The dataset of glacierized area in Geladandong, with 10 years interval, was established on the CORONA satellite images in 1964 and the Landsat MSS/TM/ETM images from 1976 to 2010. As the glacierized surface is relatively clean, the uncertain of glacierized area, about 1%~2% of the total area, mainly caused by the satellite image resolution (Landsat) and different operators. The contrast of glacierized area in different periods shows that the total glacierized area in Geladandong decreased by 45.75 km2 from 1964 to 2010 and the relative change amount was 6.80%; the annual average change rate was 0.99 km2·a-1 and the relative change rate was 0.15%·a-1. Generally the glacier in Geladandong retreated slowly. Among 138 glaciers there are 14 ones having significant changed in the past 50 years and not all the glaciers having retreated. Nine glaciers had advanced at different periods and one of them advances all the time. There is a glacier at the source of the Yangtze River (north branch of Jianggudiru Glacier) having advanced twice during the periods of 1964-1977 and 2000-2010.
Glacier mass balance is the most direct and reliable parameter to reflect the status of a glacier. Based on the measured stakes/firn data from 2008 to 2012, the mass balance of the Xiao Dongkemadi Glacier was calculated. Combined with related meteorological data, the influence factors on the variation of mass balance were analyzed. The results showed that the glacier terminus retreated by 19.7 m from 2009 to 2012 with an average annual retreating ratio of 4.9 m, 2.3 times of that in the middle and late 1990s. In the same time the equilibrium line altitude was 5 720 m, 120 m higher than that in the early 1990s. Compared to that in 1995, the glacierized area shrunk 0.095 km2 and the terminus altitude rose 40 m. The mass balance was -1 584 mm w.e., equivalent to 1.76 m ice reduction, during the observing period. Particularly, in 2009/2010 the mass balance reached -996 mm w.e., the maximum negative mass balance throughout the whole observation period in the glacier. The higher summer air temperature and lower albedo caused by the pollution due to maintaining the Qinghai-Tibet Highway were the main reasons for this value. It is found that both air temperature, especially the summer air temperature, and the net radiation are the controlling factors of the mass balance.
Freezing and thawing is an important geomorphic process of the periglacial environment. Its activity is a direct reflection of climate change and thus it is an important part of the Cryosphere process. Based on a long-term monitoring in the source region of the Vrümqi River from 1991 to 2011, a discussion in detail on the characteristics of sorted circles and frost heaving mechanism in the Tianshan Mountains is made in this article. In the source region, the effect of frost heaving is strongest within the surface layer of 20 cm deep, while the stake of 3 cm in diameter is least affected by frost heaving. Inside a sorted circle the frost heaving becomes weaker along radius from the center to the edge. Frost heaving in sorted circle area is stronger than that in the area without sorted circle. The altitude has significant effect on frost heaving. At the altitude range from 3 500 to 4 000 m, frost heaving enhances with altitude and reaches a maximum at 3 900 m, the equilibrium line altitude of glaciers. Correlation analysis demonstrates that the development of frost heaving and sorted circles has closely relation with moisture and thermal regime in the warm half year (from May to October). Frost heaving has positive relation with precipitation in the warm season, the transfer days when ground temperature undulates around 0℃ is also an important factor. The sorted circle monitoring reveals that periglacial landform is sensitive to regional climate change and has an active respond to the air temperature rising in recent two decades.
Using the data observed from the meteorology gradient tower and within the active layer at the Tanggula Observation Site on the Tibetan Plateau in 2007, combined with the SHAW model, the soil hydro and thermal features within the active layer were simulated. Meanwhile, three different programs of surface albedo have been tested during the process of simulation.Comparing the observed data with the three simulated values, it is revealed that the SHAW model could successfully simulate the surface energy fluxes and the soil temperature features within the active layer in permafrost regions, while the simulation of soil unfrozen water is not so good, but the simulated changing tendency seems better. In the simulation, it will have obvious improvements in the simulation of the surface energy flux and soil temperature and moisture within the active layer when the monthly average surface albedo of each month in a year is taken as the model input. After revising the model input parameters by using the computing results from a parameterization scheme of the surface albedo, the simulation results of the soil temperature and moisture within the active layer has improved significantly. However, there is not obvious advance in the simulation of the surface energy fluxes. Overall, the SHAW model has advantage in simulating the soil freezing and thawing process in permafrost regions of the Tibetan Plateau. It is an ideal land surface model used to study the hydro and thermal processes within the active layer in the permafrost regions with higher elevations.
