检索结果-南通市图书馆

Stochastic modelling of soil moisture dynamics in a grassland of Qilian Mountain at point scale

Science china Earth sciences 2007年第12期50卷 1844-1856页

作者： LIU Hu,ZHAO WenZhi HE ZhiBin & ZHANG LiJie Linze Inland River Basin research Station,chinese Ecosystem research Network Laboratory of Watershed Hydrology and Ecol-ogy,cold and arid regions environmental and engineering research institute,chinese academy of sciences,lanzhou 730000,china Linze Inland River Basin research Station Chinese Ecosystem Research Network China Laboratory of Watershed Hydrology and Ecology Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China

Stochastic modeling of soil moisture dynamics is crucial to the quantitative understanding of plant responses to water stresses,hydrological control of nutrient cycling processes,water competition among plants,and some other ecological dynamics,and thus has become a hotspot in ecohydrology at *** this paper,we based on the continuously monitored data of soil moisture during 2002―2005 and daily precipitation date of 1992―2006,and tried to make a probabilistic analysis of soil moisture dynamics at point scale in a grassland of Qilian Mountain by integrating the stochastic model improved by Laio and the Monte Carlo *** results show that the inter-annual variations for the soil moisture patterns at different depths are very significant,and that the coefficient of variance(CV) of surface soil moisture(20 cm) is almost continually kept at about 0.23 whether in the rich or poor rainy ***,it has been found that the maximal CV of soil moisture has not always appeared at the surface *** of the analytically derived soil moisture probability density function(PDF) with the statistical distribution of the observed soil moisture data suggests that the stochastic model can reasonably describe and predict the soil moisture dynamics of the grassland in Qilian Mountain at point *** extracting the statistical information of the historical precipitation data in 1994―2006,and inputting them into the stochastic model,we analytically derived the long-term soil moisture PDF without considering the inter-annual climate fluctuations,and then numerically derived the one when considering the inter-annual fluctuation effects in combination with a Monte-Carlo *** was found that,though the peak position of the probability density distribution significantly moved towards drought when considering the disturbance forces,and its width was narrowed,accordingly its peak value was increased,no significant bimodality was observed in the soil moistur

关键词： soil moisture dynamics, stochastic modelling, Monte Carlo method, probability density function, grassland ecosystem

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Vicissitude of Sogo Nur and environmental-climatic change during last 1500 years

引用

Science china Earth sciences 2004年第z1期47卷 61-70页

作者： JIN Heling, XIAO Honglang, SUN Liangying, ZHANG Hong, SUN Zhong & LI XiaozeKey Laboratory of Desert and Desertification, cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china School of Resources and Environment, lanzhou University, lanzhou 730000, china Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China School of Resources and Environment Lanzhou University Lanzhou China

Lakes in arid zone are sensitive to climatic changes. The lacustrine sediment sequence in Sogo Nur has well and truly recorded climatic events such as the Sui-Tang Dynasty Warm Period, the Song-Liao Dynasty cold Period, the Medieval Warm Period, the Little Ice Age and the 20th Century Warm Period. Commonly, the climate in warm Periods was relatively humid,accordingly the lake area extended and water level rose, and vice versa. Apart from climatic change, human activity is also an important factor of influencing lake vicissitude, and they played the dominant role alternatively during different periods; the factor of climatic change predominated in historical period, while since the beginning of the 20th century the utilization of water resources by human has became decisive.

关键词： granularity, soluble salt, lake vicissitude, climatic change, Sogo Nur.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Impact of land-use change on hydrological processes in the Maying River basin, china

引用

Science china Earth sciences 2006年第10期49卷 1098-1110页

作者： WANG Genxu1,3, ZHANG Yu2, LIU Guimin2 & CHEN Lin3 1. institute of Mountain Hazards and Environment, chinese academy of sciences, Chengdu 610041, china 2. cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china 3. Resource and Environment School, lanzhou University, lanzhou 730000, china institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China Resource and Environment School Lanzhou University Lanzhou China cold and arid regions environmental and engineering research institute Chinese Academy of Sciences Lanzhou China

