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Modeling effects of temperature and precipitation on carbon characteristics and GHGs emissions in Abies fabric forest of subalpine

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Journal of Environmental Sciences 2008年第3期20卷 339-346页

作者： LU Xuyang CHENG Genwei XIAO Feipeng fan jihui Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China

Abies fabric forest in the eastern slope of Gongga mountain is one type of subalpine dark coniferous forests of southwestern China. It is located on the southeastern edge of the Qinghai-Tibet plateau and is sensitive to climatic changes. A process-oriented biogeochemical model, Forest-DNDC, was applied to simulate the effects of climatic factors, temperature and precipitation changes on carbon characteristics, and greenhouse gases （GHGs） emissions in A. fabric forest. Validation indicated that the Forest-DNDC could be used to predict carbon characteristics and GHGs emissions with reasonable accuracy. The model simulated carbon fluxes, soil carbon dynamics, soil CO2, N2O, and NO emissions with the changes of temperature and precipitation conditions. The results showed that with variation in the baseline temperature from -2℃ to ＋2℃, the gross primary production （GPP） and soil organic carbon （SOC） increased, and the net primary production （NPP） and net ecosystem production （NEP） decreased because of higher respiration rate. With increasing baseline precipitation the GPP and NPP increased slightly, and the NEP and SOC showed decreasing trend. Soil CO2 emissions increased with the increase of temperature, and CO2 emissions changed little with increased baseline precipitation. With increased temperature and decreased baseline temperature, the total annual soil N2O emissions increased. With the variation of baseline temperature from -2℃ to ＋2℃, the total annual soil NO emissions increased. The total annual N2O and NO emissions showed increasing trends with the increase of precipitation. The biogeochemical simulation of the typical forest indicated that temperature changes strongly affected carbon fluxes, soil carbon dynamics, and soil GHGs emissions. The precipitation was not a principal factor affecting carbon fluxes, soil carbon dynamics, and soil CO2 emissions, but changes in precipitation could exert strong effect on soil N2O and NO emissions.

关键词： carbon characteristics greenhouse gases (GHGs) Forest-DNDC Abies fabric forest

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Distribution Characteristics and Influencing Factors of Geological Hazards in Tibet

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Wuhan University Journal of Natural Sciences 2006年第4期11卷 806-812页

作者： fan jihui WU Caiyan Cheng Genwei Institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu 610041 Sichuan China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Tibet is one of the areas with most serious geological hazards in China, and the distribution of disasters has obvious local charac teristics. Tibet can be classified as three parts through zoning the danger degree, the mountain canyon high danger zone of east and southeast Tibet, the plateau mountain lake basin and valley middle danger zone of south Tibet, and the Plateau Mountain lake basin low danger zone of south Tibet. This paper takes the debris flow, collapse, landslide as the key points to analyze the distribution characteristics of geological hazards, and analyze the factors which influence the distribution of geological hazards, such as terrain landform, formation lithology, geologic structure pattern, precipitation, earthquake, human activity and so on. finally, as a conclusion., in whole Tibet, the geological hazards are more in southeast than in northwest, more in mountainous area which in the edge of plateau and river valley than in the interior of plateau and lake basin. And most hazards distribute in the regions where human activity is stronger than in other regions, for example towns or strips along the highway.

关键词： Tibet geological hazards distribution characteristics influencing factors

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Determining Critical Support Discharge of a Riverhead and River Network Analysis： Case Studies of Lhasa River and Nyangqu River

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Chinese Geographical Science 2016年第4期26卷 456-465页

作者： SHA Yukun LI Weipeng fan jihui CHENG Genwei Key Laboratory of Mountain Surface Process and Ecological Regulation Institute of Mountain Hazard and Environment Chinese Academy of Sciences Chengdu 610041 China University of Chinese Academy of Sciences Beijing 100049 China

