http://hdl.handle.net/2117/506 2013-06-19T02:34:53Z http://hdl.handle.net/2117/19383 Title: Breaching of a barrier beach under extreme events: the role of morphodynamic simulations Authors: Gracia Garcia, Vicente; García León, Manel; Grifoll Colls, Manel; Sánchez-Arcilla Conejo, Agustín Abstract: A study of three breaching episodes of the Trabucador barrier beach (Spanish Mediterranean coast) is presented. The analysis is done from a modeling perspective using XBEACH and SWAN. The morphodynamic model (XBEACH) has been validated with the available information. The so obtained Brier Skill Score index has been 0.44 which can be considered as acceptable. Results indicate that in all cases breaching was taking place after 8 hours of wave action (storm) or less. Besides, four main parameters control the final morphodynamic response of the barrier: the storm intensity, the water level and the initial emerged topography and the storm duration. Major breaching occurs when swell waves are in coincidence with high water levels whereas if they are uncoupled the barrier tends to be breached by a diversity of smaller channels. 2013-05-23T12:53:26Z http://hdl.handle.net/2117/19382 Title: Meteo-oceanographic simulations and observations to assess the potential of offshore wind farm in a NW Mediterranean shelf Authors: Sánchez-Arcilla Conejo, Agustín; González Marco, Daniel; Sospedra Iglesias, Joaquim; Palomares, Ana; Sierra Pedrico, Juan Pablo; Schuon, Frieder; Espino Infantes, Manuel; Grifoll Colls, Manel; Pallarès López, Elena; Jiménez, Pedro Angel; Navarro, Jorge Abstract: Renewable marine energy is important in squeezed Mediterranean coastal zones. Wind turbines deployed over the narrow Catalan continental shelf require accurate wind/wave/current fields for a reliable design, operation and maintenance. This paper presents the large (comparative to other open sea areas) errors in meteo-oceanographic predictions for semi enclosed domains such as the coastal sea off the Ebro Delta coast. The emphasis is on the sequence of high resolution coupled and nested models and the role of in situ collocated measurements for calibration and validation. 2013-05-23T12:45:24Z http://hdl.handle.net/2117/19375 Title: Impulsive wave loads on rigid structure, an experimental approach Authors: Marzeddu, Andrea; Gironella Cobos, Xavier; Sánchez-Arcilla Conejo, Agustín Abstract: Within the European project ‘Hydralab IV’, HyRes we aim to improve the characterization of wave loads on rigid structures and the associated response by carrying out some laboratory experiments. Wave loads on rigid structures are divided into quasi static loads and impact loads. If the physics of quasi-static loads due to waves is well known, this cannot be said the same for wave impact loads. A comprehensive method to design maritime rigid structures under impact loads does not exist yet and the actual design method suggests avoiding scenarios where impact loads can take place. In the last decade, some laboratory experiments have been carried out; however some questions remain still unanswered. The use of different sensors can lead to significant changes in the results and an “exhaustive comparison” between dissimilar types of sensors has not been done yet. Even the magnitude of these forces can be underestimated during a laboratory test just for the choice of sample frequencies which are too low. This paper describes the experiments performed on a small scale flume at UPC on a scaled vertical breakwater in order to compare the results of pressure transducers and force load cells. Moreover, a high frequency sampler (up to 20 KHz) was used in order to understand the importance of sample frequency on the magnitude of the results. A simplified scenario has been set up in order to make the data analysis easier. 2013-05-22T15:48:53Z http://hdl.handle.net/2117/19291 Title: Desarrollo de herramientas para la evaluación preliminar de la peligrosidad de corrientes detríticas Authors: Bregoli, Francesco; Bateman Pinzón, Allen; Medina Iglesias, Vicente César de; Hurlimann Ziegler, Marcel Abstract: Con el objetivo de proporcionar recomendaciones para la alerta temprana de fenómenos potencialmente desencadenantes de corrientes detríticas (“Debris Flow”), uno de los temas principales es la identificación preliminar de zonas de riesgo. Esta identificación es sustancialmente diferente de los mapas de riesgo que se suelen realizar por las autoridades de cuenca con el fin de dar una guía para planes de gestión del territorio. En el caso de alerta temprana, una identificación más aproximativa de las zonas de riesgo es suficiente. En esta perspectiva, los dos componentes del riesgo, peligrosidad y vulnerabilidad, se pueden estimar de una manera simplificada. En este trabajo se han desarrollado unas herramientas para la evaluación rápida de peligro por corrientes detríticas. Se han adaptado metodologías existentes y modelos simplificados y se ha llevado a cabo un útil paquete común de metodologías para una rápida evaluación de la peligrosidad. Se modelan tanto la iniciación como la propagación de corrientes detríticas. Uno de los requisitos del proyecto es definir una herramienta utilizable en diferentes contextos donde el nivel de detalle en los datos de entrada puede ser muy variado. Para lograr este objetivo se define un enfoque multinivel. La metodología se aplica en tres cuencas con características diferentes. 