Land use/land cover change (LUCC) is a focus of the research of global environmental changes. The middle and upper reaches of the Yangtze River, which are the most ecologically fragile mountainous area in China as wel...Land use/land cover change (LUCC) is a focus of the research of global environmental changes. The middle and upper reaches of the Yangtze River, which are the most ecologically fragile mountainous area in China as well as one of the areas in China with most notable LUCC, have been on the Chinese Government's list of priority areas for ecological restoration. This paper is to reveal the trend of LUCC and the ecological degradation arising from it, and to provide a basis for the future sustainable use of land resources in the region based on a detailed analysis of Yiliang County. Based on the county's land use/cover maps in 1960, 1980 and 2000 drawn with the aid of aerial photograph interpretation, field investigation and GIS based spatial-temporal data analysis, LUCC during 1960~2000 period and the ecological degradation arising from it were analyzed. Using the Markv model, the paper brings out a forecast of what the county's LUCC would be like if the county's current land use continues, as well as the reasons and countermeasures for restoring degraded ecosystems.展开更多
In the upper reaches of Yangtze River and other rivers of southwestern China, the debris flows develop and lead to most serious disasters because of the various landforms, complex geological structures and abundant ra...In the upper reaches of Yangtze River and other rivers of southwestern China, the debris flows develop and lead to most serious disasters because of the various landforms, complex geological structures and abundant rainfall. The distribution of debris flows has regularity in the regions with different landform, geological structure, and precipitation. The regularities of distribution of debris flows are as following： （1） distributed in transition belts of different morphologic regions; （2） distributed in the area with strong stream trenching; （3） distributed along fracture zones and seismic belts： （4） distributed in the area with abundant precipitation; （5） distribution of debris flow is azonal. The activity of abundant debris flows not only brings harm to Towns, Villages and Farmlands, Main Lines of Communication, Water-Power Engineering, Stream Channels etc., but also induces strong water and soil loss. According to the present status of debris flow prevention, the problems in disasters mitigation and soil conservancy are found out, and the key works are brought up for the future disasters prevention and soil conservancy.展开更多
The remote sensing （RS） and geographical information system （GIS） technologies were adopted and a mathematic method was developed to evaluate the changes of ecosystem services in the upper reaches of Minjiang Rive...The remote sensing （RS） and geographical information system （GIS） technologies were adopted and a mathematic method was developed to evaluate the changes of ecosystem services in the upper reaches of Minjiang River-valley for providing advices to manage the ecosystem. The results showed that the land use change mainly occurred on forest, farmland and grassland. From 1986 to 1994, the area of farmland increased by 477% （60801 hm^2）, while the area of forest decreased by 4.97% （89012.17 hm^2）. From 1986 to 2000, the eco-service value of forest was degressive but that of farmland increased greatly as the increasing of planting area, while the total eco-service value decreased by 771.11×10^8 yuan RMB due to the rapid increase of population in this region. The driving force of eco-service change was also discussed in the paper. The nation policy of Natural Forest Protection Project has taken effect in preventing the decline of eco-services.展开更多
[Objective] Species composition and flora of vascular plants in the middle and upper reaches of the Yarlung Zangbo River were analyzed,to provide scientific basis for the estimation and protection of plant diversity,c...[Objective] Species composition and flora of vascular plants in the middle and upper reaches of the Yarlung Zangbo River were analyzed,to provide scientific basis for the estimation and protection of plant diversity,construction of ecological security shelter for the Tibetan Plateau.[Methods] In the middle and upper reaches of the Yarlung Zangbo River,quadrat (line transect) method was applied to investigate the phytocoenoses in sample plots,and relative literature was used to analyze the floristic composition and floristic element of vascular plants in the middle and upper reaches of the Yarlung Zangbo River.[Results]① There are 96 species (including subspecies and variations),69 genera of 35 vascular plant families,accounting for 16.83%,5.48%,1.66% and 11.63%,2.02%,0.31% of total vascular plant families,genera and species in Tibet and China.② There are 24 monotypic-genus families,accounting for 68.57% of the total family number in the local area;22 monotypic-species families,accounting for 62.86% of the total family number in the local area.Local flora shows the characteristics of ancient relict,such as Euphorbiaceae,Rubiaceae,Liliaceae and Ranunculaceae,they are all ancient primitive groups of the third flora and the fourth flora.③ Local vascular plant genera fall into 10 areal types and 8 variations.④ Temperate elements are much more than tropical elements,R/T is 0.19,indicating that vascular plants have typical temperate nature and residual tropical nature.There are only a few endemic genera,but more endemic species to the local area,and these species are closely related,of which there are some transitional species,indicating that local flora is too young to experience more differentiation and specialization.⑤ There are 24 Chinese endemic species,accounting for 25% of total number of species in the local area;among which there are 12 endemic species to Tibet,accounting for 50% of endemic species to China,12.5% of total number of species in the local area.Four key wild plant species are included in the second batch of national key protection.[Conclusions]① There are scarce plant groups in the local area.② Among the obvious advantages,single-genus (species) families possess the absolute advantage,and the flora has ancient origins.③ The local flora has diversified distribution types,and the complicated geographical elements.④ Temperate species possess obvious advantages,and the flora is young.⑤ Rich unique and rare species have high species diversity protection and research value.展开更多
