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Experimental investigation on debris flow resistance and entrainment characteristics:effects of the erodible bed with discontinuous grading

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Journal of mountain Science 2022年第8期19卷 2397-2419页

作者： LI Pu WANG Jia-ding HU Kai-heng QIU Hai-jun XIE Jia-lin State Key Laboratory of Continental Dynamics/Department of Geology Northwest UniversityXi'an 710069China Key Laboratory of mountain hazards and Earth Surface Processes Chinese Academy of SciencesChengdu 610041China institute of mountain hazards and Environment Chinese Academy of Sciences&Ministry of Water ConservancyChengdu 610041China College of Urban and Environmental Sciences Northwest UniversityXi'an 710127China

Debris flow deposits in natural channels typically have a wide grain size distribution(GSD).The effects of bed sediment GSD on the basal entrainment rate are neglected in current debris flow erosion *** investigations have detected three different vertical graded bedding structures:normal,inverse,and mixed-gradation,characterized by discontinuous gradation sediment and almost without intermediate-sized *** study conducted small-scale flume experiments to investigate the debris flow resistance forces and entrainment characteristics by incorporating the effects of discontinuous grading bed *** graded bed sediments with varying fine particle content,volumetric water content(VWC),and roundness were designed for *** flow resistance in erodible beds generally increased in the group with gravel of larger-sized coarse particle,lower roundness,and higher bed sediment *** discontinuous grading bed sediment,the entrained depths increased in the group with gravel of smaller coarse particle sizes,larger amounts of fine particles,and higher sediment roundness,and decreased with larger *** abnormality may be attributed to the disproportionately large effects of viscous flow resistance in our small-scale flume *** maximum erosion rates of the continuous bed sediment were higher than those of the corresponding discontinuous bed sediment with the same maximum coarse gravel *** is because,for discontinuous grading bed sediments,localized failure of intermediate-sized sediment grains may cause a large-scale collapse of the solid grain skeleton and enhance basal entrainment rates.A revised formula for calculating the debris flow entrainment rate is proposed by incorporating the kurtosis coefficient,which describes the distribution of discontinuous bed sediments and fine particle *** revised formula could facilitate an elaborate estimation of basin erosion and sediment runoff and reveal the development an

关键词： Debris flow Resistance force Entrainment characteristic Discontinuous gradation Roundness Entrainment model

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Assessment of Soil Erosion by Compensatory Hoeing Tillage in a Purple Soil

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Journal of mountain Science 2012年第1期9卷 59-66页

作者： SU Zhengan ZHANG Jianhui XIONG Donghong LIU Gangcai Key Laboratory of mountain hazards and Earth Surface Processes Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China institute of mountain hazards and Environment Chinese Aeademy of SciencesChengdu 610041China

This study explores the role of a traditional tillage method,i.e.,compensatory hoeing,for sustainable agro-ecosystem management in the hilly areas of the Chongqing municipality,south-western *** validate the effects of compensatory tillage on the terraced slopes,the tillage method of noncompensatory hoeing was conducted on a linear *** acquire information about 137 Cs inventories and soil texture,soil samples were collected by a core sampler with a 6.8-cm diameter at 5.0-m intervals along the toposequence and the linear slope in the dry season(March) of ***,a tillage erosion model was used for evaluating the spatial pattern of tillage *** 137 Cs data showed that on the terraced slope,soil was lost from the upper slope,and soil deposition occurred at the toe slope positions on each *** a result,abrupt changes in the 137 Cs inventories of soil were found over short distances between two sides of terrace *** obtained from the tillage erosion model and the 137 Cs data indicate that soil redistribution mainly results from tillage erosion in the terraced *** non-compensatory tillage caused soil redistribution on the linear slope,resulting in thin soil profile disappearing at the top and soil accumulating at the bottom positions of the linear *** result further validates that compensatory tillage could avoid the complete erosion of the thin soil layer at the summit ***,this traditional ***,i.e.,compensatory tillage,has maintained the soil quality at the summit of the slope in the past decades.

