scholarly journals Survival analysis of water distribution network under intermittent water supply conditions

2020 ◽  
Vol 20 (8) ◽  
pp. 3531-3541
Author(s):  
Ali Mohammadi ◽  
Mohammadreza Jalili-Ghazizadeh ◽  
Iman Moslehi ◽  
Ehsan Yousefi-Khoshqalb
Keyword(s):  
Survival Analysis ◽  
Water Supply ◽  
Water Distribution ◽  
Supply And Demand ◽  
Demand Management ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Probability Of Failure ◽  
Failure Rates ◽  
Intermittent Water Supply

Abstract Intermittent water supply (IWS) is established temporarily or continuously in many water distribution networks (WDNs) worldwide due to prolonged drought, low rainfall periods, water scarcity and high level of leakage. IWS causes several adverse consequences on the network operation, resulting in ineffective supply and demand management. This paper presents a survival analysis of the network elements, including water mains, service connections, and valves using the Kaplan-Meier approach to determine the survival probability and the probability of failure rates of events of interest. The objective is to explore the changes in failure rates of network elements after implementing an IWS scheme. The non-parametric survival method is applied to the large zone (Zone-5) of the WDN in Tehran (Iran) based on the frequency of failures before, during, and after the implementation of an IWS regime. The results show that the probability of failure rates significantly increase after implementing the IWS scheme, and can remain for several years after, even when the network returns to continuous water supply (CWS). The results of this study can assist utility managers to understand the detrimental effects of IWS systems on increasing failure rates.

scholarly journals Multi-objective optimization for improving equity and reliability in intermittent water supply systems

2020 ◽  
Vol 20 (5) ◽  
pp. 1592-1603 ◽  
Author(s):  
Passwell Pepukai Nyahora ◽  
Mukand Singh Babel ◽  
David Ferras ◽  
Andres Emen
Keyword(s):  
Decision Making ◽  
Water Supply ◽  
Water Distribution ◽  
Investment Decision ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Water Supply Systems ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Intermittent Water Supply

Abstract Intermittent water systems suffer from several drawbacks such as unfair distribution among users, low reliability and poor water quality. Given limited water and financial resources, making decisions for improving intermittent water supply (IWS) becomes a complex process. The paths to continuous supply are a priori undefined, however, the provision of efficient service is crucial. In the scientific literature, limited research addresses how to improve intermittent systems, to enhance the current service while transitioning to continuous supply. A multi-objective optimization (MOO) tool using a genetic algorithm has been developed to assist in investment decision-making. This approach uses multiple cost-effective intervention options to maximize equity and reliability while minimizing cost implications in an IWS system. The costs in such interventions include expenditure on pipe replacement, booster pump and elevated tank installation. The approach was first tested on a benchmark Hanoi synthetic network, and then applied to the water distribution network of Milagro (Ecuador). The developed tool reveals the extent to which equity and reliability can be driving objectives, and how they can be factored into decision-making. The application of the MOO tool in intermittent systems in order to improve existing distribution networks with strategic infrastructure addition can provide greater equity and reliability.

A study on appropriate investment of pipeline rehabilitation for water distribution network

2005 ◽  
Vol 5 (2) ◽  
pp. 31-38
Author(s):  
A. Asakura ◽  
A. Koizumi ◽  
O. Odanagi ◽  
H. Watanabe ◽  
T. Inakazu
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Water Supply ◽  
Water Distribution ◽  
Ad Hoc ◽  
Distribution Network ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Optimal Basis ◽  
Model Case

In Japan most of the water distribution networks were constructed during the 1960s to 1970s. Since these pipelines were used for a long period, pipeline rehabilitation is necessary to maintain water supply. Although investment for pipeline rehabilitation has to be planned in terms of cost-effectiveness, no standard method has been established because pipelines were replaced on emergency and ad hoc basis in the past. In this paper, a method to determine the maintenance of the water supply on an optimal basis with a fixed budget for a water distribution network is proposed. Firstly, a method to quantify the benefits of pipeline rehabilitation is examined. Secondly, two models using Integer Programming and Monte Carlo simulation to maximize the benefits of pipeline rehabilitation with limited budget were considered, and they are applied to a model case and a case study. Based on these studies, it is concluded that the Monte Carlo simulation model to calculate the appropriate investment for the pipeline rehabilitation planning is both convenient and practical.