Taking Zhongba County, Angren County, Rikaze City located at the Upper and Middle Reaches of Yarlung Zangbo River as landscape units , this paper studied the difference of the landscape pattern under various degrees o...Taking Zhongba County, Angren County, Rikaze City located at the Upper and Middle Reaches of Yarlung Zangbo River as landscape units , this paper studied the difference of the landscape pattern under various degrees of human disturbance in the three areas. The results showed that： the three areas all reflected the same characteristic of landscape pattern in Qinghai-Tibet Plateau, the natural landscapes were in the absolute dominant position. However, from Zhangba to Rikaze, with human disturbance intensity increasing, anthropogenic features of landscapes became more and more outstanding, In Zhongba, the landscape structure appeared to be simpler with coarse grains and a less rich diversity, Conversely, in Rikaze, the landscape showed a complicated shape with finer grains and a relatively richer diversity, This reflected that the impact of human activities to natural landscape behaved a gradually-growing trend from the upper reach to the middle one of Yarlung Zangbo River Basin.展开更多
This paper explores and identifies the rules of the unsteady evolution of COD in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly COD data for the last six years provided by th...This paper explores and identifies the rules of the unsteady evolution of COD in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly COD data for the last six years provided by the Water Quality Monitoring Station,Minjiang River Bridge,Leshan City,Sichuan Province.The results of the wavelet analysis indicate that the COD index oscillates alternatively and differently at each time-scale in an oneyear cycle,and the density of COD,subjected to the runoff volume,the effects of Wenchuan Earthquake and agricultural seeding and industrial construction,etc.,is high in winter and spring,mild in summer and autumn.展开更多
By studying typical "Top Eight Views" in cities like Xining,Lanzhou and Yinchuan in the upper reaches of the Yellow River,mountain and water landscapes in the study area were analyzed in terms of natural eco...By studying typical "Top Eight Views" in cities like Xining,Lanzhou and Yinchuan in the upper reaches of the Yellow River,mountain and water landscapes in the study area were analyzed in terms of natural ecology;bridges,canals,ferries,pavilions,mansions,towers,temples,historical sites,production and living landscapes were analyzed in terms of humanistic ecology.On this basis,"Top Eight Views" in the upper reaches of the Yellow River were compared and the following conclusions obtained:mountain landscapes were distributed in the whole region,waterscapes unevenly valued in different cities,bridges,canals and ferries mostly located in Ningxia,temples commonly found in all cities,garden arts introduced into cities,traditional cultures carried forward by historical relics.Then the relationship between "Top Eight Views" and regional eco-cultures was analyzed,and it was proposed that humanistic and cultural connotations of these "Top Eight Views" contributed a lot to beautifying urban environment,satisfying needs of the locals' spiritual life,carrying forward local history and culture,enriching urban cultural connotations,expanding living spaces of local residents and improving integrated functions of cities."Top Eight Views" culture complied with the construction gist of urban ecological cultures,and was of great referential value for the construction of urban ecological cultures in the upper reaches of the Yellow River,and also the healthy,scientific and sustainable development of local cities.展开更多
Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth genera...Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.展开更多
Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical ...Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical and representative. In this study, the relationship between settlements and topography, rivers and transportation, and the spatial distribution patterns of settlements, such as the aggregation and orientation characteristics of settlements, have been studied. The main conclusions include: 1) The settlement density decreases with the increase of elevation, slope, and distance from rivers and roads;76.25% and 63.17% of the settlements are distributed in the range of elevation 1500 - 3000 m and slope 6° - 25°, the upper reaches of the Min River are mostly alpine valley terrain, the bottom of the river has a low altitude, the landscape is undulating. The warm and humid climate is suitable for farming, conducive to agricultural production, and an ideal living environment for mountain residents. 2) The nuclear density of the settlement is distributed in strips along the axis of the river, and the closer to the river, the greater the nuclear density value. 3) Mathematical statistical methods were applied for the first time to realize the quantitative expression of the coupling of settlement and river direction. The influence of topographic conditions in different watersheds on the coupling degree of settlement extension and river flow direction was revealed. The slope of the fitted straight line between the settlement and river direction was 0.897, and the two directions were consistent. Except for the mainstream of the Min River, the larger values of the standard deviation ellipse flattening of settlements in each basin appeared in the upper reaches of the bay, and the overall trend showed a gradual decrease from the upstream to the downstream, which was consistent with the topographic change characteristics of the basin.展开更多
