Study of the efflux velocity induced by two propellers

Present analysis is related with seabed erosion caused during docking and undocking maneuvering. Twin propellers without rudder were studied using a physical model with a fixed clearance distance and three different rotating velocities. Experimental results were compared to theoretical expressions of the efflux velocity, axial velocity and finally maximum bed velocity. Efflux velocity equations overestimate the experimental results, whereas axial velocity computed using the Dutch method fits reasonably well the experimental data. However, when maximum bed velocity expressions are compared to experimental results, German method behaves better with an over estimation if a quadratic superposition of the single jets is used.Postprint (published version

Assessment of the importance of the current-wave coupling in the shelf ocean forecasts

International audienceThe effects of wave-current interactions on shelf ocean forecasts is investigated in the framework of the MFSTEP (Mediterranean Forecasting System Project Towards Enviromental Predictions) project. A one way sequential coupling approach is adopted to link the wave model (WAM) to the circulation model (SYMPHONIE). The coupling of waves and currents has been done considering four main processes: wave refraction due to currents, surface wind drag and bottom drag modifications due to waves, and the wave induced mass flux. The coupled modelling system is implemented in the southern Catalan shelf (NW Mediterranean), a region with characteristics similar to most of the Mediterranean shelves. The sensitivity experiments are run in a typical operational configuration. The wave refraction by currents seems to be not very relevant in a microtidal context such as the western Mediterranean. The main effect of waves on current forecasts is through the modification of the wind drag. The Stokes drift also plays a significant role due to its spatial and temporal characteristics. Finally, the enhanced bottom friction is just noticeable in the inner shelf

Un modelo numérico en elementos finitos para la corriente inducida por la marea. Aplicaciones al Estrecho de Gibraltar

Mediante un modelo numérico quasi-3D en elementos finitos que resuelve las ecuaciones de aguas someras a través de una técnica de descomposición armónica, se ha estudiado el comportamiento de la marea en el Estrecho de Gibraltar. En esta región se acoplan dos regímenes de marea sustancialmente diferentes, el correspondiente al océano Atlántico y el de la cuenca mediterránea. Los resultados del modelo confirman la preponderancia de la circulación inducida por la marea en el flujo local de la zona. También se ha comprobado la importancia que en este ámbito tienen los efectos de la difusión turbulenta, de la fricción con el fondo, de la geometría del dominio y de la interacción de las componentes mareales con la circulación residual. El empleo de una interpolación de orden superior para la altura de la superficie libre y de una formulación no lineal para la fricción con el fondo debe permitir mejorar el grado de ajuste entre los resultados numéricos obtenidos y los datos disponibles.Tidal wave propagation patterns in the Gibraltar Strait are analyzed by means of a quasi- 3D finite element model of the shallow water equations whose solver is based on a harmonic descomposition technique. In this region, two substantially different tidal regimes are coupled, the one corresponding to the Atlantic Ocean and that of the Mediterranean basin. The model results confirm that the tidal contribution is prevailing within local circulation patterns. Moreover, our solutions suggest that the turbulent diffusion of momentum, bottom friction effects, the geometry of the Strait and the tide-current interactions have an important influence on the tidal propagations patterns. The use both of a higher order interpolation scheme for the sea surface height and a non-linear formulation for bottom friction is envisaged as a means to obtain better agreement between model results and experimental data.Peer Reviewe

Seasonal circulation over the Catalan inner-shelf (northwest Mediterranean Sea)

This study characterizes the seasonal cycle of the Catalan inner-shelf circulation using observations and complementary numerical results. The relation between seasonal circulation and forcing mechanisms is explored through the depth-averaged momentum balance, for the period between May 2010 and April 2011, when velocity observations were partially available. The monthly-mean along-shelf flow is mainly controlled by the along-shelf pressure gradient and by surface and bottom stresses. During summer, fall, and winter, the along-shelf momentum balance is dominated by the barotropic pressure gradient and local winds. During spring, both wind stress and pressure gradient act in the same direction and are compensated by bottom stress. In the cross-shelf direction the dominant forces are in geostrophic balance, consistent with dynamic altimetry data. Key Points A hydrodynamic model is implemented for the first time in Catalan inner-shelf. Frictional and pressure gradient are revealed as the main forcing mechanisms A clear seasonal pattern is found in the current velocity.Peer ReviewedPostprint (published version

