Urbanisation causes a range of adverse impacts on stream physical and ecological conditions due to increases in catchment runoff caused by increased imperviousness. Developing ways to reduce these impacts on in-stream ecosystems is a major challenge and requires innovative catchment specific, high-time-resolution modelling methods. We employed a combination of high-time-resolution data collection, analysis and modelling methods to understand the underlying hydrological processes and evaluate a potentially significant management option – stormwater harvesting. A set of sensitive parameters of the Storm Water Management Model (SWMM) were optimised using an automatic calibration method and hourly data in eight catchments in South East Queensland, Australia. Systematic investigation of the effects of urbanisation and its mitigation through stormwater harvesting was achieved by modelling the impacts of increasing impervious area for three of the relatively undeveloped catchments. As the extent of impervious areas across the catchments increased we typically found increases in the duration of high flow spells together with increases in mean flow and the frequency of runoff events. However, many hydrologic responses to increasing imperviousness were specific to the physical characteristics of catchments, and to the spatio-temporal pattern of urbanisation. By implementing stormwater harvesting options the hourly flows were reduced by up to 60 % but the maximum flow was unchanged. Thus the option was able to reduce, but not totally ameliorate, the negative hydrological impacts of increasing imperviousness.

Detailed prediction of water demand by their end-uses at multiple scales is essential to support planning of Integrated Urban Water Management, an increasingly applied approach to deal with the problem of water scarcity. This paper presents an urban residential water demand modeling framework that can predict end-use water demand at multiple scales, especially at small scales with a robust explanatory capacity. This is achieved by integrating the complex water demand dynamics of urban residential water use and their underlying variables into a single model. The model described in this study can predict shower, toilet, tap, dishwasher, clothes washer, irrigation, evaporative cooler, bath, and other uses which account for the entire household water use. The model aims to predict water demand at multiple spatial (household/cluster/suburb) and temporal scales (hourly, daily, weekly and seasonal) by considering behavioral differences triggered by factors such as seasonality and presence of people at home. The model incorporates an improved representation of spatial variability by considering behavioral differences between customer groups, and improves the capability to deal with areas with different demographic and housing characteristics. This research confirms the capacity of stochastic modeling methods to represent unexplained behavior of water consumers. (C) 2016 Elsevier B.V. All rights reserved.

Water grids are emerging as a response to water scarcity in many urban areas. These grids are comprised not only of traditional surface and groundwater supplies, but also alternative, climate-independent water sources such as desalination and wastewater recycling, as well as one and two-way pipelines connecting surface-water supplies in different regions. The complexity and heterogeneity of these water supply networks brings new challenges to water management. Water managers need to determine strategies to operate the system in terms of multiple objectives, subject to uncertainty and boundary conditions relating to climate, demand and infrastructure. This paper outlines a framework of methodologies for developing optimal operating plans for short-term planning for water grids, in terms of the objectives of interest.