The upper reaches of the Yellow River in northeastern Tibetan Plateau are geohazards areas.The evolution of the Yellow River,chronology of some landslides,and spatiotemporal distribution characteristics of super large...The upper reaches of the Yellow River in northeastern Tibetan Plateau are geohazards areas.The evolution of the Yellow River,chronology of some landslides,and spatiotemporal distribution characteristics of super large scale and giant landslides within the region are summarized using paleoclimate evidence,and the relationship between the intensive landslide period and climatic changes since the Last Glacial period is analyzed.It is concluded that （1） Super large scale and giant landslides are distributed widely within the region,particularly in the Qunke-Jianzha basin.（2） The chronological sequence of landslides is established by dating the slip zones of landslides and analyzing the relations between landslides and their overlying or underlying loess formations.Five landslide development periods are determined：53-49 ka BP,33-24 ka BP,10-8 ka BP,5-3.5 ka BP,and the present.（3） These correspond closely to warm and wet periods during the last 100,000 years,i.e.,two weak paleosol development stages of Malan loess deposited during the last Glacial period in the Chinese loess Plateau,L1-4 and L1-2 that belong to the marine oxygen isotope stage 3,the last deglaeial period,the Holocene Optimum,and the modern global warming period.（4） Landslide triggers may be closely linked to warm and wet periods related to rapid climatic transitions.展开更多
Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archiv...Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that： the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation （PDO） coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong （weak） solar activity is generally correlated to the dry （wet） periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale.展开更多
Ecological security assessment and early warning research possess the attributes of spatiality, non-linearity and randomicity, so we must process much spatial information. Spatial analysis and data management are the ...Ecological security assessment and early warning research possess the attributes of spatiality, non-linearity and randomicity, so we must process much spatial information. Spatial analysis and data management are the advantages of GIS, which can define distribution trend and spatial relations of environmental factors, and show ecological security pattern graphically. Spatial differences of ecological security assessment based on GIS are discussed in this paper, of which the middle and lower reaches of the Liaohe River is taken as a study case. First, to work out pressure-state-response (P-S-R) assessment indicators system, and investigate in person and gather information; second, to digitize the watershed; third, to quantize and calculate by the fuzzy method; last, to construct GIS grid database, and expound spatial differences of ecological security by GIS interpolation and assembly analysis.展开更多
Thirteen sediment core samples(0-10 cm) were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus(P) fractions in the sedime...Thirteen sediment core samples(0-10 cm) were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus(P) fractions in the sediments of the shallow lakes in the area.The organic P fractions in the sediments were in the order of moderately labile organic P(MLOP) > moderately resistant organic P(MROP) > highly resistant organic P(HROP) > labile organic P(LOP),with average proportional ratios of 13.2:2.8:1.3:1.0.LOP,MLOP,and MROP were significantly related to the contents of total organic carbon(TOC),water-soluble P(WSP),algal-available P(AAP),NaHCO3-extractable P(Olsen-P),total P(TP),organic P(OP),and inorganic P(IP).However,HROP was significantly related to OP and weakly correlated with TOC,WSP,AAP,Olsen-P,TP or IP.This suggested that organic P,especially LOP and MLOP in sediments,deserved even greater attention than IP in regards to lake eutrophication.In terms of organic P,sediments were more hazardous than soils in lake eutrophication.Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment,LOP and MLOP were higher in the heavily polluted sediment,which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.展开更多
Based on the data for meteorology, hydrology, soil, planting, vegetation, and socio-economic development of the irrigation region in the middle reaches of the Heihe River basin, Northwest China, the model of balance o...Based on the data for meteorology, hydrology, soil, planting, vegetation, and socio-economic development of the irrigation region in the middle reaches of the Heihe River basin, Northwest China, the model of balance of water supply and demand in the region was established, and the security of water resource was assessed, from which the results that the effects of unified management of water resources in the Heihe River basin between Gansu Province and Inner Mongolia on regional hydrology are significant with a decrease in water supply diverted from Heihe River and an increase in groundwater extracted. In addition, it was found that the groundwater level has been steadily decreasing due to over pumping and decrease in recharges. In present year （2003）, the volume of potential groundwater in the irrigation districts is far small because of the groundwater overdraft; even in the particular regions, there is no availability of groundwater resources for use. By 2003, water supply is not sufficient to meet the water demand in the different irrigation districts, the sustainable development and utilization of water resources are not secured, and the water supply crisis occurs in Pingchuan irrigation district. Achieving water security for the sustainable development of society, agriculture, economy, industry, and livelihoods while maintaining or improving the abilities of the management and planning of water resources, determining of the reasonable percentage between water supply and groundwater utilization and water saving in agricultural irrigation are taken into account. If this does not occur, it is feared that the present performance of water development and planning may further aggravate the problem of scarcities of water resources and further damage the fragile ecological system.展开更多
Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly inf...Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly influenced by the specific geographical environment and ecological conditions of mountains.Based on field investigation,this paper uses physical,geographical,and ecological theories to make a comprehensive study of rural settlements and mountain disasters in the upper Min River,which is an ecologically fragile area with high-frequency disasters(collapse,landslide,debris flow,etc.) and a minority inhabit district.By applying these modern scientific theories,this paper attempts to shed some light on the relationship between rural settlements and mountain disasters.Consequently,an in-depth understanding of this relationship was achieved as follows:(1) Rural settlements and mountain disasters are mainly distributed in the intercepted flows of water and soil; and both quantity and quality of arable lands in mountains are important indicators of these flows.(2) The Small Watershed Management Project is a complex system of rural settlements and mountain disasters that interacts with and constrains the ecological system.By this project,the human survival will be better guaranteed.Being fundamental for the ecological reconstruction,the coupling mechanism of rural settlements and mountain disasters is not only an engine to promote harmonious development between human and nature,but also a bridge to link them.展开更多
Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the...Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River （MLRYR） and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River （MLRYR）. Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating （cooling） caused by the vertical thermal advection as well as the diabatic heating （cooling） caused by diabatic processes can explain the formation of the high （low） temperature events in the middle and lower reaches of the Yangtze River （MLRYR） in boreal summer.展开更多
Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using fie...Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages： early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.展开更多
Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitat...Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitation and topographical variables are established to extract the effect of topography on the annual and seasonal precipitation in the upper-middle reaches of the Yangtze River. Then, this paper uses a successive interpolation approach (SIA), which combines GIS techniques with the multiple regressions, to improve the accuracy of the spatial interpolation of annual and seasonal rainfall. The results are very satisfactory in the case of seasonal rainfall, with the relative error of 6.86%, the absolute error of 13.07 mm, the average coefficient of variation of 0.070, and the correlation coefficient of 0.9675; in the case of annual precipitation, with the relative error of 7.34%, the absolute error of 72.1 mm, the average coefficient of variation of 0.092, and the correlation coefficient of 0.9605. The analyses of annual mean precipitation show that the SIA calculation of 3-5 steps considerably improves the interpolation accuracy, decreasing the absolute error from 211.0 mm to 62.4 mm, the relative error from 20.74% to 5.97%, the coefficient of variation from 0.2312 to 0.0761, and increasing the correlation coefficient from 0.5467 to 0.9619. The SIA iterative results after 50 steps identically converge to the observed precipitation.展开更多
Studies of the Pb, Sr and Nd isotopic composition of Mesozoic intrusive rocks indicate that the basement of the copper-gold metallogenic belt of the middle and lower reaches of the Yangtze River has “two-layer struct...Studies of the Pb, Sr and Nd isotopic composition of Mesozoic intrusive rocks indicate that the basement of the copper-gold metallogenic belt of the middle and lower reaches of the Yangtze River has “two-layer structure” and partly has “multi-layered structure”, and is inhomogeneous and shows the distinct feature of E-W provincialism. The calculated model lead ages (t1) are mostly greater than 2600 Ma, and the model neodymium ages (TDM) vary from 953 to 2276 Ma and concentrate in two time intervals: 1800–2000 Ma and 1200–1600 Ma. It is concluded that the basement of the MBYR is composed of the Late Archaeozoic to Middle Proterozoic metamorphic series and that the crust was initiated in the Archaean and continued to grow in the Early and Middle Proterozoic, and the proportion of new crust formed by mantle differentiation during the Late Proterozoic is low.展开更多
The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwa...The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwater in the region of the middle and lower reaches of the YangtzeRiver and their relations to the composition of the water-bearing media, properties of the overly-ing rocks and soils, redox environment, and groundwater flow condition, mineralization and pHof groundwater.展开更多
基金the result of the project(No.400610o6)funded by the National Natural Science Foundation of China.
文摘Land use/land cover change (LUCC) is a focus of the research of global environmental changes. The middle and upper reaches of the Yangtze River, which are the most ecologically fragile mountainous area in China as well as one of the areas in China with most notable LUCC, have been on the Chinese Government's list of priority areas for ecological restoration. This paper is to reveal the trend of LUCC and the ecological degradation arising from it, and to provide a basis for the future sustainable use of land resources in the region based on a detailed analysis of Yiliang County. Based on the county's land use/cover maps in 1960, 1980 and 2000 drawn with the aid of aerial photograph interpretation, field investigation and GIS based spatial-temporal data analysis, LUCC during 1960~2000 period and the ecological degradation arising from it were analyzed. Using the Markv model, the paper brings out a forecast of what the county's LUCC would be like if the county's current land use continues, as well as the reasons and countermeasures for restoring degraded ecosystems.
基金the Knowledge Innovation Program of Chinese Academy of Sciences (KZCX-SW-352)
文摘In the upper reaches of Yangtze River and other rivers of southwestern China, the debris flows develop and lead to most serious disasters because of the various landforms, complex geological structures and abundant rainfall. The distribution of debris flows has regularity in the regions with different landform, geological structure, and precipitation. The regularities of distribution of debris flows are as following： （1） distributed in transition belts of different morphologic regions; （2） distributed in the area with strong stream trenching; （3） distributed along fracture zones and seismic belts： （4） distributed in the area with abundant precipitation; （5） distribution of debris flow is azonal. The activity of abundant debris flows not only brings harm to Towns, Villages and Farmlands, Main Lines of Communication, Water-Power Engineering, Stream Channels etc., but also induces strong water and soil loss. According to the present status of debris flow prevention, the problems in disasters mitigation and soil conservancy are found out, and the key works are brought up for the future disasters prevention and soil conservancy.