Determination of Neutral Point in Water Distribution Network Pipes with Variable Discharge on Route

2014 ◽  
Vol 909 ◽  
pp. 428-432 ◽  
Author(s):  
Ioan Sarbu ◽  
Gabriel Ostafe
Keyword(s):  
Water Supply ◽  
Distribution System ◽  
Water Distribution ◽  
Distribution Network ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Neutral Point ◽  
Water Supply Systems ◽  
Proposed Model

Distribution networks are an essential part of all water supply systems. Distribution system costs within any water supply scheme may be equal to or greater than 60% of the entire cost of the project. The reliability of supply is much greater in the case of looped networks. The pipe networks have concentrated outflows or uniform outflow along the length of each pipe. In some pipes with variable discharge of a looped distribution network, water velocity could be reversed between its extremities. Thus, it is a water stall point denominated neutral point in which the discharge is null. In this paper a mathematical model for the determination of water stall point location in the pipes with distributed consumption is developed. This model has been implemented in a computer program for PC microsystems. Numerical example will be presented to demonstrate the accuracy and efficiency of the proposed model.

scholarly journals Continuous-time quadratic cost flow problems with applications to water distribution networks

1996 ◽  
Vol 37 (4) ◽  
pp. 530-548 ◽  
Author(s):  
A. T. Ernst
Keyword(s):  
Network Flow ◽  
Water Distribution ◽  
Optimization Problems ◽  
Supply And Demand ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Flow Problems ◽  
Linear And Nonlinear Constraints ◽  
The Cost ◽  
And Storage

AbstractThis paper deals with a class of network optimization problems in which the flow is a function of time rather than static as in the classical network flow problem, and storage is permitted at the nodes. A solution method involving discretization will be presented as an application of the ASG algorithm. We furnish a proof that the discretized solution converges to the exact continuous solution. We also apply the method to a water distribution network where we minimize the cost of pumping water to meet supply and demand, subject to both linear and nonlinear constraints.

Hybrid genetic algorithm in the optimization of energy costs in water supply networks

2010 ◽  
Vol 10 (3) ◽  
pp. 315-326 ◽  
Author(s):  
L. H. M. Costa ◽  
H. M. Ramos ◽  
M. A. H. de Castro
Keyword(s):  
Genetic Algorithm ◽  
Water Supply ◽  
Distribution Systems ◽  
Water Distribution ◽  
Hybrid Genetic Algorithm ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Energy Costs ◽  
Efficient Operation ◽  
Operational Strategies

Efficient operation of water distribution systems is linked with the assurance of water availability to the population. In general, the operational rules applied to water distribution networks have as a sole objective the continuity of the water supply and disregards saving energy costs related to the operation of the pumps. The task of determining optimal operational procedures involves several elements such as the daily variation of water consumption, energy cost rates and the level of the tanks and reservoirs. This work presents a hybrid genetic algorithm which is connected to the widely known software EPANET, in order to determine operational strategies in water supply with reduced energy costs. The model is applied to a hypothetical example and to a real water distribution network located in the city of Ourém, in Portugal.

scholarly journals Influence of intermittent water supply operations on the vulnerability of water distribution networks