Observation data at NMQ Station was used as the atmospheric forcing data of the general land surface processes model (Community Land Model, CLM3.0) and Simultaneous Heat and Water (SHAW). Single point simulation studies were carried out for the seasonal frozen soil regions of the central Tibetan Plateau. Comparing the observed and simulated values from the two land surface processes models, it is found that simulation values of upward shortwave and upward long wave radiations from SHAW model are similar to those from CLM3.0. However, both models have not considered the effects of upward shortwave radiation from new snow and of upward long wave radiation due to latent heat release in daily freeze-thaw cycle. In addition, the daily variation of ground temperature has been well simulated by the SHAW model and CLM3.0 mode, but for the upper layers is better than for the lower layers. As compared with SHAW mode, the simulation value from CLM3.0 is closer to the measured value. For simulating soil water content, as the depth lees than 60 cm (including 60 cm), SHAW model and CLM3.0 mode all have their advantages and disadvantages, but as the depth more than 60 cm, the SHAW model is better than CLM3.0, especially for the process of soil freeze-thaw.
Glacier albedo links glacier to climate, hydrological processes in cold regions, and is an important factor that restricts the development of the distributed glaciers energy-material balance model. Snow albedo change will change the energy balance of the earth-atmosphere system, and also cause local, as well as global, climate change. In this paper, Landsat TM and ETM+ data are utilized to retrival the albedo on the Qiyi Glacier in the Qilian Mountains by using different equations to convert narrow band to wide band snow cover. A best inversion formula is chosen based on error analysis. It is revealed that the equation proposed by Duguay and Leddew (1992) is able to guarantee four images, whose inversion with measured value has absolute errors within 0.05. Inversion albedo from the equation might input to the mass balance model and the distributed glacier mass-energy balance models more accurately, improving glacier mass balance study.
The Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) 3B43 product is evaluated using the gauge precipitations from 9 weather stations in Heihe River basin at different time steps and spatial distribution. It is found that TMPA-3B43 performing result at time step and spatial scale is not so satisfactory. Regional average annual precipitation evaluated by TMPA is overvalued by 27.3%. At the same temporal resolution, in the humid region, such as the upstream of the Heihe River, TMPA performs better than that in the arid regiones, such as downstream of the river. Specially, during summer the overvalued precipitation is obvious in the downstream of the river. The goodness of fit between TMPA precipitation and observed precipitation is better in summer (R2=0.851) than in winter (R2=0.332). TMPA can express annual and month variation trends of precipitation well. Regional average linear trends of annual mean precipitation is estimated to be 30 mm·(10a)-1 from TMPA. In addition, TMPA estimated data can express the spatial distribution of precipitation in the basin. Annual precipitation increases with height with a rate of 11.1 mm·(100m-1). Precipitation decreases from east to west and the zone of maximum precipitation lies between 2800 to 4 900 m a.s.l.
The sensible and latent fluxes from 1st July, 2010 to 30th June, 2011 in permafrost region of the Mahan Mountain were calculated by using meteorological-gradient approach. At the same time, the characteristics of the surface energy balance were analyzed in combination with net radiation. It is found that: The net radiation in this region has significant annual variation, a little more than that in Xidatan and less than that in Tanggula of the Tibetan Plateau; the net radiation in permafrost region of Mahan Mountain mainly converts into sensible heat in winter and spring, and converts into latent heat in summer and autumn, similar to the characteristics of annual variation of sensible heat flux and latent heat flux in the permafrost regions of the Tibetan Plateau; the annual average latent heat flux is a little more than the sensible heat flux in permafrost region of Mahan Mountain, because of the protective effect of marsh landscape and adequate moisture condition in this region. In addition, the existence of underground ice protects the permafrost effectively in the region.
