Proceedings of 1st International Conference on Water and Environmental Engineering (iCWEE), Sydney, Australia, 20-22 November, 2017

ISBN: 978-0-6480147-4-4

Abstract: The South West of Western Australia (SWWA) has experienced a significant decrease in rainfall since the 1970s which has adversely affected the agricultural and water supply sector in this region. The decreasing trend has been attributed to lesser interactions between cloud bands and cold fronts and the major changes in the large scale atmospheric circulation in the Indian Ocean region. Though many studies have been carried out to understand the decline of rainfall in SWWA, the total quantitative change of rainfall in the study area in terms of volume and area still remains uninvestigated. The objective of this study is to examine the change in total rainfall volume and wet areas in SWWA. Daily gridded rainfall data from 1930 to 2009 from the Bureau of Meteorology were used in this study. The method used is linear regression which identifies how the rainfall volume and wet area has varied over the years. Three rainfall categories were considered for this study namely, rainfall greater than 0.2mm (total rain), rainfall greater than 10 mm (heavy rain) and rainfall less than or equal to 10 mm (light rain). The results indicated that although rainfall volume has showed a decreasing trend, it is not statistically significant. The area receiving highest number of rain days per year showed a significant decreasing trend in all three rainfall categories. It was also noted that the area receiving higher number of rain days has been reduced and the area receiving lower number of rain days per year has expanded.

Abstract: Rainwater harvesting (RWH) has grown in popularity over the last 15 years and has attracted a significant amount of research. The economic viability of RWH systems has been reported with various outcomes. The water demand profile is complex and of all domestic demands, outdoor irrigation use is potentially the largest and most variable. The quantity of water available for harvest is influenced not only by the rainfall pattern and tank size, but also by the area of the roof used to harvest the water (the RWH system’s catchment). Roof area can vary considerably with the size of the house, or because parts of the roof are unsuitable for harvesting (e.g. due to overhanging trees, practicality and/or cost of the guttering arrangement). A versatile economic evaluation tool named ERain has been developed to analyse the economics of various RWH system arrangements. ERain combines performance analysis using daily rainfall data with life cycle cost analysis. Outputs from the model include economic indicators such as benefit cost ratio (BCR) and net present value (NPV) reported against performance indicators such as reliability (% of days the demand is met) and efficiency (% of available water used – i.e. that not lost to overflow). Here ERain has been used to assess the effects of varying roof size or irrigation area on the economic viability of RWH systems for tank sizes ranging from 1-7kL. Results show that excluding outdoor use, the BCR increases with roof size along with reliability while efficiency decreases. Interestingly, the larger roof area has the most significant effect in terms of reliability on the smaller tanks. Including outdoor use reduced reliability overall and increases efficiency and BCR indicating that it is better financially to use the RWH system for outdoor use when reliability is not a concern. However, the pattern of BCR and NPV is different from when no outdoor use is attached. When outdoor uses are not connected reliability is high even with a smaller tank, and so a larger tank offers little advantage. However, once outdoor use is connected small tanks have a low reliability which can be increased with a larger tank. When analysing various irrigation areas tank sizes up to 15kL were considered. The larger NPVs and BCRs occur with the larger irrigation areas as this increases water use and hence monetary water savings. The highest BCR occurs with a 15kL tank; while the highest (least negative) NPV occurs with a 10kL tank as it did without outdoor use connected. Within the 1-7kL tank range, the 7kL tank is the most favourable when outdoor irrigation use is connected.

Abstract: Chlorophenols are highly toxic chemicals that are widely detected in reticulated water and in the environment, the main source being herbicides and precursors applied in industrial manufacturing processes. These micropollutants are unamenable to degradation by conventional treatment methods. Photocatalytic technology is one that can treat and remove these pollutants in the water systems. The exact photocatalytic mechanisms for functional group transformations are not adequately understood, as reactions associated with this protocol are diverse and complicated. This study attempted the determination of molecular entities associated with different semiconductor facilitated reaction schemes. Identification of products and intermediates was performed using advanced GCMS data processing. The analytical objective was to construct an ion trace profile of each intermediate detected and verify the absence of chemical products of reaction groups not detected from the mechanisms evaluated. The more efficient methods to perform this task is through quantification of base peak intensity (BPI), base peak intensity represents the intensity of the most intense peak at every point in the analysis, and these are presented as numerical ratios. It was found that the photocatalytic oxidation process is not one that follows a strict mechanistic reaction scheme. The evaluation of the oxidation pathways through screening of intermediates showed that reductive and oxidation pathways are both involved in the photocatalytic treatment of organics. It was determined and concluded that the degradation mechanisms and reactions pathway schemes are dependent on many factors of the photocatalysis principle, as well as the properties of the chemical groups being investigated along with its manipulations.