Since the 1960s, dramatic changes have taken place in land-use patterns characterized by the persistent expansion of cultivated land and a continuous decrease in natural woodland and grassland in the arid inland river basins of china. It is very important to assess the effects of such land-use changes on the hydrological processes so vital for water resource management and sustainable development on the catchment scale. The Maying River catchment, a typical arid inland watershed located in the middle of the Hexi Corridor in northwest china, was the site chosen to investigate the hydrological responses to land-use changes. The annual runoff, base flow, maximum peak flow, and typical seasonal runoff in both spring and autumn flood periods were selected as the variables in the hydrological processes. Statistical-trend analysis and curvilinear regression were utilized to detect the trends in hydrological variables while eliminating the climatic influence. The relationship between cultivated land-use and hydrological variables was analyzed based on four periods of land-use variation data collected since 1965. A runoff model was established composed of two factors, i.e., cultivated land use and precipitation. The impact of land use changes, especially in the large ar- eas of upstream woodland and grassland turned into cultivated lands since 1967, has resulted in a mean annual runoff decrease of 28.12%, a base flow decline of 35.32%, a drop in the maximum peak discharge of 35.77%, and mean discharge decreases in spring and autumn of 36.05% and 24.87% respectively, of which the contribution of cultivated land expansion to the influence of annual runoff amounts to 77%-80%, with the contribution to the influence of spring discharge being 73%-81%, and that to the influence of base flow reaching 62%-65%. Thus, a rational regulation policy of land use patterns is vitally important to the sustainable use of water resources and the proper development of the entire catchment.

关键词： land-use change, arid inland river catchment, hydrological process, impact, Maying River.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Impacts of permafrost changes on alpine ecosystem in Qinghai-Tibet Plateau

引用

Science china Earth sciences 2006年第11期49卷 1156-1169页

作者： WANG Genxu1,3 , LI Yuanshou2 , WU Qingbai2 & WANG Yibo3 1. institute of Mountain Hazards and Environment, chinese academy of sciences, Chengdu 610041, china 2. cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china 3. Resource and Environment School, lanzhou University, lanzhou 730000, china institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China Resource and Environment School Lanzhou University Lanzhou China cold and arid regions environmental and engineering research institute Chinese Academy of Sciences Lanzhou China

Alpine cold ecosystem with permafrost environment is quite sensitive to climatic changes and the changes in permafrost can significantly affect the alpine ecosystem. The vegetation coverage, grassland biomass and soil nutrient and texture are selected to indicate the regime of alpine cold ecosystems in the Qinghai-Tibet Plateau. The interactions between alpine ecosystem and permafrost were investigated with the depth of active layer, permafrost thickness and mean annual ground temperature (MAGTs). Based on the statistics model of GPTR for MAGTs and annual air temperatures, an analysis method was developed to analyze the impacts of permafrost changes on the alpine ecosystems. Under the climate change and human engineering activities, the permafrost change and its impacts on alpine ecosystems in the permafrost region between the Kunlun Mountains and the Tanggula Range of Qinghai-Tibet Plateau are studied in this paper. The results showed that the per- mafrost changes have a different influence on different alpine ecosystems. With the increase in the thickness of active layer, the vegetation cover and biomass of the alpine cold meadow exhibit a significant conic reduction, the soil organic matter content of the alpine cold meadow ecosystem shows an exponential decrease, and the surface soil materials become coarse and gravelly. The alpine cold steppe ecosystem, however, seems to have a relatively weak relation to the permafrost environment. Those relationships resulted in the fact that the distribution area of alpine cold meadow decreased by 7.98% and alpine cold swamp decreased by 28.11% under the permafrost environment degradation during recent 15 years. In the future 50 years the alpine cold meadow ecosystems in different geomorphologic units may have different responses to the changes of the permafrost under different climate warming conditions, among them the alpine cold meadow and swamp ecosystem located in the low mountain and plateau area will have a relatively