基金This study was supported and funded by the projects of NKBRSF, P.R. China (No. 2002CB111506)
文摘The remote sensing （RS） and geographical information system （GIS） technologies were adopted and a mathematic method was developed to evaluate the changes of ecosystem services in the upper reaches of Minjiang River-valley for providing advices to manage the ecosystem. The results showed that the land use change mainly occurred on forest, farmland and grassland. From 1986 to 1994, the area of farmland increased by 477% （60801 hm^2）, while the area of forest decreased by 4.97% （89012.17 hm^2）. From 1986 to 2000, the eco-service value of forest was degressive but that of farmland increased greatly as the increasing of planting area, while the total eco-service value decreased by 771.11×10^8 yuan RMB due to the rapid increase of population in this region. The driving force of eco-service change was also discussed in the paper. The nation policy of Natural Forest Protection Project has taken effect in preventing the decline of eco-services.
基金Supported by National Key R&D Program of china(2016YFC0502006)Major Science and Technology Projects of Tibet(Z2016C01G01/02)
文摘[Objective] Species composition and flora of vascular plants in the middle and upper reaches of the Yarlung Zangbo River were analyzed,to provide scientific basis for the estimation and protection of plant diversity,construction of ecological security shelter for the Tibetan Plateau.[Methods] In the middle and upper reaches of the Yarlung Zangbo River,quadrat (line transect) method was applied to investigate the phytocoenoses in sample plots,and relative literature was used to analyze the floristic composition and floristic element of vascular plants in the middle and upper reaches of the Yarlung Zangbo River.[Results]① There are 96 species (including subspecies and variations),69 genera of 35 vascular plant families,accounting for 16.83%,5.48%,1.66% and 11.63%,2.02%,0.31% of total vascular plant families,genera and species in Tibet and China.② There are 24 monotypic-genus families,accounting for 68.57% of the total family number in the local area;22 monotypic-species families,accounting for 62.86% of the total family number in the local area.Local flora shows the characteristics of ancient relict,such as Euphorbiaceae,Rubiaceae,Liliaceae and Ranunculaceae,they are all ancient primitive groups of the third flora and the fourth flora.③ Local vascular plant genera fall into 10 areal types and 8 variations.④ Temperate elements are much more than tropical elements,R/T is 0.19,indicating that vascular plants have typical temperate nature and residual tropical nature.There are only a few endemic genera,but more endemic species to the local area,and these species are closely related,of which there are some transitional species,indicating that local flora is too young to experience more differentiation and specialization.⑤ There are 24 Chinese endemic species,accounting for 25% of total number of species in the local area;among which there are 12 endemic species to Tibet,accounting for 50% of endemic species to China,12.5% of total number of species in the local area.Four key wild plant species are included in the second batch of national key protection.[Conclusions]① There are scarce plant groups in the local area.② Among the obvious advantages,single-genus (species) families possess the absolute advantage,and the flora has ancient origins.③ The local flora has diversified distribution types,and the complicated geographical elements.④ Temperate species possess obvious advantages,and the flora is young.⑤ Rich unique and rare species have high species diversity protection and research value.
文摘Taking Zhongba County, Angren County, Rikaze City located at the Upper and Middle Reaches of Yarlung Zangbo River as landscape units , this paper studied the difference of the landscape pattern under various degrees of human disturbance in the three areas. The results showed that： the three areas all reflected the same characteristic of landscape pattern in Qinghai-Tibet Plateau, the natural landscapes were in the absolute dominant position. However, from Zhangba to Rikaze, with human disturbance intensity increasing, anthropogenic features of landscapes became more and more outstanding, In Zhongba, the landscape structure appeared to be simpler with coarse grains and a less rich diversity, Conversely, in Rikaze, the landscape showed a complicated shape with finer grains and a relatively richer diversity, This reflected that the impact of human activities to natural landscape behaved a gradually-growing trend from the upper reach to the middle one of Yarlung Zangbo River Basin.
文摘This paper explores and identifies the rules of the unsteady evolution of COD in the upper and middle reaches of Minjiang River through multi-scale analysis on the weekly COD data for the last six years provided by the Water Quality Monitoring Station,Minjiang River Bridge,Leshan City,Sichuan Province.The results of the wavelet analysis indicate that the COD index oscillates alternatively and differently at each time-scale in an oneyear cycle,and the density of COD,subjected to the runoff volume,the effects of Wenchuan Earthquake and agricultural seeding and industrial construction,etc.,is high in winter and spring,mild in summer and autumn.
基金Supported by Hebei Provincial Social Science Foudation " Ecological Environment and Urban Development in the Upper Reaches of the Yellow River (1368 - 1928) " (HB10GJ016) ~~
文摘By studying typical "Top Eight Views" in cities like Xining,Lanzhou and Yinchuan in the upper reaches of the Yellow River,mountain and water landscapes in the study area were analyzed in terms of natural ecology;bridges,canals,ferries,pavilions,mansions,towers,temples,historical sites,production and living landscapes were analyzed in terms of humanistic ecology.On this basis,"Top Eight Views" in the upper reaches of the Yellow River were compared and the following conclusions obtained:mountain landscapes were distributed in the whole region,waterscapes unevenly valued in different cities,bridges,canals and ferries mostly located in Ningxia,temples commonly found in all cities,garden arts introduced into cities,traditional cultures carried forward by historical relics.Then the relationship between "Top Eight Views" and regional eco-cultures was analyzed,and it was proposed that humanistic and cultural connotations of these "Top Eight Views" contributed a lot to beautifying urban environment,satisfying needs of the locals' spiritual life,carrying forward local history and culture,enriching urban cultural connotations,expanding living spaces of local residents and improving integrated functions of cities."Top Eight Views" culture complied with the construction gist of urban ecological cultures,and was of great referential value for the construction of urban ecological cultures in the upper reaches of the Yellow River,and also the healthy,scientific and sustainable development of local cities.
