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field observation of debris-flow activities in the initiation area of the Jiangjia Gully, Yunnan Province, China

Journal of Mountain Science 2022年第6期19卷 1602-1617页

作者： YANG Hong-juan ZHANG Shao-jie HU Kai-heng WEI Fang-qiang WANG Kai LIU Shuang Key Laboratory of Mountain Hazards and Earth Surface Process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China Chongqing Institute of Green and Intelligent Technology Chinese Academy of SciencesChongqing 400714China

The Jiangjia Gully, which is located in Dongchuan District, Yunnan Province, China, is a watershed prone to debris flows and has long-term recorded data of debris-flow occurrence. However, the initiation mechanism has mainly been studied by experiments in this watershed. To further reveal debris-flow formation mechanism in the Jiangjia Gully, debris-flow activities in the initiation zone were observed with hand-held video cameras in the summer of 2016 and 2017. In these two years, six debris-flow events were triggered in Menqian Gully, a major tributary of the Jiangjia Gully, while debrisflow activities in some sub-watersheds of Menqian Gully were recorded with video cameras in four events. The video recording shows that landslides constituted an important source for sediment supply in debris flow. Some landslides directly evolved into debris flows, while the others released sediment into rills and channels, where debris flows were generated for sediment entrainment by water flow. Therefore, debris-flow occurrence in the Jiangjia Gully is influenced both by infiltration-dominated processes and by runoff-dominated processes. In addition, rainfall data from four gauges installed in Menqian Gully were analyzed using mean intensity(I), duration(D), peak 10-minute rainfall(R10min) and antecedent rainfall(AR) up to 15 days prior to peak 10-minute rainfall. It reveals that debris-flow triggering events can be discriminated from nontriggering events either by an I-D threshold or by an R10min-AR threshold. However, false alarms can be greatly reduced if these two kinds of thresholds are used together. Moreover, behaviors including intermittency of debris flow, variance in moisture content and volume among surges, and coalescence of multiple surges by temporary damming were observed, indicating the complexity of debris-flow initiation processes. These findings are expected to enhance our knowledge on debris-flow formation mechanism in regions with similar environmental settings.

关键词： Debris flow field observation Initiation mechanism Rainfall threshold Jiangjia gully

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field observation and Analysis of Wave-Current-Sediment Movement in Caofeidian Sea Area in the Bohai Bay, China

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China Ocean Engineering 2014年第3期28卷 331-348页

作者：左利钦陆永军汪亚平刘怀湘 State Key Laboratory of Hydrology Water Resources and Hydraulic EngineeringNanjing Hydraulic Research Institute School of Geographic and Oceanographic Sciences Nanjing University

In order to study the mechanism of flow-sediment movement, it is essential to obtain measured data of water hydrodynamic and sediment concentration process with high spatial and temporal resolution in the bottom boundary layer （BBL）. field observations were carried out in the northwest Caofeidian sea area in the Bohai Bay. Near 2 m isobath （under the lowest tidal level）, a tripod system was installed with AWAC （Acoustic Wave And Current）, ADCP （Acoustic Doppler Current Profilers）, OBS-3A （Optical Backscatter Point Sensor）, ADV （Acoustic Doppler Velocimeters）, etc. The accurate measurement of the bottom boundary layer during a single tidal period was carried out, together with a long-term sediment concentration measurement under different hydrological conditions. All the measured data were used to analyze the characteristics of wave-current-sediment movement and the BBL. Analysis was performed on flow structure, shear stress, roughness, eddy viscosity and other parameters of the BBL. Two major findings were made. Firstly, from the measured data, the three-layer distribution model of the velocity profiles and eddy viscosities in the wave-current BBL are proposed in the observed sea area; secondly, the sediment movement is related closely to wind-waves in the muddy coast area where sediment is clayey silt： 1） The observed suspended sediment concentration under light wind conditions is very low, with the peak value generally smaller than 0.1 kg/m^3 and the average value being 0.03 kg/m^3; 2） The sediment concentration increases continuously under the gales over 6-7 in Beaufort scale, under a sustained wind action. The measured peak sediment concentration at 0.4 m above the seabed is 0.15-0.32 kg/m^3, and the average sediment concentration during wind-wave action is 0.08-0.18 kg/m^3, which is about 3-6 times the value under light wind conditions. The critical wave height signaling remarkable changes of sediment concentration is 0.5 m. The results show that the suspended load sediment concentration is mainly influenced

