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Journal of Geographical Sciences 2024年第6期34卷 1157-1173页

作者： LI Hao LIU Shuang hu kaiheng ZHANG Xiaopeng State Key Laboratory of Mountain Hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentCASChengdu 610299China University of Chinese Academy of Sciences Beijing 100049China

Glaciers in the Yarlung Zangbo Downstream Basin(YZDB) are sensitive to global climate change. The equilibrium-line altitude(ELA) is a key indicator of glacial development.Current models for simulating the meteorological ELA underestimate the extent of glacial advance during the Last Glacial Maximum(LGM) in the YZDB and cannot explain the large-scale glacial extension compared with the Yarlung Zangbo Midstream Basin(YZMB). In this study, the distribution of ELA in the LGM is reconstructed using high-resolution 80-km ECHAM5 simulations and empirical relationships between temperature and precipitation.Changes in ELA between the LGM and pre-industrial era(PI) are compared. Our simulated ELA closely fits the published field data. In the YZDB, simulated LGM ELAs range from ca.3500 m to over 4900 m, representing declines of ca. 300–950 m. The ECHAM5 simulations better reflect the complex topographic features than most coarse-resolution climate models,and the ELA distribution is controlled by the spatial arrangement of river valley systems and mountain ranges and their impact on precipitation. Compared with the PI era, most of the monsoon precipitation in the LGM was concentrated in the YZDB, which is the main driver of glacial extension and the differential response of the downstream and midstream basins.

关键词： glacier extension glacier equilibrium-line altitudes Yarlung Zangbo Downstream Basin southeastern Tibetan Plateau high-resolution paleoclimate simulations

Evaluation of rainfall threshold models for debris flow initiation in the Jiangjia Gully,Yunnan Province,China

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Journal of Mountain Science 2024年第6期21卷 1799-1813页

作者： YANG Hongjuan ZHANG Shaojie hu kaiheng WEI Fangqiang LIU Yanhui State Key Laboratory of Mountain Hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China Chongqing School University of Chinese Academy of SciencesChongqing 400714China China Institute of Geo-Environment Monitoring Beijing 100081China

Systematically determining the discriminatory power of various rainfall properties and their combinations in identifying debris flow occurrence is crucial for early warning systems.In this study,we evaluated the discriminatory power of different univariate and multivariate rainfall threshold models in identifying triggering conditions of debris flow in the Jiangjia Gully,Yunnan Province,China.The univariate models used single rainfall properties as indicators,including total rainfall(R_(tot)),rainfall duration(D),mean intensity(I_(mean)),absolute energy(Eabs),storm kinetic energy(E_(s)),antecedent rainfall(R_(a)),and maximum rainfall intensity over various durations(I_(max_dur)).The evaluation reveals that the I_(max_dur)and Eabs models have the best performance,followed by the E_(s),R_(tot),and I_(mean)models,while the D and R_(a)models have poor performances.Specifically,the I_(max_dur)model has the highest performance metrics at a 40-min duration.We used logistic regression to combine at least two rainfall properties to establish multivariate threshold models.The results show that adding D or R_(a)to the models dominated by Eabs,E_(s),R_(tot),or I_(mean)generally improve their performances,specifically when D is combined with I_(mean)or when R_(a)is combined with Eabs or E_(s).Including R_(a)in the I_(max_dur)model,it performs better than the univariate I_(max_dur)model.A power-law relationship between I_(max_dur)and R_(a)or between Eabs and R_(a)has better performance than the traditional I_(mean)–D model,while the performance of the E_(s)–R_(a)model is moderate.Our evaluation reemphasizes the important role of the maximum intensity over short durations in debris flow occurrence.It also highlights the importance of systematically investigating the role of R_(a)in establishing rainfall thresholds for triggering debris flow.Given the regional variations in rainfall patterns worldwide,it is necessary to evaluate the findings of this study across diverse watersheds.

