Dragan Savic FREng

Optimisation tools are a practical solution to problems involving the complex and interdependent constituents of water resource systems and offer the opportunity to engage with practitioners as an integral part of the optimisation process. A multiobjective genetic algorithm is employed in conjunction with a detailed water resource model to optimise the “Lower Thames Control Diagram”, a set of control curves subject to a large number of constraints. The Diagram is used to regulate abstraction of… Meer weergeven

Optimisation tools are a practical solution to problems involving the complex and interdependent constituents of water resource systems and offer the opportunity to engage with practitioners as an integral part of the optimisation process. A multiobjective genetic algorithm is employed in conjunction with a detailed water resource model to optimise the “Lower Thames Control Diagram”, a set of control curves subject to a large number of constraints. The Diagram is used to regulate abstraction of water for the public drinking water supply for London, UK, and to maintain downstream environmental and navigational flows. The optimisation is undertaken with the aim of increasing the amount of water that can be supplied (deployable output) through solely operational changes. A significant improvement of 33 Ml/day (1% or £59.4 million of equivalent investment in alternative resources) of deployable output was achieved through the optimisation, improving the performance of the system whilst maintaining the level of service constraints without negatively impacting on the amount of water released downstream. A further 0.2% (£11.9 million equivalent) was found to be realisable through an additional low-cost intervention. A more realistic comparison of solutions indicated even larger savings for the utility, as the baseline solution did not satisfy the basic problem constraints. The optimised configuration of the Lower Thames Control Diagram was adopted by the water utility and the environmental regulators and is currently in use. Minder weergeven

The application of Evolutionary Algorithms (EAs) to real-world problems comes with inherent challenges, primarily the difficulty in defining the large number of considerations needed when designing complex systems such as Water Distribution Networks (WDN). One solution is to use an Interactive Evolutionary Algorithm (IEA), which integrates a human expert into the optimisation process and helps guide it to solutions more suited to real-world application. The involvement of an expert provides the… Meer weergeven

The application of Evolutionary Algorithms (EAs) to real-world problems comes with inherent challenges, primarily the difficulty in defining the large number of considerations needed when designing complex systems such as Water Distribution Networks (WDN). One solution is to use an Interactive Evolutionary Algorithm (IEA), which integrates a human expert into the optimisation process and helps guide it to solutions more suited to real-world application. The involvement of an expert provides the algorithm with valuable domain knowledge; however, it is an intensive task requiring extensive interaction, leading to user fatigue and reduced effectiveness. To address this, the authors have developed methods for capturing human expertise from user interactions utilising machine learning to produce Human-Derived Heuristics (HDH) which are integrated into an EA's mutation operator. This work focuses on the development of an adaptive method for applying multiple HDHs throughout an EA's search. The new adaptive approach is shown to outperform both singular HDH approaches and traditional EAs on a range of large scale WDN design problems. This work paves the way for the development of a new type of IEA that has the capability of learning from human experts whilst minimising user fatigue. Minder weergeven

The design, construction and maintenance of Critical Infrastructures (CI) is commonly based on standards that are rigorous, so as to withstand any climate or weather-linked pressures. However, due to climate change, climate characteristics may shift, resulting in increased frequency/magnitude of potential failures, or exposure to new unknown risks. As vital components for the normal functioning of modern societies, the resilience of CIs under climate stressors encompasses their structural… Meer weergeven

The design, construction and maintenance of Critical Infrastructures (CI) is commonly based on standards that are rigorous, so as to withstand any climate or weather-linked pressures. However, due to climate change, climate characteristics may shift, resulting in increased frequency/magnitude of potential failures, or exposure to new unknown risks. As vital components for the normal functioning of modern societies, the resilience of CIs under climate stressors encompasses their structural integrity, their operational elements, and their capacity to maximize business output. In this work, we propose an integrated and participatory methodological approach to enhance the resilience of interconnected CIs to urban flooding under climate change, by assessing the risk and introducing adaptation measures.

The main objectives of the proposed methodology and approach are: (i) to provide scientific evidence for better understanding of how future climate regimes might affect normal operation of interconnected CI in urban areas during their lifespan; (ii) to assess the cost-effectiveness of different adaptation measures; (iii) to involve local stakeholders and operators in the co-design of the approach, as well as the assessment and the evaluation of adaptation measures; (iv) to combine computational modelling with advanced 3D visualisation techniques for effectively engaging stakeholders in decision making; (v) to include risk assessment and damage functions co-designed by end-users and local stakeholders; (vi) to integrate all of the aforementioned components in a specifically designed cloud platform as a Decision Support System for end-users, (vii) to validate the DSS by the end users and local stakeholders.

