Los ríos catalanes tienen un problema de acumulación de sedimentos/Catalonian rivers have a problem of accumulation of sediments

Investigadores catalanes han estudiado las nueve cuencas fluviales de Cataluña que desembocan en el Mediterráneo, y han analizado sus características geomorfológicas, climáticas, hidrológicas, de uso del suelo y de sedimentos. La investigación apunta que su descarga sedimentaria al mar ha disminuido en las últimas décadas por la urbanización en las cuencas fluviales, las extracciones de agua, y la retención de los embalses
Aunque es muy difícil cuantificar los factores medioambientales y antropogénicos que afectan a la descarga de sedimentos que los ríos hacen en el mar, un equipo de científicos catalanes ha recopilado datos para caracterizar y evaluar la descarga sólida de sedimentos de nueve cuencas fluviales de Cataluña: Ter, Foix, Gaia, Besós, Llobregat, Francolí, Tordera, Muga, y Fluvia. “Una tarea lenta y no exenta de dificultades”,según Miquel Canals de la Universidad de Barcelona (UB).
Las cuencas fluviales catalanas tienen “un relieve pronunciado, litologías poco resistentes a la erosión, un notable recubrimiento vegetal, y escasa precipitación”. Camino Liquete, autora principal de la investigación y doctora de la UB, afirma que estas cuencas “pueden tener unas de las descargas de agua y de sedimento más bajas de los ríos que vierten al Mediterráneo”.

Catalonian researchers have studied the nine Catalonian fluvial river basins ending at the Mediterranean, and have analyzed their geomorphological, climatic and hydrologic characteristics, as well as the use of ground and the sediments. The investigation seems to suggest that their sedimentary delivery to sea has diminished in the last decades, due to the urbanization in the fluvial river basins, the water extractions, and the retention of the dams.
Although it is very difficult to quantify the environmental factors and anthropogenic that affect the runoff of sediments from rivers to sea, a team of Catalan scientists has collected data to characterize and to evaluate the solid discharge of sediments of nine fluvial river basins of Catalonia: Ter, Foix, Gaia, Kisses, Llobregat, Francolí, Tordera, Muga, and Fluvia. “A task slow and charged of difficulties”, according to Miquel Canals of the University of Barcelona (UB).
The Catalan fluvial river basins have “a pronounced relief, lithologies with a small resistence to the erosion, a remarkable vegetal covering, and lscarce precipitations”. Camino Liquete, main author of the investigation and doctor of the UB, says that these river basins “can have one of the lower water and sediment runoffs of he rivers that spill to the Mediterranean sea”.

Más información/ More information Plataforma SINC

Resumen de la publicación/Abstract of the research paper
Liquete, Camino; Canals, Miquel; Ludwig, Wolfgang; Arnau, Pedro.
“Sediment discharge of the rivers of Catalonia, NE Spain, and the influence of human impacts” Journal of Hydrology 366(1-4): 76-88.
The environmental and anthropogenic factors controlling sediment delivery to the sea are numerous, intricate and usually difficult to quantify. Mediterranean watersheds are historically amongst the most heavily impacted by human activities in the world. This study analyzes some of these factors for nine river systems from Catalonia, NE Spain, that open into the Northwestern Mediterranean Sea, and discusses the results obtained from sediment yield models and sediment concentration data series.
General models indicate that the natural suspended sediment yield by individual catalan rivers ranged within a fork from 94 to 621 t km2 yr1. Such a sediment yield would be noticeably reduced (moving the fork to 7–148 t km2 yr1) because of lithological factors and direct anthropogenic and, possibly, climatic impacts. Damming, water extraction and urbanization appear as the most important direct anthropogenic impacts in Catalonia. Water discharge and sediment concentration measurements by basin authorities provide much lower sediment yield estimations, from 0.4 to 19.8 t km2 yr1, which is probably due to the lack of measured sediment loads during flood events, as it is the case in many other Mediterranean rivers.
The Catalan watersheds have some of the smallest runoff values amongst Mediterranean rivers. Of the nine river systems studied, water discharge tends to decrease in two and to increase in one. The other six river systems do not show any clear tendency. Related to climatic parameters, temperature raised in all the watersheds between 1961 and 1990, while precipitation did not show significant trends.