Tectonic-triggered drainage reorganizations between the two largest tributaries of the Yangtze River, China

<p>The reorganization of the drainage system is a crucial process on the Earth's surface. However, there is insufficient understanding of the process and driving mechanism of the reorganization of the mountainous drainage system. Here we demonstrate an example of tectonic subsidence-induced drainage reorganizations between the two largest tributaries (Jialing and Han) of the Yangtze River. The upstream tributaries of the Han River, flowing in parallel from north to south, undergo an abrupt eastward deflection of approximately 90° within an intermontane basin. Through river profile analysis, we identified four knickpoints with progressively younger ages towards the west, indicating successive stream captures. We reconstructed the relict river profile upstream of the knickpoint, which consistently aligns with the downstream remnant features, including wind-gaps and terraces. Combining with landscape evolution models, we reconstructed the evolutionary history between the Han and Jialing Rivers. The Jialing River was once flowing southward. Following the tectonic subsidence of the intermontane basin during the late-Miocene to Pliocene, the south-flowing streams from the catchment of the paleo-Jialing River were progressively captured by the Han River from the east along the intermontane basin. Our findings highlight that tectonic subsidence can trigger mountainous drainage reorganization. Additionally, we suggest that the processes of basin infilling, drainage integration, and positive feedback are also essential components in the evolution of mountainous drainage networks.</p>