RT info:eu-repo/semantics/article T1 Sediment organization and adjustment in a torrential reach of the upper Ijuez river, central Spanish Pyrenees T2 Organización y ajuste de sedimentos en un tramo torrencial de la cabecera del río Ijuez, Pirineo central español A1 Gómez Villar, Amelia A1 Sanjuán, Yasmina A1 García Ruiz, José María A1 Nadal Romero, María Estela A1 Álvarez Martínez, Javier A1 Arnáez Vadillo, José A1 Serrano Muela, María Pilar K1 Naturaleza - España - Pirineos K1 Pirineos (España y Francia) - Geografía K1 Sedimentos (Geología) - España K1 Ríos - Huesca K1 Hidrografía - España - Pirineos K1 2505 Geografía K1 2506 Geología AB The dynamics of the torrential upper reach of the Ijuez River, Central Spanish Pyrenees, was analyzed in relation to the spatial organization of grain size. The reach is located in the Eocene flysch, which usually acts as a high sediment production area, particularly during periods of intense human activity. The Ijuez Valley was cultivated and densely populated until the middle of the 20th century, resulting in general deforestation and the development of debris flows, shallow landslides, sheet wash erosion and deep gullies. As a consequence, the alluvial plain became characterized by the presence of large quantities of coarse sediment. The spatial organization of sediment showed a progressive downstream decline in the cobble and boulder size, especially in the channel, whereas the remainder of the alluvial plain showed large variability. No trend in the occurrence of the largest boulders was evident throughout the reach, confirming the importance of debris and hyperconcentrated flows in sediment transport. The torrential reach did not have a negative exponential longitudinal profile, in contrast to that usually observed for mountain rivers. This was attributed to the large quantity of heterometric sediment derived from the hillslopes, which resulted in no marked decline in sediment size and consequent change in the longitudinal profile. A recent trend of scouring was detected, reflecting the reduction in sediment supply following farmland abandonment and reforestation, which have reduced connectivity between the hillslopes and the channel. PB Universidad de La Rioja SN 0211-6820 YR 2014 FD 2014 LK https://uvadoc.uva.es/handle/10324/55917 UL https://uvadoc.uva.es/handle/10324/55917 LA eng NO Cuadernos de investigación geográfica: Geographical Research Letters, Nº 40, 1, 2014 (Ejemplar dedicado a: Geomorfología Fluvial / Fluvial geomorphology), págs. 191-214 NO Producción Científica DS UVaDOC RD 26-dic-2024