The paper presents computational background and tools. Additionally, it describes a Case Study in Torbay, UK, where the full methodology and the proposed participatory approach have been applied. Minder weergeven

Water quality sensors are often spatially distributed in water distribution systems (WDSs) to detect contamination events and monitor quality parameters (e.g., chlorine residual levels), thereby ensuring safety of a WDS. The performance of a water quality sensor placement strategy (WQSPS) is not only affected by sensor spatial deployment that has been extensively analyzed in literature, but also by possible sensor failures that have been rarely explored so far. However, enumerating all possible… Meer weergeven

Water quality sensors are often spatially distributed in water distribution systems (WDSs) to detect contamination events and monitor quality parameters (e.g., chlorine residual levels), thereby ensuring safety of a WDS. The performance of a water quality sensor placement strategy (WQSPS) is not only affected by sensor spatial deployment that has been extensively analyzed in literature, but also by possible sensor failures that have been rarely explored so far. However, enumerating all possible sensor failure scenarios is computationally infeasible for a WQSPS with a large number of sensors. To this end, this paper proposes an evolutionary algorithm (EA) based method to systematically and efficiently investigate the WQSPS′ global resilience considering all likely sensor failures. First, new metrics are developed in the proposed method to assess the global resilience of a WQSPS. This is followed by a proposal of an efficient optimization approach based on an EA to identify the values of global resilience metrics. Finally, the sensors within the WQSPS are ranked to identify their relative importance in maintaining the WQSPS’s detection performance. Two real-world WDSs with four WQSPSs for each case study are used to demonstrate the utility of the proposed method. Results show that: (i) compared to the traditional global resilience analysis method, the proposed EA-based approach identifies improved values of global resilience metrics, (ii) the WQSPSs that deploy sensors close to large demand users are overall more resilient in handling sensor failures relative to other design solutions, thus offering important insight to facilitate the selection of WQSPSs, and (iii) sensor rankings based on the global resilience can identify those sensors whose failure would significantly reduce the WQSPS’s performance thereby providing guidance to enable effective water quality sensor management and maintenance. Minder weergeven

Capacity of urban drainage systems (UDSs) can substantially influence flooding properties of urban catchments. This motivates many studies to optimally design UDSs often using multiobjective evolutionary algorithms (MOEAs) as they can explore trade‐offs between conflicting objectives (e.g., cost vs. system reliability). However, MOEA‐based approaches are typically computationally demanding and their solutions are often practically unacceptable as engineering domain knowledge is often not… Meer weergeven

Capacity of urban drainage systems (UDSs) can substantially influence flooding properties of urban catchments. This motivates many studies to optimally design UDSs often using multiobjective evolutionary algorithms (MOEAs) as they can explore trade‐offs between conflicting objectives (e.g., cost vs. system reliability). However, MOEA‐based approaches are typically computationally demanding and their solutions are often practically unacceptable as engineering domain knowledge is often not explicitly considered. To address these two issues, this paper proposes an efficient optimization framework for UDS design, where an engineering‐based design method (EBDM) is developed to generate approximate solutions to initialize the MOEA's search, thereby greatly enhancing the optimization efficiency. To improve the solution practicality, two ideas have been implemented in the proposed optimization method (PM): (i) the variability of peak depths across pipes is minimized and (ii) a constraint is introduced to ensure that sizes of pipes in the downstream direction are no smaller than their corresponding upstream diameters. Two real‐world UDSs of different size are used to demonstrate the effectiveness of the PM. Results show that (i) the proposed EBDM is effective in producing initial solutions that are very close to the final solutions identified by the optimization methods, (ii) the minimization of the variability of peak depths in pipes is practically meaningful as it can facilitate to identify solutions with great ability in handling future uncertainties (e.g., rainfall variability), and (iii) the PM significantly improves optimization efficiency and solution practicality compared to the traditional optimization approach, with benefits being more prominent for larger UDSs. Minder weergeven

Water system design problems are complex and difficult to optimise. It has been demonstrated that involving engineering expertise is required to tackle real-world problems. This paper presents two engineering inspired hybrid evolutionary algorithms (EAs) for the multi-objective design of water distribution networks. The heuristics are developed from traditional design approaches of practicing engineers and integrated into the mutation operator of a multi-objective EA. The first engineering… Meer weergeven

Water system design problems are complex and difficult to optimise. It has been demonstrated that involving engineering expertise is required to tackle real-world problems. This paper presents two engineering inspired hybrid evolutionary algorithms (EAs) for the multi-objective design of water distribution networks. The heuristics are developed from traditional design approaches of practicing engineers and integrated into the mutation operator of a multi-objective EA. The first engineering inspired heuristic is designed to identify hydraulic bottlenecks within the network and eliminate them with a view to speeding up the algorithm's search to the feasible solution space. The second heuristic is based on the notion that pipe diameters smoothly transition from large, at the source, to small at the extremities of the network. The performance of the engineering inspired hybrid EAs is compared with Non-Dominated Sorting Genetic Algorithm II and assessed on three networks of varying complexity, two benchmarks and one real-world network. The experiments presented in this paper demonstrate that the incorporation of engineering expertise can improve EA performance, often producing superior solutions both in terms of mathematical optimality and also engineering feasibility. Minder weergeven

Critical infrastructures (CIs) are commonly designed, built and maintained based on rigorous standards in order to withstand the climate and weather-related pressures. However, shifts in climate characteristics may result in increases of the magnitude and frequency of potential risks, or expose specific CI to new or increased risks not previously considered. As vital components of the normal functioning of modern societies, their resilience encompasses the operational elements, their structural… Meer weergeven

Critical infrastructures (CIs) are commonly designed, built and maintained based on rigorous standards in order to withstand the climate and weather-related pressures. However, shifts in climate characteristics may result in increases of the magnitude and frequency of potential risks, or expose specific CI to new or increased risks not previously considered. As vital components of the normal functioning of modern societies, their resilience encompasses the operational elements, their structural integrity and the capacity to maximise business output under climate stressors. In this work, we apply an integrated and participatory methodological approach to assess the risk and enhance the resilience of interconnected CIs to urban flooding under climate change. The proposed methodology has been applied to an extended case study in Torbay to extend previous works, which seeks to protect coastal communities from future events through using the proposed methodology to justify future investment in coastal defences, as a part of the validation of EU-CIRCLE projects developed methodologies. Minder weergeven