基金supported by the National Natural Science Foundation of China(Grant Nos.42230612,41620104009,41705019,42075186,and 41975058)the Projects of the S&T Development Foundation of the Hubei Meteorological Bureau(Grants No.2021Q04 and 2020Y04)。
文摘Here,we analyze the characteristics and the formation mechanisms of low-level jets(LLJs)in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5)reanalysis dataset.Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs)concentrated at heights of 900-1200 m.The BLJs occur most frequently at 2300 LST(LST=UTC+8 hours)but are strongest at 0200 LST,with composite wind velocities>14 m s^(-1).Synoptic-system-related LLJs(SLLJs)occur most frequently at 0800 LST but are strongest at 1100LST,with composite wind velocities>12 m s^(-1).Both BLJs and SLLJs are characterized by a southwesterly wind direction,although the wind direction of SLLJs is more westerly,and northeasterly SLLJs occur more frequently than northeasterly BLJs.When Wuhan is south of the mei-yu front,the westward extension of the northwest Pacific subtropical high intensifies,and the low-pressure system in the eastern Tibetan Plateau strengthens,favoring the formation of LLJs,which are closely related to precipitation.The wind speeds on rainstorm days are greater than those on LLJ days.Our analysis of four typical heavy precipitation events shows the presence of LLJs at the center of the precipitation and on its southern side before the onset of heavy precipitation.BLJs were shown to develop earlier than SLLJs.
文摘Under the background of the uplift of the Qinghai-Tibet Plateau, the settlements in the upper reaches of the Min River are significantly affected by the mountain environment, and their spatial distribution is typical and representative. In this study, the relationship between settlements and topography, rivers and transportation, and the spatial distribution patterns of settlements, such as the aggregation and orientation characteristics of settlements, have been studied. The main conclusions include: 1) The settlement density decreases with the increase of elevation, slope, and distance from rivers and roads;76.25% and 63.17% of the settlements are distributed in the range of elevation 1500 - 3000 m and slope 6° - 25°, the upper reaches of the Min River are mostly alpine valley terrain, the bottom of the river has a low altitude, the landscape is undulating. The warm and humid climate is suitable for farming, conducive to agricultural production, and an ideal living environment for mountain residents. 2) The nuclear density of the settlement is distributed in strips along the axis of the river, and the closer to the river, the greater the nuclear density value. 3) Mathematical statistical methods were applied for the first time to realize the quantitative expression of the coupling of settlement and river direction. The influence of topographic conditions in different watersheds on the coupling degree of settlement extension and river flow direction was revealed. The slope of the fitted straight line between the settlement and river direction was 0.897, and the two directions were consistent. Except for the mainstream of the Min River, the larger values of the standard deviation ellipse flattening of settlements in each basin appeared in the upper reaches of the bay, and the overall trend showed a gradual decrease from the upstream to the downstream, which was consistent with the topographic change characteristics of the basin.
基金financially supported by the National Nature Science Foundation of China under Grant No. 41372333, 40802089, 41172158China Geological Survey (grant No. 1212011220123)
文摘The upper reaches of the Yellow River in northeastern Tibetan Plateau are geohazards areas.The evolution of the Yellow River,chronology of some landslides,and spatiotemporal distribution characteristics of super large scale and giant landslides within the region are summarized using paleoclimate evidence,and the relationship between the intensive landslide period and climatic changes since the Last Glacial period is analyzed.It is concluded that （1） Super large scale and giant landslides are distributed widely within the region,particularly in the Qunke-Jianzha basin.（2） The chronological sequence of landslides is established by dating the slip zones of landslides and analyzing the relations between landslides and their overlying or underlying loess formations.Five landslide development periods are determined：53-49 ka BP,33-24 ka BP,10-8 ka BP,5-3.5 ka BP,and the present.（3） These correspond closely to warm and wet periods during the last 100,000 years,i.e.,two weak paleosol development stages of Malan loess deposited during the last Glacial period in the Chinese loess Plateau,L1-4 and L1-2 that belong to the marine oxygen isotope stage 3,the last deglaeial period,the Holocene Optimum,and the modern global warming period.（4） Landslide triggers may be closely linked to warm and wet periods related to rapid climatic transitions.