关键词： permafrost environment, alpine cold ecosystem, statistics relationship, climate change, impacts, Qinghai-Tibet Plateau.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

research progress of desert science in china

引用

chinese Science Bulletin 2000年第24期45卷 2209-2213页

作者： XIA Xuncheng & FAN ShengyueXinjiang institute of Ecology and Geography, chinese academy of sciences, Urumqi 830011, china cold and arid Region Environment and engineering research institute. chinese academy of sciences, lanzhou 730000. china Xinjiang institute of Ecology and Geography Chinese Academy of Sciences Urumqi China cold and arid Region Environment and engineering research Instiute Chinese Academy of Sciences Lanzhou China

research of desert science in china began in the 1930s, when Chen Zongqi et al. first made apreliminary investigation in several deserts. Shortly after the founding of the People’s Republic ofchina a few studies were carried out to meet the demand for the establishment of windbreak andsandbreak forests, for example, the studies of moving sand dunes in Yulin. Jingbian and Dingbianregions of Shaanxi Province. However, the comprehensive study of desert science in china

关键词： research progress of desert science in china

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Temperature variations recovered from tree-rings in the middle Qilian Mountain over the last millennium

引用

Science china Earth sciences 2005年第4期48卷 521-529页

作者： LIU Xiaohong1,2, QIN Dahe1, SHAO Xuemei , CHEN Tuo1 & REN Jiawen12 1. cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china 2. institute of Geographical sciences and Natural Resources research, chinese academy of sciences, Beijing 100101, china cold and arid regions environmental and engineering research institute Chinese Academy of Sciences Lanzhou China institute of Geographical sciences and Natural Resources research Chinese Academy of Sciences Beijing China

Based on the cross-dated tree-ring samples collected from the middle Qilian Moun- tain, a standard ring-width chronology had been developed, which covered the period AD 1000 to 2000. The correlations between the chronology and climatic records from the nearby meteorological stations indicated that temperature was the dominant climatic factor for tree growth at upper timberline, and the most important climatic factor for the tree growth in the area was the mean temperature from previous December to current April. The temperature variations recovered from the ring-width data showed a cold period during the “Little Ice Age” and the con- tinuous warming during the twentieth century. Comparison between the ring-width chronology and δ18O records from the Dunde ice core in the Qilian Mountain indicated that there was a con- sistent trend in both time series. A significant correlation existed between our ring-width chro- nology and the Northern Hemispheric temperature, suggesting that the climate changes in the Qilian Mountain were not only driven by regional factors, but also responsive to the global cli- mate.

关键词： middle Qilian Mountain, tree-ring width chronology, temperature variations.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Responses of distribution pattern of desert riparian forests to hydrologic process in Ejina oasis

引用

Science china Earth sciences 2004年第z1期47卷 21-31页

作者： ZHAO Wenzhi, CHANG Xueli & HE ZhibinLinze Inland River Basin Comprehensive research Station, cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china Yantai Normal University, Yantai 264005, china Linze Inland River Basin Comprehensive research Station Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China Yantai Normal University Yantai China

By using the theories and methods of landscape ecology and the technology of GIS and RS, a study has been carried out on the responses of distribution pattern of desert riparian forest to hydrologic process on the basis of the hydrologic data from 1990 to 2000 and the TM image of 2001 year. The results showed that: (1) there appears an even distribution pattern for the relative forest area in oasis, however, the degenerated forest diaplays an increasing tendency from west to east; (2) the desert riparian forest in Ejina is in completely degenerated process at the patch scale; (3) the number of patch is influenced not only by hydrologic process,but also by agricultural activity such as cultivation. The severe deterioration of the degraded vegetation in whole oasis initiates from lower reaches, and gradually impels to upstream; the fragmentation of landscape in the terminal site is more obvious, which is influenced by river shape and decreasing flux of water. It is found that the influence of surface hydrologic process to the ground hydrologic process of desert riparian forest in Ejina oasis is little for the recent ten years. The relative area of the degenerated forest increased with increasing ground water depth in the direction of parallel to river channel. On the contrary, in the direction perpendicular to river channel, there is a decreasing tendency for the average patch area of the forest and the degenerated forest with increasing ground water depth.

