Abstract

Landscape evolution models suggest that thalweg morphometry is influenced by a combination of factors, including the rate of rock uplift, the soil erodibility, the channel geometry, the sediment properties and availability, and the climate changes. Approximately 6 Ma ago, the uppermost catchment of the El Transito river (?29°S, Central Andes) captured an intermontane basin containing thick alluvial successions dating 19 to 13 Ma. We carried out an analysis of thalweg profiles to explore morphometric changes by this intermontane basin capture. The valleys that captured this basin exhibit flat profiles, with stationary knickpoints located at the basin boundaries. We propose that the supply of alluvial gravels from the intermontane basin shielded the thalweg upstream, reducing incision, while simultaneously providing abrasive material that favored incision downstream. Our findings underscore the importance of considering the long-term influence of sedimentary deposits capture when interpreting the morphometry of arid valleys in the Central Andes. © 2025 Elsevier Ltd