Estudio hidrológico de la cuenca del río Isábena (Pirineos, España). II: respuesta hidrológica

Abstract

Se analiza la respuesta hidrológica de la cuenca y las subcuencas del río lsábena (Cuenca del Ebro, Pre-Pirineo). Los datos de partida los proporcionan un estudio pluviométrico de detalle y las medidas de caudal en el periodo abril 2000 - abril 2002. La modelización hidrológica se ha realizado mediante el modelo del Número de Curva calibrado. Los resultados indican una estacionalldad marcada de las crecidas, con máxlmos en otoño y primavera. las subcuencas de la parte alta aportaron el 80% de la escorrentía durante crecidas (60% desde la subcuenca de Cabecera y 20% desde la de Villacarli). En eventos tormentosos locales y convectivos los aportes máximos se desplazaron hacia el tramo medio, concretamente hacia las subcuencas de Vlllacarll y Carrasquero. las cuencas septentrionales presen­taron tiempos base superiores a 10 horas y coeficientes de escorrentía del 15%, mientras que en las subcuencas de la parte media los valores fueron de 8 h y del 4%, respectivamente. El estudio constata que la modelización hidrológica con el método del Número de Curva conlleva notables errores en estudios de crecidas de bajo periodo de retorno y que resulta de vital importancia calibrar alguno de sus parámetros con medidas de campo, como por ejemplo el caudal pico.

The sediment budget of a highly dynamic mesoscale catchment: The River Isábena

“…Cabecera, as the largest subbasin draining the headwaters of the Isábena, experienced the highest Q, with a maximum recorded value of 63 m 3 s − 1 . The Q at Capella is mainly controlled by the input from Cabecera that, on average, yielded 68% of the runoff of the entire catchment (very similar to values reported by Verdú et al, 2007b). The irregular distribution of rainfall and the different runoff responses were reflected in the occurrence of floods at each of the subcatchments (21 flood events occurred in Cabecera, 24 occurred in Carrasquero, 31 in Ceguera, and 33 floods in Lascuarre).…”

“…These values are considered as moderately dry compared to the long-term mean water yield (i.e., 177 hm 3 y − 1 for the period 1945-2008) but are averaged in relation to those obtained during the monitoring period in the Isábena (121 hm At the subbasin scale, and confirming the results obtained by Verdú et al (2007b), clearly Cabecera controls the hydrology of the Isábena basin while Villacarli and Lascuarre contribute most of the SSL, as we will present later. Carrasquero and Ceguera yielded low water and SSL (Table 4).…”

“…Mean temperature varies from 11°C to 14°C in the southern part and between 9°C and 11°C in the northern zone, again reflecting a strong south-north gradient (Verdú et al, 2007b). Vegetation is mainly composed of deciduous woodland, agriculture, pasture, and bushes in the valley bottoms with evergreen oaks, pines, and bushes on higher ground.…”

Suspended sediment transport in a highly erodible catchment: The River Isábena (Southern Pyrenees)

“…In its lower part, the basin is mainly composed of Cretaceous chalks together with Tertiary clay rocks and conglomerates. From a geomorphologic point of view, active incision/accretion processes have not been observed in the main watercourses during the last 10 years (Verdú et al, 2006b), so the more contemporary active geomorphologic processes are mass movements and, especially, fluvial erosion on slopes and in the badlands. The soils of the Isábena basin are rather thin and developed over calcilutites, limestones, sandstones, and conglomerates; they can be classified as Xerorthents (Soil Survey Staff, 1996), with silt loam texture and low organic content (b2%).…”

Flood‐based analysis of high‐magnitude sediment transport using a non‐parametric method

“…Discharge at Capella (i.e. the catchment outlet) is quantitatively mainly controlled by the behaviour of Cabecera, which, on average, yielded twothirds of the runoff of the entire catchment, while Villacarli only represents one-fifth (Verdú et al, 2006b). The delay of the onset of the floods at Capella when compared with Villacarli varied greatly and even preceded the latter for some cases, showing the effect of small downstream flashy tributaries and heterogeneous rainfall distribution.…”