Snow chemistry on the glaciers of high mountains is good indicator for studying atmospheric environment change. During the summer of 2006, snow samples were taken from three snowpits at different altitude on the Laohugou Glacier No.12 in the West Qilian Mountains of China, and then snow chemistry characteristics of the samples were measured. Correlation analysis and sea-salt tracing methods were used in this study to reveal the sources of major ions and dust particles. It is found that major ions in the snow have obvious seasonal variation. The major ionic concentrations rank as Ca2+> SO42->NH4+>NO3->Cl->Na+>Mg2+>K+. Ca2+ is the dominate cation, and SO42- is the dominate anion. The ionic correlation coefficient analysis shows that all the ions, except NO3-, have very good correlation. The glacier regions are mainly affected by dust activities. Moreover, the major ions, especially Na+ and Cl-, are significantly affected by ocean in west, owing to precipitation mainly coming from west. Besides, there are part ions originating from the dust sources in central Asian.
In order to explore the chemical characteristics and sources of PM2.5 aerosol ion components in the west Qilian Mountains, 46 PM2.5 aerosol samples near the Qilian Shan Station of Glaciology and Ecologic Environment were collected form July 2010 to July 2011. The soluble inorganic ions were analyzed with Ion Chromatography. The results showed that SO42-, NO-3, Ca2+ and NH+4 in the fine particles were the major components of cations and anions on the regional atmosphere. The soluble ion concentration was far lower than that in the sites affected by human activities seriously. It was close to the remote regional background atmospheric level, but it also had its own characteristics. The concentration showed significantly higher in spring and summer and lower in autumn and winter. The ratio of the ions in different seasons was not the same. The nature of regional atmospheric fine particles was exhibited alkaline by calculation of ion balance. Correlation analysis was used in this study to find out the major forms and the source of ions. There were high correlations between Cl-, Ca2+, Na+ and Mg2+. The correlations between SO42- and NO-3 and most of the cations were very high. It means part of sulfate coming from natural source of the sand and dust areas of Central Asia, rather than human activities. NH+4 passes the correlation testing only with SO42-, indicated that NH3 is mainly neutralizes by sulfate. Atmospheric environment is mainly controlled by natural sources. However, during the summer monsoon, man-made pollution emission can not be ignored; it is also verified by the calculation of HYSPLIT trajectory model.
There is a very close connection between the equilibrium line altitude (ELA) and the local climate, particularly solid precipitation and air temperatures. Fluctuations in the ELA therefore provide a pronounced indicator of glacier response to climate change, and help to reconstruct the former climates and to predicate the future glacier behavior. For the glaciers at present, direct observation of glacier mass balance over several years is an ideal method to obtain accurate ELA. However, for a greater range, other estimating methods have to employed, e.g., accumulation area ratio (AAR), area altitude balance ratio (AABR), toe-to-headwall altitude ratio (THAR), terminal to summit altitude method (TSAM), maximum elevation of lateral moraines (MELM), cirque-floor altitudes (CF) and glaciation threshold (GT). Due to the combined influence of avalanches and snow drift, debris cover and topographic effects (glacier morphologies and styles), the ELAs of a glacier estimated with various methods may have discrepancies of several hundred meters. It is necessary to employ multiple methods, together with an appraisal of their reliability. Furthermore, the tectonic uplift should be considered as well.
Because of the particular natural characteristics and human activities, the way of land use in the upper reaches of the Heihe River, located in arid region of Northwest China, is different from that in the middle and lower reaches of the river. The variation processes of the land use structure in the upper reaches have an important affect on water resources and eco-environment of the whole watershed. In this paper, the upper reaches are taken as research object. Three sets of Landsat Satellite images over the study area in 1987, 1999 and 2010 were selected to be basic data. Transfer matrix and principal component analysis were employed to analyze quantitatively the process of dynamic change of the woodland, grassland and cultivated land in the study area. Then the dynamic mechanism of the land use in the area was revealed. The following conclusion can be drawn: 1) The land use change has evident periodicity: in the stage of 1987-1999 cultivated land increasing with woodland and grassland decreasing, but in the stage of 1999-2010 grassland increasing and woodland decreasing with cultivated land increasing; 2) The spatial pattern of a land use type has great difference: woodland is in east more than in west, and in north more than in south; grassland is in east more than in west and in south more than in north, but cultivated land mainly concentrates along the river valleys and around the urban settlements even near the piedmonts; 3) Human activity is the key influencing factor to the dynamic change in land use.