Abstract: Biochar has received increasing attention as a potential cost-effective and eco-friendly adsorbent to treat metal-contaminated wastewater. The purpose of this study was to investigate the removal of Cu2+ and Ni2+ ions from single component aqueous solutions by adsorption onto biochar derived from date seed biomass (DSB). The biochar was prepared through slow pyrolysis process at 550 °C and a heating time of 3 h. Batch experiments were conducted to study the effects of solution pH, contact time, and initial metal ions concentration. Adsorption removal of the heavy metals was found to be pH dependent and the maximum adsorption capacities were achieved at pH 6. The maximum adsorption capacities for single ions were 0.292 and 0.228 mmol/g for Cu2+ and Ni2+ ions, respectively. Adsorption equilibrium data fitted adequately to the Freundlich isotherm model. The kinetic experimental data were well fitted by the pseudo second-order kinetic model with R2 values of 0.98 and 0.99 for Cu2+ and Ni2+ systems, respectively; thus, indicating chemisorption process involving valence forces through the sharing or exchange of electrons. The results showed that date seed derived biochar may be an effective and low-cost adsorbent for the removal of Cu2+ and Ni2+ ions from aqueous systems.

Abstract: The river Ganges (or Ganga as it is well known in the Indian sub-continent) has forged significant economic, social, environmental, religious, political and cultural values in India for several thousand years. However, over the years, rapid population growth, improved standards of living and exponential growth of industrialisation and urbanisation within the basin has subjected the river to various forms of degradation. This ultimately has limited the opportunity to access clean and safe water by the populace who rely on the Ganges. Records indicate that since 1979 the Government of India has taken numerous steps to rejuvenate this river. However, nurturing the Ganges back to life and creating a safe and sustainable ecosystem in the river basin area has so far been a seemingly daunting task. In order to achieve a viable solution to the problem, clear understanding of the socio-political, economic, environmental, technological and institutional aspects of this mighty river at the micro levels is vital. This paper discusses the current understanding on the state of Ganges in terms of its pollution and degradation and relevant management interventions that have been undertaken to improve its condition during the last three decades.

Abstract: Climate change is affecting the water cycle in many different ways such as by increasing flood risk, and duration and severity of droughts. Bangladesh is one of the worst affected countries by climate change. In Dhaka city, the capital of Bangladesh has numerous water problems such as frequent flooding, water logging, intermittent and contaminated water supply, declining groundwater level, contaminated surface water in the nearby rivers, poor drainage network and polluted stormwater runoff. In this city, about six million people live in slums where there is no piped water supply. Women generally fetch water for these six million people. In this paper we review how these women are affected by water related problems and how climate change is likely to affect them in future in relation to household water management. The existing literature has tended to focus on the challenges faced by women due to climate change in rural areas. Adequate research on the everyday life experience specific to water use and management in urban context is needed to address the research gap. Hence, it is recommended to conduct further research on how women in Dhaka city, in particular those who live in slum areas, will be affected by climate change induced water problems.

Abstract: Rapid urbanization has led to an increase in runoff and pollution in urban waterways. Water sensitive urban design (WSUD) is a sustainable means of reducing the impacts of urbanisation on urban water cycle. Permeable pavement system (PPS) is a component of WSUD that can reduce both runoff volume and pollution. PPS is generally used in low-traffic areas such as car parks, pedestrian footpaths, cycle paths and driveways. In this paper, we present a review of PPS highlighting its major benefits and limitations and recommend areas of further research. It has been found that PPS has a number of benefits such as reduction of urban runoff volume, removal of pollutants from stormwater runoff, enhancement of groundwater recharge, and reduction of heat island effects. The major limitations are related to its maintenance, clogging effects, lifecycle cost analysis and strength and durability. The future research and development potentials of PPS are identified in this paper.