Evolución en planta/perfil de una playa. Métodos predictivos

[ES] La regeneración/alimentación artificial de una playa supone reproducir una costa sedimentaria que, al igual que las costas naturales, estará sometida a una serie de procesos evolutivos. Estos procesos se esquematizan mediante el estudio de los cambios en planta y perfil de la playa, los cuales son comunes tanto para costas naturales como artificiales. A lo largo de este trabajo se presentan una serie de herramientas para evaluar tales cambios y, por tanto, para estimar la durabilidad de las obras de regeneración o, al menos, las fases evolutivas por las que pasarán.Parte de este trabajo ha sido realizado gracias a la colaboración del Programa de Clima Marítimo (Ente Público de Puertos del Estado) a través del convenio Procesos Hidrodinámicos en Zona de Rompientes.Sánchez-Arcilla Conejo, A.; Jiménez, JA. (1995). Evolución en planta/perfil de una playa. Métodos predictivos. Ingeniería del Agua. 2(1 Extraordinario):119-132. https://doi.org/10.4995/ia.1995.2662SWORD11913221 ExtraordinarioBerenguer, J.M. y Enríquez, J. (1988). Design of pocket beaches. Proc. 21st Coastal Eng. Conf.,ASCE, 1411-1425.Bodge, K. (1992). Representing equilibrium beach profiles with an exponential expression. J. of Coastal Research. 8, 47-55.Bruun, P. (1953). Forms of equilibrium coasts with littoral drift.Tech. Rep. 3, University of California, Engineering Research Laboratory, Berkeley.Bruun, P. (1954). Coast erosion and the development of beach profiles. Beach Erosion Board, Techn. Memo. 44.CUR. (1988). Manual on Artificial Beach Nourishment.Rijkswaterstaat, The Netherlands, 195 pp y anejos.Dalrymple, R.A. (1992). Prediction of storm/normal beach profiles. J. of Waterway. Port. Coastal and Ocean Engineering. 118, 2, 193-200.Dalrymple, R.A. y Thompson, W. (1976). Study of equilibrium beach profiles. Proc. 15th Coastal Eng. Conf.. ASCE. 1277-1296.Dean, R.G. (1973). Heuristic models of sand transpon in the surf zone. Proc. of the Conf. on Engineering Dynamics in the surf zone. 208-214.Dean, R.G. (1977). Equilibrium beach profiles: US Atlantic and Gulf Coasts. Dept. of Civil Eng., Ocean Eng. Tech. Rep. 12, Univ. of Delaware.Dean, R.G. (1997). Equilibrium beach profiles: characteristics and applications. J. of Coastal Research. 7, 1, 53-84.Dean, R.G. y Maurmeyer, E.M. (1983). Models for beach profile response. En: Komar, P.D. (ed.), Handbook of Coastal Processes and Erosion.CRC Press, Boca Ratón, 151-166.Dean, R.G. y Yoo, C. 1993. Predictability of beach nouríshment perfomance. En: Stauble, D.K. y Kraus, N.C. (eds.), Beach Nourishment Engineering and Management Considerations.ASCE, 86-102.De Vriend, H.J.; Zyserman, J.; Nicholson, J.; Roelvink, J.A.; Pechón, P. y Southgate, H.N. (1994). Medium-term 2DH coastal área modelling. Coastal Engineering. 21. 193-224.Garau, C. (1979). Condicionantes de la estabilidad de playas. A nálisis de la función polar de los salientes. II Curso de Ingeniería Oceanogràfica y Portuaria. Santander.Hedegaard, I.B.; Roelvink, J.A.; Southgate, H.; Pechón, P.; Nicholson, J. y Hamm, L. (1992). Intercomparison of coastal profile models. Proc. 23rd Coastal Eng. Conf.. ASCE, 2108-2121.Horikawa, K. (1988) Nearshore Dynamics and Coastal Processes. University of Tokyo Press, Tokyo.Hoyle, J.W. y King, G.T. (7955). The orígin and stability of beaches. Proc. 6th Coastal Eng. Conf.. ASCE,'281-301.Hsu, J.R.C. y Evans, C. (1989). Parabolic hay shapes and applications. Proc. Institution of Civil Engineers. 87, 557-570.Inman, D.L.; Elwany, M.H.S. y Jenkins, S.A. (1993). Shoreríse and bar-berm profiles on ocean beaches. J. of Geophysical Research, 98. C10.18181 -18199.Jiménez, J.A. (1995). BEACH1L. Laboratori d'Enginyeria Marítima, Universitat Politécnica de Catalunya, Barcelona, 41 pp y anejos.Jiménez, J.A. y Sánchez-Arcilla, A. (1992). Simulación de cambios a corto plazo en la línea de costa. Revista de Obras Públicas. 