关键词： field observation wave-induced sediment suspension wave-current interaction bottom boundary layer （BBL） Caofeidian Bohai Bay

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field observations of Near-Surface Wind Flow Across Expressway Embankment on the Qinghai–Tibet Plateau

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Engineering 2022年第7期8卷 169-180页

作者： Yanhu Mu Wei Ma Zhaohui(Joey)Yang Xiaolin Li Kun Zhang Yuncheng Mao State Key Laboratory of Frozen Ground Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China College of Engineering University of Alaska AnchorageAnchorageAK 99508USA College of Civil Engineering and Architecture Jiaxing UniversityJiaxing 314001China School of Civil Engineering Northwest Minzu UniversityLanzhou 730024China

Crushed rock layers(CRLs),ventilation ducts(VDs)and thermosyphons are air-cooling structures(ACSs)widely used for maintaining the long-term stability of engineered infrastructures in permafrost environments.These ACSs can effectively cool and maintain the permafrost subgrade’s frozen state under climate warming by facilitating heat exchange with ambient air in cold seasons.As convection is a crucial working mechanism of these ACSs,it is imperative to understand the near-surface wind flow(NSWF)across a constructed infrastructure,such as an embankment.This article describes a yearlong field observation of the NSWF across an experimental expressway embankment,the first of its kind on the Qinghai–Tibet Plateau(QTP).The wind speed and direction along a transect perpendicular to the embankment on both the windward and leeward sides and at four different heights above the ground surface were collected and analyzed.The results showed that the embankment has a considerable impact on the NSWF speed within a distance of up to ten times its height,and in the direction on the leeward side.A power law can well describe the speed profiles of NSWF across the embankment,with the power-law indices(PLIs)varying from 0.14 to 0.40.On an annual basis,the fitted NSWF PLI far away from the embankment was 0.19,which differs substantially from the values widely used in previous thermal performance evaluations of ACSs on the QTP.Finally,the significance of the NSWF to the thermal performance of the ACSs,particularly the CRLs and VDs,in linear transportation infrastructure is discussed.It is concluded that underestimating the PLI and neglecting wind direction variations may lead to unconservative designs of the ACSs.The results reported in this study can provide valuable guidance for infrastructure engineering on the QTP and other similar permafrost regions.

关键词： Near-surface wind flow field observation Air-cooling structures Linear transportation infrastructure Qinghai–Tibet Plateau

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Long-term winter observation of nitrous acid in the urban area of Beijing

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Journal of Environmental Sciences 2022年第4期34卷 334-342页

作者： Chaofan Lian Weigang Wang Yan Chen Yusheng Zhang Jingwei Zhang Yongchun Liu Xiaolong Fan Chang Li Junlei Zhan Zhuohui Lin Chenjie Hua Wenyu Zhang Mingyuan Liu Junling Li Xuefei Wang Junling An Maofa Ge State Key Laboratory for Structural Chemistry of Unstable and Stable Species CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of the Chinese Academy of Sciences Beijing 100049China Aerosol and Haze Laboratory Advanced Innovation Center for Soft Matter Science and EngineeringBeijing University of Chemical TechnologyBeijing100029China State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry(LAPC) Institute of Atmospheric Physics(IAP)Chinese Academy of SciencesBeijing 100029China State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Center for Excellence in Urban Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China

The particulate matter(PM)pollution has been significantly improved by carrying out various valid emission control strategies since 2013 in China.Meanwhile the variation trend of nitrous acid(HONO)is worthy to investigate due to its vital role in the atmospheric oxidation process.In this study,field observation in the winter is conducted to investigate the concentration of HONO in an urban area of Beijing.In the winter of 2019,the mean HONO concentration is 1.38 ppbV during the whole winter.Photo-enhanced NO_(2)heterogeneous reactions on the ground and aerosol surfaces were found as the possible daytime sources of HONO.Compared to O_(3),photolysis of HONO dominates the primary OH sources during the winter time.To understand the HONO pollution patterns by years variation,multi-year data is summarized and finds that primary pollutants including CO and NO decreased,but secondary pollutants i.e.,HONO(mostly generated via secondary process)increased.Our study highlights the requirement to mitigate secondary pollution by control HONO concentration.