The South Australian Water for Good Strategy outlines the actions that are required to ensure South Australia's water supplies are secure, safe, reliable and able to sustain continued growth. It supports diversification of supplies to reduce the reliance on rain-dependant sources. A study has been initiated by the Goyder Institute for Water Research in this regard, in particular to inform the identification of optimal mixes of water sources for metropolitan Adelaide. As part of this study an integrated system simulation model of metropolitan Adelaide's water system is being developed. This is to quantify supply implications and stormwater and wastewater discharges at defined points in the urban water system, when utilising different mixes of water sources, under both historical and future climatic conditions. This information is used to evaluate an objective function that aims at minimising life cycle cost of infrastructure, energy consumption and the potential impact on Adelaide's coastal waters, and maximising supply security, as part of a multi-objective optimisation based decision-support framework. The aim of the decision-support framework is to generate knowledge that can support the identification of the most cost-effective mix of fit-for-purpose water sources available to meet the needs of the community in metropolitan Adelaide, in an environmentally and financially sustainable manner. The sources to be considered are River Murray, surface water from Mount Lofty Ranges catchments, desalinated sea water, recycled wastewater, stormwater including roof water, ground water and the potable water savings through various demand management options. The objective of this paper is to describe the process followed to develop the simulation component of the combined simulation-optimisation approach.The modelling platform used to develop the simulation model is Source Integrated Modelling System (IMS), which is emerging as Australia's national hydrologic modelling platform for river basins. Hence it has not been applied widely yet, particularly for urban water systems. The study reported in this paper one of the first application of eWater Source to urban water systems. The application process has been an exploratory process where modelling methods have to be developed for the each water source considered in this study using the available functionalities. Also, there are modelling methods currently in place in most cities to inform planning and operation of each city's water supply system. In general, when a new modelling method is introduced, quantitative evidence is required to demonstrate the performance of the new methodology is comparable to that of the existing methodology. Thus the process to develop the simulation component of the simulation-optimisation approach was staged and comprised the development of firstly a Test Case, secondly a Base Case before developing the Scenario Cases. In this paper, we describe the Test Case and the Base Case. Development of Scenario Cases is in progress. The purpose of the Test Case is to examine the ability of the eWater Source to represent key features of metro Adelaide's water supply system, to an adequate level. The 'adequacy' was defined as the ability of eWater Source to generate outputs (e. g. pumping volumes and storage volumes) of a similar order of magnitude from an existing water supply planning and operation model that is currently used by the South Australian Water Corporation. The Base Case model represents the 'business as usual' scenario for supplying water from the three main drinking water supply sources for Adelaide, i. e. River Murray, Mount Lofty Ranges catchments and Adelaide Desalination Plant. The simulation is performed over 50 years, on a monthly basis. The optimisation time horizon is 25 years, from 2013. The simulation model is provided with functionalities using the Expression Editor capability in the eWater Source to evaluate the objective function, consisting of net present value of life cycle cost of infrastructure, energy consumption and the volumetric reliability of supply. Development of Scenario Cases is in progress, which will include adding the other sources mentioned above. The Scenario Cases will also provide information to minimise potential impact of wastewater and stormwater discharges to Adelaide's coastal waters. The results of the Test Case showed that eWater Source can adequately represent the existing water sources in Adelaide's water supply. The results of the Base Case showed that eWater Source can produce the expected behaviour of the supply system. The project is in progress.

Increases in the impervious area due to urbanisation have been shown to have negative impacts on the physical and ecological condition of streams, primarily through increased volume and frequency of runoff. The harvesting and detention of runoff has a potential to decrease this impact. This paper describes the effects of urbanisation on catchment flow and of stormwater harvesting on reducing those adverse impacts on a stream in South East Queensland (SEQ), Australia. A largely undeveloped catchment located southeast of Brisbane city was calibrated and validated using the Stormwater Management Model (SWMM). This model was used to investigate the effect of a range of future increases in urbanisation (represented by impervious area) on stream hydrology as well as the potential of stormwater harvesting to return the catchments to predevelopment flow conditions. Stormwater harvesting was modelled according to flow frequency measures specified in current SEQ development guidelines. These guidelines stipulate the capture of the first 10 mm of runoff from impervious areas of 0-40% and the first 15 mm from impervious areas of 40% or greater for urban developments. We found that increases in the impervious area resulted in increases in the mean, frequency and duration of high flows, and an increase in the mean rate of rise and fall for storm events in the catchment. However, the predevelopment (non-urbanised) flow distribution was very flashy in comparison with all urbanised scenarios; i.e. it had the quickest response to rainfall indicated by a high rate of rise to and fall from peak flow volume, followed by a return to zero flow conditions. Capturing the runoff according to the development guidelines resulted in a reduction in flow towards the flow distribution of a lower impervious area, however this was insufficient to meet predevelopment conditions. This suggests a stronger influence of impervious areas in this catchment on the volume of runoff than flow frequency measures are able to ameliorate.