关键词：耕作方法土壤侵蚀紫色土补偿评估农业生态系统空间分布格局侵蚀模型

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Mechanism of action of cracks water on rock landslide in rainfall

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Journal of Central South University 2010年第6期17卷 1383-1388页

作者：吴永何思明李新坡 Key Laboratory of mountain hazards and Surface Process Chinese Academy of Sciences institute of mountain hazards and Environment Chinese Academy of Sciences

In worldwide,the most common triggering factor of rock landslides is extended and intense ***,different from the soil slope failure caused by softening action of infiltration rainwater,the mechanism of rock landslide in rainfall is not *** the view of fracture mechanics,the propagation of cracks on rock slope and the development of sliding surface were *** based on hydraulics formulas and using Sweden arc method,the influence of crack water on stability of rock slope was quantitatively ***,an example was given to check the theoretical *** result shows that the development of sliding surface of rock slope is mainly caused by crack propagation under hydrostatic pressure when the stress intensity factor KI at crack tip is bigger than the toughness index of rock fractures KIC,and the failure of slope is the result of hydraulic action of crack water and the softening of materials on sliding surface when the depth of crack water is bigger than a minimum value hmin.

关键词：击碎水破裂力学繁殖 hydraulics 瑞典弧方法岩石山崩

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REGIONAL ASSESSMENT OF SOIL NITROGEN MINERALIZATION IN DIVERSE CROPLAND OF A REPRESENTATIVE INTENSIVE AGRICULTURAL AREA

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Frontiers of Agricultural Science and Engineering 2023年第4期10卷 530-540页

作者： Peng XU Minghua ZHOU Bo ZHU Klaus BUTTERBACH-BAHL Key Laboratory of mountain Surface Processes and Ecological Regulation Institute of Mountain Hazards and EnvironmentChineseAcademyof SciencesChengdu610041China institute for Meteorology and Climate Research Atmospheric Environmental Research(IMK-IFU)Karlsruhe Institute of Technology(KIT)Garmisch-Partenkirchen 82467Germany

Soil nitrogen mineralization(Nmin)is a key process that converts organic N into mineral N that controls soil N availability to ***,regional assessments of soil Nmin in cropland and its affecting factors are lacking,especially in relation to variation in *** this study,a 4-week incubation experiment was implemented to measure net soil Nmin rate,gross nitrification(Nit)rate and corresponding soil abiotic properties in five field soils(A-C,maize;D,flue-cured tobacco;and E,vegetables;with elevation decreasing from A to E)from different altitudes in a typical intensive agricultural area in Dali City,Yunnan Province,*** results showed that soil Nmin rate ranged from 0.10 to 0.17 mg·kg^(-1)·d^(-1)N,with the highest value observed in field E,followed by fields D,C,B,and A,which indicated that soil Nmin and Nit rates varied between fields,decreasing with *** soil Nit rate ranged from 434.2 to 827.1μg·kg^(-1)·h^(-1)N,with the highest value determined in field D,followed by those in fields E,C,B,and *** rates of soil Nmin and Nit were positively correlated with several key soil parameters,including total soil N,dissolved organic carbon and dissolved inorganic N across all fields,which indicated that soil variables regulated soil Nmin and Nit in cropland *** addition,a strong positive relationship was observed between soil Nmin and *** findings provide a greater understanding of the response of soil Nmin among cropland fields related to spatial *** is suggested that the soil Nmin from cropland should be considered in the evaluation of the N transformations at the regional scale.

关键词： cropland gross nitrification rate regulatory factors soil nitrogen mineralization spatial variation

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Geographical Space Development Zone Classification:An Essential Guide for Transformation of mountain Resource Cities

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Chinese Geographical Science 2015年第3期25卷 361-374页

作者： ZHANG Jifei DENG Wei LIU Shaoquan institute of mountain hazards and Environment Chinese Academy of Sciences

