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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    A Simple Analytical Method to Assess Multiple-Priority Water Rights in Carryover Systems
    Ren, P ; Stewardson, M ; Peel, M (Wiley, 2022-12-01)
    Simple analytical storage–reliability–yield relationships have traditionally only considered a single reliability for a single yield, yet many reservoirs supply water of different priorities. Simulation models may be used to handle such multiple-priority water rights but these models are complex and usually system specific. Here we propose a simple analytical method based on Gould-Dincer to estimate yields in dual and triple priority allocation systems from a carryover storage. This allows rapid assessment of changes in water resource availability for different water priorities, potentially over large spatial scales. We use a dam simulation model to assess this method at 15 sites across six continents and find that the “dual-priority” and “triple-priority” G-D methods can reproduce the results of the dam simulation model. Thus, the method could be generalized for multiple priority allocation systems use. We demonstrate the potential utility of the “dual-priority” G-D method through an evaluation of the optimum yield between high and low-priority water rights (HPWR and LPWR) from hypothetical (but realistic) carryover systems. It confirms the possibility that “dual-priority” water allocation may be beneficial overall compared to a single-priority water right. By balancing the yield of HPWR and LPWR, the optimum marginal value of available water (i.e., sum of high- and low-priority water) can be achieved. Overall, the method provides a simple way for rapid assessment across multiple sites allowing insights into optimal allocation practices and the interacting driving factors that affect them at a regional-to-global scale.
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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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    Micro-computed tomography scanning approaches to quantify, parameterize and visualize bioturbation activity in clogged streambeds: A proof of concept
    Lakhanpal, G ; Black, JR ; Casas-Mulet, R ; Arora, M ; Stewardson, MJ (WILEY, 2023-05)
    Abstract Fine particle clogging and faunal bioturbation are two key processes co‐occurring in the hyporheic zone that potentially affect hyporheic exchange through modifications in the sediment structure of streambeds. Clogging results from excessive fine sediment infiltration and deposition in rivers, and it is known to decrease matrix porosity and potentially reduce permeability. Faunal bioturbation activity may compensate for the negative effect of clogging by reworking the sediment, increasing porosity, and preventing further infiltration of fines. Although both processes of clogging and bioturbation have received significant attention in the literature separately, their combined effects on streambed sediment structure are not well understood, mostly due to the lack of a standard methodology for their assessment. Here, we illustrate a novel methodology using X‐ray computed tomography (CT), as proof of concept, to investigate how, together, clogging and bioturbation affect streambed porosity in a controlled flow‐through flume. By visualising gallery formations of an upward conveyor macroinvertebrate; Lumbriculus variegatus as a model species, we quantified bioturbation activity in a clogged streambed, focusing on orientation, depth, and volume at downwelling and upwelling areas of the flume. Gallery creation increased the porosity of the streambed sediment, suggesting a potential improvement in permeability and a possible offset of clogging effects. We illustrate the promising use of X‐ray CT as a tool to assess bioturbation in clogged streambeds, and the potential role of bioturbation activity supporting hyporheic exchange processes in streambeds, warranting further studies to understand the extent of bioturbation impacts in natural systems.
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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.