Glacier area change (1993-2019) and its relationship to debris cover, proglacial lakes, and morphological parameters in the Chandra-Bhaga Basin, Western Himalaya, India

Glacier inventories serve as critical baseline data for understanding the impacts of climate change on glaciers.The present study maps the outlines of glaciers in the Chandra-Bhaga Basin(western Himalaya)for the years 1993,2000,2010,and 2019 using Landsat Thematic Mapper(TM),Enhanced Thematic Mapper(ETM),and Operational Land Imager(OLI)datasets.A total of 251 glaciers,each having an area above 0.5 km^(2),were identified,which include 216 clean-ice and 35 debris-covered glaciers.Area changes are estimated for three periods:1993-2000,2000-2010,and 2010-2019.The total glacierized area was 996±62 km^(2) in 1993,which decreased to 973±70 km^(2) in 2019.The mean rate of glacier area loss was higher in the recent decade(2010-2019),at 0.036 km^(2),compared to previous decades(0.029 km^(2) in 2000-2010 and 0.025 km^(2) in 1993-2000).Supraglacial debris cover changes are also mapped over the period of 1993 and 2019.It is found that the supraglacial debris cover increased by 14.12±2.54 km^(2)(15.2%)during 1993-2019.Extensive field surveys on Chhota Shigri,Panchi II,Patsio,Hamtah,Mulkila,and Yoche Lungpa glaciers were carried out to validate the glacier outlines and supraglacial debris cover estimated using satellite datasets.Controls of various morphological parameters on retreat were also analyzed.It is observed that small,clean ice,south oriented glaciers,and glaciers with proglacial lakes are losing area at faster rates than other glaciers in the basin.

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

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 performed.The western region of Sichuan Province frequentlysuffers from geohazards such as debris flow, and thegovernment has adopted many mitigation measures.This 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 centre of economic development.

The Critical Rainfall Characteristics for Torrents and Debris Flows in the Wenchuan Earthquake Stricken Area

Critical rainfall assessment is a very important tool for hazard management of torrents and debris flows in mountainous areas. The Wenchuan Earthquake 2008 caused huge casualties and property damages in the earthquake-stricken area,which also generated large quantities of loose solid materials and increased occurrence probabilities of debris flows. There is an urgent need to quantify the critical rainfall distribution in the area so that better hazard management could be planned and if real time rainfall forecast is available,torrent and debris flow early-warning could be issued in advance. This study is based on 49-year observations (1954-2003) of up to 678 torrent and debris flow events. Detailed contour maps of 1 hour and 24 hour critical rainfalls have been generated (Due to the data limitation,there was insufficient 10 minute critical rainfall to make its contour map). Generally,the contour maps from 1 hour and 24 hours have similar patterns. Three zones with low,medium and high critical rainfalls have been identified. The characteristics of the critical rainfall zones are linked with the local vegetation cover and land forms. Further studies and observations are needed to validate the finding and improve the contour maps.

Disaster Reduction Decision Support System Against Debris Flows and Landslides Along Highway in Mountainous Area

Highways in mountainous areas are easy to be damaged by such natural disasters as debris flows and landslides and disaster reduction decision support system (DRDSS) is one of the important means to mitigate these disasters. Guided by the theories and technologies of debris flow and landslide reduction and supported by geographical information system (GIS), remote sensing and database techniques, a DRDSS against debris flow and landslide along highways in mountainous areas has been established on the basis of such principles as pertinence, systematicness, effectiveness, easy to use, open and expandability. The system consists of database, disaster analysis models and decisions on reduction of debris flows and landslides, mainly functioning to zone disaster dangerous degree, analyze debris flow activity, simulate debris flow deposition and diffusion, analyze landslide stability, select optimal highway renovation scheme and plan disaster prevention and control engineering. This system has been applied successfully to the debris flow and landslide treatment works along Palongzangbu Section of Sichuan-Tibet Highway.

Magnitude-frequency relationship of debris flows in the Jiangjia Gully, China

The magnitude-frequency(MF) relationship of debris flows is the basis for engineering designs and risk quantification. However, because of the lack of debris flow monitoring data, research progress in this area has been relatively slow. The MF relationship of debris flows in Jiangjia Gully, Yunnan Province was evaluated based on a regression analysis of 178 debris flow events that occurred from 1987-2004. The magnitude-cumulative frequency(MCF) relationship of the debris flows in the Jiangjia Gully is consistent with the linear logarithmic transformation function. Moreover, observed data for debris flows in Hunshui Gully of Yunnan Province and Huoshao Gully, Liuwan Gully, and Niwan Gully of Gansu Province were used to verify the function. The results showed that the MCF relationship of highfrequency debris flows is consistent with the power law equation, although the regression coefficients in the equation are considerably different. Further analysis showed a strong correlation between the differences in the constants and the drainage area and daily maximum precipitation.

