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WaterNSW is currently building ten catchment models for the operational Decision Support System (DSS), which links a set of hydrological-hydrodynamic-water quality models. The very first step of the DSS is to build, calibrate and validate these catchment models with the objective of producing a set of inflow boundary condition data to the lake/reservoir models for a particular scenario. This paper identifies challenges encountered and solutions identified as part of the calibration and validation of the Avon, Cataract and Nepean catchment models developed in the first stage. Sub-catchments of these models were delineated based on the points of interests in the catchments ensuring relatively small variations within the sub-catchment sizes. Typically, the 80% of the period was selected for calibration and the remaining 20% for validation, however, this was tailored for each calibration gauge ensuring both the calibration and validation periods comprised of a range of flow conditions and recurrences. Calibration was undertaken for approximately 65% of the gauged time series available and validation is undertaken for the remaining 35%, excluding the data for 4 years following whenever at least 10% of catchment was burnt. Models were built at an hourly time step using disaggregated daily gridded rainfall and evapotranspiration data and has shown to provide a satisfactory representation of historical flows. Twenty-two Sacramento meta parameters were calibrated for each catchment and the 3 parameters related to land-use runoff generation (ADIMP, PCTIM and PFREE) were kept consistent across the models. This paper discusses the calibration strategy adopted to calibrate the meta-parameters and the performance of the calibrated models against the adopted peer-reviewed performance measures as well as the adjustments made to improve the model performance. [ABSTRACT FROM AUTHOR]

WaterNSW is responsible for the management of Sydney's drinking water catchment and the prevention or reduction of water quality risks through the supply system from catchment to customer in line with the principles of the Australian Drinking Water Guidelines. WaterNSW is currently in the process of developing an integrated modelling system for both water quantity and quality that encompass the entire supply chain. This paper will focus on the water quality calibration and validation of grazing, forested, and roads and rails land uses across the drinking water catchments of Avon and Cataract. The primary land use within each catchment drove the manual calibration for the land use across all other catchments, using Event Mean Concentration and Dry Weather Concentration models in Source. The manual input process was automated with a python script. Simulation periods used for calibration and validation of each catchment were constrained by fire exclusion periods and data availability, with calibration using 80% of data and validation using the remaining 20% of data. The water quality parameters calibrated and validated within the models were selected for their impact on the receiving lake models. These include Ammonium, Nitrogen Oxides, Soluble Reactive Phosphorus, Total Kjeldahl Nitrogen, Total Nitrogen and Total Phosphorus. This paper discusses the water quality calibration and validation results through timeseries, cumulative and flow percentile box plots, and pollutograph and cumulative load graphs. It will also discuss the challenges encountered in the process, with a focus on the outcomes of calibrating for multiple land uses across multiple catchments. [ABSTRACT FROM AUTHOR]

WaterNSW is currently building a set of hydrological models for the Greater Sydney water supply catchments to enable operational and long-term planning assessments. The catchment models for the Greater Sydney area are currently under calibration and validation to estimate long-term and operational inflows into the receiving reservoirs. To accurately represent the hydrological and water quality characteristics of the catchment, a good calibration and validation approach must be established. Calibration and validation of these models is underway and uses a common peer reviewed methodology. Throughout the modelling project, the calibration and validation has focussed on the full recurrence curve of the flows measured in the catchment. The model domains have a rapid response and therefore for operational and water quality requirements, hourly models are developed. Calibrating across such a large variation in catchment conditions and flow pattens has proven especially challenging in the Warragamba catchment. The catchment runoff is influenced by the variation in land-uses, soil conditions, point source inflows and water usage by irrigators and town water supplies, particularly during low flow events. This paper will highlight the challenges encountered in calibrating to the low flow conditions within the catchments and the solutions identified. It will focus on the log NSE and its implications and effects on the calibration statistics and how this influenced the low-flow calibration across this catchment. [ABSTRACT FROM AUTHOR]

WaterNSW has the responsibility of managing and operating the Greater Sydney Dams, which provide water to over 5 million population across Sydney, the Illawarra, Blue Mountains, Shoalhaven, Goulburn, and Southern Highlands regions. To further enhance its integrated water resources management capabilities, WaterNSW is currently developing an integrated modelling system for both water quantity and quality that encompass the entire supply chain, from catchment to water supply systems in the Greater Sydney area. The modelling system will enable WaterNSW to optimise the management of water demand, water supply operations, and system reliability, improving the overall performance of the water supply sustainability. The Prospect supply system is a critical component of Sydney's bulk water supply, consisting of Prospect Reservoir, Warragamba Dam and pipelines, and the Upper Canal open channel, which transfers flows from the Upper Nepean Dams. One of the important aspects in the integrated water modelling is to understand the water and constituent transport from the upstream waterbodies to the Prospect supply system. This study uses a schematic modelling approach for estimating water quantity and quality within the Prospect supply system using the eWater Source model. The connections among supply points, environmental flows, open-channel flows, and storage inflows were conceptualised using a combination of the lagged flow routing and storage routing. To support the water operation decision making, the model is calibrated and validated against operational data between 2015 and 2022 with the bushfire and maintenance periods excluded. The study has found that the schematic modelling approach yields satisfactory results for the purposes of water supply and demand estimates in terms of water flows. The efficiency of the model enables timely scenario modelling for decision support in water diversion configurations, to optimise raw water supply during water quality events. [ABSTRACT FROM AUTHOR]