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Map of the River Murray from Lock 15 downstream to the Murray Mouth. The location of Locks 1–15 are indicated, as is the position of major anabranch systems, namely Lindsay–Mullaroo, Chowilla, Pike and Katarapko.
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The hydraulic characteristics of lotic systems are fundamental to ecological processes and patterns. In the lower River Murray, Australia upstream dams and diversions have altered hydrology, whilst sequential low-level weirs have fragmented and homogenised a once lotic system. In this paper we (1) use modelling and empirical data to quantify change...
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Context 1
... lower River Murray is defined as the 830 km of river and associated floodplain from the junction of the Murray and Darling Rivers downstream to the Murray Mouth ( Figure 1). Here, we also include the reach up to the "end-of-influence" of the Lock 11 (Mildura) weir-pool, as this reach is morphologically similar to the lower River Murray and represents the most upstream of the sequential main channel weirs. ...
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One of method for balancing the water potential and water of agricultural area is building Meninting Dam. In obtaining perfection of design is testing the physical model hydraulics spillway. The purpose of this study is knowing the hydraulic phenomena on the side channel spillway Meninting Dam with 1:40 scale physical model test.
In this study of p...
Citations
... Ten low-level locks (situated 29-88 km apart) have fragmented the channel in the lower River Murray, turning the 830 km stretch of lotic river into a series of cascading, predominantly lentic weir pools (Bice et al., 2017;Walker, 2006). Furthermore, upstream diversion has reduced the frequency, magnitude and duration of high flows and floods, disrupting longitudinal and lateral connectivity, which was widespread, co-occurring and integrated during natural river conditions (Walker, 2006). ...
... The mean and median annual flows into South Australia are 5,300 and 3,700 GL, respectively (observed data, 1/7/1977-30/06/2022DEW, 2022). In contrast, mean and median flow into South Australia modelled under natural conditions were 12,800 and 11,600 GL, respectively (Bice et al., 2017;Murray-Darling Basin Authority, 2012). ...
... The River Murray from Lock 15 to its terminus at the Southern Ocean, detailing Locks 1-15 and the major anabranch systems, namely Lindsay-Mullaroo, Chowilla, Pike and Katarapko(Bice et al., 2017). ...
... This highlights the ecohydraulic requirements of pelagophilic spawners with periodic or opportunistic life-history strategies and their dependence on a range of mainstem and tributary discharge events (Humphries et al., 2020;Winemiller & Rose, 1992). The protection of flow events should also extend to minimising or preventing direct removal of early recruits from the ecosystem in association with floodplain water harvesting, the capture of water for consumptive use, mortality associated with downstream passage past instream structures and the settlement of juveniles in unproductive weir pool habitats (Baumgartner et al., 2006;Bice et al., 2017;Boys et al., 2021;King & O'Connor, 2007). ...
Freshwater ecosystems are under extreme stress due to anthropogenic influences including changing climate, river regulation and water abstraction. Improving our understanding of the hydrological determinants of key life‐history processes of fish, as well as the spatial scales over which these processes occur, is fundamental to inform effective recovery actions. We monitored the spawning response of native fish to a drought‐breaking long‐distance flow pulse that was protected from extraction by a legal intervention order in Australia's northern Murray–Darling Basin. Sampling sites were distributed across >1600 km of the Barwon–Darling River and three of its major tributaries. Larvae of the pelagophilic golden perch ( Macquaria ambigua ) were captured at all sites, with the size and age distribution indicative of both mainstem and tributary spawning. A mismatch between estimated hatch dates and river discharge at some locations suggested substantial flow‐assisted dispersal from upstream spawning sites, although this was site‐specific and more prevalent at downstream locations. Early life growth rates were the highest at tributary sites compared with mainstem sites, and within mainstem sites, golden perch grew faster in upper reaches compared with lower reaches. The present study provides insight into the environmental benefit of a post‐drought protected flow event whereby connected lotic habitats promoted fish spawning and dispersal over a large spatial scale. Protection of future flow events should occur to support the conservation of golden perch and other pelagophil species, particularly following future drought periods which are forecast to become more intense and frequent.
... With the limited water that will be available for the environment, it is imperative that we learn to do more with less. The dream of a river running unimpeded to the sea was lost with river regulation early last century (Bice et al. 2017). The challenge for modern river managers is to work within these constraints to protect and enhance the natural assets of the river; the wetlands, plants, fish, and bird communities. ...