3315, 41-51.Jiménez, J.A. y Sánchez-Arcilla, A. (1993). Influencia de la pendiente en la evolución del perfil de playa. II Jornadas Españolas de Ingeniería de Costas y Puertos. Gijón (en prensa).Jiménez, J.A.; Sánchez-Arcilla, A. y Stive, M.J.F. (1993). Discussion on Prediction of storm/normal beach profiles. J. of Waterway, Port, Coastal and Ocean Engineering, 119, 4, 466-468.Jiménez, J.A.; Valdemoro, H. y Sánchez-Arcilla, A. (1995). Discussion on A nalysis of bayed beaches in static equilibríum. J. of Waterway. Port. Coastal and Ocean Engineering.Mav/June (en prensa).Komar, P.D. (1976). Beach Processes and Sedimentation. Prentice-Hall. Englewood Cliffs, 429 pp.Komar, P.D. y McDougal, W.G. (1994). The analysis of exponential beach profiles. J. of Coastal Research. 10, 1, 59-69.Kraus, N.C. (1985). Prediction models of shoreline change. En: Horikawa, K. (ed.), Nearshore Dynamics and Coastal Processes. University of Tokyo Press, Tokyo, 321-366.Kriebel, D.L. y Dean, R.G. (7995). Convolution method for time-dependent beach-profile response. J. of Waterway. Port. Coastal and Ocean Engineering. 119, 2, 204-226.Kriebel, D.L.; Kraus, N.C. y Larson, M. (1991). Engineering methods for predicting beach profile response. Coastal Sediments' 91.ASCE, 557-571.Larson, M. (1955). Ouantification of beach profile change.Report 1008, Dept. of water Resources Eng., Lund University.Larson, M. (1991). Equilibríum beach profiles of a beach with varying grain size. Coastal Sediments'91. ASCE, 905-919.Larson, M.; Hanson, H. y Kraus, N.C. (1987). Analytical solutions of the one-line model of shoreline change. Tech. Rep. CERC-87-15.Le Blond, P.H. (1972). On the formation of spiral beaches. Proc. 13th Coastal Eng. Conf.. ASCE, 1331-1345.Negro, V. (1990). La variabilidad de los perfiles de playa. Perfiles de verano e invierno. Análisis histórico(1a parte). Revista de Obras Publicas. Marzo 1990, 23-29.Ozasa, H. y Brampton, A.H. (1980). Mathematical modelling of beaches backed by seawalls. Coastal Engineering. 4, 1, 47-64.Pelnard-Considere, R. (1956). Essai de theorie de l'evolution des formes de rivage de sable et de galets. 4th Journees de l'Hydraulique. Question III, Rapport 1, 289-298.Rivero, F. (1995). PROPS. Laboratori d'Enginyeria Marítima, Universitat Politécnica de Catalunya, Barcelona.Sánchez-Arcilla, A. y Jiménez, J.A. (1994). Ingeniería de playas (I): conceptos de morofología costera. Ingeniería del Agua. 1, 2, 97-114.Short, A.D. (ed.) (]993). Beach and surf zone morphodynamics. J. of Coastal Research.Special Issue 15.Silvester, R. (1970). Growth of crenulated shaped bays to equilibríum. J. of Waterways and Harbours División. 96, WW2, 275-287.Silvester, R. y Hsu, J.R.C. (1991). New and oíd ideas in coastal sedimentation. Reviews in Aquatic Sciences. 4, 4, 375-410.0Steetzel, H.J. (1993). Cross-shore transpon during storm surges.Ph.D. Thesis, Delft University of Technology, 242pp.Sunamura, T. (1984). Quantitativeprediction ofbeach-face slopes. Geological Soc. of Amer. Bull..95, 242-245.Sunamura, T. (1985). Beach morphologies and their change. En: Horikawa, K. (ed.), Nearshore Dynamics and Coastal Processes. Univ. of Tokyo Press, Tokyo, 136-157.Tan, S.K. y Chiew, Y.M. (1994). Analysis of bayed beaches in static equilibríum. J. of Waterway. Port. Coastal and Ocean Engineering. 120. 2, 145-153.Vellinga, P. (1982). Beach and dune erosión duríng storm. surges. Coastal Engineering, 6, 806-819.Vellinga, P. (1986). Beach and dune erosión during storm surges. Ph. D. Thesis, Delft University of Technology.Walton, T.L. (1994). Shoreline evolution for tapered beach fill. J. of Waterway. Port. Coastal and Ocean Engineering. 120, 6, 651-655. Wiegel, R.L. (1964) Oceanographic Engineering. Prentice-Hall, Englewood Cliffs.Wind, H.G. (1994). An analytical model of crenulate shaped beaches. Coastal Engineering. 23. 243-253.Yasso, W.E. (1965). Plan geometry of headland hay beaches. J. of Geology. 73. 702-714

