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A three-dimensional (3D) numerical model was developed to investigate the thermodynamic and sediment processes in a subtropical drinking water reservoir. Data-driven models were also established to generate the inflow conditions. The modelling outputs revealed that climatic forces such as storms and winds significantly impact lake stratification and mixing processes. The sediment transport is driven by storm events, during which sediment delivery to the reservoir is dominated by allochthonous flux. The sediments are transported from riverine zones to transition zones and finally to lacustrine zones. It is estimated that sediment accumulation could have reached 100,000 kg during the largest storm event in February 2015. The winds can lead to a strong vertical water cycle, especially at the centre of the reservoir, and strong winds result in bed erosion in shallow regions. The outcomes of this paper benefit future research by providing a modelling approach for understanding the hydrodynamics of lakes and reservoirs under a variable climate, and also the local water utility by providing insights for an improved management of the reservoir of this study.

The Mudgeeraba drinking water treatment plant, in Southeast Queensland, Australia, can withdraw raw water from two different reservoirs: the smaller Little Nerang dam (LND) by gravity, and the larger Advancetown Lake, through the use of pumps. Selecting the optimal intake is based on water quality and operators' experience; however, there is potential to optimise this process. In this study, a comprehensive hybrid (data-driven, chemical, and mathematical) intake optimisation model was developed, which firstly predicts the chemicals dosages, and then the total (chemicals and pumping) costs based on the water quality at different depths of the two reservoirs, thus identifying the cheapest option. A second data-driven, probabilistic model then forecasts the volume of the smaller LND 6 weeks ahead in order to minimise the depletion and spill risks. This is important in case the first model identifies this reservoir as the optimal intake solution, but this could lead in the long term to depletion and full reliance on the electricity-dependent Advancetown Lake. Both models were validated and proved to be accurate, and with the potential for substantial monetary savings for the water utility.

A reliable simulation of the manganese cycle in water supply system is essential for timely and effective manganese treatment strategies. A data-driven model estimating manganese levels in the treated water was developed through a threshold-based approach using raw water and supernatant return manganese levels. This data-driven model and a three-dimensional manganese cycle model for the source reservoir were integrated to simulate the overall manganese variations from the lake to the treated water. A decision support system based on the developed data-driven model was established to allow operators to react to situations that could result in elevated levels of manganese in the treated water. Scenario analyses were completed to examine the manganese variations in the reservoir, raw water and treated water due to different precipitations and wind conditions and to allow the identification of optimal strategies for manganese management from the reservoir to the water supply system.

The recent deployment of fluorescent dissolved organic matter (fDOM) probes in dam catchments and drinking water treatment plants (DWTP) for water quality monitoring purposes has resulted in the production of a large amount of data that requires scientific evaluation. This study introduces a comprehensive, transferable methodological framework for scientists and water professionals to model fluorescence site-specific quenching on fDOM probe readings caused by temperature, suspended particles, and the inner filter effect (IFE) and applies it to an Australian subtropical reservoir. The findings revealed that quenching due to turbidity and IFE effects were best predicted by threshold autoregressive models. Raw fDOM probe measurements were validated as being more reliable if they were systematically compensated using the proposed procedure. The developed fDOM compensation procedure must consider the instrument features (i.e., wavelength broadband and responsiveness) and site-specific conditions (i.e., DOM characteristics and suspended particles). A finding of particular interest was that the compensated normalized fDOM readings had a high correlation with the low (&lt, 500 Da) molecular weight fraction of the DOM, which is more recalcitrant to removal by coagulation. As a consequence, there is potential to use compensated fDOM probe readings to provide real-time, in situ information on DOM properties in freshwater systems, which will enable water treatment plant operators to optimize the coagulation process.

In order to reduce the total cost of a dual source drinking water treatment plant operation, a comprehensive hybrid prediction model was built to estimate the necessary chemicals dosage and pumping energy costs for alternative source selection scenarios. Correlations between the water quality parameters and the required treatment chemicals were estimated using historical data and the expected pH variations associated with each chemical addition, which was based on the Caldwell-Lawrence diagram. The pumping energy costs were also estimated using a data-driven approach that was based on historical plant data. The research has practical implications for water treatment operators seeking to minimize plant operational costs through selecting raw water intake volumes for their treatment plant based on multiple source options and offtake tower gate levels. Future research seeks to better link current and future water treatment dosage cost predictions directly to water quality measurements taken from vertical profiling systems. Prediction model built to estimate treatment costs for a dual source drinking WTP.Model optimises source selection proportions based on treatment and pumping costs.Model aids WTP plant operators to alter the source selection strategy in extreme events.Model utilisation for source selection optimization delivers life cycle monetary savings.