基金National Natural Science Foundation of China, No. 40331013 No.90502009 No. 40571007, No. 40701021
文摘Based on the long-term precipitation series with annual time resolution in the middle and lower reaches of the Yellow River and its four sub-regions during 1736-2000 reconstructed from the rainfall and snowfall archives of the Qing Dynasty, the precipitation cycles are analyzed by wavelet analysis and the possible climate forcings, which drive the precipitation changes, are explored. The results show that： the precipitation in the middle and lower reaches of the Yellow River has inter-annual and inter-decadal oscillations like 2-4a, quasi-22a and 70-80a. The 2-4a cycle is linked with El Nino events, and the precipitation is lower than normal year in the occurrence of the El Nino year or the next year; for the quasi-22a and the 70-80a cycles, Wolf Sun Spot Numbers and Pacific Decadal Oscillation （PDO） coincide with the two cycle signals. However, on a 70-80a time scale, the coincidence between solar activity and precipitation is identified before 1830, and strong （weak） solar activity is generally correlated to the dry （wet） periods; after 1830, the solar activity changes to 80-100a quasi-century long oscillation, and the adjusting action to the precipitation is becoming weaker and weaker; the coincidence between PDO and precipitation is shown in the whole time series. Moreover, in recent 100 years, PDO is becoming a pace-maker of the precipitation on the 70-80a time scale.
文摘Ecological security assessment and early warning research possess the attributes of spatiality, non-linearity and randomicity, so we must process much spatial information. Spatial analysis and data management are the advantages of GIS, which can define distribution trend and spatial relations of environmental factors, and show ecological security pattern graphically. Spatial differences of ecological security assessment based on GIS are discussed in this paper, of which the middle and lower reaches of the Liaohe River is taken as a study case. First, to work out pressure-state-response (P-S-R) assessment indicators system, and investigate in person and gather information; second, to digitize the watershed; third, to quantize and calculate by the fuzzy method; last, to construct GIS grid database, and expound spatial differences of ecological security by GIS interpolation and assembly analysis.
基金the China’s National Basic Research Program:"Studies on the Process of Eutrophication of Lakesand the Mechanism of the Blooming of Blue Green Alga" (No2002CB412304)
文摘Thirteen sediment core samples(0-10 cm) were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus(P) fractions in the sediments of the shallow lakes in the area.The organic P fractions in the sediments were in the order of moderately labile organic P(MLOP) > moderately resistant organic P(MROP) > highly resistant organic P(HROP) > labile organic P(LOP),with average proportional ratios of 13.2:2.8:1.3:1.0.LOP,MLOP,and MROP were significantly related to the contents of total organic carbon(TOC),water-soluble P(WSP),algal-available P(AAP),NaHCO3-extractable P(Olsen-P),total P(TP),organic P(OP),and inorganic P(IP).However,HROP was significantly related to OP and weakly correlated with TOC,WSP,AAP,Olsen-P,TP or IP.This suggested that organic P,especially LOP and MLOP in sediments,deserved even greater attention than IP in regards to lake eutrophication.In terms of organic P,sediments were more hazardous than soils in lake eutrophication.Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment,LOP and MLOP were higher in the heavily polluted sediment,which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.
基金This work was supported by the Knowledge Innovation Program from the Cold and Add Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences （CACX2003102）the Chinese Academy of Sciences （KZCX 1 - 10-03-01）the National Natural Science Foundation of China （40401012）.
文摘Based on the data for meteorology, hydrology, soil, planting, vegetation, and socio-economic development of the irrigation region in the middle reaches of the Heihe River basin, Northwest China, the model of balance of water supply and demand in the region was established, and the security of water resource was assessed, from which the results that the effects of unified management of water resources in the Heihe River basin between Gansu Province and Inner Mongolia on regional hydrology are significant with a decrease in water supply diverted from Heihe River and an increase in groundwater extracted. In addition, it was found that the groundwater level has been steadily decreasing due to over pumping and decrease in recharges. In present year （2003）, the volume of potential groundwater in the irrigation districts is far small because of the groundwater overdraft; even in the particular regions, there is no availability of groundwater resources for use. By 2003, water supply is not sufficient to meet the water demand in the different irrigation districts, the sustainable development and utilization of water resources are not secured, and the water supply crisis occurs in Pingchuan irrigation district. Achieving water security for the sustainable development of society, agriculture, economy, industry, and livelihoods while maintaining or improving the abilities of the management and planning of water resources, determining of the reasonable percentage between water supply and groundwater utilization and water saving in agricultural irrigation are taken into account. If this does not occur, it is feared that the present performance of water development and planning may further aggravate the problem of scarcities of water resources and further damage the fragile ecological system.
基金financially supported by the National Natural Science Foundation of China(Grant No.41101164 and 41371185)Directional Project of Institute of Mountain Hazards and Environment of Chinese Academy of Sciences(Grant No.SDS-135-1204-01)the key project of Education Department of Sichuan Province(Grant No.13ZA0160)
文摘Human settlements are the place where human beings live,among which the rural settlements can be regarded as a reflection of human-land relationship in mountain areas because their vertical distribution is greatly influenced by the specific geographical environment and ecological conditions of mountains.Based on field investigation,this paper uses physical,geographical,and ecological theories to make a comprehensive study of rural settlements and mountain disasters in the upper Min River,which is an ecologically fragile area with high-frequency disasters(collapse,landslide,debris flow,etc.) and a minority inhabit district.By applying these modern scientific theories,this paper attempts to shed some light on the relationship between rural settlements and mountain disasters.Consequently,an in-depth understanding of this relationship was achieved as follows:(1) Rural settlements and mountain disasters are mainly distributed in the intercepted flows of water and soil; and both quantity and quality of arable lands in mountains are important indicators of these flows.(2) The Small Watershed Management Project is a complex system of rural settlements and mountain disasters that interacts with and constrains the ecological system.By this project,the human survival will be better guaranteed.Being fundamental for the ecological reconstruction,the coupling mechanism of rural settlements and mountain disasters is not only an engine to promote harmonious development between human and nature,but also a bridge to link them.
