Criterios de selección y caracterización de episodios de lluvia. Aplicación a la Confederación Hidrográfica del Júcar (1989-2003)

El análisis espacio-temporal de la lluvia precisa de la identificación de episodios, en función del objetivo de la investigación y la escala de trabajo. En esta comunicación se proponen criterios de selección de episodios, con objetivos hidrológicos, y se aplican al territorio de la Confederación Hidrográfica del Júcar, en base a los datos diarios de 15 años (1989-2003), proporcionados por el Sistema Automático de Información Hidrológica. Se seleccionan 363 episodios y se caracterizan en base a indicadores de total, duración, intensidad e irregularidad, calculados en once unidades territoriales. El análisis de estos indicadores evidencia una dicotomía litoral-interior. El ámbito litoral (exceptuando Alicante) registra el mayor número de episodios, fundamentalmente en invierno, con un aporte más importante y mayor irregularidad. Por el contrario, en el ámbito de interior los episodios son de menor intensidad y mayor presencia en verano. El efecto orográfico es importante, no sólo por la altitud, sino por la orientación de las cadenas montañosas.Before analysing the variability of rainfall in space and time it is necessary to select rainfall events in relation to the objectives and scale of the study. This paper proposes criteria for selecting rainfall events, with hydrological objectives. These criteria are then applied to the territory of the River Jucar Water Authority and the daily data covering a 15 year period (1989-2003) recorded by the Automatic Hydrological Information System (SAIH). 363 events are chosen and characterised by indicators of total rainfall, duration, intensity and irregularity calculated over 11 regional units. The analysis of these indicators shows a littoral-interior dichotomy. The largest number of events were recorded near the coast (except in one region), mostly in winter, with greatest volumes and higher irregularity. In the interior the events were less intense and more frequent in summer. The orographic effect is important, not just in relation to altitude but also in relation to the orientation of the mountain ranges

Identification of Mediterranean rainfall events for hydrological analysis. Criteria and characterization

Since Mediterranean environments are characterized by the irregularity of their climate and hydrological processes where, for instance, twice or even three times the average annual rainfall can be registered in a single torrential rainfall event, hydrological studies are increasing focussing on the analysis of actual rainfall events. Criteria to define what constitutes a rainfall event are not yet clearly established in literature. Although we can find detailed, a posteriori, studies about specific torrential rainfall events related to floods in a given basin, detection of rainfall events with a hydrological meaning from daily rainfall records remains difficult and normally has been done with reference to floods events at catchment level. This paper proposes criteria for selecting rainfall events with hydrological objectives. We consider not only events that can produce major floods but also those events around the runoff generation threshold which can also produce significant contributions to the subsurface flow. These criteria have been applied to the territory of the River Júcar Water Authority (43.000 km2), using daily data recorded by the Automatic Hydrological Information System (SAIH), and covering a 15 year period (1989-2003). A total of 347 events were identified and characterised by indicators of total rainfall, duration, intensity and irregularity calculated over 11 regional units. The synoptic atmospheric situation responsible for each episode has also been taken into account in the analysis. As a result, a classification of the episodes has been obtained. The analysis shows a littoral-interior dichotomy. The largest number of events were recorded near the coast (except in one region), mostly in winter, with greatest volumes and high irregularity. In the interior the events were less intense and more frequent in summer. The orographic effect is important, not just in relation to altitude but also in relation to the orientation of the mountain ranges with respect to the wind direction

Problemàtica de les inundacions en la conca baixa del riu Gorgos.

