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The episodic, seasonal hydrology of Lake Eyre Basin (LEB) rivers produce a series of waterholes which provide critical aquatic refugia and essential water supply during predominantly dry periods. This study used direct measures of water loss, regional meteorological data, and waterhole bathymetry to develop calibrated waterhole persistence models in a range of waterhole types throughout the Queensland portion of the LEB. Evaporation was a major driver of waterhole persistence, whereas the influence of other water balance parameters (e.g. groundwater discharge, seepage, vegetation utilisation) varied between waterholes and years. Estimates of waterhole persistence were extrapolated to the regional scale using a modelled time-series of waterhole level data and Landsat satellite imagery (1988–2019). Strong relationships were calculated between waterhole level and waterhole area (r2 = 0.88) and waterhole level and number of waterholes (r2 = 0.79) for all regional waterhole zones. Using these relationships and predicted evaporation rates under three possible future greenhouse gas scenarios, modelling showed that, by 2070, the number of persistent waterholes could reduce by up to 67% over 12 month period without flow. Similarly, reductions in waterhole area of up to 72% are possible under drier climate scenarios. These results potentially represent a significant risk to the aquatic ecosystems and other waterhole-dependent users for an already limited resource. • Evaporation is a major driver of Lake Eyre Basin waterhole persistence. • Waterhole persistence is modelled at an individual waterhole and regional scale. • Predicted higher evaporation rates under future climate change scenarios highlights significant reductions in waterhole persistence. • Estimated reductions represent a risk to aquatic ecosystems and other waterhole-dependent users. • Results highlight the need for climate change adaptation and management strategies that support waterhole sustainability. [ABSTRACT FROM AUTHOR]

Probable impacts of climate change on water resources are a great concern for hydrologists, water managers and policy makers. Global warming and climate change is expected to change the water availability. Using physically based hydrological model Soil and Water Assessment Tool (SWAT), this study assessed the sensitivity of streamflow to individual and combined changes in temperature and rainfall for the Yass River catchment of south eastern Australia. This study also predicted the change in streamflow based on three climate scenarios (B1, A1B, A2) of Intergovernmental Panel on Climate Change Special Report on Emission Scenarios and average of four general circulation models (CNRM-CM3, CSIRO-MK3.5, ECHam5 and MIROC3.2) for three future periods (2030, 2050 and 2090). Streamflow of the Yass River was found to be highly sensitive to both temperature and rainfall changes where 1 % change in rainfall might cause 3-5 % change in streamflow and flow might be reduced up to 16 % for 1 °C rise in temperature. Simulation results based on General Circulation Models (GCM) outputs predicted that the Yass River will likely experience huge change in streamflow due to the impact of climate change. However, due to associated uncertainties regarding climate change scenarios and climate models outputs, the results need to be evaluated carefully before making decisions in future water management and planning. [ABSTRACT FROM AUTHOR]

Following an unprecedented drought, Australia's 2019/2020 "Black Summer" fire season caused severe damage, gravely impacting both humans and ecosystems, and increasing susceptibility to other hazards. Heavy precipitation in early 2020 led to flooding and runoff that entrained ash and soil in burned areas, increasing sediment concentration in rivers, and reducing water quality. We exemplify this hazard cascade in a catchment in New South Wales by mapping burn severity, flood, and rainfall recurrence; estimating changes in soil erosion; and comparing them with river turbidity data. We show that following the extreme drought and wildfires, even moderate rain and floods led to undue increases in soil erosion and reductions in water quality. While natural risk analysis and planning commonly focuses on a single hazard, we emphasize the need to consider the entire hazard cascade, and highlight the impacts of ongoing climate change beyond its direct effect on wildfires. Plain Language Summary: In 2019/2020, a chain of natural hazards impacted Australia's East Coast. Following the severest drought since weather records began, record‐breaking wildfires known as the "Black Summer" ravaged the region for months. In early 2020, the rainfall that extinguished the last of these fires caused further damage, as the burned soils repelled much of the rain. Water took the exposed soil and charred vegetation with it on its way to the rivers, flooding streets and polluting drinking water. We show an example of this cascade of hazards in a single river catchment. We found that after the wildfires, even moderate rainfall caused floods, increased soil erosion, and reduced water quality drastically. Natural risk analyses mostly focus on single types of events in isolation. However, this hazard cascade shows that, especially in the face of ongoing climate change, scientists and decision makers need to consider events not just by themselves, but connected with each other. Key Points: Australia's unprecedented wildfire season 2019/2020 was part of a complex hazard cascade of partly extreme and partly moderate eventsWe study the complete hazard cascade of drought, fire, rain, flood, and soil erosion in the Manning River catchment, New South WalesWe show that hazard cascades can amplify the impacts of moderate events, which requires renewed consideration in risk management [ABSTRACT FROM AUTHOR]

