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Landscape evolution models (LEMs) are essential tools for analyzing tectonic-climate interactions and reproducing landform-shaping processes. In this study we used a LEM to simulate the evolution of the mountains from the central Hexi Corridor in the northeastern Tibetan Plateau, where the climate is arid and the surface processes are relatively uniform. However, there are pronounced differences in the topography between the mountains around the central Hexi Corridor. The East Jintanan Shan, West Jintanan Shan and Heli Shan are located in the northern part of the corridor; and the Yumu Shan in the southern part. Firstly, several representative areas were selected from these mountains to analyze the topographic characteristics, including the uniform valley spacing, local relief, and the outlet number. Secondly, a LEM for these areas was constructed using the Landlab platform, and the landscape evolution was simulated. With uniform valley spacing and other topographic characteristics as the criteria, we compared the realistic and simulated terrain for different model ages. Finally, based on the similarity of the simulated and realistic terrain, we estimated the timing of the initial uplift and the uplift rate of the four mountain ranges. The results are consistent with previous geological and geomorphological records from these youthful stage mountains that have not yet reached a steady state. Our findings demonstrate that LEMs combined with topographic characteristics are a reliable means of constraining the timing of the initial uplift and the uplift rate of the youthful stage mountain. Our approach can potentially be applied to other youthful stage mountains and it may become a valuable tool in tectonic geomorphology research. [ABSTRACT FROM AUTHOR]

Abstract: The way in which the NE Tibetan Plateau uplifted and its impact on climatic change are crucial to understanding the evolution of the Tibetan Plateau and the development of the present geomorphology and climate of Central and East Asia. This paper is not a comprehensive review of current thinking but instead synthesises our past decades of work together with a number of new findings. The dating of Late Cenozoic basin sediments and the tectonic geomorphology of the NE Tibetan Plateau demonstrates that the rapid persistent rise of this plateau began ~8±1Ma followed by stepwise accelerated rise at ~3.6Ma, 2.6Ma, 1.8–1.7Ma, 1.2–0.6Ma and 0.15Ma. The Yellow River basin developed at ~1.7Ma and evolved to its present pattern through stepwise backward-expansion toward its source area in response to the stepwise uplift of the plateau. High-resolution multi-climatic proxy records from the basins and terrace sediments indicate a persistent stepwise accelerated enhancement of the East Asian winter monsoon and drying of the Asian interior coupled with the episodic tectonic uplift since ~8Ma and later also with the global cooling since ~3.2Ma, suggesting a major role for tectonic forcing of the cooling. [Copyright &y& Elsevier]

Abstract: The Yellow River (Huang He) downstream of the Jinshaan Canyon displays well-preserved fluvial terrace sequences below an extensive planation surface at the northeastern Ordos Plateau. Despite a series of well developed geomorphic surfaces, the landscape evolution of the plateau is largely unconstrained. The Jinshaan Canyon, formed by the deeply incising Yellow River through the Ordos Plateau, provides keys to understanding the landscape evolution of this Plateau with respect to the nearby northeastern margin of the Tibetan Plateau. This paper presents two sets of magnetostratigraphic results derived from the aeolian deposits (Red Clay and loess) on the planation surface and the uppermost Yellow River terrace in the middle part of the Jinshaan Canyon. Magnetostratigraphic analysis reveals that the planation surface and the uppermost Yellow River terrace formed respectively at circa 3.7Ma and circa 1.2Ma ago. The Ordos Plateau is the product of a period of planation culminating just before circa 3.7Ma and then was interrupted by an episode of uplift, which may be correlated with the accelerated growth of the Tibetan Plateau in the Miocene–Pliocene. The drainage system in the Jinshaan Canyon was re-organized around 3.7Ma. No correlation seems to exist between an older drainage existing prior to circa 3.7Ma and the present Yellow River network in the Jinshaan Canyon, even though sedimentary and tectonic evidence suggests that the drainage in the middle reach of the Yellow River formed in the late Miocene-early Pliocene. The Yellow River has developed its rectangular course around the Ordos Plateau only since circa 3.7Ma. [Copyright &y& Elsevier]