Camarasa Belmonte, Ana - [email protected]

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 methods have demonstrated to be more effective. One of the most used models in Spain is that developed by the US Soil Conservation Service (SCS) in 1972, and modified by Témez (1978, 1991). This is a simple, easy to apply model, which uses slope values, vegetation, land use and soil hydrological group data. In spite of the generalized application of the model and its multiple adaptations, there are still many uncertainties, mainly related to the soil hydrological groups which, together with land use, are the most sensitive variables in runoff threshold estimation. These uncertainties are especially important in small semiarid basins and Mediterranean ephemeral streams where soils are generally very heterogeneous, not well developed, highly dependent on underlying rock and have been heavily exploited. In order to improve runoff threshold estimation in semiarid environments, some authors have included detailed information about soils in the model but without improving the results significantly. Others have assigned the soil hydrological group directly from lithology, without considering soil type. This paper proposes some modifications to the SCS method related to the assignation of the soil hydrological group in order to improve runoff threshold estimation in Mediterranean basins. In these environments, hydrological behavior is highly determined by the strong interaction between geomorphological structure, lithology and edaphology. These three variables are combined at basin scale, in order to assign the soil hydrological group with the aim of using hidrogeomorphological interpretation to improve runoff threshold estimation. The method has been applied, using GIS, to several small basins located in the Mediterranean Spanish region. Although the estimation of runoff threshold using a GIS is a process which can be easily automated, the proposed modification requires the expert geomorphological knowledge of the catchment. Runoff thresholds obtained with this method are presented here. Although the results have to be checked with runoff threshold data obtained by water budget, so far they are consistent with the expected values for the study area from literature references

Análisis mediante SIG de los parámetros de producción de escorrentía

El umbral de escorrentía (P0) constituye uno de los parámetros clave en el estudio de la respuesta hidrológica de una cuenca. Resulta fundamental para el estudio de episodios y hace referencia a las pérdidas de precipitación, que tienen lugar en el sistema fluvial, desde el inicio del mismo hasta que se produce escorrentía. Uno de los métodos más usado para la estimación de este umbral es el desarrollado por el US Soil Conservation Service –SCS- (1972). Este método utiliza, entre otros, valores de pendiente, vegetación, usos del suelo y características hidrológicas del suelo. Aunque los valores de las tablas originales han sido modificados para el caso español por Témez, la experiencia demuestra que, en ambientes de rambla, se necesita una mayor adaptación, dada la especificidad del entorno morfoclimático. Este trabajo propone algunas modificaciones al método para mejorar la estimación del umbral de escorrentía en ramblas mediterráneas. Se presenta una aproximación, mediante SIG, al cálculo del P0 en el Bco de Carraixet, incluyendo el análisis de las características hidrogeomorfológicas de la cuenca para la estimación de la infiltración del suelo. Además, la estimación del parámetro en varias fechas permite un estudio diacrónico, que pone de manifiesto la evolución espacio-temporal de la producción de escorrentía, en función de los cambios en el uso del suelo

Anticancerosos potenciales : síntesis de nucleósidos alquilantes derivados de triazoles

Tesis - Universidad Complutense de Madrid, 1982.Depto. de Química OrgánicaFac. de Ciencias QuímicasTRUEProQuestpu

Anticancerosos potenciales : síntesis de nucleósidos alquilantes derivados de triazoles

Tesis - Universidad Complutense de Madrid, 1982.Depto. de Química OrgánicaFac. de Ciencias QuímicasTRUEProQuestpu

The effect of observation timescales on the characterisation of extreme Mediterranean precipitation

This paper analyses the behaviour of five rainfall indicators (maximum intensity, cumulative rainfall, irregularity, probability of rain and persistence of rain) over different observation timescales ranging from 5 min to 24 h. It covers a large area on the Mediterranean side of the Iberian Peninsula (River J´ucar Water Authority, 43 000 km2) on a continuous basis over a period of 14 years (19942007). The results show that the behaviour of extreme Mediterranean rainfall is heavily dependent on the observation timescale. There are a number of turning points in the indicator trends which occur on different timescales (1 and 6 h in the case of rain intensity and irregularity, 6 h for cumulative rainfall and between 15 and 30 min for the persistence of rain) and may be relevant for the determination of thresholds used in wáter management