Hydrological connectivity between rivers and wetlands is considered one of the key critical factors for the integrity of floodplain landscapes. This study is a comprehensive modelling exercise on quantifying flood-induced wetland connectivity and the potential impacts of climate and water storage in an unregulated river basin in northern Australia. Flood inundation was simulated using a two-dimensional hydrodynamic model and the connectivities between wetlands and rivers were calculated using geoprocessing tools in ArcGIS. Wetlands in the floodplain were identified using waterbody maps derived from satellite imagery. A broadly representative sample of 20 wetlands were selected from 158 wetlands in the Mitchell basin considering location, size and spatial distribution. Five flood events ranging from 1 in 2 to 1 in 100 years were investigated to evaluate how connectivity changes with flood magnitude. Connectivities were assessed for the current condition as well as for two scenarios of future climate (Cwet and Cdry) and one scenario of dam storage. Results showed that a 1 in 100 years event inundated about 5450 km2 of land compared to 1160 km2 for a 1 in 2 years event. Average connectivity of wetlands in the Mitchell basin varies from 1 to 5 days for the floods of 1 in 2 to 1 in 26 years. As expected, a large flood produces longer duration of connectivity relative to a small flood. Results also showed that reduction in mean connectivity under a dryer climate (up to 1.8 days) is higher than the possibility of increase under a wet climate (up to 1 day). The impacts of a water storage, in the headwater catchment, are highly pronounced in terms of inundation and wetland connectivity (e.g., mean connectivity reduced by 1.7 days). The relative change in connectivity is higher for a small flood compared to that of a large event. These results demonstrate that there is a possibility of both increase and decease in connectivity under future climate. However, any water storage will negatively impact the connectivity between floodplain waterbodies and thus reduce the material exchange resulting in a reduction in primary and secondary productions in rivers and wetlands. [ABSTRACT FROM AUTHOR]

Determining the mean transit times (MTTs) and water sources in catchments at different flow conditions helps better understand river functioning, and manage river health and water resources. Despite being common in a range of environments, the MTTs and water sources in intermittent streams are much less well understood compared to perennial streams. Major ion geochemistry, stable isotopes, 14 C, and 3 H were used in this study to identify water sources and MTTs of the periodically intermittent upper Wimmera River from southeast Australia at different flow conditions, including zero-flow periods. The disconnected pool waters during the zero-flow period in the summer months of 2019 had 3 H activities of 0.64 to 3.29 TU. These and the variations in total dissolved solids and stable isotopes imply that these pools contained a mixture of older groundwater and younger stream water impacted by evaporation. 3 H activities during the high-flow period in July 2019 were 1.85 to 3.00 TU, yielding MTTs of up to 17 years. The 3 H activities at moderate and low-flow conditions in September and November 2019 ranged from 2.26 to 2.88 TU, implying MTTs of 1.6 to 7.8 years. Regional groundwater near the Wimmera River had 3 H activities of < 0.02 to 0.45 TU and 14 C activities of 57 to 103 pMC, and was not recharged by the river at high flows. The Wimmera River and other intermittent streams in southeast Australia are sustained by younger catchment waters from relatively small near-river stores than comparable perennial streams, which have older deeper regional groundwater inputs. This results in these intermittent streams being more susceptible to short-term changes in climate and necessitates the protection of near-river corridors to maintain the health of the riverine systems. [ABSTRACT FROM AUTHOR]