Abstract: Groundwater contamination is a major concern in industrial areas of Saharanpur district. Long term use of wastewater as irrigation source contributed considerably to the metal concentration in the groundwater. Serious health related issues are prevalent in the area due to contaminated groundwater. Hand-pumps are the major equipment for drawing groundwater for household purposes. Surveying with local people revealed the fact that 80% of the population suffering from health related issues use private hand-pumps, which was further justified by the estimation of heavy metal concentration sampled from both private and government installed hand-pumps. Total of 30 samples; 11 samples from government installed hand-pumps and 19 from private hand-pumps were collected and heavy metal contamination was analysed. Samples from private hand-pumps were found to be more contaminated than government installed hand-pumps. High concentration of As, Cd, Cr, Ni and Pb; 5.28µg/l, 0.54 µg/l, 16.3 µg/l, 71.4 µg/l and 7.82 µg/l respectively were observed in the sample collected from private hand-pumps. Health risk was estimated by Health quotient (HQ) in both adult and children population; risk was found to be high in children. It has been observed that the depth at which hand-pumps are installed has a crucial impact on the quality of water. Survey also revealed that most of the private hand-pumps installed at the depth of 18.2 m to 56.38 m whereas government hand-pumps are installed on average of 67.05 m depth. The upper level of water aquifer is highly contaminated due to poor environmental management strategies, lack of environmental education in the population and various other factors which has been briefed in this work.

Abstract: Water scarcity has adverse health consequences in the form of morbidity and even mortality. Globally, 2 in 5 people, including in Indonesia, are affected by water scarcity. However, research on water scarcity in Indonesia is limited. Therefore, in this paper, we sought to address the correlates of water scarcity among households in Indonesia. We analysed data from the 2nd round of Baseline Health Research conducted by the National Institute of Health Research and Development, Ministry of Health, Republic of Indonesia. We set self-reported yearlong experience of water scarcity as the only dependent variable. Then we grouped the potential covariates into five groups, namely spatial, environmental, housing, demographic, and socio-economic variables. Finally, we fitted a multivariable logistic regression model to the data with average marginal effects (AMEs) and its 95% confidence interval (CI) as measures of association. We observed that households that reside in rural areas are more likely to experience water scarcity, besides differences of water scarcity probability across different regions. Households located near a swamp, a forest, a beach, and in a slum area were also found to report higher probability of water scarcity. Moreover, households with unimproved water source for cooking and hygiene, unimproved drinking water source and distant water source were also found to more likely to experience water scarcity compared those with improved and on-premise water sources. These associations still hold when demographic and socio-economic variables were included in the final multivariable probit regression model. The findings of this paper will enhance our understanding of water scarcity experience among Indonesian households and provide additional evidence for policymaking in the water sector in Indonesia. Further studies should collect information on the number of water shortages experienced by households in a year.

Abstract: In the present day context, climate change is due to increased release of aerosols into the earth’s atmosphere may be of either natural or anthropogenic origin, which in turn raises the atmospheric temperature causing changes in climatic parameters. Changes in rainfall is an important climatic parameter, have a direct influence on human life. This study aims to assess climate change trends focusing on time series monthly rainfall pattern at three closely located rainfall stations in Victoria, Australia for around 130 years. It has been aimed to capture spatial and temporal rainfall variation in the study area and to assess dependency of trends on the selection of the length of the data period. Thus rainfall data of selected three meteorological stations was analyzed for different time-periods: 1889-2016, 1953-2016, 1987-2016 and 1996-2009. Two non-parametric trend tests: Mann–Kendall (MK) and Sen’s slope (Q) were used for selected stations to identify trends in annual total and annual maximum rainfall. For annual total rainfall, significant decreasing trends were at the Essendon Airport station for all the periods except the longest period 1889-2016.On the other hand, it showed insignificant trends for all selected periods at the Narre Warren North station whereas a significant decreasing trend was found at the Lovely Banks station for the period 1953-2016. However, annual maximum rainfall had significant trend only at the Lovely Banks station for the period 1987-2016.In general, annual total rainfall was decreasing over time for most cases and had a higher decreasing rate in recent time periods, yet the rate was highly dependent on the time period of the data analysis selected. On the other hand, no significant conclusion can be drawn on annual maximum rainfall for all the stations except the Lovely Banks during 1987-2016. Thus, it could be concluded that climate change is not a simple process, where the interpretation of data is highly dependent on the time period of the data analysis selected.

