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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 *** 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,*** 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 ***,the I_(max_dur)model has the highest performance metrics at a 40-min *** used logistic regression to combine at least two rainfall properties to establish multivariate threshold *** 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 *** evaluation reemphasizes the important role of the maximum intensity over short durations in debris flow *** also highlights the importance of systematically investigating the role of R_(a)in establishing rainfall thresholds for triggering debris *** 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

Dynamic-based model for calculating the boulder impact force in debris flow

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Journal of mountain Science 2024年第6期21卷 1930-1940页

作者： YANG Chaoping ZHANG Shaojie YIN Yueping YANG Hongjuan WEI Fangqiang State Key Laboratory of mountain hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China University of chinese academy of sciences Beijing 100049China China institute of Geological environment Monitoring Beijing 100081China Chongqing institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China Chongqing School University of Chinese Academy of SciencesChongqing 400714China

The boulder impact force in debris flow is generally calculated by static methods such as the cantilever beam ***,these methods cannot describe the dynamic scenario of boulder collision on structures,so the inertia and damping effects of the structures are not involved causing an overestimation on the boulder impact *** order to address this issue,a dynamic-based model for calculating the boulder impact force of a debris flow was proposed in this study,and the dynamic characteristics of a cantilever beam with multiple degrees of freedom under boulder collision were *** using the drop-weight method to simulate boulders within debris flow,seven experiments of drop-weight impacting the cantilever beam were used to calibrate the error of the dynamicbased *** indicate that the dynamic-based model is able to reconstruct the impact force history on the cantilever beam during impact time and the error of dynamic-based model is 15.3%in calculating boulder impact force,significantly outperforming the cantilever beam model’s error of 285%.Therefore,the dynamic-based model can overcome the drawbacks of the static-based models and provide a more reliable theoretical foundation for the engineering design of debris flow control structures.

关键词： Debris flow Impact force Boulder collision Dynamic-based model Engineering design

Socio-scientific quantification of the comprehensive benefits of debris flow mitigation measures for villages in western Sichuan, China

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Journal of mountain Science 2024年第5期21卷 1598-1612页

作者： DENG Ting XU Pei LI Ming LU Yafeng WANG Yukuan LI Zhengyang SHRAVAN Kumar Ghimire institute of mountain hazards and environment Chinese Academy of SciencesChengdu 610299China University of chinese academy of sciences Beijing 100049China

Debris flow hazards seriously threaten thesafety and sustainable development of mountainousareas. Numerous debris flow mitigation measures havebeen implemented worldwide;however, acomprehensive assessment of the specific disasterreduction effects of these measures and their economic,social and ecological benefits is yet to be *** western region of Sichuan Province frequentlysuffers from geohazards such as debris flow, and thegovernment has adopted many mitigation *** study assessed the benefits of debris flowmitigation measures and identified the key influencingfactors via a field-based study conducted in 81 villagesin western Sichuan province, China. A framework forthe evaluation of the benefits of rural debris flowmitigation measures was constructed andquantitatively evaluated using a survey. Snowballsampling was performed to recruit 81 village leadersand 468 farmers. The results showed that managementand engineering measures were the main methodsused to mitigate debris flow;ecological measures wereauxiliary. The average satisfaction scores of farmers forthese three types of measures were 4.07, 3.90, and 3.56,respectively (as measured on a five-point Likert scale).In contrast, in terms of the benefits of these mitigationmeasures, only a small proportion of villages (11.11%)obtained a high level of comprehensive benefits fromthe debris flow mitigation measures, while the majority(88.89%) received medium to low-level benefits. Toimprove this situation, we further studied and foundthat the main factors that restricted villages fromachieving high-level comprehensive benefits were theunpredictable nature of debris flows, labour forceoutflow and remoteness. Effective control measures, agood economic environment and strong governmentassistance were reported as crucial factors forimproving these comprehensive benefits. This studyprovides socio-scientific references for decisionmakingon rural debris flow mitigation measures while keeping villages at the