Risk assessment of glacial debris flow on alpine highway under climate change: A case study of Aierkuran Gully along Karakoram Highway

Glacial debris flows(GDFs) often occur in alpine regions that are subject to rapid climate change, and pose a serious threat to road systems. However, the ways that climate change impacts GDF risks along road systems remain poorly understood. Aierkuran Gully, located in eastern Pamir along Karakoram Highway(KKH), is a hotspot for GDF activity and climate change, and was thus selected to investigate the GDF risk to road systems under climate change conditions. Reg CM4.6 climate data for northwestern China were selected as climate projections during baseline(2011–2020) and future periods(2031–2040) under the Representative Concentration Pathway(RCP) 8.5. To reflect the coupling effect of rainfall and melt water that triggers GDF, a glacial hydrological model DETIM that considers both factors was applied to calculate the peak debris flow discharge. A FLO-2D model was calibrated based on high-quality data collected from a detailed field investigation and historical debris flow event. The FLO-2D model was used to simulate the debris flow depth and velocity during baseline and future periods under RCP8.5. The debris flow hazard was analyzed by integrating the maximum flow depth and momentum. Road structure vulnerability was further determined based on the economic value and susceptibility of hazard-affected objects. The GDF risk along KKH was assessed based on the GDF hazard and vulnerability analysis. Our results show that climate change would lead to amplified peak debris flow discharge, trigger highermagnitude GDF, and induce more severe damage and threats to the road system. Compared with the baseline period, the debris flow damage risk for culverts and bridges would increase and the areas that inundate the road and pavement would expand. Our findings provide valuable insights for the development of mitigation strategies to adapt road systems to climate change, especially in alpine regions with highly active GDFs.

On the criteria to create a susceptibility map to debris flow at a regional scale using Flow-R

Studies on susceptibility to debris flows at regional scale （ioo-looo km2） are important for the protection and management of mountain areas. To reach this objective, routing models, mainly based on land topography, can be used to predict susceptible areas rapidly while necessitating few input data. In this research, Flow-R model is implemented to create the susceptibility map for the debris flow of the Vizze Valley （BZ, North-Eastern Italy; 134 km^2）. The analysis considers the model application at local scale for three sub-catchments and then it explores the model upsealing at the regional scale by verifying two methods to generate the source areas of debris-flow initiation. Using data of an extreme event occurred in the Vizze Valley （4 August 2012） and historical information, the modeling verification highlights that the propagation parameters are relatively simple to set in order to obtain correct runout distances. A double DTM filtering - using a threshold for the upslope contributing area （0.1 km^2） and a threshold for the terrain-slope angle （15°） provides a satisfactory prediction of source areas and susceptibility map within the geological conditions of the Vizze Valley.

The formation of the Wulipo landslide and the resulting debris flow in Dujiangyan City, China

The Wulipo landslide, triggered by heavy rainfall on July 10, 2013, transformed into debris flow,resulted in the destruction of 12 houses, 44 deaths, and 117 missing. Our systematic investigation has led to the following results and to a new understanding about the formation and evolution process of this hazard. The fundamental factors of the formation of the landslide are a high-steep free surface at the front of the slide mass and the sandstone-mudstone mixed stratum structure of the slope. The inducing factor of the landslide is hydrostatic and hydrodynamic pressure change caused by heavy continuous rainfall. The geological mechanical model of the landslide can be summarized as "instability-translational slide-tension fracture-collapse" and the formation mechanism as "translational landslide induced by heavy rainfall". The total volume of the landslide is 124.6×104 m3, and 16.3% of the sliding mass was dropped down from the cliff and transformed into debris flow during the sliding process, which enlarged 46.7% of the original sliding deposit area. The final accumulation area is found to be 9.2×104 m2. The hazard is a typical example of a disaster chain involving landslide and its induced debris flow. The concealment and disaster chain effect is the main reason for the heavy damage. In future risk assessment, it is suggested to enhance the research onpotential landslide identification for weakly intercalated slopes. By considering the influence of the behaviors of landslide-induced debris flow, the disaster area could be determined more reasonably.

