0000000000002340
AUTHOR
J. Soriano
Empirical study of extreme rainfall intensity in a semi-arid environment at different time scales
Abstract Mediterranean environments are typical of semi-arid regions, dominated by episodes of torrential rain in which the critical variable is not the total rainfall, but the intensity. This paper studies the maximum rainfall intensities at different observation time scales, from 5 min to 24 h, over eastern Spain from 1994 to 2007. The statistical rainfall characteristics for each time scale are analysed and the effects of specific geographical factors – altitude, aspect and distance to the sea – for each observation interval are tested. The results show that extreme intensities are heavily dependent on the time scale. There are two important turning points in this trend, at 1 h and 6 h. …
The intensity of rainfall in Mediterranean environments. Extreme values according to the scale of observation
Mediterranean environments are dominated by episodes of torrential rain, whereby the critical parameter is not so much the amount of rain these episodes accumulate, but rather the intensity they can reach. The heavy intensities that extreme events can achieve are critical in the dynamics of soil erosion; those related to triggering of debris-flow and above all in hydrology, as they affect rainfall-runoff conversion processes, runoff and coefficient thresholds and flash floods generation.
Contribution of hydrogeomorphology for mapping flood hazard in mediterranean ephemeral streams (ramblas)
Flood hazard mapping can be performed using different methods that, generally speaking, can be grouped into four main categories: historical and paleohydrological methods, hydrogeomorphological methods, hydrological-hydraulic methods, and the recently developed dendrogeomorphological methods. These groups of methods are not mutually exclusive and, in fact, they should be used complementarily. Unfortunately, in the case of ramblas, this combination is really difficult. On one hand, paleohydrological methods are not suitable for so small and torrential catchments as ramblas are and, on the other hand, hydrological-hydraulic methods demand a large amount of hydrologic data, non available in mo…
La intensidad de lluvia en entornos mediterráneos. Valores extremos según la escala de observación
Este trabajo estudia la estructura de las intensidades máximas de lluvia a diferentes escalas de observación, entre los 5 minutos y las 24 horas, en la Confederación Hidrográfica del Júcar, en base a datos del SAIH (1994-2007). Aborda además la influencia de los factores de altitud y distancia al mar, así como de la exposición del territorio: litoral-interior y compartimentación general del relieve. Los resultados muestran una gran dependencia de la intensidad en relación con la escala de observación, una influencia significativa de la distancia al mar y dos patrones de intensidad.
Using hydrogeomorphological interpretation to improve runoff-threshold estimation in mediterranean ephemeral streams (ramblas)
The runoff threshold (P0) is one of the key parameters in the study of catchment hydrological response. It is fundamental in the analysis of rainfall-runoff conversion processes, for estimating water budgets and for describing the genesis of hortonian overland flow, as it provides information on the precipitation losses within the fluvial systems, from the start of the episode until runoff is produced. There are several methods for estimating this parameter. In the case of small semiarid and Mediterranean basins, complex models are not suitable due to the specific conditions of these environments as well as the quantity of data required for the models. In these environments, empirical metho…
La interpretación geomorfológica en la cartografía de peligro de inundación
La interpretación geomorfológica de los procesos fluviales resulta fundamental para la elaboración de cartografía de peligro de inundación. Los ríos se comportan de una manera dinámica y pueden variar su topografía de una crecida a otra. Por ello, una cartografía de peligrosidad, excesivamente dependiente de modelos hidráulicos e hidrológicos, puede resultar ineficaz y quedarse obsoleta tras un suceso de alta energía. Conocer los elementos de geomorfología fluvial, así como sus procesos asociados permite una previsión a más largo plazo y una aproximación más realista al riesgo. En este trabajo se presentan ejemplos de interpretación geomorfológica de formas y procesos fluviales, en clave de…
The effect of temporal observation scale on extreme rainfall analysis
Mediterranean storms usually show high intensity and irregularity of rainfall. A single torrential event can double, even triplicate, the average annual rainfall. These features, in turn, determine rainfall-runoff conversion and other hydrological processes. As a consequence flash-floods and hydrological behaviour of ephemeral streams are dominated by these extreme events. However the internal structure of storms varies according to the time scale at which data are collected. As the observation interval is reduced, intensity becomes more significant and emphasizes the concentrated character of the precipitation. Moreover, an equivalent amount of rainfall, registered at different time scales…