检索结果-南通市图书馆

Experimental study on characteristics of trapping and regulating sediment with an open-type check dam in debris flow hazard mitigation

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2018年第9期15卷 2001-2012页

作者： SUN Hao YOU Yong LIU Jin-feng Key laboratory of Mountain Hazards and earth surface process Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu 610041China University of Chinese Academy of Sciences Beijing 100049China

Beam dams are a highly effective and commonly used open-type check dam in debris-flow hazard mitigation. In this study, dimensional analysis was used to obtain empirical equations for quantitatively determining the sediment-trapping and flow-regulating characteristics of a beam dam. To determine the coefficients of the empirical equations, flume experiments were conducted to simulate the trapping and regulating processes. The flow pattern, trapping, and regulating characteristics were investigated when debris flows passed through a beam dam. Debris-flow bulk density and peak discharge, and sediment-trapping ratios, were measured directly and indirectly. The results showed that three blocking actions occurred, and that blockage-breaking considerably influenced the trapping and regulating performance of the beam dam. The relative opening size and the sediment concentration were the two main factors affecting the performance of the beam dam. The ratio of trapping sediment decreased with relative opening, and increased with sediment concentration as well as reducing ratio of bulk density and reducing ratio of peak discharge. The sediment concentration and relative opening were the leading factors influencing the trapping and regulating sediment of a beam dam, followed by flume gradient. The results showed that the calculated values obtained using empirical equations were in good agreement with the values derived from the experiments, and that the deviation was acceptable. Finally, taking Zechawa Gully as an example, using the empirical equations we designed the opening size of a beam dam aimed to trap sediment and regulate peak discharge of debris flow in the main gully.

关键词： Debris flow Beam dam Flumeexperiment Trapping and regulating

A method characterizing urban expansion based on land cover map at 30 m resolution

在线全文

学校读者我要写书评

暂无评论

Science China earth Sciences 2016年第9期59卷 1738-1744页

作者： YU Xi ZHANG BingQi LI Qiang CHEN Jin College of Resources Science and Technology Beijing Normal University State Key laboratory of earth surface process and Resources Ecology Beijing Normal University

Based on the global land cover data at 30 m resolution(Globe Land30) in the year 2000 and 2010, the urban expansion process of 320 cities in China was analyzed using lognormal regression, and the expansion model were established. Three metrics were presented for the models, including the peak position, the full width at half maximum, and the skewness. It was found that the three metrics could reveal different patterns of the urban expansion process of cities with different sizes. Specifically, cities with larger size tend to expand outward strongly, and their expansion intensity and influence are likely to be higher. Moreover, most cities' expansion occurs around the urban core with spatially limited influence. In addition, it was also found that the city's expansion intensity is related to the city size. These results showed that the lognormal regression model could describe the distribution of urban expansion with effectiveness and robustness.

关键词： Urbanization Urban expansion Remote sensing Lognormal distribution Characteristic metrics Global land cover map

The Optimal Cross-section Design of the “Trapezoid-V” Shaped Drainage Canal of Viscous Debris Flow

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2011年第1期8卷 103-107页

作者： YOU Yong Key laboratory of Mountain Hazards and earth surface process Chinese Academy of Sciences Chengdu 610041 China Institute of Mountain Hazards and environment Chinese Academy of Sciences Chengdu 610041 China

Debris flow drainage canal is one of the most widely used engineering measures to prevent and manage debris flow *** shape and the sizes of the cross-section are important parameters when design debris flow drainage ***,how to design the appropriate shape and sizes of the cross-section so that the drainage canal can have the optimal drainage capacity is very important and few researched at home and *** study was conducted to analyze the hydraulic condition of a Trapezoid-V shaped drainage canal and optimize its *** assuming characteristic sizes of the cross-section,the paper deduced the configuration parameter of the cross-section of a Trapezoid-V shaped debris flow drainage *** theory analysis,it indicates that the optimal configuration parameter is only related to the side slope coefficient and the bottom transverse slope *** this study,the Heishui Gully,a first-order tributary of the lower Jinsha River,was used as an example to design the optimal cross-section of the drainage canal of debris flow.