A novel quantitative risk assessment for residential properties at risk of pluvial
flooding in Eindhoven, The Netherlands, is presented. A hydraulic model belonging to
Eindhoven was forced with low return period rainfall events (2, 5 and 10-year design rainfalls).
Three scenarios were analysed for each event: a baseline and two risk-reduction scenarios. GIS
analysis identified areas where risk-reduction measures had the greatest impact. Financial loss
calculations were carried… Meer weergeven

A novel quantitative risk assessment for residential properties at risk of pluvial
flooding in Eindhoven, The Netherlands, is presented. A hydraulic model belonging to
Eindhoven was forced with low return period rainfall events (2, 5 and 10-year design rainfalls).
Three scenarios were analysed for each event: a baseline and two risk-reduction scenarios. GIS
analysis identified areas where risk-reduction measures had the greatest impact. Financial loss
calculations were carried out using fixed-threshold and probabilistic approaches. Under fixedthreshold
assessment, per-event Expected Annual Damage (EAD) reached €38.2 m, with
reductions of up to €454,000 resulting from risk-reduction measures. Present costs of flooding
reach €1.43bn when calculated over a 50-year period. All net-present value figures for the riskreduction
measures are negative. Probabilistic assessment yielded EAD values up to more than
double those of the fixed-threshold analysis which suggested positive net-present value. To the
best of our knowledge, the probabilistic method based on the distribution of doorstep heights
has never before been introduced for pluvial flood risk assessment. Although this work
suggests poor net-present value of risk-reduction measures, indirect impacts of flooding,
damage to infrastructure and the potential impacts of climate change were omitted. This work represents a useful first step in helping Eindhoven prepare for future pluvial flooding. The
analysis is based on software and tools already available at the municipality, eliminating the
need for software upgrading or training. The approach is generally applicable to similar cities. Minder weergeven

CLImate-induced changes on WAter and SECurity (CLIWASEC) was a cluster of three complementary EC-FP7 projects assessing climate-change impacts throughout the Mediterranean on: hydrological cycles (CLIMB); water security (WASSERMed) and human security connected with possible hydro-climatic conflicts (CLICO). The Nile delta case study was common between the projects. CLIWASEC created an integrated forum for modelling and monitoring to understand potential impacts across sectors. This paper… Meer weergeven

CLImate-induced changes on WAter and SECurity (CLIWASEC) was a cluster of three complementary EC-FP7 projects assessing climate-change impacts throughout the Mediterranean on: hydrological cycles (CLIMB); water security (WASSERMed) and human security connected with possible hydro-climatic conflicts (CLICO). The Nile delta case study was common between the projects. CLIWASEC created an integrated forum for modelling and monitoring to understand potential impacts across sectors. This paper summarises key results froman integrated
assessment of potential challenges to water-related security issues, focusing on expected sea-level rise impacts by the middle of the century.We use this common focus to illustrate the added value of project clustering. CLIWASEC pursued multidisciplinary research by adopting a single research objective: sea-level rise related water security threats, resulting in a more holistic view of problems and potential solutions. In fragmenting research, policy-makers can fail to understand how multiple issues can materialize from one driver. By combining efforts, an integrated assessment ofwater security threats in the lower Nile is formulated, offering policy-makers a clearer picture of inter-related issues to society and environment. The main issues identified by each project (land subsidence, saline intrusion — CLIMB; water supply overexploitation, land loss — WASSERMed; employment and housing security — CLICO), are in fact related. Water overexploitation is exacerbating land subsidence and saline intrusion, impacting on employment and placing additional pressure on remaining agricultural land and the underdeveloped housingmarket. All these have wider implications for regional development. This richer understanding could be critical in making better policy decisions when attempting to mitigate climate and social change impacts. The CLIWASEC clustering offers an encouraging path for the new European Commission Horizon 2020 programme to follow. Minder weergeven

In October 2011, Section 105A (S105A) of the Water Act of 2003 transferred the ownership of previously privately owned sewers to the ten water and sewerage companies operating in England and Wales. In light of this recent legislative change, this paper discusses the asset management challenges associated with the private sewer transfer before exploring a decision-making framework used by South West Water to establish a more accurate understanding of the extent and likely condition of their… Meer weergeven

In October 2011, Section 105A (S105A) of the Water Act of 2003 transferred the ownership of previously privately owned sewers to the ten water and sewerage companies operating in England and Wales. In light of this recent legislative change, this paper discusses the asset management challenges associated with the private sewer transfer before exploring a decision-making framework used by South West Water to establish a more accurate understanding of the extent and likely condition of their newly transferred network. Minder weergeven

DOI: 10.1680/muen.13.00006
In a move towards realising a total expenditure approach, a previously successful sewer rehabilitation optimisation model has been adapted to provide a mechanism for users to evaluate the trade-offs that exist between the capital and operational benefits associated with different sewer rehabilitation schemes.

