Model d'inundacions en ventalls al.luvials: el cas de les planes costaneres valencianes

Els ventalls al.luvials que conformen les planes costaneres valencianes estan sotmesos a inundacions periòdiques, produïdes per les revingudes sobtades dels rius i barrancs que les recorren. Els diferents episodis analitzats en la darrera dècada han servit de base per a dissenyar un model d'inundacions, que intenta caracteritzar tant els processos com les formes inundables. Els ventalls són formes convexes, on hi ha una divergència dels fluxos desbordats a les corbes i als punts d'intersecció. Els paleocaixers, normalment desconnectats dels rius actuals, drenen la superfície del ventall, mentre que els espais intercons i les marjals són zones còncaves que arrepleguen les aigües desbordades dels cons i les dels caixers que hi desemboquen. Aquest funcionament natural es complica enormement degut a l'acció antròpica que modifica les condicions naturals d'aquest espais. Així, el ponts, les carreteres, els desviaments, els cobriments i les ocupacions de caixers són obres que poden interferir en els fluxos canalizats i en els desbordaments, modificant contínuament les zones inundables. Paraules clau : ventall al.luvial, risc d'inundació, processos d'inundació, concavitats, convexitats, acció antròpica

Sobre la restauració fluviali la complexitat dels rius efímers: algunes consideracions crítiques

En aquest article s"analitzen les actuacions de restauració fluvial dutes a terme a la Confederació Hidrogràfica del Xúquer entre 2008 i 2009, especialment les intervencions de restauració geomorfològica, la qual cosa ens permet una sèrie de consideracions crítiques sobre les obres. Es fan també algunes reflexions teòriques sobre els canvis ambientals i antròpics esdevinguts al llarg del segle XX i les implicacions que tenen sobre la restauració fluvial, en la mesura que aporten complexitat i incertesa a la restauració. En particular s"analitzen algunes actuacions de restauració que comprometen la connectivitat hidrològica i sedimentària, que són especialment febles en rius efímers. This paper presents a critical review of the geomorphological river restoration works carried out in the Júcar River Basin between 2008 and 2009, considering the impacts on the hydro-geomorphic systems. The scope of the environmental and anthropogenic changes occurred in the Mediterranean rivers throughout the twentieth century adds considerable complexity and uncertainty to the restoration actions. In particular several considerations are done about some restoration works that compromise the hydrological and sediment connectivity, which are particularly weak in ephemeral rivers

Efectos de una crecida en un cauce antropizado. La riada del Palància de octubre de 2000

In October of 2000, the Palància River underwent a major flood, which substantially modified the morphology of the river channel. These changes took place on a river bed previously modified by public works aimed at cleaning and simplifying the river section. The flood partially restored the braided morphology, reconstructing bars and channels. Moreover, river incision processes increased, particularly downstream the Palància bridges. This process reveals a sedimentary deficit caused by reservoirs; land use changes and gravel mining. The aim of this work is to describe these processes of change and to analyze the morphosedimentary consequences, through the interpretation of aerial photographs previous, simultaneous and subsequent to the flood.El río Palància experimentó, en octubre de 2000, una importante crecida que modificó sustancialmente la morfología del cauce. Esta transformación tuvo lugar sobre un lecho que previamente había sido arrasado por diversas obras de limpieza y regularización de la sección fluvial. La crecida restauró parcialmente la morfología braided del río, construyendo diversas barras y canales. Además, acentuó los procesos de incisión fluvial en el cauce, singularmente intensos en las inmediaciones de los puentes que cruzan el río, Este proceso denota un déficit sedimentario provocado por los cambios de usos del suelo, la extracción de áridos y la retención de sedimentos en los embalses de la cuenca. El presente trabajo, describe estos procesos de cambio y analiza sus implicaciones morfosedimentarias, a partir de la fotointerpretación de imágenes anteriores, simultáneas y posteriores a la crecida

L'aigua al terme de Xert: factors de localització i tipologia d'entitats hídriques