Summary This paper presents an extensive investigation of the mixing processes occurring in the subtropical monomictic Advancetown Lake, which is the main water body supplying the Gold Coast City in Australia. Meteorological, chemical and physical data were collected from weather stations, laboratory analysis of grab samples and an in-situ Vertical Profiling System (VPS), for the period 2008–2012. This comprehensive, high frequency dataset was utilised to develop a one-dimensional model of the vertical transport and mixing processes occurring along the water column. Multivariate analysis revealed that air temperature and rain forecasts enabled a reliable prediction of the strength of the lake stratification. Vertical diffusion is the main process driving vertical mixing, particularly during winter circulation. However, a high reservoir volume and warm winters can limit the degree of winter mixing, causing only partial circulation to occur, as was the case in 2013. This research study provides a comprehensive approach for understanding and predicting mixing processes for similar lakes, whenever high-frequency data are available from VPS or other autonomous water monitoring systems.

A series of experiments were undertaken in order to understand and predict the dosage of powdered activated carbon required to remove taste and odour compounds in an Australian drinking water treatment plant. Competitive effects with organic matter removal by aluminium sulphate during coagulation were also quantified. Data on raw and finished water quality following jar tests, as well as chemical dosages and treatment performance, were statistically analysed, and a data-driven prediction model was developed. The developed powdered activated carbon dosage prediction model can be used by the plant operators for rapid dosage assessment and can increase the preparedness of the plant to sudden taste and odour events. It was also found that total organic carbon levels and properties greatly affect the ability of powdered activated carbon to remove taste and odour compounds; on the other hand, total organic carbon removal is not affected by high taste and odour levels, since these were still much lower than organic carbon concentrations.

A good understanding of the physical processes of lakes or reservoirs, especially of those providing drinking water to residents, plays a vital role in water management. In this study, the water circulation and mixing processes occurring in the shallow, subtropical Tingalpa Reservoir in Australia have been investigated. Bathymetrical, meteorological, chemical and physical data collected from field measurements, laboratory analysis of water sampling and an in-situ Vertical Profile System (VPS) were analysed. Based on the high-frequency VPS dataset, a 1D model was developed to provide information for vertical transport and mixing processes. The results show that persistent high air temperature and stable reservoir water depth lead to a prolonged thermal stratification. Analysis indicates that heavy rainfalls have a significant impact on water quality when the dam level is low. The peak value of Dissolved Organic Carbon (DOC) concentration occurred in the wet season, while the specific UV absorbance (SUVA) value decreased when solar radiation increased from spring to summer. The study aims to provide a comprehensive approach for understanding and modelling the water mixing processes in similar lakes with high-frequency data from VPS&rsquo, s or other monitoring systems.

Periods of urban water scarcity in cities places pressure on government agencies and water utilities to improve water distribution system efficiency through reducing the amount of water lost in the network as well as deploying a range of demand management techniques to conserve existing supply. Current estimations assume customer post meter leakage accounts for up to 10% of total water consumption, particularly in the residential sector. Households identified as having post meter leakage using a citywide installation of smart metering technology were subjected to a mix of basic and tailored information regarding water loss. The primary aim of the study was to test the effectiveness of communication interventions and the attributed water savings resulting from the repair of household leaks. The residential leakage communication strategy resulted in a reduction in minimum night flows by a very significant 89% over the duration of the study, while the control group receiving no communication increased consumption by 52%. Moreover, questionnaire surveys were conducted to establish the significant factors, including leak type, demographics and household awareness, to name a few, that will influence the development of a fit-for-purpose post-meter leak rectification policy and program. The paper concludes with some key recommendations for future work to develop a predictive model for identifying, classifying and quantifying post meter loss as well as presents least cost planning implications of a leak rectification policy. The study confirmed that smart metering provides water utilities with a powerful tool to rapidly identify and action the significant volumes of post meter leakage occurring in our cities.

