Search

• Climate adaptation policy in a large river basin is explored. • Empirical study of science and policy interactions during actual reforms. • Interviews with senior research policy professionals reveal dynamics of policy formulation. • Proposes legally prescribed procedures for utilising science in environmental policy formulation. Climate change has many disruptive consequences, particularly in large river basins experiencing drying trends and declining water availability. With pressure for more adaptive policies, understanding how institutions governing water are adapting to climate risks has broad international relevance. This paper examines the challenges of climate risk assessments in Australia's Murray Darling Basin, an economically and culturally important basin where national legislation mandates a Basin Plan based on the best available science. However, despite repeated scientific warnings about a drying climate, the current Basin Plan does not reduce estimates of water resources available, and its climate risk management relies on a bricolage of policy mechanisms, which appear insufficient for the magnitude of predicted changes. This paper outlines the findings of original research exploring why this occurred. It draws on interviews with 30 senior public policy professionals and researchers with deep experience in climate and water policy. The interview data indicate that minimising political risks were the principal reasons for abandoning proposed reductions in entitlements and for relying on historical averages for estimating water availability. As the reform process evolved, decisions about water-planning techniques became increasingly politicised, and the adoption of explicit climate adaptation measures became problematic. As a result, the Basin Plan neither reflects the broad scientific consensus about climate change nor makes specific allowances for declining water availability. Climate risks are downplayed while concerns about levels of scientific uncertainties appear overstated. Importantly, lessons emerge from this examination that could contribute to the revisions of the Plan, scheduled for 2026. More generally, the research finds that proactive climate adaptation policies for large river basins require sustained and well-designed institutional reforms, particularly the adoption of legally prescribed procedures for utilising science - and accounting for its use - in controversial environmental reforms. [ABSTRACT FROM AUTHOR]

Commercial buildings are central to cities and contribute significantly to the urban demand for natural resources, including freshwater. Green building benchmarking tools include more efficient water use as key indicator of sustainability. This paper explores options for substituting mains drinking water with an alternative, non-potable water source on a fit for purpose basis. The research findings are based on a monitoring study of a commercial building in Brisbane, Australia that is harvesting rainwater for meeting non-potable water demand. The results demonstrated that the system is only achieving moderate reliability in meeting demand due to operational problems. The case study analysis has highlighted the need to include validation and monitoring to ensure the system is operating as per design intent. The paper also investigates the potential of other local, non-potable water sources for high-rise commercial buildings, in particular air conditioning condensate and groundwater inflow to a basement wet well. The paper concludes by comparing the advantages and disadvantages of different local water sources which highlights the need to undertake a site specific investigation to identify a suitable alternative water source, which considers O&M complexity and the capacity of facilities management. [ABSTRACT FROM AUTHOR]

The study conceptualises water security indicators in the regional urban context for water security policy formulation and implementation. The paper used a Process Analysis Method (PAM) to develop and apply a set of Urban Water Security (UWS) indicators suitable for the regional urban water authorities. The UWS indicators were calibrated and validated by the relevant stakeholders of the northern, tropical, urban region of Queensland, Australia. Although the priorities for different regional cities vary, the indicators are expected to help water authorities monitor, measure and track their policy performance over time. • Regional cities are having their unique water supply security challenges. • Urban water supply Indicators designed with stakeholder consultation and verification. • Indicators are developed to support urban water supply policy formulation to improve water security. • Pilots the indicators in a regional urban water context. [ABSTRACT FROM AUTHOR]

• This paper extends the residual mass concept to propose a new method to quantify water availability. • The method automates the identification of deficit periods in the residual mass curve. • The method is validated against SPI and streamflow for Australia. Water supply management for hydroclimatic extremes has commonly been analysed using the cumulative difference between inflow and demand, a concept known as the Residual Mass Curve. This paper extends the residual mass concept to develop a new method to quantify water availability, termed the Residual Mass Severity Index (RMSI). The RMSI improves on the Residual Mass Curve by allowing extreme deficit periods to be easily identified without the need for manual inspection of the Residual Mass Curve. Another advantage of the RMSI is that it does not require a temporal window to be specified to characterise extreme deficit periods, which is needed for many drought indices such as the Standardized Precipitation Index (SPI). This paper develops the method for calculating the RMSI using precipitation time series and compares it to the SPI for different drought durations across Australia. Major hydroclimatic extremes during the instrumental period are assessed using RMSI, SPI, and by comparing the RMSI estimates with streamflow data from 467 catchments with varying sizes and climate across Australia. RMSI is a useful index for water managers interested in assessing water availability with potential applicability in summarising the features of historical hydroclimatic extremes as well as future changes in water availability due to anthropogenic climate change. [ABSTRACT FROM AUTHOR]

