Infrastructure Engineering - Research Publications
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ItemNo Preview AvailableBasin-scale riverine ecosystem services vary with network geometry(ELSEVIER, 2023-10)
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ItemNo Preview AvailableThe time of emergence of climate-induced hydrologic change in Australian rivers(ELSEVIER, 2023-04)
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ItemRobust Climate Change Adaptation for Environmental Flows in the Goulburn River, Australia(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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ItemNonstationary Runoff Responses Can Interact With Climate Change to Increase Severe Outcomes for Freshwater Ecology(AMER GEOPHYSICAL UNION, 2022-02)Abstract Climate change is projected to impact multiple components of the flow regime. However, changes in some ecologically important aspects of flow seasonality and variability are not well‐represented by global climate models. We used a stress testing method and global sensitivity analysis to investigate whether interactions between five different, but plausible, change “dimensions” (hydroclimatic variables or relationships) led to worse ecological outcomes than individual changes. The five dimensions include changes in long‐term average rainfall and temperature, low‐frequency variability of rainfall, seasonality of rainfall, and the rainfall‐runoff relationship. Our case study involved regulated and unregulated sections of the Goulburn River, Australia. We found that four different modeled ecological outcomes (condition of small bodied fish, large bodied fish, in‐channel vegetation, and floodplain vegetation) are most sensitive to changes in long‐term average rainfall. Sensitivity to changes in rainfall seasonality depends on river characteristics and appears to be heavily dampened by regulation and actively managed environmental water. Changes to the rainfall‐runoff relationship (which may be triggered by long‐term drying) were found to greatly influence ecological outcomes, but remain poorly understood. However, when considering the worst outcomes that are likely to present severe threats to ecological survival, all five dimensions were significant. These worst outcomes only manifest under certain combinations of changes with interactive effects. These joint interactions have implications for climate risk assessments that do not consider multiple dimensions of change, particularly those aimed at evaluating and mitigating severe threats or extinction probability.
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ItemDoes the topology of the river network influence the delivery of riverine ecosystem services?(WILEY, 2021-02)Abstract Riverine ecosystems provide important ecosystem services reflecting their unique forms and functions. While the effects of stressors such as land cover change, climate change and growing economies on riverine ecosystem services (RES) have been well researched, the effect of the structure of the river network itself is less understood. This paper compares the capacity of different river network topologies in the delivery of selected RES. For three contrasting synthetic river network topologies (Long Trellis Narrow; Coastal Dendritic; Inland Dendritic), we applied simple functional equations to model six RES: water supply, hydropower generation, sediment retention, nutrient uptake, flood attenuation and aquatic habitat provision. Results showed that the synthetic topologies deliver different levels of RES, driven by their differences in physical structure. For example, the Inland Dendritic network removed more nitrate and better attenuated flooding due to its relatively longer lower reaches but offered poorer prospects for water supply because the longer reaches were more susceptible to transmission losses (e.g., due to bed seepage). This study provides a valuable first step in understanding the effect of river network topology on RES delivery, and the relative strengths among network types. Understanding these effects can aid decision makers in the conservation and restoration of degraded river basins to preserve RES for future generations.