To help ensure the security of water supply to urban catchments, a popular policy choice is to promote the installation of domestic rainwater tanks. While yield is primarily considered, this policy also causes a change in urban-runoff stormwater volumes and consequentially, nutrient export.Modelling tools are used to predict the yield, volumetric reliability, overflow volume, and nutrient export that the deployment of rainwater tanks will cause. These modelling tools commonly utilise an up-scaling approach to analyse the behaviour of multiple tanks, where the performance of a single tank with average characteristics is linearly scaled up to represent a larger cluster of tanks.Previous research has shown that this up-scaling method significantly overestimates the yield and volumetric reliability (Mitchell et al. 2008), and underestimates the overflow volume of the cluster (Neumann et al. 2011). A sensitivity analysis of the parameters used to represent a rainwater tank (roof catchment areas, tank storage capacities, demand) was carried out, using on-hand data for Melbourne water demand, rainfall and maximum temperature (Neumann et al. 2011). It identified that the non linearity of the tank yield and overflow in relation to some of the model parameters means that the adoption of an "average" (i.e. spatially lumped) tank to represent the behaviour of the entire cluster is subject to significant errors.This paper establishes that, accordingly, nutrient export loads are also underestimated, and describes a stochastic water balance and quality model to effectively quantify the overflow nutrient load from a cluster of rainwater tanks at the catchment-scale.In 2008, to reduce mains water consumption the South East Queensland region made rainwater tanks mandatory in new detached dwellings. It is important to accurately estimate overflow nutrient loads discharged to stormwater to identify changes at the catchment scale caused by this wide implementation of rainwater tanks.The purpose of this paper is to apply the method described in Neumann et al (2011) and Maheepala et al (2011) to South East Queensland data, avoiding the limitations of spatial lumping of the performance of an average rainwater tank. This study examines the impact on overflow loads and volumes, and potable water savings at a catchment scale of a simulated cluster of RWTs in the Brisbane region, and also analyses the model's sensitivity to geographic climate parameters. By using Brisbane water demand, rainfall, and maximum temperature data, this paper illustrates the effect that the varied climates of Melbourne and Brisbane have on the results of the model, via different rainfall and usage patterns.The results of this study for the Brisbane Local Government Area indicate an overestimation of volumetric reliability and yield, and an underestimation of the overflow volume and inflow load as well as the outflow load, which varies between 15% and 27%, depending on the nutrient. Therefore it is not recommended to use an average tank to predict the performance of a cluster of household rainwater tanks to find their contribution to potable water savings, overflow volumes and subsequent nutrient and sediment export to stormwater. Instead, we recommend using stochastic simulation of rainwater tanks, which will include the use of probability distributions to represent tank characteristics and stochastic representation of end use water demands, calibrated using local climate and observed demand and rainwater tank data.

