UBathy (v2.0): a software to obtain the bathymetry from video imagery

UBathy is an open source software developed for bathymetry estimation from video images. The proposed scheme is based on extracting the wave modes from videos of the nearshore surface wave propagation. These videos can be formed either from raw camera images, which must have been previously calibrated, or from georeferenced planviews. For each wave mode extracted from the videos, the wave frequency and the spatially dependent wavenumbers are obtained. The frequencies and wavenumbers from different videos are used to estimate the bathymetry by adjusting the dispersion relationship for linear surface water waves. The bathymetry at different times can further be weighted and aggregated using the Kalman filter. The new software is suitable for Argus-type video monitoring stations and for moving cameras mounted on drones or satellites, and it is meant for users familiar with coastal image processing and suitable for non-experienced users. The software and an application example are available on the GitHub platform.Postprint (author's final draft

Water level control on coastal landform distribution and associated processes in a highly fluctuating shallow lake (Gallocanta Lake, NE Spain)

Shallow lakes in semi-arid environments are very sensitive to hydrological alterations associated with climate change. Their shorelines and geometry can change according to water level fluctuations. Gallocanta Lake (NE Spain) is a typical example of such lacustrine conditions because it is exposed to strong winds parallel to its elongation axis and is located in a semi-arid Mediterranean environment. In this work, a high-resolution digital elevation model (DEM) of the area is used to compare the distribution of coastal forms (beaches, barrier islands, deltas, lagoons, etc.) with the frequency at which different water levels are attained. As a result, a clear relationship is obtained between presently active forms and the water levels most frequently reached in the lake. It is deduced that, once formed, the surrounding coastal plains related to these coastal forms control the permanence of water around a given height interval, favouring the development of these morphologies, in a positive feedback mechanism only broken by subsequent climate warming and lake water lowering. The hydrodynamic conditions responsible for activating the coastal forms have been analysed by applying a mathematical model of wind-driven currents in the lake that predicts the present erosional/progradational trends associated with them. The combination of the different results obtained was used to generate a synthetic map of active coastal processes and trends along the lake shore during high water episodes, with two versions according to the two dominant wind scenarios in the region. The distribution of erosion/sedimentation trends along the lake shores has helped to propose the existence of longitudinal littoral cells, each one recording different shoreline trend (retreat, progradation, and stability), depending on the prevailing wind scenario. This synthetic scheme can be useful for predicting the eco-morphological trends of the lake shore and adapting the present management practices in this protected area accordingly.Postprint (author's final draft

Vulnerabilidad sísmica y toma de decisiones

Postprint (author final draft

Sediment exchanges from the shoreline to the lower shoreface inferred from morphological changes (Llobregat Delta, Western Mediterranean)

Se realizaron 14 campañas topo-batimétricas desde la playa emergida hasta los 15 m de profundidad, a lo largo de 1 km en la playa de Castelldefels (Delta del Llobregat, Barcelona) durante el periodo 2011-2020. Se analizan las variaciones morfológicas que tienen lugar, los cambios volumétricos y sus posibles implicaciones en los intercambios sedimentarios en el perfil litoral. Los principales cambios morfológicos están causados por los desplazamientos transversales de las barras de arena, generalmente hacia tierra durante condiciones de buen tiempo y hacia mayor profundidad durante las tormentas más fuertes. Los cambios volumétricos sugieren que el retroceso de la línea de costa durante la última década aporta sedimento a la parte superior de la playa sumergida, mientras que los eventos más extremos producen una transferencia de sedimento hacia la plataforma continental, que podrían ser parcialmente irrecuperables para la dinámica litoral. El balance sedimentario resultante es negativoPostprint (updated version

Uso de modelos uni- y bidimensionales en llanuras de inundación. Aplicación al caso del río Tajo en Talavera de la Reina

[ES] En este trabajo se presenta la experiencia de uso de un modelo hidráulico unidimensional (Hec- Ras) y uno bidimensional (Feswms) en el estudio de la inundabilidad de Talavera de la Reina por el río Tajo. Se revisan los fundamentos y se analizan las aplicaciones de estos modelos, extrayendo las enseñanzas prácticas de sus virtudes e inconvenientes. La avenida de 1947 en Talavera, que teóricamente superó los 7000 m3/s se analiza con detalle.Este trabajo es un resultado del proyecto FEDER I+D 1FD972110C0201Martin Vide, JP.; López Querol, S.; Martín Moreta, P.; Simarro Grande, G.; Benito Ferrández, G. (2003). Uso de modelos uni- y bidimensionales en llanuras de inundación. Aplicación al caso del río Tajo en Talavera de la Reina. Ingeniería del agua. 10(1):49-58. https://doi.org/10.4995/ia.2003.2576OJS4958101U.S. Army Corps of Engineers, Hydrologic Engineering Center (2001) HEC-RAS. River Analysis System. Hydraulic Reference Manual. Version 3.0U.S. Department of Transportation. Federal Highway Administration. FESWMS-2DS: Finite Element Surface -Water Modelling System: Two - Dimensional Flow in a Horizontal Plane. Users ManualMartín-Vide, J.P (1997) Ingeniería fluvial. Edicions UPC, Barcelona.Martín-Vide, J.P.; Prió, J.M.; Bateman, A. "Backwater effects in arch bridges under free and submerged conditions". Journal of Hydraulic Engineering, ASCE (en revisión, 2002).Maza Alvarez, J.A.; García Flores, M. Transporte de sedimentos. Capítulo 10 del Manual de Ingeniería de Ríos. Instituto de Ingeniería de la UNAM, México 1996

Spread of a SARS-CoV-2 variant through Europe in the summer of 2020.

Following its emergence in late 2019, the spread of SARS-CoV-21,2 has been tracked by phylogenetic analysis of viral genome sequences in unprecedented detail3–5. Although the virus spread globally in early 2020 before borders closed, intercontinental travel has since been greatly reduced. However, travel within Europe resumed in the summer of 2020. Here we report on a SARS-CoV-2 variant, 20E (EU1), that was identified in Spain in early summer 2020 and subsequently spread across Europe. We find no evidence that this variant has increased transmissibility, but instead demonstrate how rising incidence in Spain, resumption of travel, and lack of effective screening and containment may explain the variant’s success. Despite travel restrictions, we estimate that 20E (EU1) was introduced hundreds of times to European countries by summertime travellers, which is likely to have undermined local efforts to minimize infection with SARS-CoV-2. Our results illustrate how a variant can rapidly become dominant even in the absence of a substantial transmission advantage in favourable epidemiological settings. Genomic surveillance is critical for understanding how travel can affect transmission of SARS-CoV-2, and thus for informing future containment strategies as travel resumes. © 2021, The Author(s), under exclusive licence to Springer Nature Limited

Near-bottom sediment dynamics on highly-protected beaches The Coastal Ocean Observatory of Barcelona

This article presents some preliminary results of the sedimentary dynamics measured during 5 months in Barcelona city beaches (NW Mediterranean). Wave storms, resuspension events and near-bottom sediment fluxes are analyzed in order to characterize the sedimentary behavior of highly-protected beaches

Numerical Analysis Group progress report January 1994 - December 1995

SIGLEAvailable from British Library Document Supply Centre-DSC:8715.1804(CCLRC-RAL-TR--96-015) / BLDSC - British Library Document Supply CentreGBUnited Kingdo