The design of District Metered Areas (DMAs) in existing water distribution networks, especially in urban areas, involves a high number of decision variables and the effects of implementing them in districts have to be evaluated, in order not to affect the quality of the service to customers. A new methodology for designing a given number of districts in looped water distribution networks, is proposed here. It is based on graph theory and takes into account some important DMA design criteria:… Meer weergeven

The design of District Metered Areas (DMAs) in existing water distribution networks, especially in urban areas, involves a high number of decision variables and the effects of implementing them in districts have to be evaluated, in order not to affect the quality of the service to customers. A new methodology for designing a given number of districts in looped water distribution networks, is proposed here. It is based on graph theory and takes into account some important DMA design criteria: the maximum and minimum size recommended for a district, the connectedness of each district to the water supply source and the absence of links between the districts: therefore it allows the creation of DMAs that are independent one from another. A recursive bisection procedure has been applied to create districts, while an algorithm for graph traversal has been used to verify whether each district can be reached from the water source and connectivity between the nodes. The successful application of the proposed methodology to a case study has proved its effectiveness for District Metered Areas design in real urban water distribution networks. Minder weergeven

With the growth in urban population and other pressures, such as climate change, the impact and severity of urban flood events are likely to continue to increase. “Intelligent water networks” are viewed as the way forward to ensure that infrastructure services are flexible, safe, reliable and economical. Reduction of flood-risk from urban drainage and sewerage infrastructure is likely to require increasingly sophisticated computational techniques to keep pace with the level of data that is… Meer weergeven

With the growth in urban population and other pressures, such as climate change, the impact and severity of urban flood events are likely to continue to increase. “Intelligent water networks” are viewed as the way forward to ensure that infrastructure services are flexible, safe, reliable and economical. Reduction of flood-risk from urban drainage and sewerage infrastructure is likely to require increasingly sophisticated computational techniques to keep pace with the level of data that is collected both from meteorological and online water monitoring systems in the field. This paper describes and characterises an example of an Early Warning System (EWS), designated "RAPIDS" (RAdar Pluvial flooding Identification for Drainage System) that deals with urban drainage systems and the utilisation of rainfall data concurrently to predict flooding of multiple urban areas in near real-time using a single multi-output Artificial Neural Network (ANN). The system has the potential to provide early warning for decision makers within reasonable time, this being a key requirement determining the operational usefulness of such systems. Computational methods that require hours or days to run will not be able to keep pace with fast-changing situations such as manhole flooding or Combined Sewer Overflow (CSO) spills and thus the system developed is able to react in close to real time. This paper includes a sensitivity analysis and demonstrates that the - predictive capability of such a system based on actual rainfall is limited to a maximum of the Time of Concentration (ToC) of each node being modelled. To achieve operationally useful prediction times, predictions of rainfall as input signals are likely to be needed for most urban drainage networks. Minder weergeven

Paper presented at the CCWI 2013 conference in Perugia, Italy.

An integrated System Dynamics Model for the water-stressed Rosetta region, Egypt, assessing water
balance, and agricultural yield and revenue to 2050, is presented. The study uses 57 simulations to
better understand impacts on water, food and economic security and their interactions, in order to
highlight potential pathways towards a more sustainable future for the Rosetta region. Current water
resource over-exploitation can be mitigated while still allowing for agricultural… Meer weergeven

An integrated System Dynamics Model for the water-stressed Rosetta region, Egypt, assessing water
balance, and agricultural yield and revenue to 2050, is presented. The study uses 57 simulations to
better understand impacts on water, food and economic security and their interactions, in order to
highlight potential pathways towards a more sustainable future for the Rosetta region. Current water
resource over-exploitation can be mitigated while still allowing for agricultural development. The
utility of the system dynamics paradigm in modelling complex systems is highlighted, with the
potential to extend the methodology to other studies. While most simulations hinted at continued
over-exploitation, some suggest that improvements can be achieved by altering parameters such as
per-capita domestic water demand and/or the cropping regime. Many policies should be considered
in parallel to introduce redundancy into the policy framework. From initial results, it was
hypothesised that by producing excess crops, international markets could be exploited, leading to
further improvements in the water balance, yield and revenue. A model extension was built which
suggested that improvements are possible, furthering local development. However, these
improvements would probably manifest after years, have to be managed carefully, and would
increase reliance on other countries. Minder weergeven

Urban population growth together with other pressures, such as climate change, create enormous challenges to provision of urban infrastructure services, including gas, electricity, transport, water, etc. Smart-grid technology is viewed as the way forward to ensure that infrastructure networks are flexible, accessible, reliable and economical. “Intelligent water networks” take advantage of the latest information and communication technologies to gather and act on information to minimise waste… Meer weergeven

Urban population growth together with other pressures, such as climate change, create enormous challenges to provision of urban infrastructure services, including gas, electricity, transport, water, etc. Smart-grid technology is viewed as the way forward to ensure that infrastructure networks are flexible, accessible, reliable and economical. “Intelligent water networks” take advantage of the latest information and communication technologies to gather and act on information to minimise waste and deliver more sustainable water services. The effective management of water distribution, urban drainage and sewerage infrastructure is likely to require increasingly sophisticated computational techniques to keep pace with the level of data that is collected from measurement instruments in the field. This paper describes two examples of intelligent systems developed to utilise this increasingly available real-time sensed information in the urban water environment. The first deals with the failure-management decision-support system for water distribution networks, NEPTUNE, that takes advantage of intelligent computational methods and tools applied to near real-time logger data providing pressures, flows and tank levels at selected points throughout the system. The second, called RAPIDS, deals with urban drainage systems and the utilisation of rainfall data to predict flooding of urban areas in near real-time. The two systems have the potential to provide early warning and scenario testing for decision makers within reasonable time, this being a key requirement of such systems. Computational methods that require hours or days to run will not be able to keep pace with fast-changing situations such as pipe bursts or manhole flooding and thus the systems developed are able to react in close to real time. Minder weergeven