Knowledge of erosion rates through time is of great importance to understand the effects of tectonics and climate on the topographic evolution of mountain belts. In this study, we present a 10Be-based paleo-erosion record for the northern Qilian Shan (NE Tibet) during the last 4.2 Ma. This new record is based on samples from a magnetostratigraphically dated drillcore from the foreland of the northern Qilian Shan (i.e., the Hexi Corridor). The 10Be-based paleo-erosion rates obtained from the drillcore lie between ~40 and ~150 m/Ma, with the exception of two transient peaks at ~3.4 Ma (~330 m/Ma) and ~2.0 Ma (~220 m/Ma). These high values may result from transitions to a generally cooler climate with more pronounced changes between glacial and interglacial periods. Apart from these peak values, erosion rates during the period from 4.2 to 2.8 Ma are rather low (~40 to ~70 m/Ma; mean: 50 m/Ma), whereas erosion rates over the last ~1.5 Ma are higher, ranging from ~80 to ~150 m/Ma (mean: ~112 m/Ma). We attribute the slower erosion between 4.2 and 2.8 Ma to a warmer climate, with more rainfall than today, and a lower relief in the sediment-source region. These factors led to a stabilization of hillslopes and caused erosion rates to be low. Subsequently, progressive cooling, aridification, and enhanced glacial and periglacial processes reduced the vegetation cover and increased hillslope erosion. In addition, ongoing rock uplift and concomitant river incision in the Qilian Shan may have increased the local relief. These factors explain the higher erosion rates in the past ~1.5 Ma. Available evidence on tectonic boundary conditions, drainage evolution, sedimentary environment, and paleo-climate conditions suggest that the geomorphology of the northern Qilian Shan has not significantly changed over that period. • We derive a 10Be-based paleo-erosion record for the Qilian Shan over the past 4.2 Ma. • Gradual cooling and glacial processes have increased hillslope erosion after 2.8 Ma. • Low erosion rates in the Pliocene were due to a warmer climate and a lower relief. [ABSTRACT FROM AUTHOR]

• A cross-disciplinary method quantifies river biogeomorphic succession phases at the reach scale. • A trial application shows that Biogeomorphic landform ratios effectively differentiate phases of river evolution. • The approach is generic and can be used in different situations. The Fluvial Biogeomorphic Succession phase model (FBS model) differentiates Geomorphic (G), Pioneer (P), Biogeomorphic (B) and Ecological (E) phases of hydro-geophysical-biological interactions in river systems. To date, quantitative applications of this model have been restricted to field surveys of vegetation composition analysis at the patch-scale. Here we develop a biogeomorphic landform mapping approach to determine the dominant biogeomorphic succession phase at the reach scale. We categorize river morphology into four biogeomorphic landform types (G-, P-, B- and E-landforms) that have particular geomorphic, substrate and vegetation cover characteristics. Ratios of these landforms are used to calculate the dominant succession phase in a given reach. A test of this method conducted for two contrasting anabranching reaches of the Upper Yellow River indicates that landform ratios provide an efficient and reliable approach to assess river biogeomorphic succession phase. The approach can be adapted to support systematic cross-scalar analyses across the range of river environments. [ABSTRACT FROM AUTHOR]

In the piedmont of uplifting mountains, alluvial fan rivers undergo significant aggradation-degradation processes, which are usually attributed to climate change. An ongoing debate is whether this process requests the participation of glaciation. To address this debate, we need the knowledge of the quantitative relationship between the ratio of water to sediment flux (q w / q s) with the aggradation/degradation process. This study examined the aggradation and degradation processes in three alluvial rivers at the piedmont of the Qilian Shan (Shan referes to Mountain) and simulated the river processes by a one-dimensional numerical model based on the transport-limited principle. Along the studied piedmont rivers, field measurements show a magnitude of 120–200 m degradation and aggradation in the Late Pleistocene. Through simulation analysis, we explored how factors like the ratio of water to sediment flux (q w / q s), channel width, and sediment grain size influence river processes and longitudinal profiles, and found distinct morphologies in different processes, where aggradation is characterized by concave-up profiles, while degradation is characterized by convex-down profiles. Additionally, the water flux is inversely proportional to the time required for the river to reach a new equilibrium profile. The simulated degradation amplitude aligns closely with the measured data in the Qilian Shan, indicating that precipitation during the Last Glacial Maximum in the region amounted to approximately ∼32% of the Holocene precipitation. This supports the notion that changes in water flux or precipitation alone can induce significant piedmont deepening without the necessity of glaciation. • Built a model to quantify the link between water-sediment fluxes and river processes. • Simulated Qilian Shan piedmont river incision: ∼32% LGM precipitation vs. Holocene. • Precipitation alone can create deep canyons without requiring glaciation. [ABSTRACT FROM AUTHOR]