Study of the bed velocity induced by twin propellers

Twin propellers without a rudder were studied using a physical model with a fixed clearance distance and three different rotating velocities. Experimental results were compared with results from theoretical expressions developed over the past 50 years for the efflux velocity, axial velocity, and maximum bed velocity. It was found that the efflux velocity equations overestimated the experimental results, whereas the computed axial velocities matched the experimental data reasonably well. However, when maximum bed velocity expressions were compared with experimental results, only one method was found to behave better; overestimation resulted if a quadratic superposition of single jets was used.Ministerio de Economía y Competitividad | Ref. TRA2015-70473-

The economic value of drought information for water management under climate change: a case study in the Ebro basin

Drought events in the Mediterranean are likely to increase in frequency, duration and intensity due to climate change, thereby affecting crop production. Information about drought is valuable for river basin authorities and the farmers affected by their decisions. The economic value of this information and the resulting decisions are of interest to these two stakeholder groups and to the information providers. Understanding the dynamics of extreme events, including droughts, in future climate scenarios for the Mediterranean is being improved continuously. This paper analyses the economic value of information on drought events taking into account the risk aversion of water managers. We consider the effects of drought management plans on rice production in the Ebro river basin. This enables us to compute the willingness to compensate the river basin authority for more accurate information allowing for better decision-making. If runoff is reduced, river basin planners can consider the reduction of water allocation for irrigation in order to eliminate the risk of water scarcity. Alternately, river basin planners may decide to maintain water allocation and accept a reduction of water supply reliability, leaving farmers exposed to drought events. These two alternatives offer different risk levels for crop production and farmers' incomes which determine the value of this information to the river basin authority. The information is relevant for the revision of River Basin Management Plans of the Water Framework Directive (WFD) within the context of climate change

Differences in assigning probabilities to coastal inundation hazard estimators: event versus response approaches