Abstract: Design flow estimation for ungauged catchments is considered to be a challenging task in hydrology. Regional Flood Frequency Analysis (RFFA) can be used to estimate design flow for ungauged catchments. Commonly adopted RFFA methods include the index flood method, the rational method and the quantile regression technique. This paper examines the applicability of the generalized additive model (GAM) in RFFA. GAM establishes a well parameterized modelling framework which describes the multivariate and nonlinear characteristics of a complex dataset. This approach allows flexible specification of regression splines to represent the functional relationships between a response variable (i.e. flood quantile) and a suite of temporal and spatial covariates that can be continuous or discrete. This is done using a link function and smooth functions of the covariates such as catchment characteristics. In this study, both the GAM and log-linear model (LLM) are applied in RFFA to a data set of 114 catchments from Victoria State in Australia. Based on independent testing, it was found that GAM generally provides more accurate flood quantile estimates than the LLM. Further study is needed to confirm this finding.

Abstract: It is well known that urbanisation has a notable effect on the hydrologic and environmental dynamics of a catchment. The purpose of this paper is to present a brief review on the effects of urbanisation and compare the various approaches taken to minimise these impacts. Urbanisation has been identified to intensify the response of a watershed, increasing the magnitude of storm peak flow, by up to a factor of 12 and reducing post-development lag time to less than half that of the pre-developed state. Large watersheds were found to be less sensitive to urbanisation due to channel transmission losses. Urban catchments are characterised by a lack of infiltration, hence the ‘first flush’ of accumulated pollutants is mobilized to the catchment outlet, rather than retained, increasing the magnitude and frequency of pollutant wash-off. In order to respond to post development effects of urbanisation, implementation of greener approaches such as permeable pavement and bio retention systems are encouraged, as well as the implementation of rainwater tanks. Moreover, the concurrent implementation of on-site detention and Water Sensitive Urban Design (WSUD) systems has been found to effectively replicate the response of a natural catchment to a large degree. Overall, this paper acknowledges that whilst on-site detention is necessary to reduce the excessive peak flows of urban catchments, the simultaneous implementation of greener approaches would better mimic natural catchment dynamics.

Abstract: Chlorination is the most used disinfection technology for drinking water treatment. Based on last research it is obvious that chlorine disinfectants are releasing harmful substances that can cause serious problems in human health. Since the discovery of harmful by products the new oxidants/disinfectants have been investigated to replace chlorination. Ferrates are a powerful oxidising agent with the strongest redox potential among all of used oxidants. These high-valent states (VI, V, IV) iron compounds can be used as green oxidants in synthetic, organic transformations, water oxidation catalysts, and efficient agents for drinking water treatment. In this study we tested commercial product ENVIFER (NANOIRON, CZ) for reduction of E. coli, faecal coliforms and cultivable microorganisms at 22 and 36 °C (European parameters legislatively observed in drinking water). The ferrates efficiency was compared with commonly used chlorination. ENVIFER in amount of 50 mg/L was much more sufficient for E. coli and microorganisms at 22 and 36 °C removal than sodium hypochlorite. Ferrates are also suitable for elimination of heavy metals (arsenic and many others) and many organic compounds. Rapid reaction with contaminants and low reagent consumption is the advantage. It can serve as an efficient alternative to sodium hypochlorite usage.