关键词： Rainfall threshold Logistic regression Maximum rainfall intensity Absolute energy Antecedent rainfall

Quantifying the impact of earthquakes and geological factors on spatial heterogeneity of debris-flow prone areas:A case study in the Hengduan Mountains

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Journal of Mountain Science 2024年第5期21卷 1522-1533页

作者： hu Xudong SHEN Yitong hu kaiheng XU Wennian LIU Daxiang HE Songtang GAO Jiazhen WEI Li LIU Shuang hubei Provincial Engineering Research Center of Slope Habitat Construction Technique Using Cement-based Materials(China Three Gorges University) Yichang 443002China hubei Key Laboratory of Disaster Prevention and Mitigation(China Three Gorges University) Yichang 443002China College of Civil Engineering and Architecture China Three Gorges UniversityYichang 443002China Shanghai Investigation Design&Research Institute Co.Ltd.Shanghai 200335China Key Laboratory of Mountain Hazards and Earth Surface Processes Chinese Academy of SciencesChengdu 610041China Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Wuhan Polytechnic Wuhan 430074China

Understanding the spatial heterogeneity of debris-flow-prone areas holds significant implications for regional risk management, particularly in seismically active regions with geological faults. Despite the significance of this knowledge, a comprehensive quantification of the influence of regional topographical and geological factors on the spatial heterogeneity of debris-flow-prone areas has been lacking. This study selected the Hengduan Mountains, an earthquake-prone region characterized by diverse surface conditions and complex landforms, as a representative study area. An improved units zoning and objective factors identification methodology was employed in earthquake and fault analysis to assess the impact of seismic activity and geological factors on spatial heterogeneity of debrisflow prone areas. Results showed that the application of GIS technology with hydrodynamic intensity and geographical units analysis can effectively analyze debris-flow prone areas. Meanwhile, earthquake and fault zones obviously increase the density of debrisflow prone catchments and make them unevenly distributed. The number of debris-flow prone areas shows a nonlinear variation with the gradual increase of geomorphic factor value. Specifically, the area with 1000 m-2500 m elevation difference, 25°-30° average slope, and 0.13-0.15 land use index is the most favorable conditions for debris-flow occurrence;The average annual rainfall from 600 to 1150 mm and landslides gradient from 16° to 35° are the main causal factors to trigger debris flow. Our study sheds light on the quantification of spatial heterogeneity in debris flow-prone areas in earthquake-prone regions, which can offer crucial support for post-debris flow risk management strategies.

关键词： debris-flow prone areas causal factors GIS-based method spatial heterogeneity Hengduan Mountains

Hydro-climatic Characteristics of Yarlung Zangbo River Basin since the Last Glacial Maximum

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Advances in Atmospheric Sciences 2022年第3期39卷 415-426页

作者： Shuang LIU kaiheng hu Weiming LIU Paul A.CARLING Institute of Mountain Hazards and Environment Chinese Academy of SciencesChengdu 610041China Geography&Environment University of SouthamptonHighfieldSouthamptonSO171BJUK

Global climate changes significantly impact the water condition of big rivers in glacierized high mountains. However,there is a lack of studies on hydrological changes within river basins caused by climate changes over a geological timescale due to the impossibility of direct observations. In this study, we examine the hydro-climatic variation of the Yarlung Zangbo River Basin in the Tibet Plateau since the Last Glacial Maximum(LGM) by combining δ18 O proxy records in Indian and Omani caves with the simulated Indian summer monsoon, surface temperature, precipitation, evapotranspiration and runoff via the Community Climate System Model and the reconstructed glacier coverage via the Parallel Ice Sheet Model. The mean river runoff was kept at a low level of 145 billion cubic meters per year until an abrupt increase at a rate of 8.7 million cubic meters per year in the B?lling-Aller?d interval(BA). The annual runoff reached a maximum of 250 billion cubic meters in the early Holocene and then reduced to the current value of 180 billion cubic meters at a rate of 6.4 million cubic meters per year. The low runoff in the LGM and Heinrich Stadial 1(HS1) is likely attributed to such a small contribution of precipitation to runoff and the large glacier cover. The percentage of precipitation to runoff was only 20%during the LGM and HS1. Comparison of glacier area among different periods indicates that the fastest deglaciation occurred during the late HS1, when nearly 60% of glacier area disappeared in the middle reach, 50% in the upper reach,and 30% in the lower reach. The rapid deglaciation and increasing runoff between the late HS1 and BA may have accelerated widespread ice-dam breaches and led to extreme outburst flood events. Combining local geological proxy records and regional simulations could be a useful approach for the study of paleo-hydrologic variations in big river basins.