This is the accepted version of the following article: Sanuy, M, Jiménez, JA, Ortego, MI, Toimil, A. Differences in assigning probabilities to coastal inundation hazard estimators: Event versus response approaches. J Flood Risk Management. 2020; 13 (Suppl. 1):e12557. https://doi.org/10.1111/jfr3.12557, which has been published in final form at https://onlinelibrary.wiley.com/doi/full/10.1111/jfr3.12557.Coastal flood risk assessment requires a reliable estimation of the frequency of inundation hazards, that is, characterising the hazard magnitude and assigning a probability of occurrence. In this work we analyse the uncertainty introduced in the assessment associated to the method to assign the probability of occurrence to coastal flood hazards. To this end we have compared the use of two general methods, the response and the event approaches. Different procedures are used to characterise coastal inundation hazards depending on the analysis scale and data availability. Thus, a range of possibilities has been analysed, from simple estimators such as run-up to modelled flood-prone areas. The analysis has been performed for all wave and water level conditions around the Spanish coast. The results show that the differences between the methods are location-dependent, and thus, determined by the exposure to wave and water level conditions. When using the event approach, the run-up or total water level (with good correlation between waves and surge) distributions reasonably approximate those of the response approach with low associated uncertainty. When the assessment aims to output overtopping discharges or inundation maps, observed differences suggest that the event approach would produce misleading conclusions in inundation-related coastal management and decision-making.Peer ReviewedPostprint (author's final draft

La red MARHIS. Una alianza estratégica para la ingeniería y las EERR marinas en España

MARHIS agradece la financiación recibida por MINECO a través de las Acciones de dinamización “Redes de Excelencia” Convocatoria 2015