Abstract: As a result of rapid urbanization, installation of complex infrastructure and variations in rainfall, anthropogenic climate change is making cities increasingly vulnerable to flooding. Downscaling of climate change results from Global Circulation Models (GCM) to urban catchment scales are needed because these models are not able to describe accurately the rainfall process at the required high temporal and spatial resolution for urban drainage studies. In the present study, the applicability of a statistical downscaling model (SDSM) is evaluated in downscaling the rainfall. The Coupled Model Intercomparison Project phase 5 (CMIP5) ensemble forced by three Representative Concentration Pathways (RCPs) (i.e. RCP 2.6, RCP 4.5 and RCP 8.5) scenarios is adapted. The daily rainfall data of a small urban catchment Lucas Creek located in Auckland, New Zealand, covering the period 1985 to 2015 is used as baseline data for calibration and validation of SDSM. While future downscaled rainfall data is analysed in three time slices 2030s (2011-2040), 2060s (2041-2070) and 2090s (2071-2100). SDSM performed well during calibration and validation. The mean daily rainfall showed a trend of insignificant changes in 2030s; excess rainfall in the 2060s; and a deficit of rainfall in the 2090s under all the three scenarios. The mean monthly, seasonal and annual daily rainfall increased in the catchment under all the scenarios. Rainfall frequency analysis was performed by fitting the Gumbel distribution to the observed and SDSM downscaled rainfall time series. The frequency analysis was performed for 2, 3, 4, 5, 10, 15, 20, 30, 50 and 100 year return periods which indicated increasing rainfall trends in the future generated time slices. The current results illustrate that SDSM have good ability to simulate the rainfall events at the urban catchment scale and, therefore, can be adopted with confidence for climate change impact studies of similar nature.

Abstract: Design floods are needed to design safe and adequate infrastructure such as bridges, levees and dams. The estimation of design floods is generally performed by at-site flood frequency analysis (FFA) when adequate historical streamflow data is available at the site of interest. The 3rd edition of Australian Rainfall & Runoff (ARR) 1987 recommended the use of the log-Pearson type 3 (LP3) distribution to estimate design floods for all Australian catchments including South West Western Australia. The 4th edition of ARR no longer prescribes a particular probability distribution for FFA in Australia. In this study six different probability distributions are used to assess which probability distribution could be recommended when performing FFA for catchments located in South West Western Australia. The distributions that are assessed in this study are: normal distribution, log-normal (LN) distribution, LP3 distribution, generalised extreme value (GEV) distribution, extreme value type 1 (EV1) distribution and generalized Pareto (GP) distribution. Use of the software package TUFLOW Flike, recommended in the 4th edition of ARR, is made to fit the LN, LP3, GEV, EV1 & GP distributions, while the R software package is used to fit the normal distribution. Goodness of fit testing is performed to assist in the ranking of the various distributions for the selected catchments. From this study of the six distributions on 103 catchments located in South West Western Australia we find that the GEV distribution provides the best estimation of design floods from FFA. However, some catchments in South West Western Australia do not follow the GEV distribution where other distribution should be applied. This study highlights the difficulties in recommending a single probability distribution for FFA in a given region.

Abstract: This study examines changes in rainfall in New South Wales (NSW), Australia using data from 200 daily rainfall stations covering the period of 1945-2014. Mann-Kendall (MK) test is applied to identify trends in the annual maximum daily rainfall (AMDR) data, while the Pettitt test is employed to determine the direction and timing of the change point along with the potential impacts of the abrupt shift in the AMDR data series. Overall, the results of the MK test do not show any consistent pattern of trends in in the AMDR data in NSW. However, southern half of NSW is dominated by decreasing trends in the AMDR data. Based on the Pettitt test it is found that 73 stations show positive trend and 127 stations show negative trend; however, only 5 stations (out of 200 stations) show a significant negative shift in the mean of the magnitude of the AMDR data.

Abstract: This study focuses on identification of hydrologically homogeneous regions in New South Wales (NSW) from 88 selected sites for regional flood frequency analysis. The heterogeneity measure proposed by Hosking and Wallis (1993) has been adopted for this study amongst the various available techniques to form homogenous region. This method applies L moments to check for homogeneity. L moments for all the 88 sites have been computed and an investigation for discordant sites has been carried out. This has been done in two steps: (i) considering all 88 sites as a single group and (ii) dividing the 88 sites into two groups based on their drainage divisions. The effect of the discordant sites has been examined both individually and as a group. The overall results show that the effect of the discordant sites on heterogeneity measure is negligible and no homogeneous regions can be established in NSW, which is similar to the findings of previous studies.