Central Asia is among the most heavily affected regions worldwide by climate change and water shortages. Impacts include changes in precipitation patterns, more frequent temperature extremes and increased aridity causing a negative impact on agricultural production, food availability, and environmental security. To combat this threat, it is important to enhance information literacy among all water users. This can be done through awareness campaigns, blended learning by providing the proper Technical and Vocational Education and Training (TVET) programs and utilizing all available facilities. This will address relevant issues, such as miscommunication, complexities of transboundary water sharing issues, overexploitation of water resources, and poor flood-drought mitigation techniques. Proper and user-friendly lifelong blended learning for scientific information dissemination focusing water issues can provide stronger support to increase awareness among water users and decision policy makers. Worldwide, especially in North America and Australia, information literacy campaigns have proven successful. This strategy can be replicated in the Mountainous Kyrgyz-Kazakh Chu-Talas transboundary river basin. The issues concerning the Mountainous KyrgyzKazakh Chu-Talas transboundary river basin is elaborated and compared with Australian, Canadian, and US river basin management programs. The foresight analysis is presented, as to what would be a rationale to improve water resources more sustainably in Central Asia. Methodologies, programs, technologies, communities-based river basin committees, snow-water collection with agroforestry, and basin-based water market opportunities were analyzed to assess potential applications in Central Asia region. [ABSTRACT FROM AUTHOR]

Restoration programmes for degraded aquatic ecosystems frequently focus on flow restoration or reinstatement, including recovery targets for volumes of water to be used for environmental benefit. Australia's Murray–Darling Basin is an example of a major system undergoing substantial water reform to balance the needs of competing users, including the environment, within the constraints of an arid climate. This reform revolves around accounting for finite volumes of water that have been shared amongst water users. We argue that while recovering water will provide good outcomes, as a sole intervention, it is not enough to deliver the desired environmental benefits of the reform given the significantly altered state of the catchment. Here, we present 10 measures that could be used to complement planned water recovery actions. These "complementary measures" integrate recovery actions, which when strategically combined with water delivery would significantly enhance water reform efforts to generate environmental outcomes in a highly modified system. [ABSTRACT FROM AUTHOR]

The effects of climate change have been observed in the Murrumbidgee River basin, which is one of the main river basins in the southeast region of Australia. The study area is the largest and most important agricultural production area within the Murray Darling Basin (MDB). It produces more than AUD 1.9 billion of agricultural products annually and accounts for about 46% of Australia's total agricultural production. Since Australia's economy largely depends on its natural resources, climate change adversely impacts the economy in various ways. According to the Intergovernmental Panel on Climate Change's fifth assessment report (IPCC, AR5), the adaptive capacity and adaptation processes have increased in Australia. The country has implemented policies and management changes in both rural and urban water systems to adapt to future drought, unexpected floods, and other climatic changes. In this study, future catchment runoff has been estimated using the hydrological model, Simplified Hydrolog (SIMHYD), which is integrated with data from three different General Circulation Models (GCMs) and future emission scenarios. Two different representative concentration pathway (RCP) emission scenarios, RCP 4.5 and RCP 8.5, have been used to obtain downscaled future precipitation and evapotranspiration data for the period of 2016 to 2100. Modeling results from the two emission scenarios showed an anticipated warmer and drier climate for the Murrumbidgee River catchment. Runoff in the Murrumbidgee catchment is affected by various dams and weirs, which yields positive results in runoff even when the monthly rainfall trend decreases. The overall runoff simulation result indicated that the impact of climate change is short and intense. The result of the Simplified Hydrolog (SIMHYD) modeling tool used in this study under the RCP 4.5 scenario for the period 2016 to 2045 indicates a significant future impact from climate change on the volumes of runoff in the Murrumbidgee River catchment. For the same period, the climate change prediction showed a decrease in total annual rainfall within the range of 2% to 62%. This reduction in rainfall is projected to decrease river runoff in the upper catchments (e.g., Tharwa, and Yass) by 17% to 58% over the projected periods. However, the runoff trends in the lower sub-catchments (e.g., Borambola) have increased by 137% to 87% under RCP 4.5 and RCP 8.5, respectively. This increasing potential runoff trend in the lower Murrumbidgee catchments gives an indication to build irrigation dams for dry season irrigation management. [ABSTRACT FROM AUTHOR]