Freshwater aquatic ecosystems can be considered sentinels of change as they integrate signals from catchment, hydrology and biogeochemistry to provide an indication of how the system fluctuates. The Coorong estuary acts as a sentinel for the Murray-Darling Basin (MDB), Australia. Its location at the terminus of the Murray-Darling River systems, which drains more than 1 million square kilometres across 22 major catchments, means that any change to climate, water extraction or land use in the upstream catchments will have repercussions for the Coorong. It therefore acts as an indicator of the health of the MDB and the effectiveness of
the Murray-Darling Basin Plan at protecting this ecosystem. Environmental water secured through the Murray-Darling Basin Plan and establishment of the Commonwealth Environmental Water Holder has been critical to preventing significant ecosystem decline in the Coorong. For most water years in the last decade environmental water has contributed to the majority of flow through the barrages. This has exported salt from the basin, reduced influx of salt from the ocean, and expanded available habitat for fish in the Coorong. However, the
environmental flows have not been sufficient to arrest sand build up, and dredges still operate at the Murray Mouth during all but the highest flow events. There is a clear case for continued water management and reform, extending beyond the boundaries of the MDB, to further increase security of water flowing along the river system through the barrages and supporting the ecological health of the Coorong, and by association the full MDB.
... River regulation and ecological restoration can improve the hydraulic characteristics and ecological processes of the river channel and have drawn considerable attention in extensive research in recent years [1][2][3][4]. As one of the most significant measures for river regulation, artificial river barriers such as spur dikes and abutments can provide an improvement in the flow regime, while simultaneously acting as a major cause of freshwater biodiversity loss with alterations of the flow pattern [5,6]. ...
... Regulation and abstraction of flow in this catchment have resulted in wetlands that fill less often (Figure 3), and the average duration of successive dry years has increased by up to three years compared with natural flow conditions (Figure 4) (Bice et al., 2017;Maheshwari et al., 1995). As such, regulation has effectively locked these wetlands into a state of perpetual "bust." ...
The regulation of river systems alters hydrodynamics and often reduces lateral connectivity between river channels and floodplains. For taxa such as frogs that rely on floodplain wetlands to complete their lifecycle, decreasing inundation frequency can reduce recruitment and increase the probability of local extinction. We virtually reconstructed the inundation patterns of wetlands under natural and regulated flow conditions and built stochastic population models to quantify the probability of local extinction under different inundation scenarios. Specifically, we explored the interplay of habitat size, inundation frequency, and successive dry years on the local extinction probability of the threatened southern bell frog Litoria raniformis in the Murray River floodplains of South Australia. We hypothesised that the changes to wetland inundation resulting from river regulation are a principal driver of L. raniformis declines in this semi-arid system. Regulation has reduced the inundation frequency of essential habitats below critical thresholds for the persistence of many fresh water-dependent species. Successive dry years raise the probability of local extinction, and these effects are strongest in smaller wetlands. Larger wetlands and those with more frequent average inundation are less susceptible to these effects. Elucidating these trends informs the prioritisation of treatment sites and the frequency of conservation interventions. Environmental water provision (through pumping or the operation of flow-regulating structures) is a promising tool to reduce the probability of breeding failure and local extinction. Our modelling approach can be used to prioritise the delivery of environmental water to L. raniformis and potentially many other frog species.
... Despite these advantages, hydraulic evaluations of ecological responses to flow regimes (i.e. quantity, timing, volume and duration of flow events; Arthington et al., 2018) that have been restored with environmental flows are rare in the literature (but for an example see Bice et al., 2017). This may be because of the interdisciplinary expertise required to address such ecohydraulic questions (Nestler et al., 2016). ...