Abstract: The coastal areas of Bangladesh are regarded as the most vulnerable region in the country due to climate change impact. Majority of the coastal population depend on water supply from rainwater harvesting (RWH) systems, pond sand filters (PSF) and rain-feed ponds. These water supply options are considered as climate resilience water supply options; however these will be seriously impacted by climate change induced tidal surge and cyclone, salinity intrusion, drought and excessive rainfall. This study was conducted to explore the operational and maintenance issues of these water supply options and the associated microbial health risk and also the possible climate change impacts on these water supply options. It reveals that both management and operational related issues contributed to microbial risk factors of ponds and PSFs water; whereas for rainwater harvesting systems, maintenance issues contributed the major risk factors. Water from all these options was found microbiologically contaminated and is not safe for drinking without further treatment. It also reveals that both pond and PSF water will be seriously impacted by storm surge and cyclone and salinity intrusion. RWH systems are found to be more resilience against climate change induced impacts and thus will be more effective. Both technical and social adaptation measures should be undertaken for a sustainable water supply in the coastal areas of Bangladesh.

Abstract: Water recycling in a sustainable manner is increasingly being practiced for protection of water resources. Greywater generated from households can be readily used for recycling due to enhanced quality of this source compared to sewage. Vacuum membrane distillation (VMD), was selected in this research which comprises of evaporation and condensation processes that mimic the water cycle in nature. Solar energy was embedded into the VMD process to minimise energy consumption from non-renewable energy sources. The hydrophobic membrane assists the vaporization of greywater at lower temperatures by means of vacuum pressure on the permeate side. However, the membrane distillation (MD) process is rarely used for wastewater treatment due to the membrane wetting phenomenon which features the penetration of the feed water through the membrane pores. This phenomenon results from active surfactants present in detergents that reduces the contact angle between feed water and the surface of the hydrophobic membrane. Active surfactants are measured as linear alkylbenzene sulphonate (LAS). The main aim of this paper is to investigate the feasibility of a pre-treatment unit, electro-coagulation (EC), for removal of LAS in greywater. EC was incorporated to overcome the complexity of pore wetting for greywater treatment. A range of current density and circulation rate of EC unit was performed, and the quality of permeate water was monitored. It has been demonstrated that, after only 12 minutes of EC, the level of turbidity, total suspended solids (TSS), chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), total phosphorous (TP), electrical conductivity and faecal coliforms were reduced by an average 94.4%, 89.9%, 83.8%, 71.0%, 73.1%, 96.1%, 30.2% and 1.32 log, respectively. Finally, the EC unit was combined with the VMD system. Water quality and energy consumption were evaluated to determine the optimised level of current density and circulation rate for EC.

Abstract: Flooding is one of the costliest natural disasters around the world and with a warming climate flooding expected to increase as a result of increases in precipitation (Seneviratne et al., 2012). However predicting changes to extreme precipitation and flooding is difficult due to the number of factors affecting flood risk in a future climate. These include changes to not just extreme precipitation intensities, but the pattern of extreme storm events as well as catchment specific conditions such as the wetness state prior to a storm event. Here, we examine the influence changes in temperature have on historical precipitation and flood records to gain an insight into what we might expect in a future warmer climate. The work presented here is based on published work in Wasko and Sharma (2017b).

Abstract: Hydrological models are indispensable tools for simulating environmental processes and informing management of water resources and water quality in watersheds and open water bodies (e.g., streams and lakes). Applicability of hydrological models depends on how well they can reproduce similar patterns of observed values of the simulated outputs. This requires adequate input data resolutions and proper model calibration and validation. Geospatial and hydro-climate inputs are chief drivers of hydrological model outputs. Several studies have been conducted to examine the effect of impact of geospatial or climatic input data resolutions (e.g., precipitation, temperature, digital elevation model, and soil maps) on model performance.