Highlights • Genetic gains of Australian wheat were associated with higher water-nitrogen co-limitation. • Higher water-nitrogen co-limitation associated with a higher nitrogen uptake per unit of evapotranspiration. • Nitrogen traits are critical for drought adaptation. Abstract The interactions between nitrogen (N) and water are manifold, and the concept of co-limitation provides a quantitative framework for integration. This paper tested the hypothesis that selection for yield increased water-N co-limitation in wheat adapted to winter rainfall environments of Australia. To test this hypothesis, we measured evapotranspiration, N uptake and yield in a historic collection of varieties released between 1958 and 2007 (exp. 1) and between 1969 and 2015 (exp. 2). Crops were grown under 5 (exp. 1) or 4 (exp. 2) environmental conditions resulting from the combination of sites, seasons, and supply of N and water. Genetic gain of yield, i.e. the slope of the regression between yield and year of release was 14–24 kg ha−1 y−1 or 0.36–0.52% y−1. This yield gain was associated with a linear increase in water-N co-limitation, in turn associated with an increase in N uptake per mm of evapotranspiration at a rate of 0.0019 kg N mm−1 y−1. Our findings highlight the critical role of nitrogen for the adaptation of wheat to low rainfall environments, and the scope for further yield improvement based on traits that integrate resources. [ABSTRACT FROM AUTHOR]

This paper empirically examines through a single case study three theoretical models of science-policy interactions identified in the literature: science-push, policy-pull and co-production. Although the literature is clear that reliance on orderly linear models of knowledge transfer from science into policy is ineffective, more precise guidance is needed for those in the scientific community interested in effectively mediating the science-policy interface to inform policy and decision-making. We examine the case of urban water management in Melbourne, Australia, which is widely regarded as a frontrunner in sustainable urban water practices. We find the prominent (interlinked) features of Melbourne’s science-policy interface are actors, networks and relationships, and funding. Overall, science-policy interactions in Melbourne are highly complex and do not neatly fit into one specific theoretical model. Prominent framings of each model vary depending on context, history and time-scale. There are strong indications however that a collaborative approach is increasingly being embraced at Melbourne’s water-management interface. This could be attributed to Melbourne’s highly network-based science-policy culture, which facilitates strong collaboration between policy-makers and scientists. We explore how the three models of interaction identified in the literature combined with insights from Melbourne can be used to frame strategies to effectively mediate the science-policy interface. These insights increase our understandings of the science-policy interface and provide practical insights and strategies for researchers interested in effective engagement with policy communities. [ABSTRACT FROM AUTHOR]

• We modify a method to assess yield of carryover reservoir with environmental flow. • The method can be applied at large scales, under historic and future climates. • We quantify yield declines due to climate change and environmental flow provision. Protecting freshwater systems to ensure sustainability requires diagnosing threats over a broad range of scales, from local to global. There is growing acceptance that environmental flows must be protected to sustain river channels and floodplain ecosystems downstream of reservoirs. Meeting environmental water requirements has proven difficult because they reduce water yield available for human use – a particular challenge in regions already experiencing declining water availability with climate change. A further challenge is the difficulty of assessing the impact of environmental water requirements on water availability for other purposes. This paper provides a modification of the Gould-Dincer method to assess the yield of carry-over reservoirs subject to environmental water requirements. The method characterizes reservoir inflows using readily available flow characteristics (annual mean and C v). We develop and test the method using ten examples with well-understood environmental water requirements and a range of annual flow C v s. We then demonstrate this method at continental scale, to investigate the impact on yield of providing high-reliability supply including environmental water requirements, under a changing climate. According to our results, considering climate change and environmental flow provision simultaneously, the decline in water yield is projected to be about 27% and 18% respectively for Australia and US (based on hypothetical reservoirs capacity of one times mean annual inflow). Adapting environmental flow demands to future hydrological conditions results in a 2% and 3% increase in Australia and US-wide yield for human use respectively. While further testing is needed, the method provides a simple and rapid way to estimate the impact of providing environmental flow on yield, applicable at global scale. [ABSTRACT FROM AUTHOR]