泥石流危险范围Laharz修正模型及其应用

泥石流危险区研究涉及触发条件、物源与地形等多种因素,需要开发快速、有效的方法进行危险范围分析。本文基于Laharz基本原理,以泥石流样本为数据基础拟合得到修正模型,并以重庆市巫溪县杨家湾沟为例,采用修正的Laharz ArcGIS工具包,在不同降雨重现期条件下对泥石流堆积范围进行模拟计算。结果表明:1)采用修正参数使Laharz模型统计量参数的和方差(SSE)和均方根误差(RMSE)减小,确定系数(R^(2))增大,拟合优度得到明显提高;2)基于数字高程模型,结合现场调查推算的物源体积,在ArcGIS平台采用Laharz工具包可快速模拟不同降雨重现期(10、20、50、100 a)条件下的泥石流堆积范围,并且模拟泥石流堆积宽度与现场调查堆积范围接近,大部分重合;3)采用Laharz修正模型与传统的FLO-2D软件模拟进行对比,其中最远冲出距离、最大堆积宽度和堆积面积在两种方法下模拟结果的差值比率分别在10.00%、15.00%和20.00%量级,采用两种方法模拟结果与实地勘查结果也相近,表明Laharz修正模型具可靠性。

海洋型冰川表碛与退缩区土壤微生物群落特征——以阿扎冰川和米堆冰川为例

以藏东南阿扎冰川和米堆冰川为研究区,采用细菌16S rRNA基因扩增子测序和真菌ITS测序技术,研究了冰川表碛与退缩区不同植被演替阶段土壤中微生物群落特征及土壤化学性质影响.结果表明,两条冰川表碛与退缩区土壤中共发现细菌门38个,其中Proteobacteria(40%)、Actinobacteriota(23%)、Bacteroidota(14%)为优势群,共发现真菌门7个,Basidiomycota(47%)和Ascomycota(45%)为优势群.阿扎和米堆冰川表碛中Patescibacteria、RCP2-54、Bacteroidota、Gemmatimonadota和Acidobacteriota的菌群丰度存在显著差异,米堆冰川表碛和退缩区土壤中微生物群落结构和丰度存在显著差异(P<0.05),而退缩区三个演替阶段之间的群落结构差异不显著.适应极端环境的微生物群落在表碛中丰度最高,而随着演替进程参与植物定殖或与植物共生的微生物群落丰度与多样性显著增加,微生物群落的α多样性上升,NMDS模型也逐渐接近重叠,群落结构在植被演替后期逐渐趋于稳定,.除全钾外,养分含量在两条冰川表碛中均较低,随着植被演替土壤pH值逐渐降低而养分逐渐增加,演替后期显著高于前两阶段.表碛中的微生物群落与pH值和全钾显著正相关(P<0.05),而退缩区土壤中则与速效钾、硝酸盐氮、全磷、可溶性有机碳显著正相关(P<0.05),并以磷限制为主.

重庆市2022年8月森林火灾火烧区特点及火后泥石流易发性评价

2022年8月重庆市江津区、巴南区、北碚区相继爆发森林火灾,总过火面积约35 km^(2)。火灾后火烧迹地植被及土壤结构遭到破坏,坡表堆积了厚度1~5 cm不等的灰烬层,受强降雨影响一旦爆发火后泥石流,将对附近村镇基础设施及群众生命财产构成严重威胁。通过遥感解译、现场调查及试验,查明了本次森林火灾火烧区空间分布特征,实测了火烧迹地灰烬层厚度、土壤饱和导水率等参数。结果表明研究区重度、中度和轻度火烧区分别占9.6%、34.0%和56.4%,其对应的坡面灰烬-结构扰动层平均厚度分别为5.10,3.28,1.15 cm。基于专家经验预测模型对火烧区共95条潜在泥石流沟道进行火后泥石流易发性评价,其中1条为高等易发,43条为中等易发,44条为低等易发,7条为不易发,分别占总数的1.05%、45.26%、46.32%、7.37%。考虑到现状条件下各泥石流沟域内中度和重度火烧区仍残留有大量灰烬、泥沙等松散固体物源,且土壤表现出较强的斥水性,中等及高等易发性沟道在雨季一旦受集中降雨影响,爆发火后泥石流的可能性较大。研究成果可为火烧迹地火后泥石流灾害预防与风险管理提供科学依据。