关键词： Yarlung Zangbo River Basin Indian summer monsoon glacier change runoff variability since the LGM

Mean Velocity Estimation of Viscous Debris Flows

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Journal of Earth Science 2014年第4期25卷 771-778页

作者： Hongjuan Yang Fangqiang Wei kaiheng hu Key Laboratory of Mountain Hazards and Earth Surface Process Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences

The mean velocity estimation of debris flows, especially viscous debris flows, is an important part in the debris flow dynamics research and in the design of control structures. In this study, theoretical equations for computing debris flow velocity with the one-phase flow assumption were reviewed and used to analyze field data of viscous debris flows. Results show that the viscous debris flow is diffficult to be classified as a Newtonian laminar flow, a Newtonian turbulent flow, a Bingham fluid, or a dilatant fluid in the strict sense. However, we can establish empirical formulas to compute its mean velocity following equations for Newtonian turbulent flows, because most viscous debris flows are tur- bulent. Factors that potentially influence debris flow velocity were chosen according to two-phase flow theories. Through correlation analysis and data fitting, two empirical formulas were proposed. In the first one, velocity is expressed as a function of clay content, flow depth and channel slope. In the second one, a coefficient representing the grain size nonuniformity is used instead of clay content. Both formulas can give reasonable estimate of the mean velocity of the viscous debris flow.

关键词： debris flow velocity one-phase flow two-phase flow viscous.

A depth-averaged two-phase model for debris flows over fixed beds

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International Journal of Sediment Research 2018年第4期33卷 462-477页

作者： Ji Li Zhixian Cao kaiheng hu Gareth Pender Qingquan Liu State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Institute of Mountain Hazards and Environment Chinese Academy of Sciences Institute for Infrastructure and Environment.Heriot-Watt University Edinburgh Campus Department of Mechanics Beijing Institute of Technology

A depth-averaged two-phase model is proposed for debris flows over fixed beds, explicitly incorporating interphase and particle-particle interactions, fluid and solid fluctuations and multi grain sizes. A firstorder model based on the kinetic theory of granular flows is employed to determine the stresses due to solid fluctuations, while the turbulent kinetic energy-dissipation rate model is used to determine the stresses from fluid fluctuations. A well-balanced numerical algorithm is applied to solve the governing equations. The present model is benchmarked against USGS experimental debris flows over fixed beds.Incorporating the stresses due to fluid and solid fluctuations and properly estimating the bed shear stresses are shown to be crucial for reproducing the debris flows. Longitudinal particle segregation is resolved, demonstrating coarser sediments around the fronts and finer grains trailing the head. Based on extended modeling exercises, debris flow efficiency is shown to increase with initial volume, which is underpinned by observed datasets.

关键词： Debris flow Two-phase model Depth-averaged model Fluctuation kinetic energy Multi grain sizes

Model and Method of Debris Flow Risk Zoning Based on Momentum Analysis

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Wuhan University Journal of Natural Sciences 2006年第4期11卷 835-839页

作者： WEI Fangqiang ZHANG Yu hu kaiheng GAO Kechang Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 SichuanChina Dongchuan Station of Debris Flow Observation and Research Chinese Academy of Sciences Dongchuan 654112Yunan China

A model of debris flow risk zoning is carried out with momentum analysis of debris flow. This model zones the debris flow inundation fan with density and velocity calculated by numerical simulation. The risk classification standard is determined according to the ultimate bearing capacities of different structures under impacting. And the ultimate bearing capacities are tested by impact failure experiment of destruction. Two structures typical in Chinese mountain towns, reinforced concrete frame construction and brickwork with concrete, are chosen in the experiment. The model makes debris flow risk zoning quantitative and the results comparable widely. The results differ much from that of other methods especially in the identification of medium and low risk zones.

