling Basin (MDB) including the Basin Plan, have been subject to possible ‘administrative capture'. Specifically, it is suggested that they have advocated for policies favoured by government agencies with the objective of gaining personal benefit, such as increased research funding. We examine evidence for this claim and conclude that it is not justified. The efforts of scientists working alongside government water agencies appear to have been misinterpreted as possible administrative capture. Although unsubstantiated, this claim does indicate that the science used in basin water planning is increasingly caught up in the politics of water management. We suggest actions to improve science-policy engagement in basin planning, to promote constructive debate over contested views and avoid the over-politicisation of basin science.
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    Monitoring of environmental flow outcomes in a large river basin: The Commonwealth Environmental Water Holder's long-term intervention in the Murray-Darling Basin, Australia
    Gawne, B ; Hale, J ; Stewardson, MJ ; Webb, JA ; Ryder, DS ; Brooks, SS ; Campbell, CJ ; Capon, SJ ; Everingham, P ; Grace, MR ; Guarino, F ; Stoffels, RJ (WILEY, 2020-05)
    Abstract The Murray–Darling Basin in south‐eastern Australia contains over 70,000 km2 of wetlands and floodplains, many of which are in poor condition. In response, Australian governments have committed to a major restoration program, the Murray–Darling Basin Plan that includes management of 2,750 Gl of environmental water to protect and restore aquatic ecosystems. The restoration is being undertaken within an adaptive management framework that includes monitoring the outcomes of environmental flows in seven river valleys. This paper provides an overview of the 5‐year monitoring project and some preliminary results. Monitoring design considered the Basin Plan's environmental objectives, conceptual models of ecosystem responses to flow, and an outcomes framework linking flow responses to the environmental objectives. Monitoring indicators includes ecosystem type, vegetation, river metabolism, and fish. Responses are evaluated to identify the contribution of environmental flows to Basin Plan environmental objectives and continual improvements in management. The program is unique in that it seeks to monitor long‐term outcomes of environmental flows at the river basin scale. Despite many challenges, the monitoring has become a key part of the adaptive management of environmental flows in the Murray–Darling Basin.
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    Quantifying and predicting the benefits of environmental flows: Combining large-scale monitoring data and expert knowledge within hierarchical Bayesian models
    Webb, JA ; de Little, SC ; Miller, KA ; Stewardson, MJ (WILEY, 2018-08)
    Abstract Despite large investments of public funds into environmental flows programs, we have little ability to make quantitative predictions of the ecological benefits of restored flow regimes. Rather, ecological predictions in environmental flow assessments typically have been qualitative and based largely upon expert opinion. Widely applicable, quantitative models would help to justify existing flow programs and to inform future planning. Here, we used a hierarchical Bayesian analysis of monitoring data coupled with expert‐derived prior distributions, to develop such a model. We quantified the relationship between the duration and frequency of inundation, and encroachment of terrestrial vegetation into regulated river channels. The analysis was informed by data from 27 sites on seven rivers. We found that longer inundation durations reduce terrestrial vegetation encroachment. For example, a 50‐day continuous inundation during winter reduced predicted vegetation cover to a median of 11% (95% CI: 7%–35%) of cover predicted under non‐inundated conditions. This effect varied among sites and rivers, and was moderated by the frequency of inundation events. The hierarchical structure improved precision of model predictions relative to simpler analysis structures. Informative prior distributions also improved precision relative to minimally informative priors. The hierarchical Bayesian analysis allows us to make quantitative predictions of ecological response under the full range of flow conditions, allowing us to assess the benefits of planned or delivered environmental flows. It can be used to make estimates of ecological effects at sites that have not been sampled, and also to scale up site‐level results to catchment and regional scales. Quantitative predictions of ecological effects provide a more objective risk‐based approach, allowing improved planning of environmental flows and building public confidence in these major investments of public funds.