Cast iron was the dominant material for buried pipes for water networks prior to the 1970s in Australia and overseas. At present, many water utilities still have a significant amount of ageing cast iron pipes. Cast iron is a brittle material and when large diameter cast iron pipes (diameters above 300 mm) further deteriorate, the consequences of failure can be substantial. Focusing on the likelihood of failure to assist risk assessment, this paper examines the performance of large-diameter cast iron pipes using probabilistic analysis, incorporating uncertainties of governing variables. Finite element analysis is first conducted to study the physical mechanism of buried pipes subjected to complex environmental conditions. The deterioration of cast iron pipes due to corrosion is considered on the basis of recent research. The uncertainties of governing variables, such as the physical properties of soil, cast iron, water pressure and corrosion patterns, in pipe failure risk assessment are considered. Using probabilistic physical modelling, the lifetime probability of failure is derived and a time-dependent sensitivity analysis is presented. The results of this probabilistic physical modelling are compared with cohorts of failure data from two Australian water utilities to examine the underlying trends from both physical modelling and statistical analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wildfires are becoming more severe and frequent and their effects increasingly expose water resources to stress. • Climate, wildfire, streamflow records (1975 to 2018), topography, and landcover data from 92 catchments were combined to quantify the contribution of wildfire to streamflow variability across Australian temperate forests. • On average wildfire regimes relatively results in 8.8% increases in streamflow across Australian temperate forests. • Wildfire effects on regional streamflow varied spatially depending on hydroclimate factors, particularly precipitation. As wildfires become more frequent and severe, there are concerns regarding their impacts on water yield from forested catchments. While there are many studies in Australia about the effects of individual wildfires on streamflow at fine scales (<1 km2) in specific geographic settings, the effects of wildfire regimes on streamflow at broad spatial scales across temperate forests in Australia are not well understood. In this paper, we combined climate, wildfire, streamflow records (1975 to 2018), topographic, and landcover data from 92 catchments (74 – 4740 km2) in the Australian temperate zone to quantify the contribution of wildfire regimes over time to streamflow variability in different hydroclimatic settings (humid, dry sub-humid, and semi-arid) and geographic regions (Southeast Australia (SEA), Southwest Western Australia (SWWA), and Tasmania (TAS)). Wildfire regimes were represented by two metrics: the burnt area to drainage area (BDA) ratio for wildfire events in each year and a spatially averaged metric of Time Since Fire (TSF), which is a spatial average of time since the last wildfire in the catchment. By comparing prefire and postfire runoff ratios our study found that on average there was a short-term increase in runoff ratio (∼3% in year 1 and ∼6% in year 2 post-fire) after wildfires with BDA > 25%. No influence of fire was found in the long-term (15–20 years after the wildfire) runoff ratio. We found that wildfire regime, measured by TSF, explained ∼8.8% of the variation in annual streamflow across the Australian temperate zone, and that with decreasing TSF (i.e., increased wildfire impact), the average streamflow increased. Streamflow variation explained by wildfire regimes varied with hydroclimate. The explained variance of streamflow by wildfire regimes in semi-arid catchments (23%) and dry sub-humid catchments (13%) were higher than humid catchments (5%). Our results provide a broad-scale understanding of how wildfire regimes influence streamflow variability at broad temporal and spatial scales, and provided important context and baseline information for determining the implications of changes in climate and fire regimes for regional water availability. [ABSTRACT FROM AUTHOR]

The prediction of future drought is an effective mitigation tool for assessing adverse consequences of drought events on vital water resources, agriculture, ecosystems and hydrology. Data-driven model predictions using machine learning algorithms are promising tenets for these purposes as they require less developmental time, minimal inputs and are relatively less complex than the dynamic or physical model. This paper authenticates a computationally simple, fast and efficient non-linear algorithm known as extreme learning machine (ELM) for the prediction of Effective Drought Index (EDI) in eastern Australia using input data trained from 1957–2008 and the monthly EDI predicted over the period 2009–2011. The predictive variables for the ELM model were the rainfall and mean, minimum and maximum air temperatures, supplemented by the large-scale climate mode indices of interest as regression covariates, namely the Southern Oscillation Index, Pacific Decadal Oscillation, Southern Annular Mode and the Indian Ocean Dipole moment. To demonstrate the effectiveness of the proposed data-driven model a performance comparison in terms of the prediction capabilities and learning speeds was conducted between the proposed ELM algorithm and the conventional artificial neural network (ANN) algorithm trained with Levenberg–Marquardt back propagation. The prediction metrics certified an excellent performance of the ELM over the ANN model for the overall test sites, thus yielding Mean Absolute Errors, Root-Mean Square Errors, Coefficients of Determination and Willmott's Indices of Agreement of 0.277, 0.008, 0.892 and 0.93 (for ELM) and 0.602, 0.172, 0.578 and 0.92 (for ANN) models. Moreover, the ELM model was executed with learning speed 32 times faster and training speed 6.1 times faster than the ANN model. An improvement in the prediction capability of the drought duration and severity by the ELM model was achieved. Based on these results we aver that out of the two machine learning algorithms tested, the ELM was the more expeditious tool for prediction of drought and its related properties. [ABSTRACT FROM AUTHOR]