Les nombroses manifestacions hídriques del terme de Xert, aprofiten els recursos subterranis, com sol ocórrer en terrenys calcaris. Les basses, les fonts, els pous, les sénies o els molins exploten els aqüífers cretàcics, tot aprofitant l'alternança d'estrats permeables i impermeables i apareixen sobretot a les litologies calcareomargoses o margocalcàries. Tanmateix, les fonts més cabaloses s'associen als aqüífers juràssics fortament carstificats

Flood events in Mediterranean ephemeral streams (ramblas) in Valencia region, Spain

This article deals with flood events in Mediterranean ephemeral streams typical of the Valencia region. The combination of the basin physical characteristics steep slopes, sparse vegetation, thin soils and permeable rock. and intense, heavy and irregularly distributed rain, generates flash floods. Runoff generation is sudden, giving rise to flash floods with sharp, narrow hydrographs with short time lags. The high amount of runoff is, nevertheless, only a small fraction of the total rainfall, since the characteristics of the river basins are such that infiltration of large amounts of water occurs. Using daily hydrological data from the Rambla de la Viuda basin and 5-min data from both the Barranc del Carraixet and the Rambla de Poyo basins, the rainfallrunoff processes have been analysed during flood events in these ephemeral streams. q2001 Elsevier Science B.V. All rights reserved

Flood processes and morphological changes in aggradational ephemeral rivers. Reconstruction of the October 1957 flood in the Rambla Castellarda (Spain)

During the latter half of the twentieth century, Mediterranean ephemeral rivers underwent a profound metamorphosis. Fluvial adjustment processes narrowed the channels, simplified their planform pattern and notably reduced sediment availability. Today, this makes it extremely difficult to analyse the behaviour of this type of river in former aggradational contexts, such as those seen at the middle part of the twentieth century. For this reason, this paper addresses a reconstruction and analysis of the 1957 flood that occurred in the Rambla Castellarda, a tributary of the Turia river. The research is based, among other sources, on a series of extraordinary, high-precision aerial photographs carried out a few weeks after the flood. These images make it possible to recreate the processes observed in this ephemeral river and map the post-event river forms. Results show the behaviour of a Mediterranean aggradational ephemeral stream, very different from the current processes, and allows a comparative reflection to be made about flood processes in different sedimentary contexts. The study reveals that in-channel agricultural activity was, together with floods, the most relevant factor conditioning the river channel adjustment trajectory in that sedimentary context. Finally, the analysis of the impact of the flood in the Tura river highlights the importance of overflows - and therefore the connection between channel-floodplain - both for in-channel processes and in the lamination of floods. Durante la segunda mitad del siglo XX, los ríos efímeros mediterráneos han experimentado una profunda metamorfosis. Han sufrido procesos de ajuste fluvial que han estrechado los cauces, han simplificado sus formas y han reducido notablemente la disponibilidad de sedimentos. Esto hace que sea extremadamente difícil analizar hoy el comportamiento de este tipo de ríos en contextos agradacionales previos, como el que tenían hasta la primera mitad del siglo XX. Por ello, este artículo aborda el análisis de la crecida de 1957 en la Rambla Castellarda, afluente del río Túria. La investigación se basa, entre otras fuentes, en una extraordinaria serie de fotografías aéreas de alta precisión llevadas a cabo pocas semanas después de la riada. Estas imágenes nos permiten reconstruir los procesos observados en este río efímero y cartografiar las formas del río post-evento. Los resultados muestran el comportamiento de un río efímero agradacional mediterráneo, muy diferente a los procesos actuales, y permiten hacer una reflexión comparativa sobre los procesos de inundación en diferentes contextos sedimentarios. El estudio revela que la actividad agrícola en el cauce fue, junto con las inundaciones, el factor más relevante que condicionó la trayectoria de ajuste del cauce del río en dicho contexto sedimentario. Finalmente, el análisis del impacto de la crecida del río Turia pone de relieve la importancia de los desbordamientos -y por tanto de la conexión cauce-llano de inundación- tanto para los procesos en el cauce como en la laminación de las crecidas