The aim of Integrated Urban Water Management (IUWM) is to provide a sustainable approach to plan and manage urban water systems. A key consideration of IUWM is to match water demands to sources of appropriate quality and quantity (i.e. supply water to fit-for-purpose). This enables use of a wide range of water sources such as grey water, roof water, stormwater, recycled water, groundwater and surface water at different spatial scales. Availability of some water sources, in particular roof water and stormwater can vary diurnally and such sources are commonly used at local scales (i.e. allotment and development). Understanding temporal and spatial variability of water demands at individual end-use scale is essential for the optimal use of alternative water sources. This understanding invariably leads to optimal use of decentralised sources as well. In addition, consideration of spatial and temporal variability of individual end uses improves the effectiveness of demand management strategies, since those strategies, such as creating awareness and promoting water efficient appliances, can be implemented more effectively by knowing where and how they are being used.End-use modelling is an approach for quantifying and predicting water demands of individual end uses using the relationships built on the data monitored at individual household scale. Recent residential end-use monitoring studies indicate that water consumption of residential end uses varies significantly. The aim of this paper is to review the suitability of currently available residential end-use models to adequately represent spatial and temporal variability of urban residential water end uses in order to enable demand dynamics to be predicted at development (or precinct), city and regional scales. This is to aid the adoption of IUWM approach to urban water planning, i.e. total water cycle management planning.The purpose of the residential end-use modelling approach is mainly to quantify residential end-uses such as toilet, garden, bath, tap, shower, dishwasher and washing machine. In general, the approach is based on the time at which water use events start and the volume for each end-use. The volume is quantified using three basic input parameters, namely frequency, flow rate and duration. These parameters are defined as a mean value, mean and standard deviation or probability distribution with or without dependence on an external variable. The parameterisation determines whether the model is stochastic or deterministic and how far it can represent spatial and temporal variability of the system.The paper found that the ability of existing residential end-use models to simulate end-use water demands with desired spatial and temporal representation especially at larger scales (city and regional scales and daily to annual scales) is limited. This is because of the use of mean values instead all plausible values for variables, difficulty in managing the complex correlations between number of variables and the lack of sufficient data to represent relationships between individual end uses and the factors that influence water consumption of individual end uses. Therefore, a single end-use model with its basic relationship is not sufficient to describe the complexity present in urban residential water demand. Conclusions of this paper indicates the need for examining improvements to the current residential end-use modelling approach with regard to spatial and temporal representation of water use. Realistic representation of spatial and temporal variability of urban water consumption at an end-use scale enables effective use of alternative water sources such as roof water, stormwater and recycled water.

Stormwater harvesting is a relatively new concept which has developed using traditional stormwater management practices as well as water resourcing and holistic water management concepts. While stormwater harvesting systems have been designed and constructed in the past, the planning and design processes have not followed an integrated approach. This paper addresses this issue and describes a decision-making framework (DMF) that determines the most appropriate stormwater harvesting scheme option based primarily on technical feasibility and financial costs with a focus on neighbourhood-scale development. A case study of an existing urban area in the suburb of Sunshine in Melbourne, Australia, was conducted to demonstrate the DMF. Comparison of all stormwater harvesting scheme options determined that while one scheme option was the most effective option in terms of cost, reliability, quantity of stormwater used and end uses met, several other options could also be examined further for detailed analysis.

Integrated urban water management (IUWM) requires the management of the urban water cycle in sympathy with the hydrological water cycle. Urban systems significantly alter the hydrological water cycle. Under natural conditions the water inputs at any point in the landscape are precipitation and overland flows; while the outputs are via surface flows, evapo-transpiration and groundwater recharge. The large volumes of piped water introduced with the change to an urban setting and the introduction of vast impervious areas strongly impact on the water balance, increasing in-flows and dramatically altering the outflow components.IUWM seeks to change the impact of urban development on the natural water cycle. One approach is to establish an inner, urban, water cycle loop through the implementation of reuse strategies. Developing this urban water cycle loop requires an understanding both of the natural, pre-development, water balance and the post-development water balance. Accounting for flows in the pre- and post-development systems is an important step toward limiting urban impacts on the natural water cycle.This paper investigates urban water balancing and preliminary identification of reuse strategies for the case study of the proposed Tamala Park development in Perth, as the first steps toward an integrated water reuse strategy. The hydrology and hydrogeology of the site are examined. Overland flows are not a feature of the site with rainfall leaving the site as either evapotranspiration or recharge to groundwater. The unconfined Superficial aquifer is identified as suited to aquifer storage and recovery.Changes to the site water balance due to urbanisation include the significant inflow and outflow of piped water. It is projected that the small allotment sizes proposed would have a beneficial impact on garden water use and hence piped inflow. Water accounting for the developed case showed a decrease in evaporation and an increase in recharge. Reuse strategies should therefore aim to exploit the excess recharge - through groundwater abstraction and roof runoff capture - as a component of an inner urban water cycle loop. Volumetrically, this excess could supply projected in-house uses. Further, if wastewater was reused for irrigation demands the need for mains supply could be eliminated and wastewater discharges halved.