Modelling offers a time efficient and cost-effective approach to integrate and analyse different components of complex peri-urban hydroecological systems. This paper evaluates and applies a catchment water balance model (Peri-Urban SimHyd) developed to simulate the complete water cycle of the South Creek catchment, a complex peri-urban catchment in Western Sydney (Australia). Peri-Urban SimHyd combined the modelling of daily rainfall-runoff from both impervious and pervious surfaces with the modelling of monthly reticulated potable water supply, wastewater flows, and surface and groundwater extractions, to simulate the monthly water balance of the catchment. The model was successful (the Nash-Sutcliffe efficiency >0.68) in simulating the monthly total wastewater discharges and streamflows in the South Creek and its main tributary, the Eastern Creek, over a period of 15 years (1992–2006). The model performance was found to be suitable for simulating macro water balance and catchment yield but not for low streamflow hydrographs. Further, the model demonstrated its applicability in assessing the impacts of water cycle management strategies, i.e. ‘ replacement flows ’ and ‘ water smart farms ’ scenarios, on monthly and annual streamflows in the South Creek catchment. In general, Peri-Urban SimHyd has a generic structure and can be employed to assess impacts of various ‘what if’ scenarios on water cycle and streamflows in other peri-urban hydroecological systems. [ABSTRACT FROM AUTHOR]

• The macadamia industry is growing rapidly. • There is limited research on macadamia water use. • Macadamia is characterised by strict stomatal regulation. • Macadamia is drought-tolerant. • The hydrological implications of macadamia expansion remain unknown. Growing macadamia nut trees continues to gain popularity due to the delicacy and nutritional value associated with the nuts. These evergreen trees are grown in areas where rainfall quantity and distribution is often inadequate to sustain optimum yields. As a result, irrigation is often required to meet demands and achieve maximum profits. However, there is little detail on the minimum volume of water required during different growth stages to obtain optimal yields. This paper reviews existing studies on the plant-water relations of macadamia nut trees from the perspective of understanding their impacts on water resources. Macadamia trees have been found to use an average 75 L tree−1 day−1 in Australia, while values range between 4 and 71 L tree−1 day−1 for trees grown in South Africa. Macadamia trees are characterised by strict stomatal control, enabling them to maintain a favourable water status for prolonged periods under water stressed conditions. However, stress during the premature nut drop and oil accumulation stages decreases yield and quality. On the other hand, imposing stress at floral initiation increases yield. Therefore, stress manipulation may be a useful management tool for improved water use efficiency in commercial orchards. This requires accurate measurements of the thresholds for the maximum stress and minimum water required at these critical stages. Yield response to irrigation has been difficult to determine with confidence. Due to the cyclical nature of macadamia yields, it has been recommended that a minimum of five years is required to establish a relationship between water use and yield. There has been a limited amount of work done on the impacts of macadamia production on water resources and financial constraints are likely to limit this in the future. However, based on the rapid development of commercial macadamia orchards, future water-related research needs to consider macadamia production beyond tree and orchard scales, viewing macadamia as part of a socioecological system where orchard water use may impact on the availability and quality of water for other users, including the environment. [ABSTRACT FROM AUTHOR]

• Remote sensing provides a way to monitor irrigation water use at the catchment scale. • Accurate irrigation simulations are observed over a range of catchment sizes and crop types. • Better results are seen in wetter years (water allocations above 40%). • Long term negative drought indices (SPIs), indicating dry years, shows a decrease in accuracy. Irrigated agriculture has been identified as using approximately 72% of water globally. Australia, like many places in the world, is subject to water sharing plans that cross government boarders and are subject to a mixture of management policies. There is a pressing need to develop a method to monitor irrigation water use to aid in water resource assessments and monitoring. This paper aims to test a method previously developed which monitors irrigation water use using remotely sensed observations over the catchment scale, without the need for in-situ observations, ground data or in-depth knowledge of crops and their planting dates. Using conservative assumptions about agricultural land management practice, irrigation is calculated as I r r = A E T - P. The method uses three vegetation indices derived from Landsat images to calculate crop coefficients (K c) based on multiple published relationships. These are combined through the FAO56 methodology using gridded rainfall and two reference evapotranspiration ( E T o) products to find actual evapotranspiration as A E T = E T o × K c , providing six E T o - K c combinations. Results indicate this study method can effectively assess irrigation water use over a range of catchment sizes from ~6000 to ~600,000 ha, although issues arise when regions have a designated low allocation volume for that season (less than40%). Comparisons with the Standardised Precipitation Index (SPI) and Evaporative Stress Index (ESI) show that the proposed method is robust to the rapid onset and short-term droughts, However, its performance was poor during the long term droughts with low water allocation years. The study results during these years has been predominately attributed to water stress in certain crops being undetected, agricultural managers skipping annual crop commodities as well as stock and domestic water use making up larger portions of total water use. This is a limitation of this approach, although when only comparing results in years with greater than 40% allocations, the results improved significantly showing it can monitor water use effectively. When adequate water is available, this approach is able to accurately predict irrigation water use for the sites examined. [ABSTRACT FROM AUTHOR]