关键词： Mitigation measures Comprehensive benefit evaluation Debris flow mountain development Rural areas

Process-driven susceptibility assessment of glacial lake outburst debris flow in the Himalayas under climate change

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Advances in Climate Change Research 2024年第3期15卷 500-514页

作者： Bin ZHOU Qiang ZOU Hu JIANG Tao YANG Wen-Tao ZHOU Si-Yu CHEN Hong-Kun YAO institute of mountain hazards and environment Chinese Academy of SciencesChengdu 610041China University of chinese academy of sciences Beijing 100049China School of environment and Resource Southwest University of Science and TechnologyMianyang 621010China

Global warming is causing glaciers to retreat and glacial lakes to expand in the Himalayas,which amplifies the risk of glacial lake outburst debris flows(GLODFs)and poses a significant threat to downstream lives and ***,the complex interplay between GLODF occurrences and associated indicators,coupled with the lack of a comprehensive susceptibility indicator system that considers the entire GLODF process,presents a substantial challenge in assessing GLODF susceptibility in the *** study proposes a process-driven GLODF susceptibility assessment indicator system responding to climate change that considers the complete process of GLODF formation,incorporating relevant parameters about upstream,themselves,and downstream of glacial ***,to mitigate subjective factors associated with traditional evaluation methods,we developed three novel hybrid machine-learning models by integrating classic machine-learning algorithms with the whale optimization algorithm(WOA)to delineate the distribution of GLODF susceptibility in the *** the hybrid models effectively predicted the GLODFs occurrence,with the WOA-SVC model demonstrating the highest prediction *** 34%of the catchments exhibit high and very high susceptibility levels,primarily concentrated along the north and south sides of the Himalayan ridge,particularly in the eastern and central *** capturing the physical formation process of hazards,such as topographic potential(highest relative importance value of 40%),can precisely identify GLODF.A total of 128 catchments pose potential transboundary threats,with 24 classified as having a very high susceptibility level and 25 as having a high susceptibility ***,the border region between China and Nepal is a prominent hotspot for transboundary threats of *** findings can provide valuable clues for disaster prevention,mitigation,and cross-border coordination in the Himalayas.

关键词： Glacial lake outburst debris flow Susceptibility assessment Climate change Himalayas

Process and Mechanism of Controlling Outburst Floods of Landslide Dams through Artificial Structures: Physical Experiments

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Journal of Earth Science 2024年

作者： Hechun Ruan Huayong Chen Xiaoqing Chen Wanyu Zhao Xiao Li Key Laboratory of mountain hazards and Surface Processes institute of mountain hazards and environment chinese academy of sciences University of chinese academy of sciences

The scale of the outburst flood resulting from a landslide dam failure significantly influences the extent of the disaster and losses downstream. This study proposes a method for controlling the discharge of landslide dam failure using the artificial structure (AS). The primary approach involves strategically arranging the designed AS on both sides of the excavated spillway. As the breach is eroded， ASs gradually falls into the breach， serving to control the discharge. Fourteen sets of flume experiments were conducted to investigate the impact of various factors， including AS types， distances from the breach boundary， arrangements， columns， numbers， on the discharge control effectiveness. The mechanism how AS controls outburst discharge was revealed. Results indicate a pronounced control effect of AS on landslide dam-break discharge， with the maximum reducing rate of the peak discharge in the experiment reaching 47.4%. In controlling outburst discharge， four-sided framed structures demonstrate superior performance compared to four-sided solid structures， and serial structures outperform discrete structures. When arranging ASs， it is essential to ensure that the structure initiates its descent into the breach at the onset of the rapid increase in outburst discharge and continues until the peak discharge occurs. Building upon this foundation， augmenting the number of ASs and columns significantly enhances the efficacy of discharge control. The fundamental rationale for this discharge control lies in the AS’s capacity to reduce the headward scarp height， constrain sediment transport， and diminish the erosion capacity of the outburst flood， ultimately lowering the breach erosion rate. Lastly， a calculation method for the size design of the AS is established based on mechanical analysis. The research findings offer a new technological option for the emergency disposal of landslide dams.