Ecological responses to changing riverine flows are often evaluated by describing the relationship between river discharge and response. However, aquatic organisms experience the hydraulics (i.e. velocity, shear stress, depth) of a river, not its discharge. Hydraulic characterizations of riverine habitats may improve our ability to predict ecological responses. We used two-dimensional hydraulic models to translate river discharge into flow velocity. We used discharge and reach-averaged velocity, along with water temperature and 8 years of field observations of fish spawning, to develop predictive models of the spawning of golden perch (Macquaria ambigua) in the Goulburn River, south-east Australia. Probability of spawning was positively related to both discharge and reach-averaged velocity. Water temperature was critical for enabling the flow response, and antecedent flows prior to spawning had a weak positive effect. Against expectations, there was little difference in predictive uncertainty for the effect of flows when reach-averaged velocity was used as the main predictor rather than discharge. The lower Goulburn River has a relatively simple channel and so discharge and velocity are monotonically related over most flows. We expect that in a more geomorphically complex environment, improvement in predictive ability would be substantial. This research only explores one example of a hydraulic parameter being used as a predictor of ecological response; many others are possible. The extra effort and expense involved in hydraulic characterization of river flows is only justified if our understanding of flow-ecology relationships is substantially improved. Further research to understand which environmental responses might be best understood through different hydraulic parameters, and how to better characterize hydraulic characteristics relevant to riverine biota, would help inform decisions regarding investment in hydraulic models. Regardless, hydraulics offers a more process-based assessment of ecological responses to changing flows, has the potential to facilitate mechanistic understanding rather than just associations, and provides the opportunity to translate hydraulic metrics that drive ecological responses across river systems of differing sizes. However, while considering ecological responses in terms of river hydraulics is more physically realistic, our results suggest that average hydraulic conditions may not result in an improved ability to predict the effects of changing flows.
... River regulation and ecological restoration can improve the hydraulic characteristics and ecological processes of the river channel and have drawn considerable attention in extensive research in recent years [1][2][3][4]. As one of the most significant measures for river regulation, artificial river barriers such as spur dikes and abutments can provide an improvement in the flow regime, while simultaneously acting as a major cause of freshwater biodiversity loss with alterations of the flow pattern [5,6]. ...
Spur dikes provide significant control for flow regimes in river regulation engineering, which can help in the regeneration of stream habitats. However, the narrowing of the flow by spur dike changes the turbulence characteristics. To clarify the turbulence characteristics around the spur dike, the method of large eddy simulation (LES) was used to investigate the horizontal turbulence structure around spur dikes with different discharges in an open-channel flume. The simulations were an exact reproduction of large-scale laboratory experiments, which showed agreement with the experimental results. The distributions of time-averaged streamwise velocity, bed shear stress, and second-order turbulence statistics obtained from the LES were analyzed. An examination of the time series of velocity fluctuation as the probability density function, quadrant analysis, the power density spectra, flow instability, and the vortex separation created in the detached shear layer were estimated. The results accurately revealed the flow field under flow separation, the turbulence statistics inside the separated shear layer, and the vortex structure and emphasized the variation in the different water depths. The results demonstrated that the form of turbulence was not significantly affected by discharge. Moreover, vortex and energy transmission displayed the same periodicity, despite variances in the structural form of turbulence at different water depths. Overall, the results of the study provide an efficient basis for understanding the turbulence around spur dikes, which is crucial for their safe design.
... The study was conducted in the Lower River Murray, South Australia, within a reach of the river in which stabilization of water levels via a series of 11 low-level (c. 3 m head) weirs has produced a shift from highly variable riverine conditions to conditions representative of a string of lakes and disconnected natural relationships between discharge, depth and velocity (Bice et al., 2017;Kilsby & Walker, 2012;Walker, 2006). The model boundaries represent 206 km of river from the Victoria -South Australian border to Lock and Weir Number 3 (henceforth referred to as 'Lock 3'). ...
The ecology of floodplain ecosystems evolved according to the historical frequency and extent of inundation. In many dryland rivers inundation frequency has reduced due to regulation, competition for water resources and climate change. In some rivers infrastructure has been constructed to enable temporary rises in water level and more frequent floodplain inundation, delivering environmental water to ecosystems that are dependent on surface water. During such events, the release of dissolved organic carbon (DOC) from inundated plant material may result in depletion of dissolved oxygen (DO). If the rate of DO depletion exceeds re‐aeration, hypoxic conditions can occur. Models have been developed to represent these processes, however there is a wide range of chemical and biological interactions, and hence model parameters, involved. The aim of this research was: 1) identify the dominant parameters through sensitivity analysis, 2) design and implement a field monitoring program to quantify the inherent variability in those parameters, and 3) translate that input variability into the modelled DO, ultimately to support risk management decisions when planning delivery of environmental water. The results indicated that the mass of organic matter on a floodplain had the greatest impact on the modelled DO concentrations. Based on the field monitoring results, the steady state load of organic matter, i.e. when the accumulation and decay rates are equal, was estimated, and vegetation mapping used to apply the field monitoring results across the floodplain for a 206 km reach of river of the River Murray, Australia. The model results from multiple, cumulative, operations identified one particular high risk operational site. The results are useful to prioritise monitoring effort to focus on the most sensitive model parameters and indicate that the likelihood of hypoxic conditions can be reduced through slower rates of inundation and timing events to coincide with periods with lower water temperature. The methodology developed can be transferred to other sites where hypoxic conditions are a potential outcome associated with delivery of environmental water. This article is protected by copyright. All rights reserved.