2013-05-16T12:17:48Z http://hdl.handle.net/2117/19255 Title: High-speed debris-flows generating 2D impulse waves: Experimental analysis Authors: Bregoli, Francesco; Bateman Pinzón, Allen; Medina Iglesias, Vicente César de Abstract: When a landslide or a debris-flow falls in a water body, a big wave, known as impulse wave or landslide tsunami wave, can be generated. That phenomenon can be highly destructive and unlikely predicted, involving dams and shorelines. Disastrous past events have been extensively analyzed and experimental studies have been carried out by different authors, but do not fully account for the description of the phenomenon. In the present study we introduce a new experimental set up installed in the fluvial-morphodynamic laboratory of the GITS team in the Technical University of Catalonia. The experimental device consists of a wheeled box sliding on a steep slope flume, releasing granular material, which enters a 2D basin. Defining a set of governing parameters and after several run of experiment, a description of the behavior of the waves was attempted. First results are here presented and analyzed. 2013-05-15T14:03:26Z http://hdl.handle.net/2117/19104 Title: Application of the gas tracer method for measuring oxygen transfer rates in subsurface flow constructed wetlands Authors: Tyroller, Lina; Rousseau, Diederik P. L.; Santa, Santa; García Serrano, Joan Abstract: The oxygen transfer rate (OTR) has a significant impact on the design, optimal operation and modelling of constructed wetlands treating wastewater. Oxygen consumption is very fast in wetlands and the OTR cannot be determined using an oxygen mass balance. This problem is circumvented in this study by applying the gas tracer method. Experiments were conducted in an unplanted gravel bed (dimensions L × W × d 125 × 50 × 35 cm filled with a 30-cm layer of 10–11-mm gravel) and a planted horizontal subsurface flow constructed wetland (HSSFCW) (L × W × d 110 × 70 × 38 cm filled with a 30-cm layer of 3.5-mm gravel with Phragmites australis). Tap water saturated with propane as gas tracer (pure or commercial cooking gas, depending on the test) was used. The mass transfer ratio between oxygen and commercial propane gas was quite constant and averaged R = 1.03, which is slightly lower than the value of R = 1.39 that is usually reported for pure propane. The OTR ranged from 0.31 to 5.04 g O2 m−2 d−1 in the unplanted gravel bed and from 0.3 to 3.2 g O2 m−2 d−1 in the HSSFCW, depending on the hydraulic retention time (HRT). The results of this study suggest that the OTR in HSSFCW is very low for the oxygen demand of standard wastewater and the OTR calculations based on mass balances and theoretical stoichiometric considerations overestimate OTR values by a factor that ranges from 10 to 100. The gas tracer method is a promising tool for determining OTR in constructed wetlands, with commercial gas proving to be a viable low-cost alternative for determining OTR. Description: 5th. IWA International Young Water Professional 2010, qua atorga la International Water association 2013-05-06T12:38:26Z http://hdl.handle.net/2117/18875 Title: Overtopping formula for vertical tiers-headed breakwaters Authors: Altomare, Corrado; Damiani, Leonardo; Gironella Cobos, Xavier Abstract: The semi-empirical methods are useful tools to understand the wave overtopping phenomena, but uncertainty remains on their applicability. It’s necessary to carry out campaign surveys or laboratory tests to support them. In this paper we apply the methods proposed in the European Overtopping Manual (2007) in order to assess the flows over a vertical breakwater, marking the need to calibrate those methodologies to take into account the peculiar geometry of the structural system. This was done by introducing appropriate correction factors. The results show an improved accuracy, among numerical results and physical ones. 2013-04-18T15:12:49Z http://hdl.handle.net/2117/18855 Title: Contaminant removal and clogging development in shallow subsurface flow wetlands: effect of primary treament and operation strategy Authors: Pedescoll Albacar, Anna; Corzo Hernández, Angélica; Alvarez, Eduardo; Puigagut Juárez, Jaume; García, Joan 2013-04-17T12:48:03Z http://hdl.handle.net/2117/18854 Title: Gravel composition related to clogging development in horizontal subsurface flow constructed wetlands Authors: Pedescoll