Dália Loureiro

Surge damping analysis in pipe systems: modelling and experiments

The current study focuses on the analysis of pressure surge damping in single pipeline systems generated by a fast change of flow conditions. A dimensionless form of pressurised transient flow equations was developed, presenting the main advantage of being independent of the system characteristics. In lack of flow velocity profiles, the unsteady friction in turbulent regimes is analysed based on two new empirical correctivecoefficients associated with local and convective acceleration terms. A new surge damping approach is also presented taking into account the pressur e peak time variation. The observed attenuation effect in the pressure wave for high deformable pipe materials can be described by a combination of the non-elastic behaviour of the pipe-wall with steady and unsteady friction effects. Several simulations and experimental tests have been carried out, in order to analyse the dynamic response of single pipelines with different characteristics, such as pipe materials, diameters, thickness, lengths and transient conditions.

Water distribution systems flow monitoring and anomalous event detection: A practical approach

Methods to detect outliers in network flow measurements that may be due to pipe bursts or unusual consumptions are fundamental to improve water distribution system on-line operation and management, and to ensure reliable historical data for sustainable planning and design of these systems. To detect and classify anomalous events in flow data from district metering areas a four-step methodology was adopted, implemented and tested: i) data acquisition, ii) data validation and normalization, iii) anomalous observation detection, iv) anomalous event detection and characterization. This approach is based on the renewed concept of outlier regions and depends on a reduced number of configuration parameters: the number of past observations, the true positive rate and the false positive rate. Results indicate that this approach is flexible and applicable to the detection of different types of events (e.g., pipe burst, unusual consumption) and to different flow time series (e.g., instantaneous, minimum night flow).

A comprehensive and well tested energy balance for water supply systems

Abstract This paper presents a novel energy balance scheme and performance indicators for assessing energy efficiency in water supply systems. This assessment consists of a three-step procedure: system characterisation and data collection, energy balance calculation and energy performance indicators assessment. The main innovation is the integrated approach between energy and water balances allowing the quantification of energy inefficiencies directly associated with water losses. Comprehensive energy performance indicators can be calculated by utilities with different maturity levels allowing a fair comparison of energy efficiency between systems with different layouts and operational schemes. This energy balance scheme has been applied by 17 water utilities in Portugal. Results have shown that systems provide more than twice the minimum energy necessary to supply their consumers and, consequently, there is a significant energy saving potential: 40% through water loss reduction, 30% for changes in network operation and layout and 30% for pump inefficiency reduction.

A Comprehensive Approach for Spatial and Temporal Water Demand Profiling to Improve Management in Network Areas

The aim of this paper is to present a comprehensive approach for spatial and temporal demand profiling in water distribution systems. Multiple linear regression models for estimating network design parameters and decision trees for predicting daily demand patterns are presented. Proposed approach is a four-step procedure: data collection, data processing, data characterization, and spatial and temporal demand profiling. Continuous flow measurements and infrastructure and billing data were collected from a large set of water network areas and combined with census data. Main results indicate that family structures (i.e., families with elderly or adolescents), individuals’ mobility (i.e., people employed in the tertiary sector and university graduates) and public consumption (i.e., public spaces’ irrigation) are key-variables to profile water demand. Profiling models are of the utmost importance to describe water demand in areas with no monitoring but with similar socio-demographic characteristics to the ones analyzed, to improve network operation and to support network planning and design in new areas. Obtained models have been tested for new areas, showing good prediction performances.

Profiling Residential Water Consumption

Understanding the factors that influence daily and weekly water consumption patterns in distribution systems is fundamental for both long term tasks, such as planning, design, expansion or rehabilitation of the systems, and short term tasks, such as routine system operation or emergency management. This paper describes the development of a Portuguese nationwide program for characterizing residential water consumption, through the use of a specific consumption data analysis protocol and the build-up of a database of demand patterns; and for associating it with a range of easily obtained, potential relatable factors that include the technical features of the network (e.g., service pressure, network state and maintenance level, use of household tanks), billing and customer statistics and a range of social-demographic variables, such as age, social-economic level and mobility of consumers, age and type of buildings, and economic activities. The program is currently being test-run on a set of 20 metering districts from 9 water utilities, comprising a variety of network types and demand characteristics across representative urban areas of Portugal. The metering districts range in size from 2,000 to 12,000 connected properties, and have mostly been monitored since 2005 (in some cases, 2004). Total consumption is continuously monitored during the main seasonal scenarios (typically winter and summer) in the areas selected. Standardized daily demand patterns and consumption statistics are produced for each day of the week, as well as for each season, in case there is seasonality in the area. Social-demographic information is based on statistics obtained from the 2001 National Census for the basic statistical units, which are around 300 dwellings in size. After the initial run, the program is to be disseminated and made accessible to all water utilities willing to participate, on a voluntary basis and with data anonymity. This will be done mostly through a dedicated website containing the consumption database, together with query and analysis tools, as well as a supervised mechanism to submit new cases in standard format. It is believed that the publication of the result database and its continued growth will provide the water industry designers, consultants and managers with much more reliable and updated data on water consumption than previously available. It will also represent a means to estimate demand through correlation and profiling, in cases when there are no records to work from. The paper discusses the demand analysis performed, as well as the development of the set of potential explanatory factors (technical features of the network and social-demographic variables), and illustrates with the results obtained so far. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF).

Identification of opportunities to improve efficiency by water consumption assessment

Characterization of water demand can be of large value for the management of water supply systems. Especially when water resources are limited, permanently or seasonally, the identification of the types of consumers and its characteristics are essential to identify opportunities to promote efficiency and demand management options. For each customer category, information to be obtained includes individual uses, typical daily usage patterns (average and dispersion), specific characteristics and magnitude. Knowledge and systematization of water uses also provides data to improve water balance and thus allows reducing uncertainty in losses estimation. In this paper, a study carried out in Algarve, a region where stress on water supply resources has been increasing, is presented aiming at better characterise water consumption in the region to improve response both to normal and in emergency situations.