The revised Bathing Water Directive (rBWD) (2006/7/EC) of the European Parliament requires monitoring of bathing water quality and, if early-warnings are provided to the public, it is permissible to discount a percentage of exceedance events from the monitoring process. This paper describes the development and implementation of both Decision Tree (DT) and Artificial Neural Network (ANN) based machine learning models for 8 beaches in south-west England, UK, as bases for early warning systems… Meer weergeven

The revised Bathing Water Directive (rBWD) (2006/7/EC) of the European Parliament requires monitoring of bathing water quality and, if early-warnings are provided to the public, it is permissible to discount a percentage of exceedance events from the monitoring process. This paper describes the development and implementation of both Decision Tree (DT) and Artificial Neural Network (ANN) based machine learning models for 8 beaches in south-west England, UK, as bases for early warning systems (EWS) and compares their performance for one beach. Weekly bacteria-count samples were gathered by the Environment Agency of England (EA) over a 12-year period from 2000-2011 during the 20-week bathing season and this data is used to calibrate and test the models. Daily sampling data were also collected at 5 of the beaches during the 2012 season to provide more robust validation of the models. As a benchmark, models are also compared with use of simple thresholds of antecedent rainfall to classify water quality exceedances. Evolutionary Algorithm-based optimisation of the ANN models is employed using single-objective approach using area under the Receiver Operating Characteristic (ROC) curve as fitness function. The optimum operating point is established using a weighting factor for the relative importance placed on false positives (passes) and false negatives (exceedances). The models use a number of input factors, including antecedent rainfall for the catchment adjacent to each bathing beach. A possible technique for automating selection of inputs is also discussed. Minder weergeven

This paper describes the application of Artificial Neural Networks (ANNs) as Data Driven Models (DDMs) to predict urban flooding in real-time based on weather radar and/or raingauge rainfall data. A time-lagged ANN is configured for prediction of flooding at sewerage nodes and outfalls based on input parameters including rainfall. In the absence of observed flood data, a hydrodynamic simulator may be used to predict flooding surcharge levels at nodes of interest in sewer networks and thus… Meer weergeven

This paper describes the application of Artificial Neural Networks (ANNs) as Data Driven Models (DDMs) to predict urban flooding in real-time based on weather radar and/or raingauge rainfall data. A time-lagged ANN is configured for prediction of flooding at sewerage nodes and outfalls based on input parameters including rainfall. In the absence of observed flood data, a hydrodynamic simulator may be used to predict flooding surcharge levels at nodes of interest in sewer networks and thus provide the target data for training and testing the ANN. The model, once trained, acts as a rapid surrogate for the hydrodynamic simulator and can thus be used as part of an urban flooding Early Warning System (EWS). Predicted rainfall over the catchment is required as input, to extend prediction times to operationally useful levels. Both flood-level analogue and flood-severity classification schemes are implemented. An initial case study using Keighley, W Yorks, UK demonstrated proof-of-concept. Three further case studies for UK cities of different sizes explore issues of soil-moisture, early operation of pumps as flood-mitigation/prevention strategy and spatially variable rainfall. We investigate the use of ANNs for nowcasting of rainfall based on the relationship between radar data and recorded rainfall history; a feature extraction scheme is described. This would allow the two ANNs to be cascaded to predict flooding in real-time based on current weather radar Quantitative Precipitation Estimates (QPE). We also briefly describe the extension of this methodology to Bathing Water Quality (BWQ) prediction. Minder weergeven

This poster describes a predictive model for bathing water quality trialled for 11 designated bathing beaches in south-west England in order to demonstrate potential for reduced health risks to bathers and beachgoers. Artificial Neural Networks (ANNs) are trained to find the relationship between bacteria counts and a number of contributing factors, such as rainfall and salinity of bathing water. Once trained for a given beach, the ANNs can be used to make a daily prediction of likely bathing… Meer weergeven

This poster describes a predictive model for bathing water quality trialled for 11 designated bathing beaches in south-west England in order to demonstrate potential for reduced health risks to bathers and beachgoers. Artificial Neural Networks (ANNs) are trained to find the relationship between bacteria counts and a number of contributing factors, such as rainfall and salinity of bathing water. Once trained for a given beach, the ANNs can be used to make a daily prediction of likely bathing water quality and beach managers can display appropriate signage and provide automated text message alerts. The method of training the ANNs uses Evolutionary Algorithms (EA) based on minimisation of both false positive rate (FPR)(not warning people on days when it is unsafe to swim) and false negative rate (FNR)(warning people not to swim, on days when it is actually safe) using a weighting factor for the relative importance placed on false negatives and false positives. Minder weergeven

OPEN ACCESS PAPER: With the increase in frequency and severity of flash flood events in major cities around the world, the infrastructure and people living in those urban areas are exposed continuously to high risk levels of pluvial flooding. The situation is likely to be exacerbated by the potential impact of future climate change. A fast flood model could be very useful for flood risk analysis. One-dimensional (1D) models provide limited information about the flow dynamics whereas… Meer weergeven