基金The key technology R&D program of China, No.2007BAC29B02Project of Jiangsu Key Laboratory of Meteorological Disaster, No.KLME060101
文摘Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River （MLRYR） and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River （MLRYR）. Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating （cooling） caused by the vertical thermal advection as well as the diabatic heating （cooling） caused by diabatic processes can explain the formation of the high （low） temperature events in the middle and lower reaches of the Yangtze River （MLRYR） in boreal summer.
基金financially supported by the National Nature Science Foundation of China under Grant No.41372333,41172158China Geological Survey(grant No.1212011220123)
文摘Several argillaceous platforms lie along the Yellow River（YR） of the eastern Guide Basin, northeastern Tibetan Plateau, and their compositions, formation processes, and geomorphic evolution remain debated. Using field survey data, sample testing, and high-resolution remote sensing images, the evolution of the Erlian mudflow fans are analyzed. The data show significant differences between fans on either side of the YR. On the right bank, fans are dilute debris flows consisting of sand and gravel. On the left bank, fans are viscosity mudflows consisting of red clay. The composition and formation processes of the left bank platforms indicate a rainfall-induced pluvial landscape. Fan evolution can be divided into two stages： early-stage fans pre-date 16 ka B.P., and formed during the last deglaciation; late-stage fans post-date 8 ka B.P.. Both stages were induced by climate change. The data indicate that during the Last Glacial Maximum, the northeastern Tibetan Plateau experienced a cold and humid climate characterized by high rainfall. From 16–8 ka, the YR cut through the Erlian early mudflow fan, resulting in extensive erosion. Since 8 ka, the river channel has migrated south by at least 1.25 km, and late stage mudflow fan formation has occurred.
基金The National 973 Project of China, No.2001CB309404 O versea O utstanding Youth Cooperation Project, N o. 40128001/D 05N ationalN aturalScience Foundation ofChina,N o.49375248 Zhejiang Province Science Research (C33)Project,N o.2004C33082
文摘Using geographic information system (GIS) techniques and the newest seasonal and annual average precipitation data of 679 meteorological stations from 1971 to 2000, the multiple regressions equations of the precipitation and topographical variables are established to extract the effect of topography on the annual and seasonal precipitation in the upper-middle reaches of the Yangtze River. Then, this paper uses a successive interpolation approach (SIA), which combines GIS techniques with the multiple regressions, to improve the accuracy of the spatial interpolation of annual and seasonal rainfall. The results are very satisfactory in the case of seasonal rainfall, with the relative error of 6.86%, the absolute error of 13.07 mm, the average coefficient of variation of 0.070, and the correlation coefficient of 0.9675; in the case of annual precipitation, with the relative error of 7.34%, the absolute error of 72.1 mm, the average coefficient of variation of 0.092, and the correlation coefficient of 0.9605. The analyses of annual mean precipitation show that the SIA calculation of 3-5 steps considerably improves the interpolation accuracy, decreasing the absolute error from 211.0 mm to 62.4 mm, the relative error from 20.74% to 5.97%, the coefficient of variation from 0.2312 to 0.0761, and increasing the correlation coefficient from 0.5467 to 0.9619. The SIA iterative results after 50 steps identically converge to the observed precipitation.
基金This study was supported by the National Natural Science Foundation of China grant 49802007.
文摘Studies of the Pb, Sr and Nd isotopic composition of Mesozoic intrusive rocks indicate that the basement of the copper-gold metallogenic belt of the middle and lower reaches of the Yangtze River has “two-layer structure” and partly has “multi-layered structure”, and is inhomogeneous and shows the distinct feature of E-W provincialism. The calculated model lead ages (t1) are mostly greater than 2600 Ma, and the model neodymium ages (TDM) vary from 953 to 2276 Ma and concentrate in two time intervals: 1800–2000 Ma and 1200–1600 Ma. It is concluded that the basement of the MBYR is composed of the Late Archaeozoic to Middle Proterozoic metamorphic series and that the crust was initiated in the Archaean and continued to grow in the Early and Middle Proterozoic, and the proportion of new crust formed by mantle differentiation during the Late Proterozoic is low.
文摘The paper deals with the background features, formation and distribution of the chemical el-ements K, Na, Ca, Mg, Si, Fe, Mn, Cr, Ni,V, Co, Ti, Mo, Cu, Pb, Zn, As, Hg, Cd, Be, Li, Sr, B,F, Cl, Br and I in the groundwater in the region of the middle and lower reaches of the YangtzeRiver and their relations to the composition of the water-bearing media, properties of the overly-ing rocks and soils, redox environment, and groundwater flow condition, mineralization and pHof groundwater.