The Hydrologic Reference Stations is a network of 467 high-quality streamflow gauging stations across Australia that is developed and maintained by the Bureau of Meteorology as part of an ongoing responsibility under the Water Act 2007. The main objectives of the service are to observe and detect climate-driven changes in observed streamflow and to provide a quality-controlled dataset for research. We investigate trends and step changes in streamflow across Australia in data from all 467 streamflow gauging stations. Data from 30 to 69 years in duration ending in February 2019 were examined. We analysed data in terms of water-year totals and for the four seasons. The commencement of the water year varies across the country – mainly from February–March in the south to September–October in the north. We summarized our findings for each of the 12 drainage divisions defined by Australian Hydrological Geospatial Fabric (Geofabric) and for continental Australia as a whole. We used statistical tests to detect and analyse linear and step changes in seasonal and annual streamflow. Monotonic trends were detected using modified Mann–Kendall (MK) tests, including a variance correction approach (MK3), a block bootstrap approach (MK3bs) and a long-term persistence approach (MK4). A nonparametric Pettitt test was used for step-change detection and identification. The regional significance of these changes at the drainage division scale was analysed and synthesized using a Walker test. The Murray–Darling Basin, home to Australia's largest river system, showed statistically significant decreasing trends for the region with respect to the annual total and all four seasons. Drainage divisions in New South Wales, Victoria and Tasmania showed significant annual and seasonal decreasing trends. Similar results were found in south-western Western Australia, South Australia and north-eastern Queensland. There was no significant spatial pattern observed in central nor mid-west Western Australia, with one possible explanation for this being the sparse density of streamflow stations and/or the length of the datasets available. Only the Tanami–Timor Sea Coast drainage division in northern Australia showed increasing trends and step changes in annual and seasonal streamflow that were regionally significant. Most of the step changes occurred during 1970–1999. In the south-eastern part of Australia, the majority of the step changes occurred in the 1990s, before the onset of the "Millennium Drought". Long-term monotonic trends in observed streamflow and its regional significance are consistent with observed changes in climate experienced across Australia. The findings of this study will assist water managers with long-term infrastructure planning and management of water resources under climate variability and change across Australia. [ABSTRACT FROM AUTHOR]

Spawning patterns in fish that use temperature as a spawning cue are responding to long‐term changes in the climate. The threatened Murray Cod, Maccullochella peelii (Mitchell), is an important apex species in inland south‐eastern Australia. Information from 1461 spawnings collected from hatcheries over 40 years was combined with environmental, meteorological, and astronomical data to (1) identify factors affecting spawning and (2) detect changes in spawning associated with climate change. The spawning season extended over four months, from late‐August at low latitudes to mid‐January at high latitudes, but locally lasted 1–2 months. Spawning events were preceded by an increase in temperature in the days leading up to spawning, whereas a decline in temperature inhibited spawning. In the Murray‐Darling River basin, the spawning season of Murray Cod began earlier and shortened in duration inversely with the mean spring temperature anomaly. Spawning is predicted to occur up to 4 weeks earlier by 2090 in response to future temperature projections in the Murray‐Darling River basin. Since climate change is affecting aquatic environments globally, findings from this study have implications to the long‐term management of temperate freshwater species that are the subject of regulations aimed to protect fish during the spawning season. [ABSTRACT FROM AUTHOR]

How populations of aquatic fauna persist in extreme desert environments is an enigma. Individuals often breed and disperse during favorable conditions. Theory predicts that adaptive capacity should be low in small populations, such as in desert fishes. We integrated satellite‐derived surface water data and population genomic diversity from 20,294 single‐nucleotide polymorphisms across 344 individuals to understand metapopulation persistence of the desert rainbowfish (Melanotaenia splendida tatei) in central Australia. Desert rainbowfish showed very small effective population sizes, especially at peripheral populations, and low connectivity between river catchments. Yet, there was no evidence of population‐level inbreeding and a signal of possible adaptive divergence associated with aridity was detected. Candidate genes for local adaptation included functions related to environmental cues and stressful conditions. Eco‐evolutionary modeling showed that positive selection in refugial subpopulations combined with connectivity during flood periods can enable retention of adaptive diversity. Our study suggests that adaptive variation can be maintained in small populations and integrate with neutral metapopulation processes to allow persistence in the desert. [ABSTRACT FROM AUTHOR]

The River Murray and the Coorong in Australia have been in a state of decline. With the prospect of extended droughts and shifts in inflows due to climate change, difficult choices loom. The options include halting the decline, triage of some assets along the River or staying with the declining river system. To support decision-making, a survey was designed to elicit willingness to pay for improvements in environmental quality. Over 3000 Australians responded to this survey. The study focuses on key River Murray environmental quality indicators: the frequency of bird breeding along the River Murray, increasing native fish populations in the River Murray, increasing the area of healthy vegetation along the River Murray, and restoring water bird habitat in the Coorong. State/Territory models were jointly estimated using a panel multinomial logit error-components model. Willingness to pay estimates for improvements in environmental quality were calculated for the River Murray and the Coorong. Respondents were found to be willing to pay most for the Coorong and to improve waterbird breeding frequency. Respondents from the Australian Capital Territory were found to have significantly higher willingness to pay whereas those in Victoria had a significantly lower willingness to pay than respondents in other states. [ABSTRACT FROM AUTHOR]