OPEN ACCESS PAPER: With the increase in frequency and severity of flash flood events in major cities around the world, the infrastructure and people living in those urban areas are exposed continuously to high risk levels of pluvial flooding. The situation is likely to be exacerbated by the potential impact of future climate change. A fast flood model could be very useful for flood risk analysis. One-dimensional (1D) models provide limited information about the flow dynamics whereas two-dimensional (2D) models require substantial computational time and cost, a factor that limits their use. This paper presents an alternative approach using cellular automata (CA) for 2D modelling. The model uses regular grid cells as a discrete space for the CA setup and applies generic rules to local neighbourhood cells to simulate the spatio-temporal evolution of pluvial flooding. The proposed CA model is applied to a hypothetical terrain and a real urban area. The synchronous state updating rule and inherent nature of the proposed model contributes to a great reduction in computational time. The results are compared with a hydraulic model and good agreement is found between the two models. Minder weergeven

This paper presents a comparative analysis of System Dynamics Modelling (SDM) and Object-Oriented Bayesian Networks (OOBN). Both techniques are extensively used for water resources modelling due to their flexibility, effectiveness in assessing different management options, ease of operation and suitability for encouraging stakeholder involvement. Conversely, both approaches have several important differences that make them complementary. For example, while SDM is more suitable for simulating… Meer weergeven

This paper presents a comparative analysis of System Dynamics Modelling (SDM) and Object-Oriented Bayesian Networks (OOBN). Both techniques are extensively used for water resources modelling due to their flexibility, effectiveness in assessing different management options, ease of operation and suitability for encouraging stakeholder involvement. Conversely, both approaches have several important differences that make them complementary. For example, while SDM is more suitable for simulating the feedback dynamics of processes, OOBN modelling is a powerful tool for modelling systems with uncertain inputs (or outputs) characterised by probability distributions. This comparative analysis is applied to the Kairouan aquifer system, Tunisia, where the aquifer plays an essential role for socio-economic development in the region. Both models produced comparable results using baseline data, and show their complementarity through a suite of scenario tests. It is shown that reducing pumping of groundwater to coastal cities may prove the key to reducing the current aquifer deficit, though local demand reduction must be considered to preserve the agricultural economy. It is suggested that water management assessment should be tackled using both approaches to complement each other, adding depth and insight, and giving a more coherent picture of the problem being addressed, allowing for robust policy decisions to be made. Minder weergeven

Highlights

► A System Dynamics Model of a complex water scarce system is presented. ► The baseline run indicates net aquifer depletion to 2050. ► Parameter tests hint at the complex non-linearity in the system. ► Reducing coastal pumping holds most promise for re-establishing recharge behaviour. ► Any viable water-saving policy should be considered given the current situation.
Keywords

System dynamics;
Kairouan aquifer;
Water scarcity assessment;
Water… Meer weergeven

Highlights

► A System Dynamics Model of a complex water scarce system is presented. ► The baseline run indicates net aquifer depletion to 2050. ► Parameter tests hint at the complex non-linearity in the system. ► Reducing coastal pumping holds most promise for re-establishing recharge behaviour. ► Any viable water-saving policy should be considered given the current situation.
Keywords

System dynamics;
Kairouan aquifer;
Water scarcity assessment;
Water resources simulation

A System Dynamics Model (SDM) assessing water scarcity and potential impacts of socio-economic policies in a complex hydrological system is developed. The model, simulating water resources deriving from numerous catchment sources and demand from four sectors (domestic, industrial, agricultural, external pumping), contains multiple feedback loops and sub-models. The SDM is applied to the Merguellil catchment, Tunisia; the first time such an integrated model has been developed for the water scarce Kairouan region. The application represents an early step in filling a critical research gap. The focus of this paper is to a) assess the applicability of SDM for assessment of the evolution of a water-scarce catchment and b) to analyse the current and future behaviour of the catchment to evaluate water scarcity, focusing on understanding trends to inform policy.
Minder weergeven

A recent trend in the development of flood simulation algorithms shows the move toward fast simplified models instead of slow full hydrodynamic models. CADDIES is a research project that aims to develop a real/near-real time pluvial urban flood simulation model using the computational speed of cellular automata (CA) algorithms. This paper presents a component of the software framework that is part of the CADDIES project. Its objective is to simplify the development of CA algorithms and their… Meer weergeven

A recent trend in the development of flood simulation algorithms shows the move toward fast simplified models instead of slow full hydrodynamic models. CADDIES is a research project that aims to develop a real/near-real time pluvial urban flood simulation model using the computational speed of cellular automata (CA) algorithms. This paper presents a component of the software framework that is part of the CADDIES project. Its objective is to simplify the development of CA algorithms and their acceleration using modern high performance hardware and techniques. The performance results obtained on a simple case study clearly demonstrate the effectiveness and efficiency of the CADDIES framework. Minder weergeven

Nowadays, the unprecedented computing power of desktop personal computers and efficient computational methodologies such as the global gradient algorithm (GGA) make large water-distribution-system modeling feasible. However, many network analysis applications, such as optimization models, require running numerous hydraulic simulations with modified input parameters. Therefore, a methodology that can reduce the computational burden of network analysis and still provide the required model… Meer weergeven