A riverhead is the demarcation point of continuous water channel and seasonal channel, which is characterized by a criti- cal flow that can support a continuous water body. In this study, the critical support discharge （CSD） is defined as the critical steady flows required to form the origin of a stream. The CSD is used as the criterion to determine the beginning of the riverhead, which can be controlled by hydro-climate factors （e.g., annual precipitation, annual evaporation, or minimum stream flow in arid season）. The CSD has a close correlation with the critical support/source area （CSA） that largely affects the density of the river network and the division of sub-watersheds. In general, river density may vary with regional meteorological and hydrological conditions that have to be considered in the analysis. In this paper, a new model referring to the relationship of CSA and CSD is proposed, which is based on the physical mechanism for the origin of riverheads. The feasibility of the model was verified using two watersheds （Duilongqu Basin of the Lhasa River and Beishuiqu Basin of the Nyangqu River） in Tibet Autonomous Region to calculate the CSA and extract river networks. A series of CSAs based on different CSDs in derived equation were tested by comparing the extracted river networks with the reference network obtained from a digitized map of river network at large scales. Comparison results of river networks derived from digital elevation model with real ones indicate that the CSD （equal to criterion of flow quantity （Qc）） are 0.0028 m3/s in Duilongqu and 0.0085 m3/s in Beishuiqu. Results show that the Qc can vary with hydro-climate conditions. The Qc is high in humid region and low in arid region, and the optimal Qo of 0.0085 m3/s in Beishuiqu Basin （humid region） is higher than 0.0028 m3/s in Duilongqu Basin （semi-arid region）. The suggested method provides a new application approach that can be used to determine the Qo of a riverhead in complex geographic

关键词： river network extraction Duilongqu Basin of Lhasa River Beishuiqu Basin of Nyangqu River critical support discharge hydro-climate conditions riverhead

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Outburst Risk of Barrier Lakes in Sichuan,China

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Journal of Mountain Science 2008年第3期5卷 189-193页

作者： CHENG Genwei WANG Xiaodan HE Xiubin fan jihui fan Jianrong Institute of Mountain Hazards and Environment CAS Chengdu China 610041

34 barrier lakes induced by earthquake have been formed by wedged debris on the river channels after a massive earthquake happening on May 12 in Sichuan, China. Among them, the Tangjiashan Barrier Lake is the largest one. It faces very urgent risk of dam breaking when water level reaches the top and begins overflow in case of storm rainfalls and continually aftershocks, threatening already devastated cities and villages with about 1.5 million people downstream. The outburst of a similar barrier lake occurred in the Minjiang River in 1933, causing a catastrophic flood. Risk analysis indicates that not all barrier lakes are highly dangerous. Only those lakes with very high dams and water to be filled up in short period need to be dealt with immediately.

关键词： Earthquake Barrier Lake risk estimation aftershock Sichuan China

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Dynamics of Above-and Below-ground Biomass and C,N,P Accumulation in the Alpine Steppe of Northern Tibet

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Journal of Mountain Science 2011年第6期8卷 838-844页

作者： LU Xuyang YAN Yan fan jihui CAO Yingzi WANG Xiaodan Key Laboratory of Mountain Environment Evolvement and Regulation Institute of Mountain Hazards and Environment CAS Chengdu 610o41 China Shenzha Alpine Steppe and Wetland Ecosystem Observation and Experiment Station Institute of Mountain Hazards and Environment CAS Shenzha 85310o China

The temporal dynamics of the biomass, as well as the carbon （C）, nitrogen （N）, phosphorus （P） concentrations and accumulation contents, in above- and below-ground vegetation components were determined in the alpine steppe vegetation of Northern Tibet during the growing season of 2OLO. The highest levels of total biomass （311.68 g m-2）, total C （115.95 g m-2）, total N （2.60 g m-2）, and total P （0.90 g m-2） accumulation contents were obtained in August in 2010. Further, biomass and nutrient stocks in the below-ground components were higher than those of the above-ground components. The dominant species viz., Stipa purpurea and Carex moorcrofli had lower biomass and C, N, P accumulations than the companion species which including Oxytropis. spp., Artemisia capillaris Thunb., Aster tataricus L., and SO on.

