Calibration of a model of an operational water distribution system containing pipes of different age (original) (raw)
Related papers
Procedia Engineering, 2015
Model of a water distribution system (WDS), containing old pipes, requires calibration to estimate the roughness of old pipes. Pipe roughness increases with age. In some cases the estimated roughness of old pipes, using optimization procedures based on measurements in operational WDS, can be quite high. Therefore it would be proper to use real diameters of the old pipes instead of high roughness values. The aim of the paper is to compare different approaches of calibration in such case. Five different calibration methods are analysed changing pipe roughness, diameter or both. Calculations have been conducted for an operational WDS. Measurements in the WDS indicated that there are quite large differences in the dynamics of demands (even for the same customer categories) in different zones of the system. It is shown that this has strong influence on the calibration results.
Pipe roughness calibration approach for water distribution network models
Results in Engineering, 2024
This paper introduces an online approach based on a nonlinear state observer (NSO) to calibrate the roughness of each pipe within a water distribution network (WDN) or a sector thereof. The NSO is designed to obtain the estimations of pipes’ friction factors, which are then used to estimate the roughness. The core of the NSO is a dynamic WDN model formulated through a structured set of ordinary differential equations derived from fundamental physical principles, taking advantage of both graph theory and rigid water column theory. By applying a coordinate transformation, the WDN model is represented as a fully connected network of damped nonlinear oscillators, with each oscillator formulated as a Liénard system. This representation allows for estimating the friction factors for each pipe using only flow rate information. The proposed approach facilitates a continuous calibration when hydrodynamic data are readily accessible, which is a capability that empowers engineers to enhance, concurrently or proactively, the day-to-day operations of water distribution networks, such as control or diagnose tasks, whenever data are available. The results of numerical simulations are presented to illustrate the practical utility of the proposed method.
Calibration Procedure for Water Distribution Systems: Comparison among Hydraulic Models
Water
Proper hydraulic simulation models, which are fundamental to analyse a water distribution system, require a calibration procedure. This paper proposes a multi-objective procedure to calibrate water demands and pipe roughness distribution in the context of an ill-posed problem, where the number of measurements is smaller than the number of variables. The proposed methodology consists of a two-steps procedure based on a genetic algorithm. Firstly, several runs of the calibrator are performed and the corresponding pressure and flow-rates values are averaged to overcome the non-uniqueness of the solutions problem. Secondly, the final calibrated model is achieved using the calibrator with the average values of the previous step as the reference condition. Therefore, the procedure enables to obtain physically based hydraulic parameters. Moreover, several hydraulic models are investigated to assess their performance on this optimisation procedure. The considered models are based either on ...
Model Performance Indicator of Aging Pipes in a Domestic Water Supply Distribution Network
Aging pipes in the domestic water distribution network have the potential to decrease the quality and quantity of the treated water supplied to the consumers. Therefore, a calibrated water distribution model is helpful to monitor and understand the behaviour of a real water distribution network. However, a comprehensive performance indicator and an integrated method to assess the efficiency of model performance have not been well established in the literature. This study developed a methodology for a model calibration exercise, with consideration of two uncertainty parameters, i.e., Hazen-Williams roughness coefficient of the pipes and Non-Revenue Water (NRW) in each nodal demand. Following this, a statistical color-coded performance indicator was established, based on the Nash-Sutcliffe Efficiency Coefficient (NSEC), the coefficient of determination (R 2), the correlation coefficient (r), and the Mean Absolute Error (MAE). The accuracy of the calibrated model was measured by Discrepancy Ratio (DR) analysis. This study concluded that the model performed well when NRW was added to the nodal demand in zone(s) with suspected water loss activities. The suggested Hazen-Williams roughness coefficient for PVC pipes was between 130 and 140 for pipes aged more than 20 years. The threshold error value to determine the accuracy of the simulated model was proposed to be between-0.05 and 0.05.
The objective of the study was to model and analyze three drinking water distribution networks, calibrate them with Epanet Calibrator software and compare their results with Darwin Calibrator. An ultrasonic flowmeter and pressure data loggers were used, which were configured to record data every ten minutes, the mean of the flows at each node of interest in the network was obtained. The pressure data was used to adjust each network and by varying the roughness, the model could be calibrated and adjusted, among those mathematically simulated with the data obtained in the field. Using this information, equations and calibration curves were established to discriminate the discrepancy between what was modeled and what was observed in the field. Hydraulic calibrations were performed using the Darcy-Weisbach and Hazen-Williams formulas. The results show for each network a variation in the calibrations of 35, 15 and 10 %. It is concluded that these two computational applications show similar results between the simulated and observed data, with the difference that calibration in Epanet is carried out node by node, while in Darwin Calibrator it can be performed by means of groups of calibrations in a given sector.