Nowadays, the unprecedented computing power of desktop personal computers and efficient computational methodologies such as the global gradient algorithm (GGA) make large water-distribution-system modeling feasible. However, many network analysis applications, such as optimization models, require running numerous hydraulic simulations with modified input parameters. Therefore, a methodology that can reduce the computational burden of network analysis and still provide the required model accuracy is needed. This paper presents a matrix transformation approach to convert the classic GGA, which is implemented within the widely available freeware EPANET 2, into a more computationally efficient enhanced global gradient algorithm (EGGA). The latter achieves improved efficiency by reducing the size of the mathematical problem through the transformed topological representation of the original network model. By removing serial nodes and serial pipe sections from the original topological representation while preserving those elements in both energy and mass balance equations, EGGA significantly improves the model’s computational efficiency without forfeiting its hydraulic accuracy. The computational efficiency and effectiveness of the EGGA approach are demonstrated on four real-life networks. Results show that the computational burden of the EGGA model is significantly lower than that of its GGA counterpart, particularly as the size of the network and/or number of service connections increases.


Read More: http://ascelibrary.org/doi/abs/10.1061/(ASCE)HY.1943-7900.0000517?journalCode=jhend8 Minder weergeven

The latest information and communications technology has enabled flood modelling in urban areas using high quality terrain data to simulate the detailed flow dynamics in local areas. However, the computational cost rises exponentially as the resolution goes finer. The advance of computing hardware is still a limiting factor for large-scale area or risk/uncertainty analysis modelling with fine resolution that describes the details of building features. Grid coarsening is the straightforward way… Meer weergeven

The latest information and communications technology has enabled flood modelling in urban areas using high quality terrain data to simulate the detailed flow dynamics in local areas. However, the computational cost rises exponentially as the resolution goes finer. The advance of computing hardware is still a limiting factor for large-scale area or risk/uncertainty analysis modelling with fine resolution that describes the details of building features. Grid coarsening is the straightforward way to reduce the computing efforts for 2D flood modelling. The traditional approach to grid coarsening usually takes the average elevation of a fine grid as the new terrain model for the coarse grid. This approach often results in loss of information that introduces errors to modelling. In this study, the building features in coarse grids were abstracted using the building coverage ratio (BCR) and the conveyance reduction factor (CRF) parameters in a 2D model to simulate flooding in urban areas. The outcome of 2D case studies showed the proposed model can minimise the errors due to terrain averaging and provide a much better accuracy of modelling results at a marginally increased computing cost. Minder weergeven

A unique methodology for the optimal specification of sewer rehabilitation investment is presented in this paper. By accounting for the critical risk of asset failure, this methodology builds on previously successful work which explored the application of multi-objective optimisation tools to assist engineers with the specification of optimal rehabilitation strategies. The conventional sewerage rehabilitation specification process relies on the expertise of professional engineers to manually… Meer weergeven

A unique methodology for the optimal specification of sewer rehabilitation investment is presented in this paper. By accounting for the critical risk of asset failure, this methodology builds on previously successful work which explored the application of multi-objective optimisation tools to assist engineers with the specification of optimal rehabilitation strategies. The conventional sewerage rehabilitation specification process relies on the expertise of professional engineers to manually evaluate CCTV inspection information when determining the nature and extent of the rehabilitation solution. This process is not only tedious and subjective but it has no quantifiable means of identifying optimal solutions or possible combinations of optimal solutions in the delivery of catchment wide rehabilitation programmes. Therefore, the purely manual process of sewer rehabilitation design leaves a number of unanswered questions, such as: (1) Does the solution offer the greatest structural benefit to the network? (2) Is the solution the most cost-effective solution available? (3) Does the solution most greatly reduce the risk of critical asset failure? The application of a multi-objective genetic algorithm optimisation model, coupled with an enhanced critical risk methodology, has successfully answered these questions when applied to a case study data set provided by South West Water (UK).

Keywords: asset management; critical risk; optimisation; planning; sewer; sewer rehabilitation Minder weergeven

Cellular automata (CA) algorithms can be used for quickly describing models of complex systems using simple rules. CADDIES is a new EPSRC and industry-sponsored project that aims to use the computational speed of CA algorithms to produce operationally useful real/near-real time pluvial urban flood models for both 1D-sewer and 2D-surface (dual-drainage) flows.
In this paper, the design of a graphical software framework for the CADDIES project is presented. This is intended to simplify the… Meer weergeven

Cellular automata (CA) algorithms can be used for quickly describing models of complex systems using simple rules. CADDIES is a new EPSRC and industry-sponsored project that aims to use the computational speed of CA algorithms to produce operationally useful real/near-real time pluvial urban flood models for both 1D-sewer and 2D-surface (dual-drainage) flows.
In this paper, the design of a graphical software framework for the CADDIES project is presented. This is intended to simplify the development, testing and use of CA algorithms, and to facilitate the handling of the peripheral tasks of data management and display; allowing the research users to focus on the central tasks of optimisation of CA models and algorithms themselves.
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Water management practice has benefited from the development of model-driven Decision Support Systems (DSS), and in particular those that combine simulation with single or multiple-objective optimisation tools. However, there are many performance, acceptance and adoption problems with these decision support tools caused mainly by misunderstandings between the communities of system developers and users. This paper presents a general-purpose decision-support system generator, GANetXL, for… Meer weergeven