关键词： Ejina oasis, desert riparian forests, vegetation pattern, hydrologic process.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Progress in studies of the climate of humid period and the impacts of changing precession in early-mid Holocene

引用

Progress in Natural Science:Materials International 2008年第12期18卷 1459-1464页

作者： Jianbin Huang~a Shaowu Wang~a Xinyu Wen~a Bao Yang~b a Department of Atmospheric sciences,School of Physics,Peking University,Beijing 100871,china b Laboratory for Desert and Desertification,cold and arid regions environmental and engineering research institute,chinese academy of sciences,lanzhou 730000,china Department of Atmospheric sciences School of Physics Peking University Beijing 100871 China Laboratory for Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Studies on the climate of humid period and the impacts of changing precession in the early-mid Holocene are reviewed in this paper. High-resolution proxy data indicated that the African Humid Period,strong summer monsoon from the Arabian Sea to South Asia, northward migration of ITCZ (lntertropical Convergence Zone) over the northern South America,and the humid period of china appeared in 10.5-5.5 kaBP,10.0-6.0 kaBP,10.5 5.4 kaBP,and 11.0-8.0 kaBP,*** studies proved that summer inso- lation over the Northern Hemisphere increased following the changes of precession in the early Holocene,which increased the land-sea temperature contrasts,intensified the summer monsoon circulation in the Northern Hemisphere,and finally induced a humid climate over the area under the influence of summer ***,modeling results underestimated the increase of precipitation and the degree of northward extension of monsoon rain belt compared with palaeo-environmental *** discrepancies between the modeling results and the palaeo-environmental data may be associated with the changes of North Atlantic circulation,sea ice and veg- etation ***,climate of the humid period was not stable,in which several droughts were inlaid on centennial *** this review,perspectives for further studies of the climate change of the humid period in the early-mid Holocene are also proposed.

关键词： Holocene Humid period Precession Summer monsoon

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Heat transfer process of roadway embankments with different type and width of road surface in permafrost regions

引用

Progress in Natural Science:Materials International 2007年第3期17卷 314-319页

作者： YU Qihao, PAN Xicai, CHENG Guodong and BAI Yang (State Key Laboratory of Frozen Soil engineering, cold and arid regions Environment and engineering research institute, chinese A-cademy of sciences, lanzhou 730000, china) State Key Laboratory of Frozen Soil engineering Cold and Arid Regions Environment and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

The stability of roadbed in permafrost areas has become a big concern with rapid development and construction of throughways, highways and railways in these areas under the current climate change since it is governed by the thermal condition, or in other words, the heat transfer process in the embankment. We carried out a finite element analysis to analyze the effects of different types of road surface and the effect of breadth of embankment on the embankment heat transfer process. The results indicated that the mean annual heat transfer rate at the bottom of the roadway embankment with asphalt surfaces is 3 times that with sandy gravel surfaces. This means annual heat transfer rate increased by 60% when the breadth of asphalt surface was doubled. The increased heat transfer rate was mainly located at the bottom of the embankment and resulted in the effect of thermal concentration,. leading to degradation of the permafrost by as much as 1.6 times. It was also found that increasing embankment height would not reduce these increases of the heat transfer rate. Therefore both asphalt road surface and increased embankment breadth can lead to an intensified heat transfer rate in roadway embankment, consequently degradating the underlying permafrost and embankment instability.

关键词： wide road surface roadway embankment permafrost regions process of heat transfer heat flux ground temperature field.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Characteristics of ^(137)Cs deposition in steppe area

引用

chinese Science Bulletin 2002年第10期47卷 848-853页

作者： ZHANG Chunlai, ZOU Xueyong,DONG Guangrong, ZHANG Xinbao & QIN ZhiLaboratory of Blown Sand Physics and engineering, cold and arid regions environmental and engineering research institute, chinese academy of sciences, lanzhou 730000, china china Center of D Laboratory of Blown Sand Physics and engineering Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China china Center of Desert research at Beijing Normal University Key Laboratory of Environmental Change and Natural Disaster of the Ministry of Education of China Beijing Normal University Beijing China institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu China institute of Modern Physics Chinese Academy of Sciences Lanzhou China

Soil wind erosion in the semiarid steppe area was studied using the 137Cs tracing technique. Comparisons of 137Cs deposition characteristics between different soil profiles indicated that slight aeolian activities occurred on sandy grasslands and semi-fixed dunes with erosion/deposition rates of less than 0.108 cm/a, whereas they were intense on semi-shifting dunes with erosion/deposition rates of higher than 1.35 cm/a.

关键词： 137Cs steppe soil wind erosion.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：