Albacar, Anna; Passos, Fabiana Lopes del Rei; Alba, Esther; García, Joan; Puigagut Juárez, Jaume 2013-04-17T12:46:03Z http://hdl.handle.net/2117/18748 Title: Incorporation of continental and urban run-off into a coastal circulation model: application to the Catalan coast Authors: Liste, Maria; Grifoll Colls, Manel; Keupers, Ingrid; Monbaliu, Jaak; Espino Infantes, Manuel Abstract: A 3D hydrodynamical model has been set up to incorporate the continental and urban run-off into the Catalan Coastal waters. Particular attention was paid to introducing correctly the freshwater plumes and attention was also paid to determinate the influence of the land discharge profile with regard to the distributed continental run-off. The model domain includes a small part of the Catalan Coast where the combination of local land topography with torrential rainfall caused considerable local runoff on a short period of time with a large impact on the receiving coastal waters. The Regional Ocean Modeling System (ROMS) simulations were used to examine the dispersal to a freshwater delivery from two relevant event; a low river discharge typical of mean conditions during April 2011 and a high discharge representative of the storm event during March 2011 are considered. We have observed the plume responses to an abrupt change in river discharge. During the mean conditions, low salinity water is concentrated around the rivers mouth while during the flood event, the plume spread offshore in the direction of river water outflow and turned downstream close to the coast. The differences between a simulation including the river outflow as a land forcing and a simulation including river and urban runoff as a land forcing suggested that the urban runoff plays an important role in the spreading and shape of the river plume. 2013-04-09T18:04:52Z http://hdl.handle.net/2117/18745 Title: Are ciliated protozoa communities affected by macrophyte species, date of sampling and location in horizontal sub-surface flow constructed wetlands? Authors: Puigagut Juárez, Jaume; Maltais-Laundry, Grabriel; Gagnon, Vincent; Brisson, Jacques Abstract: The effects of design and operational factors on the dynamics of ciliated protozoa in constructed wetlands (CWs) treating wastewater remain poorly known, although bacterivory by ciliates could have important implications for nutrient cycling in these systems. We conducted a greenhouse experiment with eight wetland mesocosms (1 m2) fed with synthetic wastewater to assess how macrophyte species (Phragmites australis, Phalaris arundinacea, and Typha angustifolia), location within CW (longitudinal, depth), and temporal fluctuations affect ciliate abundance and diversity. Urosoma similis was the most abundant taxon, but Hypotrichidae, Scuticociliates, Drepomonas revoluta, and Acineria uncinata were also abundant. Longitudinal location had the highest impact on ciliate dynamics, with more abundant and diverse communities in the initial section of wetlands. P. australis/T. angustifolia and P. arundinacea had the most and least favorable conditions for ciliates, respectively, but differences among macrophytes were mostly not significant. Ciliate abundance appeared to decline from August to November, most likely because of lower temperature and plant inputs of organic matter and oxygen. Depth had no apparent impact on ciliate dynamics, suggesting that sampling at multiple depths in CW is not necessary to adequately monitor ciliate communities. Overall, our results suggest that macrophytes, location, and date of sampling influenced ciliated dynamics but stress the need for direct manipulative experiments of ciliate abundance, diversity, and composition conducted on a full annual cycle to better understand the impact of ciliates on nutrient cycling in CWs. This is especially true to determine if the associations found in our principal component analysis are robust. 2013-04-09T16:11:18Z http://hdl.handle.net/2117/18741 Title: Improving the reliability of closed chamber methodologies for methane emissions measurement in treatment wetlands Authors: Corbella Vidal, Clara; Puigagut Juárez, Jaume Abstract: Non-homogeneous mixing of methane (NHM) within closed chambers was studied under laboratory conditions. The experimental set up consisted of a PVC vented chamber of 5.3 litres of effective volume implemented with a power-adjustable 12V fan. NHM was addressed by injecting a known volume of methane and extracting, afterwards, gas samples from the top, middle and bottom sections of the chamber. NHM within the chamber was studied under different experimental situations such as the fan position (top vs lateral), fan airflow strength (23 vs 80 cubic feet per minute) and the mixing time before sample withdrawal (5, 10, 15 and 20 minutes). The potential bias of methane flux densities caused by NHM was addressed by monitoring the difference between linearly expected