关键词： Optimal cross-section design Trapezoid- V shaped Drainage canal Viscous debris flow

Effects of spillway types on debris flow trajectory and scour behind a sabo dam

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2016年第2期13卷 203-212页

作者： CHEN Hua-yong CUI Peng CHEN Jian-gang TANG Jin-bo Key laboratory of Mountain Hazards and earth surface process CAS Chengdu 610041 China Institute of Mountain Hazards and environment CAS Chengdu 610041 China CAS Center for Excellence in Tibetan Plateau earth Sciences Beijing 100101 China

Debris flows are one of the common natural hazards in mountainous *** often cause devastating damage to the lives and property of local *** sabo dam construction along a debris flow valley is considered to be a useful method for hazard *** work has concentrated on the different types of sabo dams such as close-type sabo dam,open-type sabo ***,little attention has been paid to the spillway structure of sabo *** the paper,a new type of spillway structure with lateral contraction was *** flow patterns under four different spillway structures were *** projection theory was employed to predict trajectory of debris flow out from the spillway and to estimate the incident angle and terminal velocity before it plunged into the scour hole behind the sabo *** results indicated that the estimated data were in good agreement with the experimental *** discrepancy between the estimated and experimental values of main parameters remained below 21.82%(relative error).Additionally,the effects of debris flow scales under different spillway structures were considered to study the scour *** the debris flow pattern and scour law behind the sabo dam under different operating conditions was analyzed in this paper,further study on the scour mechanism andthe maximum scour depth estimation based on scour theory is still required in the future.

关键词： Debris Flow Spillway Sabo dam Flow trajectory Velocity Scour

Cloud-Base Distribution and Cirrus Properties Based on Micropulse Lidar Measurements at a Site in Southeastern China

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2015年第7期32卷 991-1004页

作者： Jianjun LIU Zhanqing LI ZHENG Youfei Maureen CRIBB State laboratory of earth surface process and Resource Ecology and College of Global Change and earth System Science Beijing Normal University earth System Science Interdisciplinary Center University of Maryland Jiangsu Key laboratory of Atmospheric environment Monitoring and Pollution Control Nanjing University of Information Science and Technology

The cloud fraction （CF） and cloud-base heights （CBHs）, and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time. Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05 ± 2.73 km, 2.46 ± 2.08 kin, and 3.51 ± 3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ～36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89 ± 1.65 km, 9.80 ± 1.70 kin, 10.73 ± 1.86 km and 1.83± 0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ～ 25 ± 17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34 ± 0.33. Sub-visual, thin, and dense cirrus were observed in ～12%, 43%, and 45% of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.

关键词： cloud-base distribution cirrus propertfes lidar southeastern China

Modelling spatial variation in the treatment costs of nonpoint source pollution in mountainous regions of southwest China

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2019年第8期16卷 1901-1912页

作者： LIU Ju FU Bin ZHANG Cheng-hu WANG Yu-kuan Key laboratory of environment Change and Resources Use in Beibu Gulf(Ministry of Education) Key Laboratory of Earth Surface Process and Intelligent SimulationNanning Normal UniversityNanning 530001China Institute of Mountain Hazards and environment Chinese Academy of SciencesChengdu 610041China

Non-point source(NPS) pollution is considered to be one of the main threats of the aquatic environment. Mountainous regions are particularly important water sources for urban areas. The various driving factors of NPS pollution such as terrain, precipitation, and vegetation type in mountainous regions show clear spatial heterogeneity. Consequently, the management systems required for NPS pollution in mountainous regions are complex. In this study, we developed a framework to estimate and map the treatment costs for NPS pollution in mountainous regions and applied this method in Baoxing County, a typical mountainous county in Sichuan Province of southwest China. The export levels of total nitrogen(TN) and total phosphorus(TP) in Baoxing County were estimated using the water purification model in InVEST(Itegrated Valuation of Ecosystem Services and Tradeoffs) tool. NPS pollutant treatment costs were calculated based on the level of pollutants exports, water yield, water quality targets, and treatment costs of NPS pollutants per unit mass. The results show that at the watershed level the amounts of TN and TP exported in Baoxing County were below threshold limits. However, at the sub-watershed level, TN and TP excesses of 291.64 and 2.96 tons per year were found, respectively, with mean TN and TP treatment costs of 6.58 US$/hm^2 and 0.35 US$/hm^2. Appraising pollution treatment cost intuitively reflects the overall expenditure in NPS pollution reduction from an economic perspective. This study provides a foundation for the implementation of Payment for Ecosystem Service(PES) and the prevention and control of NPS pollution.