Sustainable development of mountain areas and resource cities has been a significant issue worldwide. Transformation of mountain resource cities is facing tremendous difficulties. In the context of National Major Function-oriented Zone Planning raised to a national strategic level in China, it is important to effectively implement the planning by studying geographical space development zone classification of prefecture- and county-level cities based on their major function orientation. This research is even more critical for the transformation of mountain resource cities. In this study, we evaluated geographical space development suitability, and classified geographical space development zones for Dongchuan Distric in Kunming City of Yunan Province, China, a typical mountain resource city. A quantitative grid-based evaluation was conducted using key-factor identification and restrictive-supportive comprehensive index determinati based on a geographic information system framework with different source data. The results included a classification of geographical space of Dongchuan into five types: the prohibited development zone, the inappropriate development zone, the controlled development zone, the moderate development zone and the preferential development zone. The distribution characteristics of geographical space development zones showed that the proportion of the prohibited development zone is the highest, while that of the other four development zones is comparatively lower and significantly fragmented. The geographical space development suitability is greatly controlled by the geomorphic pattern. Although Dongchuan is extremely restrained in terms of suitable geographical space for industrialization and urbanization, it still has the certain preferential and moderate development zones with an area of 207.81 km2 with large parts being concentrated and contiguous, which makes these areas the most favorable for development. Only by adapting to this reality and im

关键词：资源型城市地理空间开发区城市转型图形分类城市可持续发展可持续发展能力南山

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Soil microbial community composition and its driving factors in alpine grasslands along a mountain elevational gradient

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Journal of mountain Science 2016年第6期13卷 1013-1023页

作者： CUI Hai-jun WANG Gen-xu YANG Yan YANG Yang CHANG Rui-ying RAN Fei institute of mountain hazards and Environment Chinese Academy of Sciences

Understanding the vertical distribution patterns of soil microbial community and its driving factors in alpine grasslands in the humid regions of the Tibet Plateau might be of great significance for predicting the soil microbial community of this type of vegetation in response to environmental *** phospholipid fatty acids(PLFA),we investigated soil microbial community composition along an elevational gradient(3094~4131 m above sea level) on Mount Yajiageng,and we explored the impact of plant functional groups and soil chemistry on the soil microbial *** for Arbuscular Mycorrhizal fungi(AM fungi) biomarker18:2ω6,9 increasing significantly,other biomarkers did not show a consistent trend with the elevational *** biomass quantified by total PLFAs did not show the elevational trend and had mean values ranging from 1.64 to 4.09 μmol per g organic carbon(OC),which had the maximum value at the highest *** PLFAs exhibited a similar trend with total PLFAs,and its mean values ranged from0.82 to 1.81 μmol(g OC)^(-1).The bacterial to fungal biomass ratios had the minimum value at the highest site,which might be related to temperature and soil total nitrogen(TN).The ratios of Gram-negative to Gram-positive bacteria had a significantly negative correlation with soil TN and had the maximum value at the highest *** plant coverage and soil TN explained 58% of the total variation in the soil microbial community and could achieve the same interpretation as the whole *** factors may influence the soil microbial community through interaction with leguminous plant coverage and soil *** chemistry and plant functional group composition in substantial amounts explained different parts of the variation within the soil microbial community,and the interaction between them had no impact on the soil microbial community maybe because long-term grazing greatly reduces *** sum,although there were obvious differences in so

关键词：土壤微生物群落海拔梯度群落组成驱动因素高山草原植物功能群组成土壤化学性质丛枝菌根真菌

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Impact of glacier changes and permafrost distribution on debris flows in Badswat and Shishkat catchments,Northern Pakistan

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Journal of mountain Science 2023年第12期20卷 3687-3702页

作者： HASSAN Wajid SU Feng-huan LIU Wei-ming HASSAN Javed HASSAN Muzammil BAZAI Nazir Ahmed WANG Hao YANG Ze-wen ALI Muzaffar CASTELLANOS Daniel Garcia institute of mountain hazards and Environment Chinese Academy of SciencesChengdu 610041China China-Pakistan Joint Research Center on Earth Sciences CAS-HECIslamabad 45320Pakistan University of Chinese Academy of Sciences Beijing 100049China DTU Space Technical University of DenmarkKongens Lyngby 2800Denmark Department of Environmental Science Karakoram International UniversityGilgit-Baltistan 15100Pakistan Key Laboratory of mountain hazards and Earth Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China Instituto de Ciencias de la Tierra Jaume Almera ICTJA-CSICSoléi Sabarís s/nBarcelona 08028Spain