关键词： debris flow risk zoning momentum ultimate bearing capacity

Experimental Study on the Viscoelastic Behaviors of Debris Flow Slurry

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Journal of Mountain Science 2012年第4期9卷 501-510页

作者： WANG Yuyi TAN Rongzhi hu kaiheng CHEN Feiyue YANG Hongjuan ZHANGJinshan LV Juan Key Laboratory of Mountain Hazards and Earth Surface Process Dongchuan Debris Flow Observation and Research Station Chinese Academy of Sciences Chengdu 610041 China Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Shanghai Representative Office Anton Paar GmbH Shanghai 200040 China

The rheological properties of most liquid in nature are between liquids and solids,including both elastic changes and viscosity changes,that is socalled "viscoelastic".Dynamic oscillatory test was used to quantitatively study the distinct viscoelastic behaviors of debris flow slurry in the shear stress conditions for the first time in this study.The debris flow slurry samples were from Jiangjiagou Ravine,Yunnan Province,China.The experimental results were found that at the low and middle stages of shearing,when the angular velocity ωG'.At the late stage of shearing,when the angular velocity ω≧72.46 s-1,the storage modulus was greater than or equal to the loss modulus,i.e.G'≧G",tanδ≦1(where phase-shift angleδ=G"/G'),and the debris flow slurry was in a gel state.Therefore,the progress of this experimental study further reveals the mechanism of hyperconcentrated debris flows with a high velocity on low-gradient ravines.

关键词：粘弹行为泥石流粘弹性实验剪切作用储能模量流变学特性角速度

Fractal Structure of Debris Flow

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Wuhan University Journal of Natural Sciences 2007年第4期12卷 595-598页

作者： LI Yong LIU Jingjing hu kaiheng CHEN Xiaoqing Key Laboratory of Mountain Hazards and Surface Process Chinese Academy of Sciences/Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 Sichuan China

One of the most remarkable characteristics of debris flow is the competence for supporting boulders on the surface of flow, which strongly suggests that there should be some structure in the fluid body. This paper analyzed the grain compositions from various samples of debris flows and then revealed the fractal structure. Specifically, the fractality holds in three domains that can be respectively identified as the slurry, matrix, and the coarse content. Furthermore, the matrix fractal, which distinguishes debris flow from other kinds of flows, involves a hierarchical structure in the sense that it might contain ever increasing grains while the total range of grain size increases. It provides a possible mechanism for the boulder suspension.

关键词： debris flow fractal structure grain composition

A Probabilistic View of Debris Flow

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Journal of Mountain Science 2008年第2期5卷 91-97页

作者： LI Yong SU Pengcheng CUI Peng hu kaiheng Key Laboratory of Mountain Hazards and Surface Process Chinese Academy of Sciences Chengdu 610041 Sichuan P.R.China Institute of Mountain Hazards and Environment CAS Chengdu P. R. China

Most debris flows occur in valleys of area smaller than 50 km2. While associated with a valley, debris flow is by no means a full-valley event but originates from parts of the valley, i.e., the tributary sources. We propose that debris flow develops by extending from tributaries to the mainstream. The debris flow observed in the mainstream is the confluence of the tributary flows and the process of the confluence can be considered as a combination of the tributary elements. The frequency distribution of tributaries is found subject to the Weibull form (or its generalizations). And the same distribution form applies to the discharge of debris flow. Then the process of debris flow is related to the geometric structure of the valley. Moreover, viewed from a large scale of water system, all valleys are tributaries, which have been found to assume the same distribution. With each valley corresponding to a debris flow, the distribution can be taken as the frequency distribution of debris flow and therefore provides a quantitative description of the fact that debris flow is inclined to occur at valley of small size. Furthermore, different parameters appear in different regions, suggesting the regional differentials of debris flow potential. We can use the failure rate, instead of the size per se, to describe the risk of a valley of a given area. Finally we claim that the valleys of debris flow in different regions are in the similar episode of evolution.

关键词：概率视图概率分布岩石支流