Debris flow gullies have high potential energy and geomorphic characteristics including a steep longitudinal slope and abundant loose material sources. They often experience debris flow with a strong impact force and a large instantaneous flow. Drainage engineering measures are most commonly used for mitigation in these gullies. However, the abrasion of drainage channels with large gradients (DCLG) is complex and strong because of the high-speed flushing of debris. In this study, the abrasion behavior of debris flow in DCLG is analyzed based on the kinematic characteristics and the theory of composite abrasive wear. Energy dissipation and anti-wear measures are suggested, and their effects are summarized with reference to a case study and in situ observation. The results show that there are four main types of wear morphology in drainage channels. The abrasion system of drainage channels shows the characteristics of system dependency, time dependency and multidisciplinary coupling. Energy dissipation and anti-wear measures include prefabricated reinforced concrete boxes as substrate, transverse roughening belts, adding a wear-resistant admixture, etc. The flow velocity of the debris flow is reduced by 5.7–37.1% after passing through the energy dissipation section. The distribution of abrasion and the mud depth show that the variation trend of the flow velocity in the channel is ”acceleration → deceleration → reacceleration“. According to tracking observations during two flood seasons, the energy dissipation and anti-wear measures are the most effective.

《地球科学》(ISSN 1000-2383;CN42-1874/P) (原刊名《地球科学——中国地质大学学报》ISSN 1000-2383;CN42-1233/P)，创刊于1957年，是由教育部主管、中国地质大学主办的综合性地学学术理论期刊，月刊，2015年改名为《地球科学》,她以反映中国地质大学教学与科研最新的、高水平的基础地质、应用地质、资源与环境地质及地学工程技术研究成果为主要任务。

Understanding the damage mechanism of glacial debris flow mitigation systems is crucial for the risk prevention and assessment of the 200 km traffic corridor in the Southeast of the Tibetan Plateau, where the Sichuan-Tibet railway and expressway have been planned. Based on the phenomena, position and residual efficiency of damaged engineering, our analysis of satellite imagery and field investigation in multitype spatial reveals the damage types and influencing factors of glacial debris flow mitigation engineering. An evaluation model which can be used to estimate the engineering damage grade is established by using the relationship between mono engineering works and mitigation systems. In the new model, the engineering damage is divided into five grades: undamaged, slightly damaged, relatively damaged, seriously damaged, and totally damaged. For glacial debris flow in the Parlung river basin, the five grades of damage of mitigation works account for 8.70%, 34.78%, 21.74%, 13.04% and 21.74%, respectively. Furthermore, the soil source type and channel profile gradient are the key factors in engineering damage. Design defect of profile gradient is the controlling factor of damage in drainage channel engineering. Based on those results, an engineering damage model is established, which can provide an important reference for risk reduction and prevention of hazards due to the increasing development of traffic engineering.

Channel erosion and sediment entrainment amplify rainstorm-triggered debris flows, but their interaction with topographic constraints remains poorly quantified. To reveal the controlling mechanism of erosion amplification on the disaster-forming process of rainstorm-type debris flows, using the 2016 Zhangba Xiaosha River event in Yunnan, China, we reconstructed debris-flow motion, erosion, and deposition with RAMMS::DEBRISFLOW. Five bed-erosion scenarios (0, 0.25, 0.50, 0.75 and 1.0 m) were used to assess changes in deposit thickness, runout, velocity, impact pressure, and volume amplification. The 1.0 m baseline scenario successfully reproduced the observed path, depositional extent, and representative deposit thickness. Increasing the equivalent erosion depth from 0 to 1.0 m increased the total debris-flow volume from 2.0 × 10⁴ to 4.27 × 10⁴ m³, yielding an amplification factor of 2.14; without erosion, maximum runout was 44.2% shorter. Along-channel erosion supply increases the mass, flow depth and momentum of the moving mass, forming an amplification chain of “sediment supply−scale amplification−momentum maintenance−frontal propagation”. Feedback may exist between actual erosion intensity, flow velocity and flow depth, but the equivalent erosion depth in RAMMS scenarios in this study is a predefined parameter. Topography exerted reach-specific controls: steep upstream channels promoted initiation and acceleration, the middle reach dominated erosional bulking, and the wider, gentler downstream reach enhanced dissipation and deposition. Within the erosion scenarios of 0.75–1.0 m set in this study, when the equivalent erosion depth increased further, the newly entrained sediment mainly increased deposit thickness and inundation extent, while the increment of maximum runout distance was limited. The event disaster scale resulted from coupled erosion-induced amplification and longitudinal topographic constraints. Hazard assessments should integrate initial initiation volume, erodible channel sediment, and local reach-scale topography.

The Yizhong River Basin, located in an alpine gorge on the southeastern Tibetan Plateau, experiences recurrent landslide-derived debris flows originating from moraine-covered source areas. This study integrates unmanned aerial vehicle (UAV)-based geomorphic interpretation, field geological profiling, laboratory direct shear tests, rainfall analysis, and sequential SEEP/W–FLAC3D modeling to examine source-area preconditioning and rainfall-related slope response. Present-day UAV-derived profiles and field observations support a two-layer configuration in which unconsolidated moraine deposits overlie fractured bedrock and are consistent with an inferred sequence of headward incision, gully deepening, and lateral expansion; this sequence is interpreted conceptually rather than as a chronologically resolved reconstruction. The moraine cover represents a substantial high-elevation sediment source, with an approximate potential volume on the order of 3.9 × 10⁵ m³. Laboratory wetting from the natural state (6.3% water content) to a controlled wet state (16.8%) reduced cohesion from 24.5 to 15.3 kPa and the internal friction angle from 30.2° to 26.4°. Under an idealized 8 h equal-total rainfall scenario, the sequential seepage–stability model yielded a factor-of-safety decrease from 1.33 to 0.92 and a maximum downward displacement of 22.3 cm, with deformation concentrated near the mapped collapse–slide zone. The recurrent activity is therefore interpreted as a feedback pathway linking moraine-slope instability, gully erosion, sediment recharge, and renewed failure. The results provide a case-based assessment of how moraine–bedrock preconditioning and rainfall-related weakening may jointly contribute to recurrent source-area instability, highlighting the combined roles of geological structure, sediment supply, and hydrological weakening in debris-flow initiation and recurrence.