关键词： Nonpoint source pollution Water treatment cost Water purification model InVEST Tool Export coefficient Spatial variation

Analyses of Extreme Climate Events over China Based on CMIP5 Historical and Future Simulations

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2014年第5期31卷 1209-1220页

作者： YANG Shili FENG Jinming DONG Wenjie CHOU Jieming State Key laboratory of earth surface process and Resource Ecology Beijing Normal University Key laboratory of Regional Climate–environment for East Asia Institute of Atmospheric PhysicsChinese Academy of Sciences College of Global Change and earth System Science Beijing Normal University

Based on observations and 12 simulations from Coupled Model Intercomparison Project Phase 5 （CMIP5） models, cli- matic extremes and their changes over China in the past and under the future scenarios of three Representative Concentration Pathways （RCPs） are analyzed. In observations, frost days （FD） and low-temperature threshold days （TN10P） show a de- creasing trend, and summer days （SU）, high-temperature threshold days （TX90P）, heavy precipitation days （R20）, and the contribution of heavy precipitation days （P95T） show an increasing trend. Most models are able to simulate the main char- acteristics of most extreme indices. In particular, the mean FD and TX90P are reproduced the best, and the basic trends of FD, TN10P, SU and TX90P are represented. For the FD and SU indexes, most models show good ability in capturing the spatial differences between the mean state of the periods 1986--2005 and 1961-80; however, for other indices, the simulation abilities for spatial disparity are less satisfactory and need to be improved. Under the high emissions scenario of RCP8.5, the century-scale linear changes of the multi-model ensemble （MME） for FD, SU, TN10P, TX90P, R20 and P95T are -46.9, 46.0, -27.1, 175.4, and 2.9 days, and 9.9%, respectively; and the spatial change scope for each index is consistent with the emissions intensity. Due to the complexities of physical process pararneterizations and the limitation of forcing data, great uncertainty still exists with respect to the simulation of climatic extremes.

关键词： extreme climate China CMIP5 RCPs

A preliminary study of the failure mechanisms of cascading landslide dams

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2015年第3期30卷 223-234页

作者： Gordon G.D Peng Cui Xinghua Zhu Jinbo Tang Huayong Chen Qicheng Sun Key laboratory of Mountain Hazards and earth surface process/Institute of Mountain Hazards and environment Chinese Academy of Sciences(CAS) CAS Center for Excellence in Tibetan Plateau earth Sciences State Key laboratory for Hydroscience and Engineering Tsinghua University

Landslide dams commonly form when mass earth or rock movements reach a river channel and cause a complete or partial blockage of the *** rainfalls can induce upstream flows along a sloping channel that significantly affect downstream landslide *** a series of landslide dams are collapsed by incoming mountain torrents(induced by intense rainfall),large debris flows can form in a very short ***,the failure of these dams can amplify the magnitude and scale of debris flows in the flow *** catastrophic debris flows that occurred in Zhouqu County,China on 8 August 2010 were caused by intense rainfall and the upstream cascading failure of landslide dams along the *** the role of outburst floods associated with the complete or partial failure of landslide dams is an interesting problem usually beyond the scope of analysis because of the inherent modeling *** understand the cascading failure modes of a series of landslide dams,and the dynamic effect these failures have on the enlargement of debris flow scales,experimental tests are conducted in sloping channels mimicking field conditions,with the modeled landslide dams distributed along a sloping channel and crushed by different upstream *** failure modes of three different cascades of landslide dams fully or partially blocking a channel river are parametrically *** study illustrates that upstream flows can induce a cascading failure of the landslide dams along a *** is the primary failure mechanism,while piping and erosion can also induce failures for different constructed landslide dams.A cascading failure of landslide dams causes a gradually increasing flow velocity and discharge of the front flow,resulting in an increase in both diameter and percentage of the entrained coarse ***,large landslide blockages can act to enhance the efficiency of river incision,or conversely to induce aggradation of fluvial se

关键词： Cascading failure Landslide dam Upstream flow Failure mode Landscape evolution Debris flow

Dynamic process simulation with a Savage-Hutter type model for the intrusion of landslide into river

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Mountain Science 2016年第7期13卷 1265-1274页

作者： LIU Wei He Si-ming Ou Yang Chao-jun Key laboratory of Mountain Hazards and surface process Chinese Academy of Science Institute of Mountain Hazards and environment Chinese Academy of Sciences Center for Excellence in Tibetan Plateau earth Sciences Chinese Academy of Sciences

Natural damming of rivers by mass movements is a very common and potentially dangerous phenomena which has been documented all over the world. In this paper, a two-layer model of Savage-Hutter type is presented to simulate the dynamic procedure for the intrusion of landslide into rivers. The two-layer shallow water system is derived by depth averaging the incompressible Navier-Stokes equations with the hydrostatic assumption. A high order accuracy scheme based on the finite volume method is proposed to solve the presented model equations. Several numerical tests are performed to verify the realiability and feasibility of the proposed model. The numerical results indicate that the proposed method can be competent for simulating the dynamic process of landslide intrusion into the river. The interaction effect between both layers has a significant impact on the landslide movement, water fluctuation and wave propagation.

关键词： Landslide Two-layer model Savage Hutter type Numerical simulation