Water management practice has benefited from the development of model-driven Decision Support Systems (DSS), and in particular those that combine simulation with single or multiple-objective optimisation tools. However, there are many performance, acceptance and adoption problems with these decision support tools caused mainly by misunderstandings between the communities of system developers and users. This paper presents a general-purpose decision-support system generator, GANetXL, for developing specific applications that require multiobjective optimisation of spreadsheet-based models. The system is developed as an Excel add-in that provides easy access to evolutionary multiobjective optimisation algorithms to non-specialists by incorporating an intuitive interactive graphical user interface that allows easy creation of specific decision-support applications. GANetXL’s utility is demonstrated on two examples from water engineering practice, a simple water supply reservoir operation model with two objectives and a large combinatorial optimisation problem of pump scheduling in water distribution systems. The two examples show how GANetXL goes a long way toward closing the gap between the achievements in optimisation technology and the successful use of DSS in practice.. Minder weergeven

Authors: Dragan A. Savic; John K. Banyard
Hardbound ISBN: 978-0-7277-4112-7
Ebook ISBN: 978-0-7277-4160-8
Publication Date: January 2011
DOI: 10.1680/wds.41127
Format: Hardbound, Electronic

Water Distribution Systems is a comprehensive introduction to the topic, covering fundamental concepts and exploring the latest ideas of good practice. Water industry professionals have to address, not only classic design and management problems but also… Meer weergeven

Authors: Dragan A. Savic; John K. Banyard
Hardbound ISBN: 978-0-7277-4112-7
Ebook ISBN: 978-0-7277-4160-8
Publication Date: January 2011
DOI: 10.1680/wds.41127
Format: Hardbound, Electronic

Water Distribution Systems is a comprehensive introduction to the topic, covering fundamental concepts and exploring the latest ideas of good practice. Water industry professionals have to address, not only classic design and management problems but also, increasingly, environmental and sustainability requirements and concerns. Drawing together information that is currently scattered across several sources, this book is a concise update of modern practice and current developments. Each chapter has been written by both academics and practitioners, balancing what’s theoretically possible against what’s practical in key areas such as modelling, planning, and operational and management issues, as well as more advanced topics such as leakage management, optimal design, asset planning and management. A good starting point for exploration of a complex topic, Water Distribution Systems is a key text for students and early-stage practitioners training to become water industry practitioners, and a useful reference book for practising engineers, particularly to provide up-to-date information on practices in today’s increasingly complex water industry.

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The goal of this project was to provide concise, comprehensive, and user-friendly guidance on the development,calibration, and application of hydraulic models for distribution systems.
A considerable effort has been made over the last 30 years to develop hydraulic models of water distribution systems. These models have evolved from iterative hand calculations to sophisticated software linking with advanced data applications. While modeling was originally only considered to
be available to… Meer weergeven

The goal of this project was to provide concise, comprehensive, and user-friendly guidance on the development,calibration, and application of hydraulic models for distribution systems.
A considerable effort has been made over the last 30 years to develop hydraulic models of water distribution systems. These models have evolved from iterative hand calculations to sophisticated software linking with advanced data applications. While modeling was originally only considered to
be available to sophisticated water utilities, the improvement in computing power and accessibility of software has opened up the modeling field to utilities of all sizes and capabilities. Throughout the evolution of modeling, the water industry has struggled with defining appropriate calibration techniques and standards. This struggle has been complicated by the system-specific nature of modeling and the wide range of model uses, each requiring different degrees of certainty in the outcome.

This project began with a compilation of modeling practices from published literature, participating utilities, workshop attendees, and practitioners from around the world. The 12 participating utilities in this project completed questionnaires outlining their model development, application, calibration,
and typical usage. The responses were compiled to provide a snapshot of current modeling practices and to document lessons learned in modeling. The modeling practice information was organized into sections for model development, calibration, and application.
The project then focused on developing a method to evaluate current models and plan for modeling projects. The project team worked with the participating utilities and modeling practitioners to create a flexible framework that could be adapted to a variety of distribution system configurations
and diverse modeling applications. Minder weergeven

This study proposes and assesses a novel numerical chlorine decay model with four parameters that are independent of the loading conditions for a given water sample. The model is based on kinetic equations derived from the rate law for concurrent bimolecular second order reactions with chlorine.

Hydraulic water distribution system (WDS) simulation models are widely used by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems. Similarly, water quality models that work in concert with hydraulic models are now commonly used to simulate the dispersion of and changes in water quality in a water distribution network. As with all mathematical models, WDS model parameters (hydraulic and water… Meer weergeven

Hydraulic water distribution system (WDS) simulation models are widely used by planners, water utility personnel, consultants and many others involved in analysis, design, operation or maintenance of water distribution systems. Similarly, water quality models that work in concert with hydraulic models are now commonly used to simulate the dispersion of and changes in water quality in a water distribution network. As with all mathematical models, WDS model parameters (hydraulic and water quality) require calibration before useful results may be obtained. Nowadays, automated calibration procedures are widely available for hydraulic models, but less so for water quality models. Even when they are available as commercial software, the use of these advanced calibration tools in engineering practice has been limited. This paper provides a review of model calibration approaches and considers future challenges and directions. Minder weergeven

This study examines using residual disinfectant data to calibrate a water quality model under unknown or uncertain demands by calibrating a residential demand multiplier pattern in tandem with the WQM parameters.

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