... discharge) and hydraulic (e.g. water level and velocity) variability, and reduced floodplain inundation (Maheshwari et al. 1995;Bice et al. 2017). The Murray River downstream of the Darling River junction is modified by a series of low-level (<3 m) weirs (Figure 1), changing a connected flowing river to a series of weir pools (Walker 2006). ...
... depth/water level or flow velocity) of fluvial ecosystems result from the interaction of discharge and physical features (e.g. channel morphology, woody debris, man-made structures, etc.), and have a profound influence on river ecosystem structure and function (Statzner and Higler 1986;Biggs et al. 2005;Bice et al. 2017) (also see Section 1.1). It is these hydraulic characteristics that biota can sense and respond to, i.e. a change in velocity or water level, rather than a change in discharge. ...
... The updated knowledge collated here is used to provide a specific case study of a conceptual hydrograph for the SMDB that includes some key components of hydraulic diversity important for three species, namely the Murray cod, a riverine nesting species, and golden perch and silver perch, which are pelagic spawners, indicating the likely benefits to these and other species (Fig. 11; Table 14). These species all require lotic habitats (identified as a key habitat loss in regulated rivers; Table 3), which could be achieved with increased flows or a combination of flow and weir lowering or removal (Bice et al. 2017;Mallen-Cooper and Zampatti 2018). Wetland specialist species would require a different emphasis for their hydrograph, which may describe hydraulic characteristics such as wetland depth, area and persistence, partial wetting and the spatial connective links to the river. ...
... For example, extensive river reaches ($1000 km) of the lower Murray and Barwon-Darling rivers were converted from lotic to lentic environments by the imposition of weirs and reduced flows (Maheshwari et al. 1995;Walker 2006; in press) Remediation of hydraulic effects occurring within these reaches is unlikely from a generically designed hydrograph or by changes to river flows alone. A combination of integrated actions, such as weir removal or lowering in combination with flow restorations, may be required Bice et al. 2017;Mallen-Cooper and Zampatti 2018). A further summary perspective on broader restoration actions for MDB fishes is provided in Fig. 11) for Murray cod (flow components 1-5) and golden perch and silver perch (flow components A-D) and the benefits to these and other species Note that this is conceptual for a river with reversed seasonality in the SMDB and the references provide context rather than direct support. ...
... Zampatti et al. 2014;Bice et al. 2017;Mallen-Cooper and Zampatti 2018) and effects of floodplain regulators(Mallen-Cooper et al. 2008 Barriers restricting juvenile and adult movement(Baumgartner et al. 2014b).Genetic studies have suggested that flow regulation per se may not have been the most critical threat to the persistence of Murray cod over the past century compared with the reduced frequency of large floods, overfishing and chemical pollution; see also Rowland 2005) Considered moderately tolerant to drought) and climate change effects(Chessman 2013); susceptible to postwildfire sediment flows(Lyon and O'Connor 2008) ...
Many freshwater fishes are imperilled globally, and there is a need for easily accessible, contemporary ecological knowledge to guide management. This compendium contains knowledge collated from over 600 publications and 27 expert workshops to support the restoration of 9 priority native freshwater fish species, representative of the range of life-history strategies and values in southeastern Australia's Murray-Darling Basin. To help prioritise future research investment and restoration actions, ecological knowledge and threats were assessed for each species and life stage. There is considerable new knowledge (80% of publications used were from the past 20 years), but this varied among species and life stages, with most known about adults, then egg, juvenile and larval stages (in that order). The biggest knowledge gaps concerned early life stage requirements, survival, recruitment, growth rates, condition and movements. Key threats include reduced longitudinal and lateral connectivity, altered flows, loss of refugia, reductions in both flowing (lotic) and slackwater riverine habitats, degradation of wetland habitats, alien species interactions and loss of aquatic vegetation. Examples and case studies illustrating the application of this knowledge to underpin effective restoration management are provided. This extensive ecological evidence base for multiple species is presented in a tabular format to assist a range of readers.