Cartografía de vulnerabilidad frente a inundaciones en llanos mediterráneos. Caso de estudio del Barranc de Carraixet y Rambla de Poyo

Este trabajo aborda la cartografía de vulnerabilidad frente a inundaciones, en dos pequeños llanos mediterráneos pertenecientes al Barranc de Carraixet y la Rambla de Poyo. Ambos forman parte del Área Metropolitana de Valencia, integrando las comarcas de l"Horta Nord y l"Horta Sud, respectivamente. Constituye un ensayo metodológico, basado en estimadores socioeconómicos sencillos, obtenidos a partir de los usos del suelo. La vulnerabilidad se evalúa en función del valor económico del suelo y de la exposición humana al peligro. El valor económico del suelo se calcula a partir del Catastro. La exposición se calcula para tres supuestos de densidad de ocupación del espacio en función de la franja horaria: jornada laboral, noches y días festivos. Los resultados ponen de manifiesto dos patrones de vulnerabilidad diferentes para cada llano. La vulnerabilidad en el de Carraixet es mayor por la noche y en los días festivos que durante las jornadas laborales, en relación con los usos agrícolas y residenciales dominantes. En Poyo no existen grandes contrastes en términos absolutos, entre el día y la noche, si bien resultan evidentes las diferencias en la ubicación de los espacios vulnerables, que durante el día están asociados a polígonos industriales y comerciales (en torno a los ejes de comunicación), y, por la noche, se limitan a las áreas residenciales. This paper considers vulnerability to flooding in the two small Mediterranean flood plains of the Barranc de Carraixet and Rambla de Poyo catchments. Both plains form part of the Metropolitan Area of Valencia within the Horta Nord and Horta Sud districts respectively. The work presented constitutes a test of a methodology based on simple socioeconomic estimators obtained from land uses. The vulnerability is evaluated as a function of the economic land value and human exposure to hazard. The land value is taken from the Cadastre whilst the exposure is calculated for three models for the intensity of use related to different time periods: working hours, days, nights, and weekends and holidays. The results show different patterns of vulnerability for each plain. The vulnerability in the Carraixet is greater at night and on weekends and holidays than during working hours, related to the dominant agricultural and residential land uses. In the Poyo plain there are no major contrasts in absolute terms between day and night time, although shifts in the locations of vulnerable spaces were evident: during the day vulnerability is higher in industrial and commercial areas (around communication routes) whilst at night it is the residential areas that are vulnerable

Cambios en los usos del suelo y producción de escorrentía en ramblas mediterráneas: Carraixet y Poyo (1956-1998)

[email protected] [email protected] trabajo analiza el efecto de los cambios recientes en los usos del suelo en la génesis de escorrentía en ramblas mediterráneas utilizando un SIG. Para el cálculo de la producción de escorrentía se ha utilizado el método desarrollado por el S.C.S. modificado por Témez (1978) que combina los mapas de pendientes, usos del suelo y grupo hidrológico del suelo. Se ha aplicado una adaptación del método propuesta por Camarasa et al. (2006) basado en la interpretación hidrogeomorfológica de la cuenca para la estimación del grupo hidrológico de suelo. Los resultados muestran una variabilidad espacial y temporal importante en la dinámica de producción de escorrentía, de forma que los valores promedio obtenidos para el conjunto de una cuenca enmascaran comportamientos diferentes según los sectores y dependiendo del período de tiempo.This paper attempts to determine the influence of recent land use changes on runoff production in Mediterranean ephemeral streams by means of GIS. The runoff threshold has been estimated by the US Soil Conservation Service method (1972) modified by Témez (1978) which combines values of slope, vegetation, land use and hydrological soil type. The method has been adapted by Camarasa et al. (2006) to estimate the hydrological soil type from the hydrogeomorphological characteristics of the catchment. The results show a very high spatial and temporal variability in runoff production. Overall values calculated for a catchment are not good indicators because they hide changes occurring in different sectors and tendencies that changes in periods of time