Abstract: Floodplain inundation modelling becomes increasingly important for flood forecasting and river basin management for engineering, ecological and environmental perspectives. While flooding is disastrous from economic and social point of view, it is the single most beneficial component for ecological and biodiversity values of floodplain wetlands. Flood flows provide an opportunity for off-stream wetlands to be connected to the main river channel. The high biodiversity found in many unregulated floodplain systems are thought to be largely dependent upon these ‘flood pulses’. An important issue for the management of wetlands on river-floodplain ecosystem is to acquire knowledge of the extent, timing, duration and frequency of inundation and their hydrological connectivity to the main channel.

Abstract: Australian water authorities supply water to around 20 million customers via piped network and they mostly use surface water resources. Urban population in Australia is lightly populated, implying vast network is needed to supply smaller population. In some states, water supply is blessed with abundant water while some states live under scarcity of surface water resources and hence resort to various other means such as desalination and groundwater recharge and withdrawal. Next to the scarcity issue is the water quality issue. Since the invention of disinfection by-products suspected of causing cancer in humans when chlorine is used as a disinfectant, many water supply utilities faced many challenges in reducing the disinfection by-products. Some utilities have adopted a different disinfectant and some utilities moved to treat water extensively before chlorine is applied. The talk will address the success stories and challenges remain to be resolved.

Abstract: Climate change impact remains major risk for water security across the world. Water supply security assessment in Australia is primarily based on estimated inflow data over last 100 years assuming future inflow variability will follow the past. However droughts within the records periods and paleo records show evidence of significant climate variability. Urban supply systems are designed using extended synthetic hydrological data to withstand droughts worse than recorded. The drinking water for Sydney’s over 4 Million residents is primarily supplied by surface water sources in the Hawkesbury-Nepean river system. The Climate Change Impact assessment methodology included techniques of interpretation of Global Climate Model (GCM) estimates, downscaling of results to catchment scale, plus catchment rainfall-runoff and water supply system modelling. The recent assessment incorporated NSW / ACT Regional Climate Model (NARCliM) developed for the purpose. The availability of multiple model ensemble results in terms of plausible extremes has greatly improved Risk management adaptation planning for climate change. The presentation deals with uncertainty about future climate, incorporating the attributes of supply system resilience (the ability to bounce back after unexpected) and robustness (the ability to cope with the unexpected), and communicating complex results and difficult-to-visualize trade-offs.

Abstract: WaterNSW uses WATHNET, a generic water balance model for strategic and technical planning of the Greater Sydney water supply system. The model is run for a series of synthetic replicates containing stochastic climate and streamflows data similar to historic data. The WaterNSW’s Greater Sydney water supply system yield is the maximum annual average demand that can be supplied by the system whilst conforming to the design criteria. Sydney’s raw water supply system is designed to meet service standards to ensure supply continuity and to minimise the frequency and duration of water restrictions. The system’s performance is assigned against a series of criteria such as reliability, robustness and security. The WATHNET model was used to develop Greater Sydney Metro Water Paln in 2004, 2006 and 2010. After the Metro Water Plan scenario modelling, all the scenarios were costed for further assessemnt. This was done outside the system model Wathnet. A need was identified that it would be more efficient and transparent if an economic assessment of the system’s performance for each of the synthetic inflow replicates was performed through the system model. The new version of WATHNET modelling softwatre incorporated an economic functionality along with the system supply system simulation model and the model was used to firstly build a model which closely represents the WaterNSW’s Greater Sydney water supply system previously simulated using WATHNET. The purpose of this paper is to demonstrate the new Wathnet model’s economic functionality and its application in asset planning.

Abstract: In this study, local scour around two vertical submerged circular piles installed on a sandy bed was investigated through numerical simulations. A three-dimensional finite element numerical model was established for simulating local scour around submerged cylinders. The Reynolds-Averaged Navier-Stokes equations are coupled with the bed morphological model to simulate the scour process. Both suspended load and bed load sediment transport rates are taken into account in the model. Efforts are made to reduce the computational time associated with parallel computing techniques. Scour around a submerged wall mounted vertical circular cylinder is simulated and the numerical results are validated against the test data. The scour depth at the upstream side of the upstream pile is found to increase with the gap ratio between the two piles. The scour mechanism around two submerged piles is investigated using the present numerical model.

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