Sarai Díaz

• Professor (Associate) at University of Castilla-La Mancha

Water age or time of residence is frequently adopted as surrogate indicator for water quality in water distribution networks. High water ages, which are expected in terminal branches and meshed areas with low renovation rates, are associated with different physical, chemical and/or biological issues. However, the identification of critical areas is...

The effect of different temporal (from seconds to months) and spatial aggregation scales (from individual users to full urban areas) on water demand behavior has been explored to a limited degree. The effort described here extends those works by evaluating the scale effects of residential water consumption in a unique US data set that covers 10,000...

Hydraulic State Estimation (HSE) is an effective tool for water supply systems monitoring. This technique provides the most likely hydraulic state of the network by making use of the available measurements through the system and the associated hydraulic model, enabling to track uncertainty through the process. HSE has been applied to water transpor...

Water demand is the main random factor that conditions flow variability across water supply systems. Water demand measurements or pseudomeasurements (i.e. estimations based on historical data) are associated with a time interval (sampling rate), which affects the variability of water demands. Considering a long time interval implies losing informat...

Hydraulic State Estimation allows to estimate the most likely state of a water supply network considering multiple sources of information and their associated uncertainty. It is set out as an optimization problem, often addressed according to the Weighted Least Squares criterion. It can be formulated differently depending on the selected set of sta...

La temperatura afecta a los procesos físicos, químicos y biológicos involucrados en el transporte del agua potable, por lo que condiciona la calidad del agua suministrada. Diferentes trabajos han puesto de manifiesto el papel de esta variable de modo específico en cada proceso o fenómeno. A su vez, se han desarrollado investigaciones sobre el compo...

Peak demand plays a major role in water distribution system design. Peak demand assessment is currently facing a double challenge: shifting toward a probabilistic approach, and considering the effect of different spatial and temporal resolutions. Most probabilistic approaches so far have focused on inferring scaling laws by analyzing measurement ti...

Hydraulic State Estimation (HSE) is a suitable tool to gain real-time understanding of water supply systems. This technique enables to estimate the most likely hydraulic behavior in the network, as well as its associated uncertainty, from available measurements. HSE has been successfully applied to trunk mains, but additional work is required to im...

p>Una buena caracterización de las demandas es esencial para modelizar correctamente el flujo y la calidad del agua en sistemas de abastecimiento, especialmente en las zonas terminales de la red. En la actualidad existen dos tipos de modelos estocásticos de demanda, que requieren una adecuada monitorización de viviendas o la realización de encuesta...

Water demands are the main random factor that conditions flow variability within drinking water supply systems. The importance of using high-resolution demands in distribution mains is already well known, but there is little knowledge of how the temporal scale (i.e., sampling frequency) affects the ability of a metering or monitoring system to expl...

End-uses at water supply systems typically follow a random pulse behavior, which blurs as consumptions are aggregated upstream, affecting flow rate variability along the spatial scale. Instantaneous variability has impact on the capacity of a hydraulic model to represent rapidly changing flow network scenarios, but traditional models only simulate...

p class="Resumen">Las Obras de Drenaje Transversal (ODTs), frecuentes en obras lineales para recomponer la red natural de drenaje interceptada por ellas, deben ser capaces no solo de drenar el agua de su cuenca sino también de controlar la erosión local en sus inmediaciones debido a las fuertes avenidas. Su funcionamiento hidráulico y en consecuenc...

Leak detectability or leakage awareness refers to the capability of sensing losses from a water supply system. Several methods exist in the technical literature to tackle this problem, but only few address it with a state estimation approach. The aim of this paper is to present a new methodology that enables probabilistic assessment of the extent t...

State estimation (SE) techniques can be applied to compute the most likely hydraulic state of a water distribution system from the available measurements at a given time. Different approaches exist in the technical literature to undertake such an analysis, but in all of them it is assumed that pump and valve statuses are known beforehand. Such cons...

The implementation of state estimation techniques to water systems enables the hydraulic state of a given network to be computed at any time. However, errors in both measurements and model parameters can severely affect the quality of the state estimate, thus sensitivity analysis is crucial to assess its performance. The aim of this paper is to pro...

Calibration of model parameters is of utmost importance to ensure the good performance of hydraulic simulation models. In this work, calibration is conceived within a joint multi-period parameter and state estimation approach, where model parameters (i.e. roughness coefficients) and hydraulic variables should be computed from available measurements...

Las técnicas de estimación de estado permiten determinar el estado hidráulico más probable de una red de abastecimiento a partir de las medidas disponibles en tiempo real. Pese a su interés a nivel académico, en el que estas técnicas han sido ampliamente trabajadas, apenas han sido implementadas en sistemas reales a nivel operacional. Esto supone u...

State estimation techniques have been widely discussed in academia in the context of water distribution systems, but there are few real-life applications. The aim of this paper is to show the potential advantages of systematically implementing state estimation techniques for on-line monitoring water distribution systems. With this purpose, two stat...

Traditionally, Spanish schools of civil engineering provide their students a class on “Technical English” in order to develop their language skills. However, this class does not cover all the skills that the student would need in the labor market and mainly focuses in the reading and writing skills, and in a lower degree in the speaking and listeni...

The aim of observability analysis (OA) is to determine if a given measurement setting is sufficient to compute the current status of a water distribution network. There are several approaches in the technical literature to making such an analysis. With all of them there is an assumption that the lie of the land of the network in terms of the status...

Implementation of state estimation (SE) techniques to water networks seems to be the best way to obtain as much information as possible from current monitoring systems. However, to guarantee the correct implementation of SE, the measurement configuration must be adequate, i.e., the network must be observable, as not any measurement distribution wou...

In this paper, an alternative uncertainty treatment for the traditional unconstrained weighted-least-squares (WLS) method is presented. This treatment enables hydraulic constraints (i.e., null demands at transit nodes or null flows at closed pipes, pumps, or valves, etc.), high-precision measurements, and upper and lower variable bounds (i.e., head...

Este artículo presenta una técnica alternativa a los métodos existentes en la literatura para el análisis de observabilidad (AO) de redes de agua, paso previo imprescindible para la adaptación de las técnicas de estimación de estado (EE) a estos sistemas. La metodología propuesta parte de un estado de flujo conocido y asume distribuciones aleatoria...

State estimation (SE) techniques are being applied to different network systems in order to convert system measurements into real information about the network state. SE applications to water systems are relatively novel, but these techniques have been implemented in other fields for decades. In those applications, observability analysis (OA) is re...

La facilidad de las compuertas inflables para adaptarse a distintas condiciones de flujo las hace interesantes para su ubicación en vertederos de presa, permitiendo aumentar el volumen embalsado en explotación ordinaria, y permitiendo el desinflado y restauración de la geometría original en situación extraordinaria. El objetivo de este estudio es a...