Climate change affects natural systems, leading to increased acceleration of global water cycle and substantial impacts on the productivity of tropical rivers and the several ecosystem functions they provide. However, the anticipated impacts of climate change in terms of frequency and intensity of extreme events (e.g., droughts and floods) on hydrological systems across regions could be substantially different. This study therefore aims to assess the impacts of climate change on the streamflow of a large river basin located in central Australia (Cooper Creek-Bulloo River Basin). Modified version of the hydrological model Hydrologiska Byråns Vattenbalansavdelning (HBV) was used in this study to generate daily streamflow. This model was first calibrated (2001–2010) and then validated for two independent periods (1993–1997 and 2011–2015). The model depicted a good performance in simulating observed streamflow. Climate projection data from multiple general circulation models (ACCESS1.0, CanESM2, CESM1-CAM5, CNRM-CM5, GFDL-ESM2M, HadGEM2-CC, MIROC5, NorESM1-M, ACCESS1-0, ACCESS1-3, CCSM4, CNRM-CM5, CSIRO-Mk3.6, GFDL-CM3, GFDL-ESM2M, HadGEM2, MIROC5, MPI-ESM-LR, and NorESM1-M) in various forms (raw, statistically downscaled, dynamically downscaled, and bias adjusted) were considered in this study. Results showed that three high resolution dynamically downscaled and bias adjusted models (ACCESS1-3, CNRM-CM5, and MPI-ESM-LR) from Terrestrial Ecosystem Research Network (TERN) dataset (v1.0.2) have better performance than other models considered, that is, in terms of capturing observed precipitation over the basin. Future climate projections of ensemble of these three models forced with RCP 4.5 and RCP 8.5 emission scenarios were then used to generate streamflow for 2050s (2040–2069) and 2080s (2070–2099). Results of the study indicated that mean annual precipitation was projected to decrease by up to −8% in 2050s and temperature was projected to increase by up to 4.66 °C in 2080s under the average and extreme emission scenarios, respectively. Mean annual, mean seasonal (December–February, March–May, June–August, September–November), and mean monthly streamflow were projected to decrease under different emission scenarios in 2050s and 2080s. These results indicate decreased water availability in the future as well as water cycle intensification. These changes in streamflow might have impacts on agriculture, natural ecosystem, and could lead to water restrictions. The outcome of this study can directly feed into frameworks for sustainable management of water resources and support adaptation strategies that rely on science and policy to improve water resources allocation in the region. [ABSTRACT FROM AUTHOR]

The Murray-Darling Basin (MDB) is Australia's major agricultural region. The southern MDB receives most of its annual catchment runoff during the cool season (April–September). Focusing on the Murrumbidgee River measurements at Wagga Wagga and further downstream at Hay, cool season river heights are available year to year. The 27-year period April–September Hay and Wagga Wagga river heights exhibit decreases between 1965 and 1991 and 1992–2018 not matched by declining April-September catchment rainfall. However, permutation tests of means and variances of late autumn (April–May) dam catchment precipitation and net inflows, produced p-values indicating a highly significant decline since the early 1990s. Consequently, dry catchments in late autumn, even with average cool season rainfall, have reduced dam inflows and decreased river heights downstream from Wagga Wagga, before water extraction for irrigation. It is concluded that lower April–September mean river heights at Wagga Wagga and decreased river height variability at Hay, since the mid-1990s, are due to combined lower April–May catchment precipitation and increased mean temperatures. Machine learning attribute detection revealed the southern MDB drivers as the southern annular mode (SAM), inter-decadal Pacific oscillation (IPO), Indian Ocean dipole (IOD) and global sea-surface temperature (GlobalSST). Continued catchment drying and warming will drastically reduce future water availability. [ABSTRACT FROM AUTHOR]