Based on thedata of dust storms and dust-floating weather events in the Lanzhou City, Gansu Province during 1955-2010, we build the classificationof the intensity of dust storms and dust-floating weather events, we employed the Markov model to studied the probability of occurrence of different intensity of dust storms and dust-floating weather events, and forecast and testing the probability of occurrence of the weather events in2011 in Lanzhou. The results show: the probability of occurrence of dust storm with very strong years, strong years, less strong years, general years, loweryears were [0.022, 0.00, 0.044, 0.044, 0.888]. in2011 in Lanzhou. In fact, Lanzhou dust storm event is not happen in 2011, to belong loweryears, the forecast result has confirmed.For dust-floating weather eventin 2011,the probability of occurrence of dust-floating weather events with very strong years, strong years, less strong years, general years, lower years were [0.20, 0.1, 0.00, 0.30, 0.40], and in fact the 2011, there are9 dust-floating weather events, to belong intensity of between general years and loweryears less, in line with the predicted results.With extension of the dataseries, Markov model willbe an effective way of short-term sandstorm dust weather forecast.
Warm and ice-rich frozen soil belongs to plastic frozen soil, of which the compressibility is remarkable under loading. In order to study the compressive properties of the warm and ice-rich frozen soil, compression tests under constant temperature and stepped load were conducted at temperatures of -0.3, -0.5, -0.7, -1.0, -1.5℃ andwith water contents of 40%, 80%, 120%, respectively. Then the volume compressibility coefficients were obtained. The test results indicate that: The compressibility of the soil is considerable. For example, the volume compressibility coefficient of the clay specimen at -0.3℃ with water content of 40% could reach to 0.328 MPa-1, which belongs to high compressibility soil. 2) exists in the soil during the process of compression, and mostly occurs in the initial stage of loading. 3) Temperature and water content of the soil, which control the volumetric unfrozen water content, are the most important factors to impact the compressibility. 4) Under the test conditions mentioned above, the compressibility of the soil increases with temperature rising and water content decreasing. When the temperature is higher, the effect of water content on the compressibility is remarkable, but it is not obvious when the temperature is relatively low.
In the construction of subgrade in loess areas, some methods like pre-collapse are always taken to make the subgrade more stable. However, in seasonal frozen soil areas, there are some loess subgrades having disease, such as vast uneven settlement or collapse, after running a few years. In order to study and analyze the reason how the freeze-thaw cycle influence the secondary collapse of loess, experiments were done in the laboratory. First, loess specimen was collapsed in a big volume, and then the specimen experienced freeze-thaw cycles and finally experienced second collapse. It is found from these experiments that the intact loess and the remolded loess's coefficients of secondary collapse come to a same value gradually with freeze-thaw cycle increasing; both the intact loess and the remolded loess's coefficients of secondary collapsibility are larger than 0.015, which is the standard to identify whether the loess has the ability to collapse, so both the intact loess and the remolded loess have the ability of secondary collapse under freeze-thaw cycle.
Combined with the data of debris flow control engineering of the post-disaster reconstruction in Zhouqu County, Gansu Province three-dimensional model is built with the software of 3ds model such as 3ds Max, Maya, etc. A 3D visualization scene is also established based on Skyline 3D GIS platform. In this paper, the key technologies of construction of 3D visualization scene, data processing and the process of modeling 3D scene are described in detail. Created 3D scene of post-disaster reconstruction in Zhouqu will visually show its terrain and the circumstances of debris flow control engineering. It will provide a decision support for the local government to manage the similar situation. In addition, the software of the current advanced fluid and rigid body simulation can be applied to dynamic modeling the process of large torrential debris flows, similar to "8.8" debris flow, and the effect will be perfect.