2017 ◽  
Vol 19 (6) ◽  
pp. 838-852 ◽  
Author(s):  
Agathoklis Agathokleous ◽  
Chrystalleni Christodoulou ◽  
Symeon E. Christodoulou
Keyword(s):  
Water Supply ◽  
Water Distribution ◽  
Research Work ◽  
Distribution Networks ◽  
Water Shortage ◽  
Operating Conditions ◽  
Water Distribution Networks ◽  
Intermittent Water Supply ◽  
Water Board ◽  
Deterioration Rate

Abstract Water authorities in countries facing water shortage problems are implementing intermittent water supply (IWS) policies, as a measure to conserve and control their national water resources. Implementation of such measures affects the behaviour of the water pipe systems during the operation stage. The research work presented herein presents a model simulating the behaviour of urban water distribution networks (WDNs) under normal operating conditions, as well as during a period of IWS operations. The modelling and analysis, based on an eight-year dataset (2003–2010) from a local Water Board, takes into account information related to breakage incidents within the WDN as well as external factors to perform vulnerability assessment of the pipe network. The results of the performed survival and cluster analysis show that during the implementation period of IWS operations, and right after that period, there is a significant increase in the deterioration rate of the affected network. Further, there is a change in the comparative importance of the factors affecting the network condition and their contribution to the WDN vulnerability.

scholarly journals GIS use of Land Use/Land Cover layers and historical data for water losses indices

2019 ◽  
Vol 85 ◽  
pp. 07009
Author(s):  
Alexandru Aldea ◽  
Mihaela Aldea ◽  
Sorin Perju
Keyword(s):  
Water Supply ◽  
Water Distribution ◽  
Historical Data ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Water Supply Systems ◽  
Land Use Land Cover ◽  
Water Losses ◽  
Decision Factors ◽  
Supply Systems

The population growth and/or its use and development of the land is a continuous preoccupation of the decision factors regarding the water supply system in general and the development of the potable water distribution networks in particular. This issue is even more critical especially in the areas of big cities and important urban growing. As the urbanization of land outgrows the existing water supply systems, one of the possible solutions is to expand the water distribution network in order to cover this urban growth. The present paper analyses further the possibilities to define and use certain indices of urban development together with water loss indices in order to determine trends or issues related with the provision of water supply services and connectivity.

scholarly journals Flood Impacts on a Water Distribution Network

2017 ◽  
Author(s):  
Chiara Arrighi ◽  
Fabio Tarani ◽  
Enrico Vicario ◽  
Fabio Castelli
Keyword(s):  
Water Supply ◽  
Water Distribution ◽  
Water Distribution Network ◽  
Distribution Networks ◽  
Supply System ◽  
Water Supply System ◽  
Flood Impacts ◽  
Drinking Water Supply System ◽  
Recurrence Intervals ◽  
Failure Scenario

Abstract. Floods cause damage to people, buildings and infrastructures. Due to their usual location near rivers, water utilities are particularly exposed; in case of flood, the inundation of the facility can damage equipment and cause power outages. Such impact leads to costly repairs, disruptions of service, hazardous situations for personnel and public health advisories. In this work, we present an analysis of direct and indirect damages of a drinking water supply system considering the hazard of a riverine flooding as well as the exposure and vulnerability of the system components (i.e. pipes, junctions, lifting stations etc.). The method is based on the combination of a flood model and an EPANET-based piping network model implementing Pressure-Driven Demand, which is more appropriate when modeling water distribution networks with many off-line nodes. The two models are linked by a semi-automated GIS procedure. The evaluation of flood impact on the aqueduct network is carried out for flood scenarios with assigned recurrence intervals. Vulnerable elements exposed to the flood are identified and analyzed in order to determine their residual functionality and simulate failure scenarios. Impact metrics are defined to measure service outage and potential pipe contamination. The method is applied to the water supply system of the city of Florence (Italy), serving approximately 385 000 inhabitants. Results show that for the worst failure scenario 420 km of pipeworks would require flushing and disinfection with an estimated cost of 21 Mio €, which is about 0.5 % of the direct flood losses evaluated for buildings and contents.

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