Evidence suggests that catchment state variables such as groundwater can exhibit multiyear trends. This means that their state may reflect not only recent climatic conditions but also climatic conditions in past years or even decades. Here we demonstrate that five commonly used conceptual "bucket" rainfall‐runoff models are unable to replicate multiyear trends exhibited by natural systems during the "Millennium Drought" in south‐east Australia. This causes an inability to extrapolate to different climatic conditions, leading to poor performance in split sample tests. Simulations are examined from five models applied in 38 catchments, then compared with groundwater data from 19 bores and Gravity Recovery and Climate Experiment data for two geographic regions. Whereas the groundwater and Gravity Recovery and Climate Experiment data decrease from high to low values gradually over the duration of the 13‐year drought, the model storages go from high to low values in a typical seasonal cycle. This is particularly the case in the drier, flatter catchments. Once the drought begins, there is little room for decline in the simulated storage, because the model "buckets" are already "emptying" on a seasonal basis. Since the effects of sustained dry conditions cannot accumulate within these models, we argue that they should not be used for runoff projections in a drying climate. Further research is required to (a) improve conceptual rainfall‐runoff models, (b) better understand circumstances in which multiyear trends in state variables occur, and (c) investigate links between these multiyear trends and changes in rainfall‐runoff relationships in the context of a changing climate. Key Points: Environmental state variables such as groundwater display multiyear trends in response to sustained climate anomaliesWe show that five commonly used conceptual "bucket" rainfall runoff models are unable to replicate such trendsBecause of this, the models fail to extrapolate realistically to different climatic conditions, compromising runoff projections Plain Language Summary: It is common in science to use a mental picture or metaphor that simplifies a complex phenomenon. A common metaphor used for a water supply catchment is that of a leaky bucket. When it rains, the bucket fills up; when it does not rain for a while, the bucket empties due to evaporation and water used by trees; and leaking water is like river flow. Computer models based on variants of this metaphor are common and can provide predictions of how much streamflow might occur under future scenarios. This paper explores limitations of the bucket metaphor and associated models. Recently, during a 13‐year drought in Australia, river catchments gradually started to dry up. With each passing year, the depth to groundwater increased gradually as the water used by trees was not replenished by rainfall. We compare this long, slow behavior to that of five commonly used "bucket" models. The models do not show the long, slow drying up—they only show the seasonal ups and downs, and their predictions of streamflow over the drought are poor. This is surprising, and it means we should choose our models carefully and seek out models that can simulate this behavior and its impact on streamflow. [ABSTRACT FROM AUTHOR]

The Murray Darling Basin is the primary watershed of the Australian continent. It is central to the national imaginary as both major food bowl and natural resource. Two hundred years of unsustainable pastoral and farming practices are threatening its ecological future and with it the nation-state's industrial agricultural economic base. I am a visual artist who works in multiple media. For most of my career I have been living and working in this region. A major component of my intellectual and artistic expression has been expended in a critical and aesthetic response to this watershed. The artworks documented in this essay were part of a 20-year (1989-2009) survey exhibition of my mediations and responses to the crisis of water allocation in the Murray Darling Basin. [ABSTRACT FROM AUTHOR]

Climate change is a material threat to Australia’s economic, social and environmental interests. Strong emergency management frameworks that enable agile responses to these threats are an important element to ensure a resilient economy. This paper considers recent blue green algae outbreaks in the Murray Darling Basin and considers some of the limitations to effective prevention, preparation, response and recovery. This paper proposes an alternative model that includes the responsibilities of the Commonwealth and the state and territory governments in the management of the basin’s resources. [ABSTRACT FROM AUTHOR]

Immediate and foreseeable threats to groundwater-dependent ecosystems (GDEs) are widely acknowledged, many linked to altered groundwater regimes including changes in groundwater flow, flux, pressure, level and/or quality (Eamus et al. in Aust J Bot 54:97-114, ). Natural resource managers and other decision-makers often lack sufficient information at an appropriate scale to understand the groundwater dependency of ecosystems and ensure that GDEs are adequately considered in decision-making processes. This paper describes a new catchment scale mapping method for GDEs based on the integration of local expert knowledge with detailed spatial datasets to delineate GDEs at a scale compatible with management and planning activities. This overcomes one of the key criticisms often levelled at broader scale mapping methods-that information from local and regional experts, with significant understanding of landscape processes and ecosystems, is not incorporated into the datasets used by decision-makers. Expert knowledge is conveyed in the form of pictorial conceptual models representing the components, processes and interrelationships of groundwater within a catchment and the ecosystems dependent on it. Each mapped GDE is linked to a pictorial conceptual model and a mapping rule-set to provide decision-makers with valuable information about where, how and why GDEs exist in a landscape. [ABSTRACT FROM AUTHOR]