关键词： Biomass Nutrient concentration Nutrient accumulation Alpine steppe Northern Tibet

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Incorporating a rainfall intensity modification factorγinto the I a-S Relationship in the NRCS-CN method

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International Soil and Water Conservation Research 2020年第3期8卷 237-244页

作者： Pengcheng Hu Jialiang Tang jihui fan Shumiao Shu Zhaoyong Hu Bo Zhu Key Laboratory of Mountain Environment Evolution and Regulation Institute of Mountain Hazards and EnvironmentChinese Academy of SciencesChengdu610041China University of Chinese Academy of Sciences BeijingChina

The Natural Resources Conservation Service runoff curve number(NRCS-CN)method is widely used to simulate direct runoff,but the impact of rainfall intensity has not been *** this study,a rainfall intensity modification factor(γ)was incorporated into the Ia-S relationship of the NRCS-CN method,and the modified method(NRCS-CN-γ)was compared with the NRCS-CN method withλ=0.2 andλ=0.05 in three watersheds of the Walnut Gulch Experimental Watershed(WGEW).The results showed that for 2016-2018 period,the simulation performance of the NRCS-CN-γmethod was close to the NRCS-CN(λ=0.05)method and better than the NRCS-CN(λ=0.2)*** the new data(2009 data with high variance)was added,the significant improvement was observed by NRCS-CN-γmethod with all the evaluation parameters being the best in the three watersheds,indicating a more adapted capa-bility of the modified method with highly uneven rainfall *** covariance between rainfall intensity and the simulated runoff were 19.01,15.14,and 16.35 for the three methods,*** the optimal CN changed,the relative errors representing CN sensitivity were 6.25,6.49 and 17.39 for the methods,*** is suggested that the NRCS-CN-γmethod outperformed the other two methods and could contribute to a more accurate estimation of direct runoff where rainfall intensity greatly varied,especially in monsoon region or under the context of climate change.

关键词： Climate change Rainfall intensity Runoff NRCS-CN method CN sensitivity

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基于InVEST模型的张家口市水源涵养功能时空差异分析

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草业科学 2020年第7期37卷 1313-1324页

作者：李怡颖范继辉廖莹中国科学院、水利部成都山地灾害与环境研究所/山地表生过程与生态调控重点实验室四川成都610041 中国科学院大学北京100049

张家口市是“首都水源涵养功能区和生态环境支撑区”,对维护区域生态安全具有重要作用。本研究基于InVEST年产水模型,估算了张家口市1981-2015年的产水量、水源涵养量,并对其时空变化特征进行分析。结果表明:1)张家口市多年平均产水深度... 详细信息

张家口市是“首都水源涵养功能区和生态环境支撑区”,对维护区域生态安全具有重要作用。本研究基于InVEST年产水模型,估算了张家口市1981-2015年的产水量、水源涵养量,并对其时空变化特征进行分析。结果表明:1)张家口市多年平均产水深度为42.51 mm,多年平均水源涵养深度为18.16 mm;2)35年来,张家口市产水量呈微弱上升趋势,水源涵养量呈微弱下降趋势,最高值均出现在1995年,最低值均出现在1993年;3)产水深度及水源涵养深度具有明显的空间差异,且分布相似,表现为康保、宣化周围区县增加,沽源、蔚县等减少;4)降水是张家口市产水量、水源涵养量变化的主要影响因素,其次为土地利用方式;5)张家口市多年平均产水量以草地和耕地为主,水源涵养量以草地为主。

关键词： InVEST模型水源涵养量时空分布土地利用气候变化

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基于局部敏感哈希的K邻近算法识别垃圾短信

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济南大学学报（自然科学版） 2023年第6期37卷 746-751页

作者：樊继慧滕少华菲律宾圣保罗大学研究生院土格加劳3500菲律宾广州理工学院计算机科学与工程学院广东广州510540 广东工业大学计算机学院广东广州510006

针对目前垃圾短信的识别算法存在的关键字及频次的规则死板,易于被不法分子探测和规避等问题,提出将局部敏感哈希的K邻近算法应用于垃圾短信分类识别;首先定义特征,然后采用局部敏感哈希算法计算向量距离,通过得到的距离衡量矩阵的相似... 详细信息