and estimated flux densities of ca. 400, ca. 800 and ca. 1600 mg CH4.m-2.d-1. Results showed that methane within the chamber was under non-homogeneous conditions. Accordingly, for mixing times before sample withdrawal ranging from 5 to 20 minutes methane concentrations at the bottom of the chamber were between 20% to 70% higher than those recorded at the middle or top sections of the chamber, regardless the fan position or fan airflow strength. Furthermore, NHM led to notable biases on flux density estimation. Accordingly, flux density estimated from top and middle sampling sections were systematically lower (ca. 50%) than those expected, regardless the flux density considered. Alternatively, flux densities estimated from bottom samples showed a lesser bias (between 10% higher to 25% lower than expected flux densities). 2013-04-09T15:08:52Z http://hdl.handle.net/2117/18740 Title: The influence of operational and design parameters on vertical redox profiles in sub-surface flow constructed wetlands: surveying the optimal scenario for microbial fuel cell implementation Authors: Garfi, Marianna; Corbella Vidal, Clara; Puigagut Juárez, Jaume Abstract: The objective of the present work was to determine the optimal redox gradient that can be obtained in sub-surface flow constructed wetlands (SSF CWs) to maximize the energy production with microbial fuel cells (MFCs). To this aim, a pilot plant based on SSF CW was evaluated for vertical redox profiles. Key operational and design parameters surveyed that influences redox conditions in SSF CW were the presence of plants (Phragmites australis) and the flow regime (continuous and discontinuous flow regime). Redox potential (EH) within the wetlands was analysed at a 5, 15 and 25 cm depth. Results obtained indicated that EH daily variation within the wetlands was small for depths of 5 cm and 25 cm, regardless operational or design conditions. On the contrary, the redox variation was of notable extent at 15 cm depth and ranging from +50 mV to – 300 mV, and especially pronounced for discontinuous flow planted wetlands. Overall, discontinuous flow and planted wetlands showed a higher redox potential at the bottom of the wetlands (between 50 and 100 mV higher) than those unplanted operated at a continuous flow. Furthermore, the maximum attainable redox gradient under the conditions here considered (redox difference between the surface of the wetland and the bottom or the middle part of the bed) is between 350 and 450 mV, being the continuous flow planted wetlands the configuration that offers the best balance between the maximum redox gradient and its stability along the day. Finally, the redox gradients obtained for planted wetlands operated under continuous flow regime would lead to a power production ranging of some 40 mW/m2 of wetland. 2013-04-09T15:03:23Z http://hdl.handle.net/2117/18467 Title: Multivariable model predictive control of water levels on a laboratory canal Authors: Horvath, Klaudia; Van Overloop, P.J.; Galvis Restrepo, Eduard; Gómez Valentín, Manuel; Rodellar Benedé, José Abstract: Automatic control of irrigation canals can reduce the loss of water in considerable amounts, therefore it is generating ecologic and economic benefits. There have been many different types of automatic controllers developed, but only few of them had the opportunity of being tested on the field due to the long delay time and the inconveniences of interrupting the operation of the irrigation. Therefore, the automatic controllers developed for large irrigation canals should be tested before by means of numerical simulations and/or laboratory experiments. The Technical University of Catalonia possesses a laboratory irrigation canal with the length of 220m, with 3 motorized gates, and 11 level sensors that are connected to a SCADA system. This facility makes it possible to test controllers of any type, since all the instrumentation and real time operation runs within a flexible working environment running in Matlab-Simulink . The canal can be configured from one pool to three pools, which allows the development of multivariable control. A numerical model of the canal has been developed using the 1D hydrodynamic model SIC. With the help of this software it is possible to simulate the hydraulics of the canal and, due to the link between SIC and Matlab, also to test any controller developed previously in the Matlab environment. In this work a centralized multivariable model predictive controller for water levels is developed and validated by means of numerical simulation. 2013-03-22T09:16:04Z http://hdl.handle.net/2117/18449 Title: Simplified modeling of a laboratory irrigation canal for control purposes Authors: Galvis Restrepo, Eduard; Horvath, Klaudia; Gómez Valentín, Manuel; Rodellar Benedé, José Abstract: http://upcommons.upc.edu/e-prints/bitstream/2117/15391/1/SAICA2011_proceedings.pdf 2013-03-21T09:38:09Z