Proposals of a procedure to asses Pollutographs. Application to Murcia's Combined Sewer Overflows (CSOs). Póster

Directives 91/271/EEC and 93/481/EEC set norms regarding the management of Combined Sewer Overflows. European Commission monitors the implementation status and implementation programmes. In fact, during the year 2019 all the utilities should be able to quantify the pollution spilled during storm events. And afterwards, plans have to be developed in order to reduce the impact of such events. In this paper, we proposed a method to estimate the transported pollution during events as well as to serve as a tool for developing plans to lessen the corresponding pollution. The procedure is divided into three steps: A. Periodical measurements of all relevant pollutants, e.g. total suspended solids and chemical oxygen demand, in wet and dry weather. Such pollutant “concentrations” are correlated with the turbidity, updating the relation among them [1]. B. Continuous measures of the turbidity. Turbidity is continously register in the sewer areas near overflow spillways. Turbidimeters are a very convenient equipment for this purpose [2]. Actually, it is reliable, its measures are very correlated with the total suspended solid concentration and its maintenance is easy. In this way, combining A. and B. turbidity measures provide us a real-time estimation of the pollutant concentration. on real time. C. Assesment of each catchment hydrograph. Depending on the available data, this step could be based on a design, a measured or a simulated hydrograph. In order to apply this methodology to Murcia’s Combined Sewer System, we have used simulated hydrographs based on real measured rainfall. Murcia’s utility has developed a calibrated SWMM model, and therefore, using the rainfall data, it is possible to estimate hydrographs for all the relevant points of the system. D. Estimation of each catchment pollutograph. Combining the pollutant concentration, estimated in the previous steps, with the hydrographs, we can asses how the mass of pollutants are transported. This information allows us to comply with EU Directives, but it will also be useful to design Murcia’s strategy to minimize environmental impacts

Evaluating energy recovery potential in Murcia's water supply system

Murcia is the 7th most populated city in Spain. Its water supply system is extensively monitored through a large number of pressure gauges and flow meters. Murcia’s water supply network is fed from distribution reservoirs at enough elevation to avoid needing pumping stations for most of the city districts. Hydraulic resources have been evaluated throughout the water supply system. Besides the pressure reducing valves, where the assessment is quite straight forward [1], District Metered Areas (DMA) inlets have been evaluated. In these areas despite the hydraulic resources are not as great as in pressure reducing valves locations, their location is quite convenient. Actually, these positions are located inside the city, therefore making easy to use the produced energy in municipal self consumption or to provide facilities to the citizens. In order to perform such evaluation, a detailed model of the water supply network has been implemented in EPANET parting from a GIS model. The first step of the evaluation has consisted in the optimizing and validation of the model. Initially, the model was reviewed by comparing pressure and flow rate measurements in the main pipes. Then, an extensive experimental campaign was designed. In that campaign valves were switched so that each day a set of District Metered Areas (DMA) have just one metered inlet or at the most a very short number of metered inlets, whereas having a set of pressure measurements within the DMA. The obtained data was used to minimize errors in pressure time series, optimising roughness of the main pipes through Levenberg/Marquardt BFGS algorithm using EPANET ToolKit through Epanet-Octave [2]. Important roughness proposed changes tended to be located surrounding particular points, where errors in the GIS were located (mainly wrong diameter assignement). After patching all the errors the algorithm eased to localise, model errors were mostly below measures uncertainty, and therefore, the model was considered validated. Then, the hydraulic potential at the DMAs inlets has been evaluated by tracking the “instantaneous” minimum pressure and head within each DMA, as well as the flow rate entering the DMA. So that, the maximum head and the range of flow rates is established for the turbine. At the moment, once that all of these potentials have been assessed, a turbine prototype is being designed