This paper describes a software tool called Hydro Planner, being developed as part of CSIRO's Water for a Healthy Country National Research Flagship Program. The main purpose of Hydro Planner is to enable urban water planners and managers to adopt a systems approach to obtain an improved understanding of how water, wastewater and stormwater systems interact with each other and with natural water systems in terms of water, contaminant and nutrient flows at city and regional scale. Hydro Planner can assist development of regional water allocation, river management, land development and urban water supply/demand strategies by allowing practitioners to assess implications of a variety of water management and land development options by considering the influence of factors such as climate change, population growth and technological changes. The aim of this paper is to describe conceptual design and implementation aspects of Hydro Planner.The modelling approach adopted in Hydro Planner utilises E2 model integration framework (www.toolkit.net.au/e2) to link models that can simulate various components of total water cycle in an urban context. The component models included in Hydro Planner support continuous simulation of runoff and constituent generation from water supply and urbanised catchments, urban and environmental water needs, supply system behaviour such as reservoir storage levels and demand shortfalls and routing of both flows and constituents through a stream network down to the tidal limits in estuaries. Hydro Planner is being developed with a view toward generic integration of these components. Our aim is to provide an integrated modelling system of the total water cycle in any given urban area through linking of component models of a complexity appropriate to the questions being addressed and the available data and knowledge.Hydro Planner consists of seven modules: (1) catchment module - supports linking of models that can simulate constituent and runoff generation processes from supply catchments; (2) water supply module - supports linking of models that can simulate water supply system behaviour; (3) consumption module - supports linking of models that can simulate urban water consumption; (4) stormwater module - supports linking of models that can simulate stormwater and associated constituent generation and routing process; (5) wastewater module - supports linking of models that can simulate wastewater and associated constituent generation and routing processes; (6) receiving water module-supports linking of models that can simulate flow and constituent routing through a stream network; and (7) integration module - supports translation and computation of input/output data between modules and the Graphical User Interface.The E2 framework contains component models needed for the catchment and receiving water modules. Hydro Planner adds models to support the remaining modules. Implementation of Hydro Planner is currently in progress. At present, catchment, water consumption, water supply and receiving water modules are nearing completion. The water consumption module provides functionalities to access Water Services Association's End Use Model and the water supply module provides functionalities to communicate with the REALM model. The catchment module supports a number of rainfall/runoff models and constituent generation models. The receiving water module supports a number of routing models.Currently, a case study is underway using Benalla water supply system, to test functionalities of catchment, water consumption, water supply and receiving water modules of Hydro Planner. The test case study is used to assess: potential impacts of 2030 climate change scenarios; and the potential impacts of changing end water use behaviours. The test case considers the effect of climate change, population growth and various demand and supply side management options on the supply system performance such as system yield and the quality of water in Ryans Creek.

This paper describes a probability-based method for assessing the potential impact of climate change on urban water supply systems. Specifically, the assessment method uses probability distributions to place a confidence level on the plausible values of response variables. The Benalla water supply system has been used to demonstrate applicability of the proposed assessment method. For the application, the impact of the 2030 climate change scenarios on streamflows and system yield has been examined. The preliminary results have demonstrated that the proposed assessment method can provide valuable insights into the impact of climate change on water supply systems, allowing it to be incorporated into planning decisions.

Stochastically generated hydrologic data have been used in the past by water worhorities world-wide for long-term planning of water resources development projects. These data are also currently being used in short- and medium-term planning and operation of water resource systems. For valid and realistic results, it is necessary that the generated data sequences preserve all statistical properties of historical data. This paper presents an improved disaggregation method for generation of alternative sequences of monthly hydrologic data. The method is designed explicitly to preserve the over-year monthly serial and cross correlations, in addition to other monthly and annual parameters of the historic sequence. The method is applied to both single-site and multi-site cases, and compared with two other disaggregation models that are used in Australia. The comparison of results shows that the developed method satisfactorily preserves both monthly and annual statistical parameters of the historic data sequences including the over-year monthly correlations.