关键词： Nitrous acid field observation Winter air pollution

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Long-chain alkanes in the atmosphere:A review

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Journal of Environmental Sciences 2022年第4期34卷 37-52页

作者： Junling Li Kun Li Hong Li Xuezhong Wang Weigang Wang Ke Wang Maofa Ge State Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China Laboratory of Atmospheric Chemistry Paul Scherrer InstituteVilligen 5232Switzerland State Key Laboratory for Structural Chemistry of Unstable and Stable Species Beijing National Laboratory for Molecular SciencesCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

As a representative species of intermediate volatile organic compounds(IVOCs),long-chain alkanes are considered to be important precursors of secondary organic aerosols(SOA)in the atmosphere.This work reviews the previous studies on long-chain alkanes in the atmosphere:(1)the detection methods and filed observations of long-chain alkanes in both gas and particle phases are summarized briefly;(2)the laboratory studies of long chain alkanes are reviewed,the kinetic data,reaction mechanism,SOA yields,and physicochemical properties of SOA are included in detail;(3)the research progress related to model simulations of long-chain alkanes are also discussed.In addition,based on available research results,several perspective contents are proposed that can be used as a guideline for future research plans.

关键词： Long-chain alkanes Detection methods field observation Laboratory study Model simulation

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Local scour at offshore windfarm monopile foundations: A review

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Water Science and Engineering 2022年第1期15卷 29-39页

作者： Da-wei Guan Yu-xuan Xie Zi-shun Yao Yee-Meng Chiew Ji-sheng Zhang Jin-hai Zheng Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing 210098China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Department of Civil and Environmental Engineering The University of AucklandAuckland 1142New Zealand School of Civil and Environmental Engineering Nanyang Technological UniversitySingapore 639798Singapore

In this article,current research findings of local scour at offshore windfarm monopile foundations are presented.The scour mechanisms and scour depth prediction formulas under different hydrodynamic conditions are summarized,including the current-only condition,wave-only condition,combined wave-current condition,and complex dynamic condition.Furthermore,this article analyzes the influencing factors on the basis of classical equations for predicting the equilibrium scour depth under specific conditions.The weakness of existing researches and future prospects are also discussed.It is suggested that future research shall focus on physical experiments under unsteady tidal currents or other complex loadings.The computational fluid dynamics-discrete element method and artificial intelligence technique are suggested being adopted to study the scour at offshore windfarm foundations.

关键词： Offshore windfarm Monopile foundation Scour mechanisms Scour depth prediction Numerical modeling field observation Artificial intelligence Literature review

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Shanghai center project excavation induced ground surface movements and deformations

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Frontiers of Structural and Civil Engineering 2018年第1期12卷 26-43页

作者： Guolin XU Jiwen ZHANG Huang LIU Changqin REN Department of Civil Engineering Southwest Forestry University Kunming 650224 China Department of Civil Engineering University of Kentucky Lexington KY 40506-0281 USA Shanghai Geotechnical Investigations & Design Institute Company Limited Shanghai 200032 China

Empirical data on deep urban excavations can provide designers a significant reference basis for assessing potential deformations of the deep excavations and their impact on adjacent structures. The construction of the Shanghai Center involved excavations in excess of 33-m-deep using the top-down method at a site underlain by thick deposits of marine soft clay. A retaining system was achieved by 50-m-deep diaphragm walls with six levels of struts. During construction, a comprehensive instrumentation program lasting 14 months was conducted to monitor the behaviors of this deep circular excavation. The following main items related to ground surface movements and deformations were collected：（1） walls and circumferential soils lateral movements; （2） peripheral soil deflection in layers and ground settlements; and （3） pit basal heave. The results from the field instrumentation showed that deflections of the site were strictly controlled and had no large movements that might lead to damage to the stability of the foundation pit. The field performance of another 21 cylindrical excavations in top-down method were collected to compare with this case through statistical analysis. In addition, numerical analyses were conducted to compare with the observed data. The extensively monitored data are characterized and analyzed in this paper.

