Abstract. Intracontinental endorheic basins are key elements of source-to-sink systems as they preserve sediments eroded from surrounding catchments. Drainage reorganization in such a basin has strong implications on the sediment routing system and on the landscape evolution at a cratonic scale. The Ebro and Duero basins in the north Iberian plate represent two foreland basins, which were filled in relation with the growing of surrounding compressional orogens as the Pyrenees and the Cantabrian mountains to the north, the Iberian and Central Ranges to the south, and the Catalan Coastal Range to the east. They were once connected as endorheic basins in the Early Oligocene. By the end of the Miocene, they were disconnected and started to flow into the Mediterranean Sea and the Atlantic Ocean, respectively, in a post-orogenic context. Although these two hydrographic basins recorded similar histories, they are characterized by very different morphologic features. The Ebro basin is highly excavated, whereas the Duero basin is well preserved and may be considered as almost still endorheic. These two bordering basins then show contrasting preservation states of their endorheic stages and represent an ideal natural laboratory to study what factors (internal / external) control drainage divide mobility, and drainage network and landscape evolution in post-orogenic basins. To that aim, we use field and map observations and we apply the Chi-analysis of river profiles across the divide along the boundary between the Ebro and Duero drainage basins in the Northern Iberian Peninsula to evaluate the migration of their divide. We show here that contrasting excavation of the Ebro and Duero basins drives a reorganization of their drainage network through a series of captures and resulted in the southwestward migration of their main drainage divide. Fluvial captures have strong impact on drainage areas, fluxes, and so on incision capacity, especially for the captured basin. Thus, we conclude that drainage reorganization, and capture of the Duero rivers by the Ebro ones, independently from tectonics and climate, enable endorheism in the Duero basin due to drainage area loss.
The mobility of Atlantic baric depressions leading to intense precipitation over Italy: a preliminary statistical analysis
