How the strong segmentation of cascade reservoir dams and the spatiotemporal changes of sediment interception volume affect the river morphology adjustment in the reservoir area is a scientific issue worthy of exploration. This study aims to reveal the adjustment mechanism of the longitudinal profile of the thalweg in cascade reservoirs. Taking the Xiangjiaba and Xiluodu reservoirs in the lower Jinsha River as research objects, based on the multi-period observation data of the thalweg elevation in the reservoir sections before and after dam construction, relevant methods of statistics, geomorphology, and sedimentology are used to analyze the change characteristics of the measured curve, trend curve, and theoretical fitting curve of the longitudinal profile of the thalweg. Two types of adjustment modes of the longitudinal profile of cascade reservoirs are revealed: concave curve type and convex curve type. The former is characterized by slight scouring and silting of the riverbed→rapid aggradation in the upstream section of the reservoir area after the dam has closed→slow aggradation in the entire reservoir area. This is the commonality of reservoirs built earlier and relatively located downstream (such as the Xiangjiaba Reservoir). The latter is characterized by the adjustment of the longitudinal profile from a straight line (or concave curve) with slight scouring and silting of the riverbed → a convex curve type with strong siltation after the dam has completed. This is the characteristic of reservoirs built later and relatively located upstream (such as the Xiluodu Reservoir). The adjustment of the longitudinal profile of cascade reservoirs is controlled by the spatiotemporal changes of sediment deposition volume and sedimentation rate in the reservoir area. The hydrodynamic gradient and alternating changes of regulation mode affect the spatial heterogeneity of sedimentation rate. The research results are helpful for understanding the adjustment mechanism of the longitudinal profile of cascade reservoirs in similar areas and play a guiding role in predicting the adjustment trend of the longitudinal profile of cascade reservoirs without observation data.

The formation and evolution of rivers are closely related to the regional environment and human activities. The Hongshui River is located in the middle reaches of the Shiyang River Basin, which is an important area for the study of environmental changes and paleocultural evolution in Northwest China. Based on five consecutively collected profiles along the Hongshui River, combined with historical geographic data and TraCE-21ka simulation, this study investigates the natural and human factors in the formation and evolution of the Hongshui River during the Late Holocene. Besides, this study reveals the hydrodynamic change process of the Hongshui River during the Late Holocene by analyzing the grain size distribution characteristics of the typical lake-phase layers in the profiles HSH01, HSH04 and HSH05. It is found that: In the Late Holocene Northwest China showed an aridization trend, the ancient Wushi Lake completely shrunk in 2000 a BP, and the modern channel of the Hongshui River began to be formed by downcutting. In order to strengthen the control of the Hexi Corridor, the strong central dynasties of the Han, Tang, Ming and Qing adopted the policy of "Tuentian Border Policy" and emphasized the construction of water conservancy facilities, which led to the rapid development of agriculture in the Hongshui River Basin. The proliferation of water use for agriculture led to further reductions in the flow of the Hongshui River. The Hongshui River Basin had a complex sedimentary environment and variable sedimentary phases in Late Holocene, and heavy precipitation events or floods may have occurred in the Hongshui River Basin since 2 ka BP.

The Dadu River and the Upper Minjiang River are located on the eastern margin of the Tibetan Plateau, where the active coupling of internal and external dynamics causes the occurrence and sudden formation of massive landslide disasters and river damming events. Numerous researchers have analyzed the local river reaches for single landslide damming events. Building on this foundation, this study uses remote sensing interpretation, field verification, and topographic data to systematically investigate landslide damming events in the Dadu and Upper Minjiang rivers in the mountainous region on the eastern margin of the Tibetan Plateau. The results identify 226 paleolandslide damming events, with 135 in the Minjiang River Basin and 91 in the Dadu River Basin. Of these, 9 are small, 41 are medium, 69 are large, 94 are super large, and 13 are giant events. The heights of the landslide dams range from 4 to 404 m, with the number of dams decreasing as height increases (75% of the dam heights are less than 100 m). The volume distribution of the landslides ranges from 1.8×10⁴ to 7.3×10⁸ m³. The backwater area of the dam lakes ranges from 3.8×10² to 6.0×10⁷ m², with volumes ranging from 5.2×10³ to 8.6×10⁹ m³. Dam height correlates positively with both landslide dam volume and lake volume, with R² values of 0.72 and 0.85, respectively. This result indicates that dam height significantly affects the scale of river damming by landslides in this study area. In addition, the backwater area correlates positively with lake volume, with R² = 0.95. Approximately 94% of the landslide dams were located in unstable regions, and about 59% of the peak discharge of landslide outburst floods are greater than that of the maximum rainstorm flood. The impact of outburst floods cannot be ignored in establishing flood-control standards. These research results clarify the distribution and characteristics of landslide dams in this study area and lay the foundation for predicting future landslide damming events.

Subterranean rodent excavation activities constitute one of the factors influencing soil redistribution and erosion on hillslopes. Investigating these activities in depth contributes to a better understanding of the complex mechanisms of soil erosion. To explore the spatial distribution characteristics of subterranean rodent excavation activities and their impact on soil erosion in the Loess Plateau, this study conducted six months of fixed-point repeated monitoring on a typical hillslope (665 m²) in Pingdingshan, Huanxian county, located in the central part of the Loess Plateau. Utilizing unmanned aerial vehicle (UAV) surveying combined with field investigations, the study tracked the spatial distribution of subterranean rodent excavation activities, analyzed their effects on soil properties, and quantified the soil erosion generated by excavation activities on the study hillslope. The results indicate that: (1) Subterranean rodents exhibit a preference for feeding and burrowing activities in areas with gentle slopes, dispersed flow, and convex slope regions. (2) Excavation activities decrease the bulk density of fresh soil mounds by 14% (P < 0.05) compared to undisturbed soil, while porosity and saturated hydraulic conductivity increase by 11% (P < 0.05). (3) Over the observation period, subterranean rodent excavation activities overturned 0.13 t of soil onto the surface, with an associated slope transport flux of approximately 2.18 cm³/(cm·a). If all these fluxes were converted into soil erosion, the erosion modulus would be approximately 397 t/(km²·a). These results highlight the significant role of excavation activities in soil redistribution on hillslopes of the Loess Plateau, contributing to approximately 10.1% of the total soil erosion, which warrants attention in future assessments and modeling of soil erosion and loss.