Análisis de la evolución de la línea de costa entre Alcossebre y Oropesa a partir de la fotografía aérea (1956-2015)

[ES] El artículo presenta un análisis de la evolución de la línea de costa entre Alcossebre y Orpesa, a partir de fotografías aéreas y ortofotografías, entre 1956 y 2015. La digitialización de 12 líneas de costa ha permitido calcular los cambios netos y máximos, así como la tasa de cambio entre los diferentes años. Los resultados muestran una costa recesiva, con una gran variabilidad espacio-temporal. Conviven sectores con crecimiento sostenido provocado por la acción antrópica (deriva arriba de los espigones y regeneraciones de playa) o causas naturales (prominencias costeras), con otros claramente erosivos (deriva abajo de espigones). Además, el análisis de las isobatas del estrán sumergido, ha permitido explicar cómo la configuración de este espacio puede incrementar o frenar la erosión. Los temporales son los responsables de los grandes cambios, mientras que el déficit hidrosedimentario de los ríos a lo largo del siglo XX, subyace como causa última del comportamiento erosivo del área de estudio, tendencia que ya se manifestaba antes de la aparición de la acción antrópica. Así, la fotografía aérea, a pesar de su baja resolución temporal, compensa este déficit con la amplitud de sus series, lo que permite conocer el comportamiento de la línea de costa en un momento en el que la presión antrópica sobre este espacio era baja.[EN] This article presents an analysis of the coastline evolution between Alcossebre and Orpesa, based on aerial photographs and orthophotographs between 1956 and 2015. Twelve digitalized shoreline positions have allowed the calculation of net and maximum changes, as well as the rate of change between the different years. The results show a recessive coast, with a large spatial and temporal variability. Sectors with sustained accumulation, caused mainly by anthropic action (updrift sediment retention by groins and artificial nourishment of beaches) or natural causes (prominences) coexist with other clearly erosive (sediment deficit groins downdrift). In addition, the analysis of the isobaths of the submerged beach, has allowed to explain how the configuration of this space can increase or reduce the erosion. The big coastal storms are the main cause of the major changes, while the rivers hydrosedimentary deficit, generated along the twentieth century, underlies as the primary cause of the erosive behavior of the whole sector, which already were detected before the beginning of the main anthropic actions. Despite its low temporal resolution, the comparison of enough long series of aerial photography has allowed us to detect and quantify the coastline main changes when anthropogenic pressure was scarce.El presente trabajo forma parte de los proyectos de investigación CGL2013-44917-R, RESETOCOAST (CGL2015-69906-R) y EPHIMED (CGL2017-86839-C3-1-R) del Programa Estatal de Investigación, Desarrollo e Innovación Orientada a los Retos de la Sociedad, del Ministerio de Economía, Industria y Competitividad y están cofinanciados con fondos FEDER. Los autores agradecen las sugerencias de dos revisores anónimos que han mejorado notablemente el presente trabajo.Pardo Pascual, JE.; Roca-Moya, R.; Segura-Beltrán, F. (2019). Análisis de la evolución de la línea de costa entre Alcossebre y Orpesa a partir de fotografía aérea (1956-2015). Cuadernos de Geografía de la Universitat de València. 102:39-72. https://doi.org/10.7203/CGUV.102.14511S397210

Unforgiveness Motivations in Romantic Relationships Experiencing Infidelity: Negative Affect and Anxious Attachment to the Partner as Predictors

Infidelity is considered an unforgivable betrayal. However, not all behaviors considered unfaithful affect the person who suffers them in the same way. Therefore, to have a better understanding of unforgiveness according to different extradyadic behaviors, two studies were designed. Study 1 (N = 240) explored which extradyadic behaviors are considered as more indicative of infidelity. The results revealed that sexual behaviors were considered more unfaithful when compared with technological, emotional/affective, and solitary behaviors. Study 2 (N = 378) examined the influence of experienced extradyadic behaviors on unforgiveness, negative affect, and anxious attachment to the partner. The results showed that (a) sexual and technological behaviors were less frequently forgiven and promoted a more intense negative affect, (b) anxious attachment was predictive of unforgiveness for sexual and technological behaviors, and (c) negative affect mediated the relationship between anxious attachment and unforgiveness for sexual and technological behaviors. These findings and their possible implications for romantic relationships are discussed