Lake Mungo is a currently dry lake basin in the semi-arid zone of southeastern Australia. The transverse dune system on the downwind side contains a record of human occupation of international importance. It also contains one of the most continuous records of climate change over the last glacial cycle in the Australia desert. In this paper we provide a framework for the interpretation of lake level history from before the arrival of people (>41 ka) until after the establishment of the pastoral industry in the area. We present 83 optically stimulated luminescence ages from the Lake Mungo lunette. The lake level history is reconstructed from 34 stratigraphic sections along three transects through the lunette. The dating reveals considerable lake level fluctuations through time which occur over a depth range of ∼10 m in the basin. At its height, probably at multiple times before 20 ka, the lake held more than 1 km3 of water and at its final level at ∼19 ka, contained only 0.03 km3. The inception of Lake Mungo appears to have taken place during the mid-Pleistocene between ∼256 and 369 ka. During the last glacial cycle, Lake Mungo was almost continuously wetter than present from shortly after 60 ka until ∼19 ka. The Upper Mungo, Arumpo and Zanci units represent a succession of lake filling and drying events, briefly interspersed by soils. The final Zanci unit does not represent a single high lake phase, but an initial lake filling followed by a series of short-lived lake level events within a brief period of a few thousand years. At the conclusion of this event, the lake remained dry until the present day. Four OSL ages from a linear dune upwind of Lake Mungo indicates regional aeolian activity from ∼30 ka until present. Widespread erosion that produces the characteristic topography of the lunette began after the arrival of British pastoralists and traditional aboriginal ways of life overlapped briefly with this erosion. The presence of water in Lake Mungo closely corresponds to periods when regional surface temperature was colder than present during the late Pleistocene. Our new data supports a model that decreased evaporation and increased runoff were primarily responsible for increased availability of surface water in the hydrological cycle. • The lake level history of Lake Mungo is reconstructed from 34 stratigraphic sections and 83 luminescence ages. • The lake level fluctuated over a depth range of ∼10 m in the basin, from more than 1 km3 of water to only 0.03 km3. • The inception of the lake appears to have taken place during the mid-Pleistocene at ∼256–369 ka. • The lake filled during the last glacial maximum. • The presence of water in Lake Mungo corresponds to when regional surface temperature was significantly colder than present. [ABSTRACT FROM AUTHOR]

• Restoration of water quality in watersheds is a major challenge in many parts of the world. • In south-western Australia stream salinity has been reversed in a 502 km2 watershed. • This was achieved through government planning and regulation and private sector investment in reforestation. Restoration of water quality in deforested watersheds is a major environmental and economic challenge in many parts of the world. In south-western Australia water quality issues manifest as salinisation, where reactivation of groundwater systems has occurred post-deforestation with the consequent discharge of salts stored in deep regolith into rivers. Prior to deforestation the stream salinity of the Denmark River (a forested watershed of 502 km2) was between 150 and 350 mg L−1TDS (Total Dissolved Solids) and was developed as a small water supply with potential for a much larger development. By the 1970s, 20% of deep rooted vegetation in the watershed was removed resulting in annual flow-weighted stream salinity of 1500 mg L−1TDS making the river unsuitable as a water supply. Two main policy approaches were used to restore this watershed: (1) the control of further deforestation on private land through regulation; and (2) a program to encourage private reforestation with eucalypt pulp-wood plantations. By 2010, 14.5% of the watershed was reforested leaving only 5.5% still deforested, with a strong relationship between streamflow and stream salinity and the amount of reforestation. River salinity had fallen to 500 mg L−1 TDS by 2017. Although streamflow had fallen from a mean 28.6 GL yr−1 in 1985–1990 to 13.6 GL yr−1 in 2012–2017 this was with water that was potable. The challenge into the future is to ensure the lower stream salinity is maintained through maintenance of forest cover. Importantly, this paper demonstrates that stream salinity can be reversed following deforestation if an appropriate scale of reforestation is deployed. [ABSTRACT FROM AUTHOR]