Knowledge of glacier changes and associated hazards is of great importance for the safety consideration of the population and infrastructure in the mountainous regions of Upper Indus Basin(UIB).In this study,we assessed the variations in glacier velocity,glacier surface elevation change,meteorological conditions,and permafrost distribution in Badswat and Shishkat catchments located in UIB to access the potential impact on the occurrence of debris flow in both *** find that the glacier surface velocity increased during the debris flow event in the Badswat catchment and the mean daily temperature was 3.7℃to 3.9℃higher in most of the *** enhanced glacier surface elevation lowering period coincide with the rise in temperature during spring and autumn months between 2015 to 2019 in Badswat *** source region of debris flow falls within the lower boundary of permafrost occurrence zone and lies below the 0℃isotherm during late spring and summer *** Shishkat catchment the 0℃isotherm reaches above the debris flow source area during August and the glacier do not show any significant variations in velocity and surface elevation *** debris flow source area is adjacent to the slow-moving rock glacier in Shishkat catchment while in Badswat catchment the debris flow initiated from the former glacier *** catchments are largely glacierized and thus sensitive to changes in climatic conditions and changes in the cryosphere response possess significant threats to the population *** monitoring of cryosphere-climate change in the region can contribute toward the improvement of disaster risk reduction and mitigation policies.

关键词： Cryosphere change Climate change Debris flow Remote sensing Permafrost Cryosphere hazard

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Forecast Method of Multimode System for Debris Flow Risk Assessment in Qingping Town,Sichuan Province,China

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Journal of mountain Science 2011年第4期8卷 592-602页

作者： KONG Jiming Key Laboratory of mountain hazards and Earth Surface Processes Chinese Academy of Sciences institute of mountain hazards and Environment Chinese Academy of Sciences

The Wenchuan Earthquake of May 12,2008 triggered large numbers of *** heavy rain on 13 August 2010 triggered debris flows with total volume of more than 6 million cubic meters and the debris flows destroyed 500 houses and infrastructure built after the Wenchuan *** study area Qingping Town was located in the northwestern part of the Sichuan Basin of China,which needs the second reconstructions and the critical evaluation of debris *** study takes basin as the study unit and defines collapse,landslide and debris flow hazard as a geo-hazard system.A multimode system composed of principal series system and secondary parallel system were established to evaluate the hazard grade of debris flow in 138 drainage basins of Qingping *** evaluation result shows that 30.43% of study basins(42 basins) and 24.58% of study area,are in extremely high or high hazard grades,and both percentage of basin quantity and percentage of area in different hazard grades decrease with the increase of hazard *** to the geo-hazard data from the interpretation of unmanned plane image with a 0.5-m resolution and field investigation after the Wenchuan Earthquake and 8.13 Big Debris Flow,the ratio of landslides and collapses increased after the Wenchuan Earthquake and the ratios of extremely high or high hazard grades were more than moderate or low hazard grades obviously.23 geo-hazards after8.13 Big Debris Flow in Qingping town region all occurred in basins with extremely high or high hazard grades,and 9 debris flows were in basins with extremely high hazard *** model of multimode system for critical evaluation could forecast not only the collapse and landslide but also the debris flow precisely when the basin was taken as the study unit.

关键词：地质灾害系统风险评估泥石流预报方法多模中国四川省危险等级

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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.

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Determination of the suspension competence of debris flows based on particle size analysis

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International Journal of Sediment Research 2014年第1期29卷 73-81页

作者： Hong-juan YANG Fang-qiang WEI Kai-heng HU Chuan-chang WANG Key Laboratory of mountain hazards and Earth Surface Process Chinese Academy of Sciences institute of mountain hazards and Environment Chinese Academy of Sciences

The determination of the critical particle size between solid and fluid phases,i.e.,the suspension competence,is fundamental for debris flow.A method for determining suspension competence based on particle size analysis is presented in this *** competence of static experimental water-debris mixtures prepared with the sediment of Jiangjia Gully is-0.025 mm if the bulk density is less than 1,800 kg m;and it increases with bulk density of more concentrated *** competence of natural debris flows in Jiangjia Gully increases exponentially with the bulk *** two data sets are compared in order to understand the suspension *** is concluded that turbulence may play a leading role in particle suspension in non-viscous and sub-viscous debris flows,while in viscous debris flows both matrix strength and excess pore water pressure play important roles.

关键词： Debris flow Suspension competence Particle size analysis Critical particle size Particle suspension mechanism

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