Using post-flood surveys and geomorphologic mapping to evaluate hydrological and hydraulic models: The flash flood of the Girona River (Spain) in 2007

This paper analyzes the Girona River (Spain) flash flood, occurred on the 12th of October 2007, combining hydrological and hydraulic modeling with geomorphologic mapping and post-flood survey information. This research aims to reproduce the flood event in order to understand and decipher the flood processes and dynamics on a system of prograding alluvial fans. The hydrological model TETIS was used to characterize the shape and dimension of the October 2007 Girona River hydrograph. Subsequently, the flood event was reproduced using the free surface flow module of the model RiverFlow2D. The combination of hydrological and hydraulic models was evaluated using post-flood surveys defining maximum flooded area and flood depths. Then, simulations with different peak discharges were carried out to estimate the hydro-geomorphologic response of the Girona River floodplain, through the identification of the activation thresholds in different geomorphic elements. Results showed that the unit peak discharge of the October 2007 flood event (5 m3 s−1 km−2) was among the largest ever recorded in the area, according to the existing literature. Likewise, the hydraulic model showed a good performance in reproducing the flood event (FitA = 76%, RMSE = 0.65 m and NSE = 0.6), despite the complexity of the case, an ephemeral and ungauged river. The model simulation revealed the existence of an activation pattern of paleochannels and alluvial fans, which was altered by the presence of some anthropogenic disturbances. This multidisciplinary approach proved to be a useful strategy for understanding flash flood processes in ungauged catchments. It allowed understanding the mechanisms governing floods in alluvial fans systems and it represented a solid contribution for early warning plans and risk mitigation policies.This collaborative research was financed with the projects CGL2013-44917-R and SLWAMED CGL2014-58127-C3-2, of the Ministry of Economy and Competitiveness of the Spanish Government. Both projects were co-financed with FEDER funds. The observed rainfall and water discharge records were provided by "Sistema Automatic de Information Hidrologica (SAIH)", which belongs to the CHJ (Spain). This work was also possible due to the kind cooperation of the members of the Plataforma Ciutadana Riu Girona and several anonymous farmers interviewed during the field works. We also thank two anonymous reviewers for their useful and thought-provoking comments.Segura-Beltrán, F.; Sanchis Ibor, C.; Morales-Hernández, M.; González-Sanchis, MDC.; Bussi, G.; Ortiz, E. (2016). Using post-flood surveys and geomorphologic mapping to evaluate hydrological and hydraulic models: The flash flood of the Girona River (Spain) in 2007. Journal of Hydrology. 541(Part A):310-329. https://doi.org/10.1016/j.jhydrol.2016.04.039S310329541Part

Estimación de la velocidad de flujo del agua en cauces efímeros no aforados a partir de datos Lidar y GPS-RTK

The Manning formula is one of the most used to calculate the average velocity of water flow in ungauged channels. In order to be applied, it is necessary to measure in field the hydraulic radius (RH), the slope of the water surface (S), and to obtain the roughness coefficient (n), usually through tables created for this purpose. This involves a difficult, inefficient and subjective data collection in the field. This study evaluates the possibility to obtain these parameters in a more efficient manner, reducing the time of the process and allowing to work in larger areas. To achieve these objectives, the data used in this work were: 1) digital terrain models generated from airborne LiDAR data with a density of 2 points/ m2 , acquired when the channel was dry; 2) the height of the waterline and channel geometry measurements in the field using GPS; 3) Flow measurements. With this information, the velocity (Ve) was estimated and related to the average velocity of water flow (Vc) calculated from data measured in the field. The coefficient of determination between both velocity values was 73.52%, suggesting that the proposed methodology is useful to obtain the average velocity of flow, especially in remote areas or dry riverbeds