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Dynamics of the spatiotemporal velocity of glaciers on the eastern slope of Mount Gongga,China,under climate change

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Advances in Climate Change Research 2024年第3期15卷 490-499页

作者： Yin FU Bo ZHANG Qiao LIU Guo-Xiang LIU Rui ZHANG institute of mountain hazards and environment Chinese Academy of SciencesChengdu 610299China Faculty of Geosciences and environmental Engineering Southwest Jiaotong UniversityChengdu 611756China

The quantitative assessment of glacier flow velocity dynamics plays a pivotal role in understanding its response mechanisms concerning climate *** work provides a systematic quantitative assessment of the deceleration status of glaciers in this region by investigating the motion evolution of typical glaciers in Mount Gongga in recent years,thereby revealing the seasonal dynamics and inter-annual evolution over an extensive time *** used the optical flow-small baseline subset(OF-SBAS)method to compute the time-series velocities of the Hai-luogou Glacier and the Mozigou Glacier using 178 archived Sentinel-1 satellite synthetic aperture radar(SAR)images from 2014 to *** findings revealed a prominent seasonal pattern in glacier motion,characterised by cyclic variations in velocity from cold to warm ***,we identified variations in velocities across distinct regions of the glacier surface,underscored by the lag in the peak time node of glacier flow with increasing *** pattern may have been determined by a combination of internal and external factors,including mass accumulation and ablation-driven subglacial drainage,as well as the glacier geomorphological ***,during 2015-2021,the glaciers on the eastern slope of Mount Gongga exhibited an overarching trend of ***,the ablation area of the Hailuogou Glacier recorded the most substantial deceleration,exceeding 8%per *** study underscores the efficacy of the OF-SBAS method in extracting long-term glacier *** work also establishes a robust foundation for the analysis of spatiotemporal fluctuations in glacier movement within the context of climate warming.

关键词： Monsoonal temperate glaciers Synthetic aperture radar(SAR) Glacier movement Hailuogou glacier Mozigou glacier Optical flow-small baseline subset(OF-SBAS)

Assessment of Crop Yield in China Simulated by Thirteen Global Gridded Crop Models

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Advances in Atmospheric sciences 2024年第3期41卷 420-434页

作者： Dezhen YIN Fang LI Yaqiong LU Xiaodong ZENG Zhongda LIN Yanqing ZHOU International Center for Climate and environment sciences Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of chinese academy of sciences Beijing 100049China institute of mountain hazards and environment Chinese Academy of SciencesChengdu 610041China State Key Laboratory of Numerical Modeling for Atmospheric sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China State Key Laboratory of Desert and Oasis Ecology Xinjiang Institute of Ecology and GeographyChinese Academy of SciencesUrumqi 830011China

Global gridded crop models(GGCMs) have been broadly applied to assess the impacts of climate and environmental change and adaptation on agricultural production. China is a major grain producing country, but thus far only a few studies have assessed the performance of GGCMs in China, and these studies mainly focused on the average and interannual variability of national and regional yields. Here, a systematic national-and provincial-scale evaluation of the simulations by13 GGCMs [12 from the GGCM Intercomparison(GGCMI) project, phase 1, and CLM5-crop] of the yields of four crops(wheat, maize, rice, and soybean) in China during 1980–2009 was carried out through comparison with crop yield statistics collected from the National Bureau of Statistics of China. Results showed that GGCMI models generally underestimate the national yield of rice but overestimate it for the other three crops, while CLM5-crop can reproduce the national yields of wheat, maize, and rice well. Most GGCMs struggle to simulate the spatial patterns of crop yields. In terms of temporal variability, GGCMI models generally fail to capture the observed significant increases, but some can skillfully simulate the interannual variability. Conversely, CLM5-crop can represent the increases in wheat, maize, and rice, but works less well in simulating the interannual variability. At least one model can skillfully reproduce the temporal variability of yields in the top-10 producing provinces in China, albeit with a few exceptions. This study, for the first time, provides a complete picture of GGCM performance in China, which is important for GGCM development and understanding the reliability and uncertainty of national-and provincial-scale crop yield prediction in China.