针对目前垃圾短信的识别算法存在的关键字及频次的规则死板,易于被不法分子探测和规避等问题,提出将局部敏感哈希的K邻近算法应用于垃圾短信分类识别;首先定义特征,然后采用局部敏感哈希算法计算向量距离,通过得到的距离衡量矩阵的相似性,量化矩阵相似程度,对本文中提出的优化模型进行实现和训练;基于短信文本内容,运用词频-逆向文本频率算法生成矩阵,利用局部敏感哈希算法求解最相似样本,记录样本类别,将训练结果导入K邻近算法分类器得到最优近邻,在测试集或验证集上对优化模型垃圾短信分类识别准确率进行评测。结果表明,经过K邻近算法分类器后,优化模型垃圾短信分类识别准确率达到98.7%。

关键词：垃圾短信识别 K邻近算法局部敏感哈希矩阵相似性

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冻融过程土壤水热力耦合作用及其模型研究进展

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草业科学 2019年第4期36卷 991-999页

作者：冉洪伍范继辉黄菁中国科学院水利部成都山地灾害与环境研究所山地表生过程与生态调控重点实验室四川成都610041 中国科学院大学北京100049 武汉理工大学资源与环境工程学院湖北武汉430070

冻融过程水热力耦合是寒区水文循环的重要内容,是寒区农业、建筑、生态领域需要迫切解决的问题。本研究对冻土冻融过程、水热力耦合机理研究进行了分析:目前对于水分迁移驱动力大多归结于土壤水势梯度,采用土壤水分特征曲线进行求解,但... 详细信息

冻融过程水热力耦合是寒区水文循环的重要内容,是寒区农业、建筑、生态领域需要迫切解决的问题。本研究对冻土冻融过程、水热力耦合机理研究进行了分析:目前对于水分迁移驱动力大多归结于土壤水势梯度,采用土壤水分特征曲线进行求解,但是这种方法并没有考虑土体温度、土体形变以及土壤的物理特性指标。水热力耦合模型实现了水分、温度、应力之间的耦合,但是水分、温度、应力的变化对土壤特征参数的反馈机制并未体现;在多场作用下的分凝冰形成机理是解决土体冻胀的关键,对该问题有待进行深入研究。同时对目前主流的水动力学模型、刚性冰模型、热力学模型3类耦合模型在适用性和准确性方面进行了讨论。最后,针对目前冻融过程水热力耦合研究存在的问题进行分析并提出研究的构想。

关键词：冻融过程水热耦合水动力学模型刚性冰模型热力学模型

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藏北高寒草地土壤冻融过程水热变化特征

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草业科学 2019年第4期36卷 980-990,I0008页

作者：冉洪伍范继辉黄菁中国科学院水利部成都山地灾害与环境研究所/山地表生过程与生态调控重点实验室四川成都610041 中国科学院大学北京100049 武汉理工大学资源与环境工程学院湖北武汉430070

为深入认知藏北高寒草地土壤冻融循环过程,依托申扎高寒草原与湿地生态系统观测试验站,开展了高寒草地土壤剖面水热变化过程监测,基于2015–2016年数据,对藏北高寒草地冻融循环过程中温度、含水率变化特征进行了分析,并探讨了冻融过程... 详细信息

为深入认知藏北高寒草地土壤冻融循环过程,依托申扎高寒草原与湿地生态系统观测试验站,开展了高寒草地土壤剖面水热变化过程监测,基于2015–2016年数据,对藏北高寒草地冻融循环过程中温度、含水率变化特征进行了分析,并探讨了冻融过程与气温、降水的关系。结果表明,土壤剖面各土层温度和含水率均呈准周期性变化,且变化幅度随深度增加而降低;11月初至次年4月底是藏北高寒草地土壤的冻结期,可分为初冻期(11月)、稳定冻结期(12月至2月上旬)、消融前期(2月中旬至3月下旬)和消融后期(3月下旬至4月中旬)4个阶段;观测期土壤冻结的最大深度在160 cm左右;冻结深度上下限和积温呈现出显著的相关关系,含水率和温度变化相互影响,水分在土壤热量传递时有着重要作用。研究结果可为进一步理解冻融水热耦合作用及生态系统对冻融的响应提供理论支持。

关键词：高寒草地冻融过程水热变化藏北高原

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