Tectonic and/or climatic perturbations can drive drainage adjustment. The capture events, significantly changing the river network topology, are the major events in river network evolution. While they could be identified through field observations and provenance analysis, reconstructing this evolution process and pinpointing the capture time remain challenging. Following a capture event, the steady-state elevation of the captor river will be much lower than that of the beheaded river. Then, the newly-formed drainage divide will migrate towards the beheaded river, a process also known as river-channel reversal. The migration of the newly-formed drainage divide provides a new perspective for identifying the reorganization of the river network. Here, we employ numerical modeling to reproduce the characteristic phenomena of drainage-divide migration following capture events and analyze the effects of different parameters on the migration rate. We find that (1) the migration of newly-formed drainage divides can last for tens of millions of years, with the migration rate decreasing exponentially over time; (2) larger captured area, higher uplift rate, and lower erosional coefficient, all of which cause a higher cross-divide difference in steady-state elevation, will cause higher migration rate of the newly-formed drainage divide. This insight was further applied to the Dadu-Anning and Yarlung-Yigong capture events. We predict the present Dadu-Anning drainage divide would further migrate ~65–92 km southward to reach a steady state in tens of millions of years. The Yarlung-Yigong capture event occurred in the early-middle Cenozoic, which implies that the late-Cenozoic increased exhumation rate is not related to the capture event.

Mechanism for fault segmentation in thrust belt is a key to understanding the orogenic process and seismic risks. A ~50 km long aftershock gap emerged between the ruptures of the 2008 Wenchuan and the 2013 Lushan earthquakes along the eastern margin of the Tibetan Plateau. Previous studies suggested that weak materials under ductile deformation cause the gap. Here we propose an alternative explanation: differential erosion drives the along-strike variation in fault activity. To testify the two competing models, we conducted low-temperature thermochronology and fluvial shear stress analyses to depict the spatial distributions of erosion. We obtained eight apatite fission track dates (6-44 Ma) in the gap and deduced erosion rates of 0.5-0.6 mm/yr and 0.3-0.4 mm/yr since ~8 Ma in the hanging -wall and footwall of the Shuangshi-Dachuan fault, respectively. We carried out linear fitting based on an empirical relationship between thermochronology-derived erosion rate and fluvial shear stress, and then calculated the erosion rate for each survey point of fluvial shear stress. Our new data reveal that in the hinterland, the erosion rate at the gap is lower than that of adjacent areas along strike, whereas in the range front, the erosion rate at the gap is greater. This spatial pattern supports the “differential erosion” hypothesis and is at odds with the “weak material” model. This study illustrates that heterogeneous erosion regulates fault segmentation in this thrust belt. Moreover, the aftershock gap acts as a barrier for the past major earthquakes, which poses substantial seismic potential to this region.