关键词： deep excavation foundation pit soft clay top-down method field observation ground surface movements,ground deformations

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Progress in Marine Meteorology Studies in China during 1999-2002

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Advances in Atmospheric Sciences 2004年第3期21卷 485-496页

作者：王东晓秦曾灏施平 Laboratory for Tropical Marine Environmental Dynamics South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301 Guangzhou Institute of Tropical and Marine Meteorology China Meteorological Administration Guangzhou 510080 Shanghai Typhoon Institute China Meteorological Administration Shanghai 200030 Laboratory for Tropical Marine Environmental Dynamics South China Sea Institute of Oceanology Chinese Academy of Sciences Guangzhou 510301he progresses of marine meteorology studies achieved in China during the four year period from 1999 to 2002 are summarized in six directions: air-sea flux marine meteorology in high latitudes marine disasters connection between ocean and weather/climate in China remote sensing applications and new methodologies in marine meteorology. Compared to the previous ones these studies adopted much more first-hand datasets and more scientific issues were involved. As an exciting remark there were so many contributions done by the young scientists. A brief statement about the research strategy of marine meteorology in China for the coming years is also given.

The progresses of marine meteorology studies achieved in China during the four year period from 1999 to 2002 are summarized in six directions: air-sea flux, marine meteorology in high latitudes, marine disasters, connection between ocean and weather/climate in China, remote sensing applications and new methodologies in marine meteorology. Compared to the previous ones, these studies adopted much more first-hand datasets, and more scientific issues were involved. As an exciting remark, there were so many contributions done by the young scientists. A brief statement about the research strategy of marine meteorology in China for the coming years is also given.

关键词： marine meteorology China field observation marine disaster remote sensing application

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On-line Measurement of Water-Soluble Ions in Ambient Particles

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Advances in Atmospheric Sciences 2006年第4期23卷 586-592页

作者：温天雪王跃思张士昱刘广仁 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC) Institute of Atmospheric Physics Chinese Academy of Sciences Environment Change Research Centre Taipei

Combining the system of rapid collection of ambient particles and ion chromatography, the system of rapid collection of fine particles and ion chromatography （RCFP-IC） was established to automatically analyze on-line the concentrations of water-soluble ions in ambient particles. Here, the general scheme of RCFP-IC is described and its basic performance is tested. The detection limit of RCFP-IC for SO4^2-, NO3^-, NO2^-, Cl^- and F- is below 0.3μg m^-3. The collection efficiency of RCFP-IC increases rapidly with increasing sized particles. For particles larger than 300 nm, the collection efficiency approaches 100%. The precision of RCFP-IC is more than 90% over 28 repetitions. The response of RCFP-IC is very sensitive and no obvious cross-pollution is found during measurement. A comparison of RCFP-IC with an integrated filter measurement indicates that the measurement of RCFP-IC is comparable in both laboratory experiments and field observations. The results of the field experiment prove that RCFP-IC is an effective on-line monitoring system and is helpful in source apportionment and pollution episode monitoring.

关键词： RCFP-IC water-soluble ions on-line basic performance field observation

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field measurement of the organic peroxy radicals by the low-pressure reactor plus laser-induced fluorescence spectroscopy

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Chinese Chemical Letters 2020年第10期31卷 2799-2802页

作者： Shule Li Keding Lu Xuefei Ma Xinping Yang Shiyi Chen Yuanhang Zhang State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China

A low-pressure reactor(LPR) was developed for the measurement of ambient organic peroxy(RO2)radicals with the use of the laser-induced fluorescence(LIF) instrument.The reactor converts all the RO_(x)(=RO2+HO2+RO+OH) radicals into HO2 radicals.It can conduct different measurement modes through altering the reagent gases,achieving the speciated measurement of RO2 and RO2^#(RO2 radicals derived from the long-chain alkane,alkene and aromatic hydrocarbon).An example of field measurement results was given,with a maximum concentration of 1.88 × 10^(8) molecule/cm^(3) for RO2 and 1.18×10^(8) molecule/cm^(3) for RO2^(#).Also,this instrument quantifies the local ozone production rates directly,which can help to deduce the regional ozone control strategy from an experimental perspective.The new device can se rve as a potent tool for both the explo ration of frontier chemistry and the diagnosis of the control strategies.

关键词： Organic peroxy radicals Flow tube reactor LIF RO_(2)measurement field observation Ozone production rate

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