Estudio experimental de bloques de impacto trapezoidales

[ESP] La misión principal de las estructuras disipadoras de energía en grandes presas es reducir el tamaño y, por tanto, el coste de los cuencos disipadores de energía. Con ellas se consigue un acortamiento de la longitud del resalto hidráulico, limitando, así, la erosión o socavación a pie de presa y su posible vuelco. El objetivo de este trabajo es la realización de un contraste teórico-práctico con otros estudios realizados por diferentes autores sobre estructuras disipadoras de energía. [ENG] The main aim of energy dissipators structures at large dams is to reduce the size, and thus the cost of stilling basins. Such reduction is obtained by shortening of the hydraulic jump length, in this way erosion in the dam base is limited as well as its own spill. The target of this research is the attainment of a theoretical and practical contrast with other research results which have been carried out by different authors about energy dissipative structures.Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT), Escuela Técnica Superior de Ingeniería Agronómica (ETSIA), Escuela Técnica Superior de Ingeniería Industrial (ETSII), Escuela Técnica Superior de Arquitectura y Edificación (ETSAE), Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos y de Ingeniería de Minas (ETSICCPIM), Facultad de Ciencias de la Empresa (FCCE), Parque Tecnológico de Fuente Álamo (PTFA), Vicerrectorado de Estudiantes y Extensión de la UPCT, Vicerrectorado de Investigación e Innovación de la UPCT, y Vicerrectorado de Internacionalización y Cooperación al Desarrollo de la UPC

Analysis of two-phase flows in plunge pools of nappe jets

This study presents an experimental work to analyse the submerged hydraulic jump generated downstream of overflow nappe impinging jets. The overflow structure consists in a sharp-crested weir located at an elevation of 2.20 m from the bottom of the plunge pool. To advance in the understanding of the phenomenon, the velocity field and air entrainment rate were measured with optical fiber and modified Pitot tube in different sections of the submerged hydraulic jump. For the Pitot tube, GE Druck model UNIK 5000 pressure transducers have been used to measure the static and the dynamic pressures. The output signal of both ports was scanned at 20 Hz for 60 s. The optical fiber measurements were carried out with a RBI-instrumentation equipment. Each point was measured during 90 s in the same locations registered by the Pitot tube. The study is focused on the analysis of the local air entrainment concentration, bubble frequency, Sauter mean bubble diameter, mean velocity near the bottom, and free surface undulation pattern.The researchers express their gratitude for the financial aid received from the Ministerio de Ciencia, Innovación y Universidades and the Fondo Europeo de Desarrollo Regional (FEDER), through the Project “La aireación del flujo en el vertido en lámina libre por coronación de presas a nivel de prototipo y su efecto en cuencos de disipación de energía”, Reference (RTI2018-095199-B-I00). The second author would like to thank the Ministerio de Educación, Cultura y Deporte for the financial aid received from the University Teacher Training Grant (FPU), reference number FPU16 / 05658

Experimental study of submerged hydraulic jumps generated downstream of rectangular plunging jets

This experimental study analyzes submerged hydraulic jumps generated in a 1.05-m wide stilling basin that receives overflow rectangular impinging jets, with the vertical distance between the sharp-crested weir and the bottom of the plunge pool being 2.20 m. Five submerged hydraulic jumps downstream of non-developed nappe jets were analyzed, with vertical falling distances to break-up length ratios between 0.76 and 0.78. The impingement velocity range was from 6.12 to 6.33 m/s, while the water depth / impingement jet thickness ratios were between 8.45 and 15.00. The velocity field and air entrapped were measured in several cross sections, with the farthest sections being located 1.0 m from the stagnation point. The entrapped air (void fraction and phase change detection) behavior measured with a phase-detection probe was classified as a function of the distance to the stagnation point / impingement jet thickness ratio and/or the mean void fraction of the vertical profiles. The maximum void fractions were observed near the free surface. However, the higher phase change detection frequencies (up to 130-140 Hz) were obtained near the bottom for local void fractions smaller than 0.15-0.20. The non-dimensional velocity distribution seems to be similar to previous published studies, extending their validity range. Furthermore, the free hydraulic jumps formula has been adapted to estimate the air rate in the shear stress layer and the growth of the characteristic length in the plunge pool.The researchers express their gratitude for the financial aid received from the "Ministerio de Ciencia, Innovación y Universidades" (MCIU), the "Agencia Estatal de Investigación" (AEI) and the (FEDER), through the Project “La aireación del flujo en el vertido en lámina libre por coronación de presas a nivel de prototipo y su efecto en cuencos de disipación de energía”, Ref: RTI2018-095199-B-I00. The work was partially funded by the "Comunidad Autónoma de la Región de Murcia" through the "Programa Regional de Fomento de la Investigación Científica y Técnica (Plan de Actuación 2018) de la Fundación Séneca-Agencia de Ciencia y Tecnología de la Región de Murcia”, Project “Análisis de la capacidad de descarga de vertederos tipo laberinto y de la disipación de energía aguas abajo de los mismos”, Ref: 20879/PI/18