The permafrost, seasonally frozen soil and snow cover are widely distributed in Northwest China. Spring snowmelt and frozen-soil thaw are normally the most important hydrological events in the region. However, modeling cold regions hydrological processes is full of problems because of lack of data in watershed scale. The Cold Regions Hydrological Model (CRHM) platform, a flexible object-oriented modeling system, was devised to solve this problem with connecting modules into model by problem objectives, scale of application and data constraints. In this study, two watersheds were chosen to validate the CRHM. One is the Binggou watershed, which is an experimental area for researching snow accumulation and ablation processes and researching the influence of snow ablation on runoff. Another one is Zuomaokong watershed, which is an experimental area for understanding the effects of soil freezing-thawing on runoff process. For Binggou watershed, the cold regions hydrological model was created within CRHM to simulate the contribution of sublimation to alpine snow mass balance and snowmelt runoff process. Comparison of simulated snow depth with observations during October 30, 2007 to May 6, 2008 shows that the snow accumulation/ablation processes can be simulated much better with a physically based snowmelt model, which includes the layered, hourly time step, energy balance snowpack ablation (Snobal CRHM) module and blowing snow module (pbsmSnobal), rather than a temperature index snowmelt model. Further comparison of simulated results through switch on/off different process modules reveals that the sublimation loss could reach to about 69 cm in the alpine region of Binggou basin, accounting for 48 % of the total snowfall (145.5 cm), and the half sublimation loss is attributed to snow drifting (about 35 cm). The conclusion could be drawn that snow sublimation loss is vital for accurately calculating snow ablation and snow drifting sublimation loss is significant in the alpine region of Binggou basin. Meanwhile, the model is able to well reproduce the measured streamflow without calibration, with RMSEof 0.52 m3·s-1and NSEvalues of 0.64. For Zuomaokong permafrost watershed, the cold regions hydrological model is created within CRHM to simulate the influence of soil freezing-thawing process on runoff. Comparison of simulated results with observation shows that model including module for handling frozen soil infiltration can capture the main runoff processes, especially that in frozen-soil thawing period in spring. The RMSEand NSEvalues between simulated and observed runoffs are 0.31 m3·s-1and 0.67, respectively. Overall, the validated results for the two watersheds show that CRHM is capable of simulating various elements of the cold regions hydrological cycle in Northwest China without calibration. This is encouraging for the model able to predict the hydrological processes in ungauged basins.
As an independent water system, the Sugan Lake water system is located in the north-west part of the Qaidam basin. River water from Harten River supply Sugan Lakes. There is water balance between river water supply and evapotranspiration from the basin. Large Sugan Lake and Small Sugan Lake are the tail of the catchment area of the basin. The major ecological landscape in the basin is Gobi desert, with a small part of ecological vegetation scattered around Large Sugan Lake and small Sugan Lake, where groundwater is less than 5 m in depth. Based on water balance evaluation, water cycle ways are analyzed for the basin. Combining with hydrogen and oxygen isotope determination and remote sensing information extraction, the following conclusion can be drawn that water recharge sources are different in Large Sugan Lake and small Sugan Lake. Change in input water from Harten River will sensitively reflect in Large Sugan Lake, and almost not any signal can be seen in small Sugan Lake. An ecological vegetation change mode is established on the basis of investigation. According to the mode, the changes in water area of Large Sugan Lake, in groundwater depth and in ecological vegetation are predicted under different diversion scenarios. It is concluded that 1.0×108m3 water diversion from Harten River will not significantly damage the ecosystem around the Sugan Lakes, but will improve the ecosystem in Dunhuang basin greatly.
In this paper, annual and seasonal variations of potential evaporation were analyzed based on meteorological data from 123 observation stations in the Yangtze River catchment during 1960-2011, in combination with Penman-Monteith model. The changing tendency in potential evaporation over the catchment was analyzed by Mann-Kendall test with trend-free pre-whitening (TFPW-MK) analysis, Rescaled Range (R/S) analysis and method of Inverse Distance Weighted (IDW) under ArcGIS. In addition, correlation analysis was used to extract the principal factor affecting the potential evaporation. The results demonstrate that the annual potential evaporation had a decreasing tendency between 1960 and 2002, but had an increasing tendency between 2003 and 2009; in its entirety, it had an increasing tendency. Spatially, in the upper plateau region, the upper basin region and the lower reaches the annual potential evaporation had a decreasing tendency, with a large amplification in the upper basin region, while in the middle region it had a decreasing tendency. The results of R/S analysis showed that potential evaporation in spring, summer, autumn and annual potential evaporation were persistent increasing, and will be increasing. The change of potential evaporation is mainly caused by the significant increase in highest air temperature and lowest air temperature.
