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Landscape of active orogens results from a competition balance between tectonic rock uplift and erosion. Drainage divide migration is a useful approach for quantifying the landscape evolution and the underpinning drivers, because the fluvial networks adjust their geometry in response to spatiotemporal changes in rock uplift, climate and lithology. Many quantitative geomorphological metrics, such as χ-anomaly, Gilbert metrics, have been proposed to analyze the drainage divide migration. However, their interpretations often yield inconsistent results, especially in tectonically active orogens with spatial changes in rock uplift. The highly elevated and tectonically active eastern margin of the Tibetan Plateau has been studied by multiple methods of different time-scales, producing abundant structural and erosion rates determinations needed for evaluating the landscape stability and evolution. Here, we evaluated the effectiveness of χ- and Gilbert metrics in quantifying the stability of the Longmenshan-Minshan divide parallel with the plateau margin, by comparing with erosion rate data of different time scales, rock uplift predicted by upper crustal structures, bedrock lithology, precipitation. Our analyses reveal that the divide has reached dynamic steady state, as shown by the consistent cross-divide Gilbert metrics and consistent spatial changes of short, medium and long-term erosion rates, indicating the overall balance between the erosion and rock uplift. The spatial changes in rock uplift underpinned by reverse faulting along a listric upper crustal fault also explains the development of cross-divide χ-anomaly that cannot be used as an index for divide migration in regions with spatially nonuniform rock uplift. The formation of the long-term stable drainage divide in the EMTP serves as a natural laboratory for studying the divide formation and evolution in response to a phase of non-uniform rock uplift. We infer that in regions of this kind, drainage divide forms and evolves from uplift-driven to erosion-driven migration, via an intervening stable state. • The χ- and ksn-anomalies in the eastern Tibetan Plateau margin reflect differential rock uplift, rather than divide migration. • Analysis of drainage divide migration in active orogenic margins must take differential rock uplift into account. • Drainage divide forms and evolves from uplift-driven to erosion-driven migration, via an intervening stable state. [ABSTRACT FROM AUTHOR]

Drainage divides can become unstable due to tectonic disturbances and therefore can be used to constrain past tectonic activity. However, many studies have focused mainly on the influence of vertical motion with less attention on the drainage divide response to strike-slip faulting. How the drainage divide response to strike-slip faulting is still uninvestigated. Here we analyze the drainage divide stability along the Beichuan-Yingxiu Fault, an active dextral strike-slip fault with a reverse component in the Longmen Shan, on the eastern margin of the Tibetan Plateau. Based on activity of the Beichuan-Yingxiu Fault and response of the local landscape, we have identified a site in the Guixi area where a river capture event may occur in the near future, and a site in the Leigu area where a river capture event may have occurred. We used the χ-plot and Gilbert metrics methods to measure drainage divide stability at these two sites. The results show that (1) drainage divides near active strike-slip faults will be unstable before and after a capture event in response to strike-slip faulting and (2) before a capture event, the drainage divide on opposing sides of the strike-slip fault will migrate in opposite directions. This study systematically reveals the drainage divide migration generated in response to strike-slip faulting. We suggest that the drainage divide stability has the potential to be used to identify strike-slip fault activity and slip sense. • A model for drainage divide migration in response to strike-slip faulting. • Divide migration in response to strike-slip faulting in the northern Longmen Shan. • χ-plot and Gilbert metrics methods are used to reveal the drainage divide stability. • Divide migrates before and after a capture event caused by strike-slip faulting. • Divide migration can be used as evidence for strike-slip fault activity. [ABSTRACT FROM AUTHOR]