Estudio numérico-experimental de la contaminación en aguas costeras

[ES] En este trabajo se presentan resultados numéricos y experimentales de la dispersión de contaminantes y trazadores en el litoral Mediterráneo. Se han utilizado dos modelos hidrodinámicos para simular la circulación horizontal producida por viento y oleaje en la plataforma y la zona de rompientes, respectivamente. Un modelo 3D de dispersión en "el campo cercano" suministra las condiciones iniciales al modelo 2D de dispersión local en el "campo lejano". Se presentan dos casos de estudio: la dispersión de trazadores en la zona de rompientes (Delta del Ebro) desde el punto de vista numérico y experimental; y la simulación de la dispersión de contaminantes urbanos -bacterias- provenientes del principal emisario submarino de Barcelona, mediante la aplicación de una secuencia de modelos numéricos. La comparación entre los experimentos y los resultados numéricos en la zona de rompientes es buena, mientras que las predicciones de contaminación en litoral cercano al emisario manifestaron la importancia de modelar con precisión los efectos de flotabilidad en el penacho o pluma. Además, se han simulado varias configuraciones de descarga, comprobándose que solo el nuevo emisario permite un grado de dilución acorde con la normativa vigente.El presente trabajo fue realizado como parte de los proyectos de investigación del LIM-UPC en Contaminación costera e Hidrodinámica de la Zona de Rompientes, financiados por el Direcc. Gral. de Medí Ambient de la Generalitat de Catalunya el primero, y conjuntamente por la Dirección Técnica Programa de Clima Marítimo (Ente Público Puertos del Estado -MOPTMA) y el Ministerio de E. y C. (DGICYT) el segundo. Los autores agradecen la colaboración de J.P. Sierra, J. Sospedra, J. Gomez y al personal involucrado en las mediciones de campo. También se agradece al Dr. G. Jirka sus comentarios sobre la dispersión en campo cercano y la disponibilidad del modelo CORMIX, y a EMSSA por la atención en suministrar datos de la planta y emisarios del Besos.Rodríguez, A.; Sánchez-Arcilla Conejo, A.; Bahía, E.; Redondo Apraiz, JM.; Collado, F. (1995). Estudio numérico-experimental de la contaminación en aguas costeras. Ingeniería del Agua. 2(2):53-62. https://doi.org/10.4995/ia.1995.2677SWORD536222Battjes, J. (1975). Modeling of turbulence in the surf zone, Proc. Sympo. on Modeling Techniques, ASCE, 1050-1061.Bravo, J. (1985). Analisis y Evaluación de la Calidad Microbiológica de las Aguas Costeras, Tesis Doctoral, Univ. Aut. de Barcelona, 257 pg.Carreras P. y Menendez A. (1990). Mathematical modelling of pollutant dispersion, Ecological modelling, Elsevier, 52, 29-40.Crickmore M.J. (1972). Tracer tests of eddy diffusion in field and model, Jour. Hyd. Div., ASCE, Vol. 98, no. HY10, 1737-1752.Deguchi I., Sawaragi T. y Ono M. (1992). Longshore current and lateral mixing in the surf zone. Proc. Int.Conf.Coast. Eng., ASCE, 2642-2654.Dean R. y Dalrymple, R. (1984). Water wave mechanics. Prentice-Hall, N. Jersey.Fredsoe J. (1984). The turbulent boundary layer in wave-current motion, Jour. Hyd. Eng., ASCE, Vol. 110, no. 8, 1103-1120.Harris T., Jordan J. McMurray W., Verwey C. y Anderson F. (1963). Mixing in the surf zone, Int.Jour. Air Wat. Poll., Vol. 7, 649-667.Holly F.M. y Usseglio-Polatera J.M. (1984). Dispersion Simulation in Two-Dimensional Tidal Flow, Jour. Hyd. Eng., ASCE, Vol. 110, no. 7(Julio), 905-926.Horikawa K., Lin M. y Sasaki T. (1978). Mixing of heated water discharged in the surf zone, Proc. Int.Conf.Coast.Eng., ASCE, 2563-2583.Jirka, G. (1991). CORMIX: Cornell Mixing Zone Expert System, I.C.E. Short Course on Hydraulics of Sea Outfalls, University of Honk Kong, Diciembre 1991.Mancini, J. (1978). Numerical estimates of coliform mortality rates under various conditions, Journal of water pollution control fed., Noviembre, 2477-2484.Mead C., y Cooper A. (1992). Three-dimensional numerical modelling of coastal hydrodynamics and pollutant dispersal, Proc. 2nd. Int. Conf. Hyd. and Env. Mod. of Coast., Est. and River Waters, Vol. 1, Ashgate Pub., 31-41.Mujeriego, R. (1989). Estudio del saneamiento de las zonas costeras de Cambrils y Vilaseca-Salou, Inf.Sec.Ing.Eng.Amb.}, DEHMA, ETSECCPB, UPC, Barcelona, Septiembre, 152 pg.Nadaoka K. y Hirose F. (1986). Modelling of diffusion coefficient in the surf zone based on physical process of wave breaking, Proc. 33rd Japan Conference Coastal Engineering, 26-30, (en japonés).Ozmidov, R. (1990). Diffusion of contaminants in the ocean, Oceanographie Sciences Library, Vol. 4, Kluwer Academic Publishers, Londres.Redondo J., Rodriguez A., Bahia E., Falqués A., Gracia V., Sánchez-Arcilla A. y Stive M.J.F. (1994). Image Analysis of Surf-Zone Hydrodynamics, Proc. Coastal Dynamics 94, ASCE, pp 350-365.Rodriguez A., Sánchez-Arcilla A., Collado F., Gracia V. y Coussirat M.G. (1994). Waves and currents at the Ebro Delta Surf Zone: measured and modelled Proc. Int.Conf.Coast.Eng., ASCE, (en prensa).Sánchez-Arcilla A.; Collado F., Lemos C. y Rivero F. (1990), Another quasi-3D model for surf-zone flows, ICCE, ASCE, pp 316-329.Sánchez-Arcilla A., Collado F., y Rodriguez A. (1992). Vertically varying velocity field in Q3D nearshore circulation, Proc. Int.Conf.Coast.Eng., ASCE, 2811-2838.Sierra J.P., Rodriguez A., Bahia E. y Sánchez-Arcilla A. (1994). Dispersió de contaminants en regions costaneres. Informe de recerca RR-LIM/ADC-94-1, Barcelona.Svendsen, I. (1987). Analysis of surf zone turbulence, Jour. Geophysical Research, 92 (C5), 5115-5124.Zeider R. (1976). Coastal Dispersion of Pollutants, Jour. Waterw. Harb. Coast. Eng., ASCE, Vol. 102, no. WW2 (May), 235-254