关键词： global gridded crop model historical crop yield China multi-model evaluation

Impacts of permafrost degradation on streamflow in the northern Himalayas

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Science China Earth sciences 2024年第6期67卷 1990-2000页

作者： Linfeng FAN Fang JI Xingxing KUANG Zhilin GUO Rui ZHANG Chunmiao ZHENG State Key Laboratory of mountain hazards and Engineering Resilience Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China Yangtze institute for Conservation and Development Hohai UniversityNanjing 210024China School of environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Eastern institute for Advanced Study Ningbo 315200China

The Himalayan water tower provides crucial water resources for *** degradation is deemed to exert important impacts on streamflow in the Himalayan ***,the magnitudes of such impacts remain poorly ***,we established a robust hydrological model that incorporated active layer deepening and ground ice melt for the drainage basin of the largest river in the northern Himalayas-the Yarlung Zangbo River(YZR).We estimated that permafrost degradation led to~0.65 km^(3)/yr decrease in surface runoff and~0.35 km^(3)/yr increase in baseflow and ground ice melt contributed~0.25% to the annual streamflow in the YZR for the period ***“fill-and-spill”mechanism helps explain the seeming contradiction of observed increasing versus decreasing baseflow in different permafrost regions *** propose that the dilution of riverine dissolved organic carbon(DOC)concentrations by baseflow may lead to the riverine DOC hysteresis *** study not only lays solid scientific basis for water resources management in the Himalayas,but also yields new insights into how to interpret measured river discharge and nutrient flux in permafrost regions over the globe.

关键词： Permafrost degradation Hydrology Streamflow Surface runoff Groundwater Himalayas

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Climate-Vegetation Coverage Interactions in the Hengduan mountains Area, Southeastern Tibetan Plateau, and Their Downstream Effects

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Advances in Atmospheric sciences 2024年第4期41卷 701-716页

作者： Congxi FANG Jinlei CHEN Chaojun OUYANG Lu WANG Changfeng SUN Quan ZHANG Jun WEN Key Laboratory of mountain hazards and Earth Surface Processes Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610299China State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Urban and environmental sciences Peking UniversityBeijing 100871China institute of Global environmental Change Xi’an Jiaotong UniversityXi’an 710049China The State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi’an 710061China College of Atmospheric sciences Chengdu University of Information TechnologyChengdu 610225China

Little is known about the mechanism of climate-vegetation coverage coupled changes in the Tibetan Plateau(TP)region,which is the most climatically sensitive and ecologically fragile region with the highest terrain in the *** study,using multisource datasets(including satellite data and meteorological observations and reanalysis data)revealed the mutual feedback mechanisms between changes in climate(temperature and precipitation)and vegetation coverage in recent decades in the Hengduan mountains Area(HMA)of the southeastern TP and their influences on climate in the downstream region,the Sichuan Basin(SCB).There is mutual facilitation between rising air temperature and increasing vegetation coverage in the HMA,which is most significant during winter,and then during spring,but insignificant during summer and *** temperature significantly enhances local vegetation coverage,and vegetation greening in turn heats the atmosphere via enhancing net heat flux from the surface to the *** atmospheric heating anomaly over the HMA thickens the atmospheric column and increases upper air *** high pressure anomaly disperses downstream via the westerly flow,expands across the SCB,and eventually increases the SCB *** effect lasts from winter to the following spring,which may cause the maximum increasing trend of the SCB temperature and vegetation coverage in *** results are helpful for estimating future trends in climate and eco-environmental variations in the HMA and SCB under warming scenarios,as well as seasonal forecasting based on the connection between the HMA eco-environment and SCB climate.

关键词： Hengduan mountains Area normalized difference vegetation index climate change net heat flux downstream effects