Aim This study aims (1) to quantify the broad-scale patterns of functional diversity and life-history strategies of freshwater fish in relation to environmental variation across Australian river basins and (2) to identify key life-history traits associated with species extinction risk in order to determine how fish communities and extinction-prone species may respond to future environmental change. Location One hundred and twenty-three river basins across eastern Australia. Methods Based on 10 key life-history traits for 194 freshwater fish we used a novel analytical approach to quantify multivariate life-history indices in relation to environmental variation within a spatio-phylogenetic framework. We assessed the utility of our analytical framework by contrasting final models against all candidate models, both with and without an eigenvector filtering procedure, and quantified the degree of autocorrelation in all model residuals. Results Temperature, habitat heterogeneity/availability, flow variability and primary productivity accounted for between 55 and 80% of the variation in life-history indices. Best-performing models were all derived from the addition of spatial and phylogenetic covariates to the analytical framework which consistently produced more parsimonious final models with higher explanatory power and insignificant levels of autocorrelation in the model residuals. Main conclusion The life-history functional diversity of fish assemblages and the composition of life-history strategies across Australian river basins is in part determined by environmental variability, stability and seasonality, highlighting both the importance of environmentally driven community assembly processes and the potential changes to freshwater fish biodiversity in response to climate change. A spatio-phylogenetic analytical framework is a key component in the effective management of autocorrelation in ecological data and the derivation of more rigorous trait-environment relationships. [ABSTRACT FROM AUTHOR]

Abstract: Economic analysis of climate scenarios and alternative water policies is critical for development and implementation of appropriate water policies and programs. Mathematical models have been developed to assess water resources policies due to their ability to explicitly represent the biophysical dynamics of natural systems while integrating these within social and economic constraints. These models have been criticised, however, due to the problems of simplification, overspecialisation, plausibility and lack of empirical validation. This paper introduces a mathematical programming model which uses positive mathematical programming method to calibrate and model agriculture and water use in the Murray-Darling Basin of Australia. This paper reviews the theoretical and technical details of the model development including the key steps taken in collating and scaling the biophysical and economic data, and to address model parameterisation issues. The paper summarises results of an application of the model for assessing climate change impacts in the form of reduced rainfall and water allocations and increased crop water use for agricultural production. The results show the degree of variability in gross values under different climate scenarios compared to the base case scenario, especially in very dry years. The results also show how on-farm adaptation options and water markets can mitigate these losses. [Copyright &y& Elsevier]

Statistical methods traditionally applied for seasonal streamflow forecasting use predictors that represent the initial catchment condition and future climate influences on future streamflows. Observations of antecedent streamflows or rainfall commonly used to represent the initial catchment conditions are surrogates for the true source of predictability and can potentially have limitations. This study investigates a hybrid seasonal forecasting system that uses the simulations from a dynamic hydrological model as a predictor to represent the initial catchment condition in a statistical seasonal forecasting method. We compare the skill and reliability of forecasts made using the hybrid forecasting approach to those made using the existing operational practice of the Australian Bureau of Meteorology for 21 catchments in eastern Australia. We investigate the reasons for differences. In general, the hybrid forecasting system produces forecasts that are more skilful than the existing operational practice and as reliable. The greatest increases in forecast skill tend to be (1) when the catchment is wetting up but antecedent streamflows have not responded to antecedent rainfall, (2) when the catchment is drying and the dominant source of antecedent streamflow is in transition between surface runoff and base flow, and (3) when the initial catchment condition is near saturation intermittently throughout the historical record. [ABSTRACT FROM AUTHOR]