Understanding and predicting Taste and Odour events is as difficult as critical for drinking water treatment plants. Following a number of events in recent years, a comprehensive statistical analysis of data from Lake Tingalpa (Queensland, Australia) was conducted. Historical manual sampling data, as well as data remotely collected by a vertical profiler, were collected; regression analysis and self-organising maps were the used to determine correlations between Taste and Odour compounds and potential input variables. Results showed that the predominant Taste and Odour compound was geosmin. Although one of the main predictors was the occurrence of cyanobacteria blooms, it was noticed that the cyanobacteria species was also critical. Additionally, water temperature, reservoir volume and oxidised nitrogen availability, were key inputs determining the occurrence and magnitude of the geosmin peak events. Based on the results of the statistical analysis, a predictive regression model was developed to provide indications on the potential occurrence, and magnitude, of peaks in geosmin concentration. Additionally, it was found that the blue green algae probe of the lake’s vertical profiler has the potential to be used as one of the inputs for an automated geosmin early warning system.

Water utilities undertake long term planning for water source security, often with forecast cycles of 20–30 years. Whilst this planning is generally involved with investigations of source water abstraction security and the need to build dams or to increase the recharge rate of groundwater aquifers, planning for water efficiency gains occurs at annual intervals. Most water utilities in Australia are heavily engaged in water efficiency initiatives with rebate schemes for domestic water-efficient devices being ubiquitous across the industry. Wide Bay Water Corporation (WBWC) also engages in these activities but is increasingly interested in the concept of Time of Use Tariffs (TOUTs) to target high water users in order to reduce their demand on the system. In 2006, WBWC introduced smart metering technology across the city which captures hourly use data. Interrogation of this data has led to the ability to identify water use patterns for every domestic and commercial water customer and to design specific interventions to encourage water efficiency, such as a TOUT for domestic customers. A TOUT has been developed that imposes a penalty on all individual consumption greater than 600 L in any hourly interval of any day in the year. The tariff was designed to reduce both the annual peak hour and peak day demand. The ability to reduce both of these infrastructure design parameters may have the potential to deliver substantial savings in infrastructure planning and deployment. This paper details the design process of this tariff, examines the infrastructure savings potential derived by network modelling and explores the regulatory framework hurdles to be overcome in order to implement such tariffs in the water industry.

The effect of ozone on the formation, breakup and re-formation of flocs generated using ferric sulphate has been investigated using conventional jar test procedure and by continuous optical monitoring using raw water. Using a range of different dosage of coagulant, the breakage of flocs was followed at a high stirring speed, corresponding to average shear rate (G) of about 518 s(-1). Most of the breakage occurred within a few seconds of increasing the shear rate. After breakage the stirring rate was reduced to the original value of 50 rpm (G approximately equals 23 s(-1)) to allow the flocs to re-grow. It was found that only limited re-growth of flocs occurred indicating irreversibility of the floc breakup process. For preozonated samples, the re-growth of flocs occurred to a much greater extent with lower residual turbidity. The findings show that the use of preozonation (1.25 and 1.50 mg/L) provides beneficial results to both improve turbidity removal and reduce coagulant requirement. Furthermore, better re-formation of flocs is achievable.

Study region Advancetown Lake, South-East Queensland (Australia). Study focus A detailed analysis of available meteorological, physical and chemical data (mostly coming from a vertical profiler remotely collecting data every 3 h) was performed in order to understand and model the manganese cycle. A one-dimensional model to calculate manganese vertical velocities was also developed. New hydrological insights for the region The soluble manganese concentration in the hypolimnion is dominantly dependent on the dissolved oxygen level, pH and redox potential, which determine the speed of the biogeochemical reactions between different manganese oxidation states. In contrast, the manganese level in the epilimnion is mainly affected by the transport processes from the hypolimnion and thus to the strength of the thermal stratification, with high concentrations recorded solely during the winter lake circulation and wind playing only a minor role. The value of the peak concentration was found to be proportional to the amount of manganese in the hypolimnion and to the temperature of the water column at the beginning of the circulation period. In case of partial circulation only, a very high peak is espected during the next full winter turnover. This issue will increase in the future due to global warming and increased number of years with partial circulations only. These findings provide water authorities with increased manganese predictive power and thus proactive water treatment management strategies.