Use of modelling error dynamics for the calibration of water distribution systems
Advances in Engineering Software, 2012
The calibration of a water distribution system remains a complex task. Leakages create additional difficulties if their proportion is high. Not all leakages are real. A part of them are apparent leakages. An optimization procedure is proposed to obtain the proportions of real and apparent leakages. The distribution of the leakages over a WDS may be made easier by analyzing the dependence of modelling errors on water flow. It is suggested that pressure measurements should be ranked according to the closeness of measurement to the water source and that modelling errors should be analysed separately for the measurements of different order (from the first to the highest). The advantage of this approach is that the analysis is confined within points of measurements of one order and it allows to redistribute fluxes of leakages (real and apparent) more reliably. Nonlinear optimization with linear constraints is used for the redistribution of leakages over a WDS. The methodology proposed allows to exclude the influence of systematic errors on the result of calibration.
CALIBRATION OF A WATER DISTRIBUTION SYSTEM – A CASE STUDY
Water is the foundation of life. Water Distribution System (WDS) plays a critical role in transporting water to various destinations. Today, a WDS consists of infrastructure that collects, treats, stores, an and consumers. A WDS should be properly designed and maintained. But, it is commonly seen that after construction WDS are not properly maintained. A well designed and maintained WDS helps to function it smoothly. C of utmost importance for the purpose of evaluating a system. It will help authorities to better understand the system and its problems. This will highlight future capital investment programmes so that the authorities may better serve This paper focuses on modeling and calibration of a typical WDS in a Metropolitan area in a well developed country using sophisticated software ArcGIS and InfoWater. The comparisons of the model results (pressure, flow and reservoir levels) with the recorded observations (pressure, flow and reservoir levels) indicated that good calibration was achieved. The performance evaluation of the water supply zone was also done which was found to be satisfactory. Water is the foundation of life. Water Distribution System (WDS) plays a critical role in transporting water to various destinations. Today, a WDS consists of infrastructure that collects, treats, stores, and distributes water between water sources and consumers. A WDS should be properly designed and maintained. But, it is commonly seen that after construction WDS are not properly maintained. A well designed and maintained WDS helps to function it smoothly. Calibration of a WDS is of utmost importance for the purpose of evaluating a system. It will help authorities to better understand the system and its problems. This will highlight future capital investment programmes so that the authorities may better serve the customers. This paper focuses on modeling and calibration of a typical WDS in a Metropolitan area in a well developed country using sophisticated software ArcGIS and InfoWater. The comparisons of the model results (pressure, flow and reservoir with the recorded observations (pressure, flow and reservoir levels) indicated that good calibration was achieved. The performance evaluation of the water supply zone was also done which was found to be satisfactory. Water is the foundation of life. Water Distribution System (WDS) plays a critical role in transporting water to various destinations. Today, a WDS consists of d distributes water between water sources and consumers. A WDS should be properly designed and maintained. But, it is commonly seen that after construction WDS are not properly maintained. A well alibration of a WDS is of utmost importance for the purpose of evaluating a system. It will help authorities to better understand the system and its problems. This will highlight future capital the customers. This paper focuses on modeling and calibration of a typical WDS in a Metropolitan area in a well developed country using sophisticated software ArcGIS and InfoWater. The comparisons of the model results (pressure, flow and reservoir with the recorded observations (pressure, flow and reservoir levels) indicated that good calibration was achieved. The performance evaluation of the water supply
Process of hydraulic models calibration
E3S Web of Conferences
Mathematical modelling of the water supply systems (WSS) and water quality changes in the system is a complex and difficult task to solve, it requires an interdisciplinary approach to considering the determinants of WSS work. Prognosis models of the WSS in relation to hydraulic quantities are well known and there are many packages that implement these models. These packages allow you to calculate the flow and pressure in the water distribution system under certain operating conditions. However, to make a hydraulic model a useful tool in the management of water supply systems, a calibration process is required. This process involves estimating model parameters to minimize the difference between model results and actual observations. This is a complex and multi-stage process where the network graph and parameters such as roughness coefficient, pump characteristics, or nodal demands are checked and corrected. The following work contains a complex process of calibration of the actual WS...
Identification of Measurement Points for Calibration of Water Distribution Network Models
Procedia Engineering, 2014
Much importance is given to determining the input data for water distribution system networks, particularly with regard to urban networks, because the design and the management of WDS are based on a verification model. Good calibration of models is required to obtain realistic results. This is possible by the use of a certain number of measurements: flow in pipes and pressure in nodes. The purpose of this paper is to analyze a new model able to provide guidance on the choice of measurement points to obtain the site data. All analyses are carried out firstly on literature networks and then on a real network using a new approach based on sensitivity matrices.