Addressing spatial connectivity in conservation planning is important to ensure the maintenance of patterns and processes needed to support the persistence of biodiversity. In freshwater ecosystems, spatial connectivity is constrained by the presence of water, which exhibits marked temporal changes in regions with wet-dry seasonal climates. Previous studies have focused on spatial connectivity and overlooked the temporal component, which is required for the functionality of spatial connections (because of temporal changes in water availability)., We identify priority areas for the conservation of freshwater fish, waterbirds and turtles in the Mitchell River catchment in the wet-dry tropics of northern Australia. We demonstrate how adequacy of freshwater conservation can be enhanced by integrating an estimate of water residency time ( WRT) into the prioritization process. WRT reflects refugial potential and connectivity in freshwater ecosystems and was quantified using Moderate Resolution Imaging Spectroradiometer ( MODIS) flood and post-flood Landsat satellite imagery. We compare the spatial allocation of priority areas and the spatial and temporal connectivity under two alternative scenarios: (i) accounting only for spatial connectivity and (ii) integrating spatial and temporal connectivity., Priority areas identified under the spatial and temporal connectivity scenario showed a 40% increase in WRT values with respect to the traditional spatial connectivity scenario. This was achieved at no additional cost in terms of total protected area and maintaining the same spatial connectivity., Despite priority areas identified under the two alternative scenarios showing intermediate spatial overlap (64%), the selection process was more efficiently biased towards planning units with high WRT values. WRT in planning units that were only selected under the temporal connectivity scenario was 2·5 times higher than in planning units that only appeared in the traditional connectivity scenario. This reveals the importance of accounting for WRT when identifying freshwater priority areas in wet-dry seasonal environments., Synthesis and applications: Considering the temporal connectivity in conservation prioritization as we propose here helps to assess periods of longest spatial connections, thereby maximizing the refugial role of freshwater priority areas during dry periods. Using publicly available satellite imagery data and software, our approach allows improved management of aquatic resources and biodiversity during periods of water scarcity, which may increase in incidence and duration with climate change. [ABSTRACT FROM AUTHOR]

The impact of future climate on runoff generation and the implications of these changes for management of water resources in a river basin are investigated by running these changes through catchment and river system models. Two conceptual daily rainfall-runoff models are used to simulate runoff across the Macquarie-Castlereagh region for historical (1895-2006) and future (∼2030) climate based on outputs from 15 of the 23 IPCC AR4 GCMs for the A1B global warming scenario. The estimates of future runoff are used as inputs to the river system model. The mean annual historical rainfall averaged across the Macquarie-Castlereagh region is 544 mm and the simulated runoff is 34 and 30 mm for SIMHYD and Sacramento rainfall-runoff models, respectively. The mean annual future rainfall and runoff across the region are projected to decrease. The modelling results show a median estimate of a 5% reduction for SIMHYD (50% confidence interval -11 to +7%) and a 7% reduction for Sacramento (50% confidence interval -15 to +8%) in mean annual runoff under a ∼2030 climate for the region. The results from the river system modelling indicate that under the ∼2030 climate scenario, the median of general security and supplementary diversions are projected to decrease by 4% +50% confidence interval -10 to +5%) and 2% +50% confidence interval -5 to +3%) respectively for the SIMHYD inflows and 8% +50% confidence interval -17 to +6%) and 5% +50% confidence interval -11 to +3%) for the Sacramento inflows. The future annual and seasonal storage volumes for the Burrendong Dam and inflows at all major locations across the region are projected to be lower than the historical records. [ABSTRACT FROM AUTHOR]

The Holocene sedimentary record in southeastern Australia is present in a range of landscape settings, such as upland swamps (dells), internally drained lake basins, alluvial fans, and mid-catchment and lowland floodplains. An assessment of the best-constrained basal radiocarbon dates in valley-fill locations between 30 and 42°S and upstream of last-glacial eustatic influences yields an intriguing pattern. The record for fluvial sites with catchment areas >30km2 exhibits a distinct gap in the alluvial record between 8 and 4 ka BP (10–4.5 ka). In contrast, data for eleven upland-swamp sites with catchment areas <50km2 exhibit a broader spectrum of basal ages, albeit with some reduction of activity during the alluvial gap. We suggest that the period 8<4 ka BP in the sedimentary record at the fluvial sites reflects the early to mid-Holocene climatic optimum independently recognized in proxy climate data in the region. It was a period of enhanced water discharges, stable well-vegetated catchments and low sediment yields, and therefore greatly limited sediment sequestration, and it has been termed the Nambucca Phase. In upland swamps, however, threshold-driven processes produce an episodic landscape responses during much of the Holocene. Contrasting results in upland compared with middle and lower basin locations demonstrate the nonuniform landscape response to climatic changes during the Holocene in southeastern Australia. [ABSTRACT FROM AUTHOR]