基于遥感解译的典型强震区泥石流物源发育及演化--以四川都汶高速沿线为例

四川都汶高速位于2008年汶川地震强震区内,震后泥石流灾害异常活跃,对人类财产造成严重损失、人居安全构成重大威胁。为了查清山体斜坡物源空间分布规律,探讨汶川震区泥石流物源成因,选择区内震前DEM、震后Landsat TM多波段融合数据及典型泥石流沟2期全色波段遥感数据,进行泥石流物源发育特征及演化分析。结果表明:①汶川地震强震区物源发育受地形坡向、坡度、高程及水系的共同控制。在坡向上具有背坡面放大效应和逆冲(错动)方向放大效应,高程和坡度选择与山体斜坡发育的动力过程相关;②地震能量释放是物源发育基础,建立了强震区物源发育密度与地震烈度的指数关系模型,并认为研究区断层的存在可能促进了泥石流物源的进一步发育;③物源演化具有面积缩小、大型物源解体为多个小型物源、小型物源汇聚而致规模增大、物源迁移、出现新物源等特征。

江苏省宜兴地区碎石土滑坡地质灾害特征及防治措施研究

针对江苏省宜兴地区典型碎石土滑坡地质灾害,开展了滑坡地质灾害特征分析和防治措施研究。结果表明,碎石土滑坡主要发育于宜兴南部山区山前缓坡地带,自然边坡坡度不大于15°;滑坡体具有上土下岩的二元结构特征,滑坡破坏模式为后退式渐进整体变形破坏的牵引式滑坡,表现为地形改造+降雨诱发;滑坡体轴向水平距离为改造后边坡前缘高差的10.0~12.0倍。采用坡面修整、抗滑桩、回填压脚、挡土墙和截排水沟等综合防治措施可有效消除滑坡地质灾害隐患,坡体水平位移、垂直位移收敛于定值,坡体稳定。

考虑冻融侵蚀型物源的不同流域单元泥石流易发性评价——以藏东贡觉地区为例

在全球气候变暖背景下,高原山区潜在泥石流暴发的概率将增大,定量评估泥石流易发性是区域减灾防灾的先行手段。基于现场调查和研究结果,首次计算了藏东贡觉地区的冻融侵蚀强度(DR)。选取物源条件和地形条件,采用加权信息量法评价了藏东贡觉地区泥石流的易发性,以四组流量阈值划分的不同流域单元作为评价单元对比分析了易发性评价结果。结果显示,四组易发性评价结果差异明显,随着流域单元划分数量的降低(流量阈值增大),研究区中风险区面积逐渐增大,高~极高风险区面积先增大后降低。受试者特征曲线(ROC)验证结果表明,使用G2组(流量阈值5000)划分得到的流域单元模型评估效果更好,AUC值为0.895,高易发区、极高易发区面积占全区约34.1%。八个评价因子中,冻融侵蚀强度(DR)、地形特征指数(TCI)和平面曲率(Pl_cv)是泥石流易发程度贡献率较大的三个因子。考虑冻融侵蚀型物源和地形水文因子建立的泥石流易发性评价模型,为冻融侵蚀现象明显的藏东地区泥石流易发性评价提供了新的方法和思路,对指导地方防灾减灾具有重要实践意义。

新疆阜康抽水蓄能电站库区泥石流危险性评价与防治措施

根据新疆阜康抽蓄库区泥石流形成条件及发育特征,通过现场调查、遥感解译、现场试验等方法确定了影响较大的4条沟谷泥石流静力、动力特征值,选取泥石流多因子综合模型评价了泥石流的危险性,并从两方面分析了泥石流对工程安全的影响,提出了“稳坡、拦挡、停淤”的综合防治体系。结果表明:西岔沟泥石流危险度最大,值为0.43,属于中度危险;库区泥石流沟的影响主要表现为淤泥作用和冲击作用;“稳、拦、停”的立体综合防治体系具有良好的防治效果,值得推广采用。