Estudio del transporte de sedimentos en la Rambla del Albujón

[ESP] El sureste español se caracteriza por ser una región semiárida. Uno de los efectos más directos del cambio climático es el hecho de que llueve con menor frecuencia y con mayor intensidad, lo que provoca la aparición de un mayor número de episodios de flujos torrenciales. En este artículo se realiza en primer lugar una validación de transporte de sedimentos de las seis formulaciones presentes en HEC-RAS y en segundo lugar un análisis de transporte de sedimentos de toda la cuenca del Albujón obteniendo la concentración de sedimentos y sedimento total que pasa por la sección de la desembocadura. [ENG] The Spanish Southeast is characterized as a semiarid region. One of the most direct effects of climate change is the fact that it rains less often and with greater intensity, causing the appearance of a greater number of episodes of torrential flows. In this paper, a validation of the sediment transport formulas present in HECRAS is made first. Secondly, an analysis of the Albujon basin sediment transport is conducted, obtaining sediment concentration and total sediment passing through the section of the mouth.Escuela Técnica Superior de Ingeniería de Telecomunicación (ETSIT), Escuela Técnica Superior de Ingeniería Agronómica (ETSIA), Escuela Técnica Superior de Ingeniería Industrial (ETSII), Escuela Técnica Superior de Arquitectura y Edificación (ETSAE), Escuela Técnica Superior de Ingeniería de Caminos, Canales y Puertos y de Ingeniería de Minas (ETSICCPIM), Facultad de Ciencias de la Empresa (FCCE), Parque Tecnológico de Fuente Álamo (PTFA), Vicerrectorado de Estudiantes y Extensión de la UPCT, Vicerrectorado de Investigación e Innovación de la UPCT, y Vicerrectorado de Internacionalización y Cooperación al Desarrollo de la UPC

Multi-parametrical tool for the design of bottom racks dIMRACK-application to small hydropower plants in Ecuador

A novel computational tool, DIMRACK, is presented for the design of the required length of bottom racks in intake systems. The users may consider clear water cases or the rack's occlusion due to sediment transport in the river. The computational tool uses a methodology based on the experimental works undertaken at the Universidad Politecnica de Cartagena from 2010. This work also presents an extension of the methodology to cover a broad range of void ratios, bar profiles, slopes, and flow rates. Designing nomograms are also proposed. These are two diagrams to allow the approximate graphical computation of the rack length with clear water. In sediment transport cases, an occlusion factor is proposed, obtained from experimental gravel tests. This parameter enables an increment in the rack length due to occlusion, depending on the bar type. The results are compared with those proposed in classical technical manuals. Finally, the results have been compared with ten existing small hydropower plants' bottom intake designs in Ecuador.The authors are grateful to the Fundación Carolina (Spain) by Patricia L. Haro, to the Escuela Politécnica Nacional (Ecuador), and to the Universidad Politécnica de Cartagena (Spain) for granting the scholarship for the development of the doctoral thesis which is one of the bases of this article. The authors would also like to thank the Faculty of Civil and Environmental Engineering of the Escuela Politécnica Nacional de Ecuador for providing us with information on design projects which helped in the process of developing the computational tool presented. This research was funded by Fundación Séneca through the project “Optimización de los sistemas de captación de fondo para zonas semiáridas y caudales con alto contenido de sedimentos. Definición de los parámetros de diseño”, grant number 19490/PI/1

Modelación física y numérica del lavado de sedimentos en embalses

Este trabajo tiene como objeto evaluar la capacidad de los modelos hidrodinámicos existentes para la simulación del lavado de sedimentos en embalses mediante flushing. Se han realizado modelos numéricos con tres programas informáticos HEC-RAS, IBER, y FLOW-3D para reproducir un ensayo de flushing realizado a escala de laboratorio. Comparativamente, los resultados obtenidos con el modelo FLOW-3D son los que más se aproximan a las mediciones del laboratorio, mientras que los resultados obtenidos con HEC-RAS e IBER presentan diferencias con dichas mediciones. En el caso de HEC-RAS se observa una sobrestimación del transporte de fondo y de la erosión, aunque los resultados presentan tendencias similares a las del ensayo de referencia. En el caso de IBER, se observa una subestimación del transporte de fondo y la erosión con tendencias distintas a las mediciones de laboratorio. Estas diferencias serán investigadas en detalle en fases sucesivas.Este trabajo ha sido desarrollado en el marco del proyecto EFISED, y está financiado por el programa Saavedra Fajardo (20403/SF/17) de la Fundación Séneca de la Agencia de Ciencia y Tecnología de la Región de Murcia

Coeficientes de resistencia, transporte de sedimentos y caudal dominante en regiones semiáridas

En regiones de morfología abrupta y régimen irregular de precipitaciones las crecidas suelen presentarse llevando una gran cantidad de transporte de sedimentos. Si bien es usual que en las regiones semiáridas se presenten flujos hiperconcentrados, el cambio climático incidirá en que estos sean cada vez más acusados, lo que obligará a controlarlos para minimizar sus efectos destructivos. Con el fin de poder diseñar sistemas efectivos de control y captación de flujos en zonas semiáridas será necesario, como primer paso, calcular la capacidad de transporte de sedimentos. En este sentido, se vienen realizando investigaciones durante décadas, pero sin obtener todavía una ecuación realmente satisfactoria que interrelacione adecuadamente las propiedades del fluido y del sedimento. Uno de los objetivos del trabajo que se está llevando a cabo es aplicar la metodología elaborada por Castillo et al (2000 y 2000b) y Castillo (2004 y 2007) para el cálculo del transporte de sedimentos en el barranco de las Angustias (Isla de la Palma), generalizándola para su aplicación en zonas semiáridas. De esta manera se presentan en el siguiente artículo un análisis de los elementos fundamentales que nos permite conocer la capacidad de transporte de sedimentos en los cauces de estas zonas; así las formulaciones de cálculo de transporte de sedimentos y la estimación de los coeficientes de resistencia para flujos macrorrugosos, los límites de aplicación de dichas formulaciones y finalmente, la determinación del caudal dominante

Air–water properties in rectangular free-falling jets

This study analyzes the air–water flow properties in overflow nappe jets. Data were measured in several cross-sections of rectangular free-falling jets downstream of a sharp-crested weir, with a maximum fall distance of 2.0 m. The flow properties were obtained using a conductivity phase-detection probe. Furthermore, a back-flushing Pitot-Prandtl probe was used in order to obtain the velocity profiles. Five specific flows rates were analyzed, from 0.024 to 0.096 m3/s/m. The measurements of the air–water flow allowed us to characterize the increment of the air entrainment during the fall, affecting the flow characteristic distributions, reducing the non-aerated water inner core, and increasing the lateral spread, thereby leading to changes in the jet thickness. The results showed slight differences between the upper and lower nappe trajectories. The experimental data of the jet thickness related to a local void fraction of 50% seemed to be similar to the jet thickness due only to gravitational effects until the break-up length was reached. The amount of energy tended to remain constant until the falling distance was over 15 times greater than the total energy head over the weir crest, a distance at which the entrained air affected the entire cross-section, and the non-aerated core tended to disappear. The new experiments related with air–water properties in free-falling jets allow us to improve the current knowledge of turbulent rectangular jets