四川龙门山强震区特大泥石流综合防控技术体系研究

强震区泥石流表现出群沟暴发、范围广、持续时间长、规模大、危害重、防治难等特点,文章以强震区数十条典型特大泥石流沟为研究对象,采用野外调查、分析统计、试验验证及示范工程应用等方法,开展了典型泥石流沟特点及其防治工程效果研究,构建了强震区特大泥石流综合防控技术体系,形成了强震区特大泥石流勘查设计技术和防控关键技术体系。勘查设计体系在现有勘查技术基础上提出震裂物源识别新技术、堵塞系数分项取值新思路等;根据泥石流沟谷形态将强震区泥石流分为窄陡型和宽缓型;防控关键技术体系针对不同沟谷形态的泥石流分别进行综合防控关键技术探讨实践,统筹考虑了窄陡型和宽缓型泥石流沟上游、中游、下游沟谷特征。组合多种综合防控措施,建立了“起动控源→过程控量→末端控灾”逐级控制的强震区特大泥石流综合防控体系。结果可为强震区泥石流综合防控提供技术支撑,也可为非震区泥石流综合防控提供参考。

沟谷型泥石流特征参数的等代面积递归精细求解

为解决“沟谷型”泥石流在不规则断面处特征参数的精细求解问题,笔者以曼宁公式为基础,建立“等代”面积递归逼近的数学模型,实现了最深泥位、流体速度、威胁范围的求解计算,其结果比较符合实际。利用该模型在豫西某泥石流受威胁对象段任取10个断面进行研究分析:①计算出10年一遇、20年一遇、50年一遇、100年一遇等降水概率工况下最深泥位、流速、行洪断面大小,研究其随雨强大小的演变规律。②定量分析了各断面泄洪能力强弱。③结合泥石流强度判定标准对所选区域进行危险度分区,划分了极高危险区、高危险区、中危险区、低危险区。该模型不仅可以为预测泥石流各项指标提供基本参数,而且可为灾害防治提供科学依据。研究成果对泥石流的精细化防治方面具有重要支撑作用。

基于非线性回归的暴雨泥石流堵河预测

堵河型泥石流灾害在汶川震区较为常见,其链式灾害效应严重威胁到了区域内人民的生命财产安全。故准确预测泥石流堵河程度,并采取相应的防治措施是至关重要的。以四川省绵竹市清平镇于2010年8月13日暴发的群发性泥石流为研究对象,通过分析因子权重,利用非线性回归建立了泥石流堵河程度的预测模型,并与已有模型进行了对比,论证了所建立模型的可用性,其后对不同降雨频率下的泥石流堵河程度进行预测。结果表明:流量比和流域面积是最佳的建模因子,所建立的模型绝对平均误差为0.049;与不同模型对比发现本文模型对于清平镇泥石流堵河预测具有很好的适用性;在极端降雨下,部分沟道堵河预测程度为1,会造成绵远河堵断。研究成果可为该地区泥石流灾害的防治和治理提供参考。

水利水电库区漂浮污物智能化综合治理技术进展

开展水利水电库区漂浮污物智能化综合治理技术研究和应用是至关重要。笔者团队经过多年的研究攻关,探索出了一套“估漂—拦漂—清漂—用漂”一体化智能化综合治理技术。研究结合水文、气象大数据信息及库区环境状况,对水面漂浮污物的来量提前进行预判;分析了行业内拦漂技术的痛点和难点,研发了适应水流速度大、水位变幅高、防翻转、防沉没的拦漂系统,实现了不同工况下水面漂浮污物的高效拦截;采用多传感系统与人工智能相融合的新一代信息技术,攻克了水面漂浮污物强识别、防误判的关键技术,研制了水面漂浮污物智能识别、自动打捞的高效清污机器人系列产品;开发了将漂浮污物快速制成有机肥、生物质燃料的资源化利用设备,解决了水面漂浮污物上岸后无害化处理的难题。相关研究突破了水面漂浮污物智能化治理的多项关键技术,从漂浮污物来量估计、高效拦截、智能打捞、无害化处理及循环利用多个方向全面开展研究工作,构建了水面漂浮污物一体化的综合解决方案,为水利水电工程的安全运行起到了积极作用。

合水地区长6_(3)深水重力流沉积特征研究

合水地区是鄂尔多斯盆地近年来原油勘探的重点区块,在系统分析沉积构造、岩石学特征、结构粒度特征等沉积相识别标志的基础上,结合区域沉积背景,开展了合水地区长6_(3)重力流沉积类型及展布特征研究。结果表明,合水地区长6_(3)油层亚组为湖泊-重力流沉积体系,发育半深湖-深湖沉积亚相,可进一步划分为浊流沉积、砂质碎屑流、滑塌沉积三种重力流沉积类型;其中砂质碎屑流及浊流为主要控砂微相,主要分布在研究区的中部、南部区域,为区内有利储集相带。