The hydrological data modeling and data sharing are the research focus of watershed science and also the basis of Digital Watershed. Analyzing the domestic and international studies, one can see that watershed information infrastructure integrating observational data and environmental information has become an important application of watershed science on Digital Earth. The hydrological information system of the Heihe River Basin is from the prototype of Arc Hydro model and CUAHSI's Hydrologic Information System, which was designed for a suitable set of the hydrological information system integrating watershed geodatabase, observing system database and data sharing publication system, to achieve the integration of various types of observational data, data sources and observational data in a watershed observation database. Through unified common data model, the surface water and groundwater information are integrated. This system may realize the function of storage, organization and online publication of the watershed relating observed data and spatial data, providing ecological environment online data services as well as the corresponding watershed observational data services for watershed science research and promoting the study of watershed science program.
Recent researches of snow hydrology are reviewed in this paper. After briefly describing the basic methods in snowmelt simulation, the key points of different methods are discussed. The discussion focuses on the details of simulation algorithms and how snow variables, such as snow cover area, are used in different models. Considering the snow distribution features in the Tibet Plateau, three main research topics are put foreword: simulation of heterogeneous snow at subgrid scale, parameterization of blowing snow simulation and snowmelt simulation on seasonal frozen soil. Latest researches in the three topics are reviewed in detailed separately. The importance of developing suitable algorithms of snow cover depletion in subgrid snowmelt simulation is emphasized. The parameterization of spatial blowing snow simulation under mountainous condition is discussed. Problems in snowmelt simulation on seasonal frozen soil are analyzed.
Watershed hydrological simulation aims to demonstrate the hydrological processes mathematically in the base of hydrological knowledge. In the case of the lack of observational data, hydrological modeling is an effective method to study hydrological processes. As a typical inland river basin, Heihe River basin is always a hot spot to study hydrology and water resources in the cold and arid regions. Hydrological modeling of mountainous runoff in the mainstream of the Heihe River also appeals to researchers to apply empirical models, conceptual models and distributed hydrological models in the study area. At the beginning of the study, empirical models are constructed by using the observation to predict the variation trend of the mountainous runoff. Furthermore, the conceptual models are employed to primitively simulate the hydrological processes in the study area. However, owing to larger glaciers, snow cover, permafrost, as well as the special geological structure and terrain conditions, the mainstream of the Heihe River has special hydrological processes characterized by high and cold, which have not been revealed in ordinary hydrological models and are ignored in most of the hydrological models. Although these are some researches having relatively accurate simulated results for the mountainous runoff via various models, most models are still limited to describe the hydrological processes characterized by high and cold at length. Taking into consideration of the special hydrological processes caused by glaciers, snow cover, and permafrost and so on, whether it is able to represent these special hydrological processes is a crucial issue for the hydrological modeling of inland river basin in highland and cold areas. In future, more in-situ observation should be carried out and carried on to acquire more observation data, and the hydrological processes of permafrost and snow cover should be investigated further, in order to develop a genuine hydrological model more suitable to highland and cold areas.
The upper reaches of the Heihe River are located in the Qilian Mountains on the eastern edge of the Tibetan Plateau. There are many reports on the hydrology and vegetation of the reaches, but less of them involve the distribution of soil bacterial communities. In this paper, soil samples were collected at different altitudes (2 814~4 130 m above sea level) from the upper reaches of the Heihe River. Cultivable soil bacteria were investigated with PYGV, R2A, NB and Czapek agar mediums. It is found that the number of cultivable bacteria ranges from 4.6 to 37.0 (106 CFU·g-1). Population fluctuation of bacteria is significant along with altitudes(P<0.05). From the soil 26 species were isolated by sequencing PCR-amplified 16S rDNA. These species are affiliated with 19 genera belonging to α-Proteobacteria,β-Proteobacteria,γ-Proteobacteria,Actinobacteria,Bacteroides,Firmicutes and Verrucomicrobia. Among them, Agreia pratensis, Mucilaginibacter ximonensis, Cryobacterium psychrophilum and Arthrobacter oxydans are dominant species. The relative abundance of Cryobacterium psychrophilum obviously concentrates at high altitude, but that of Agreia pratensis decreases with altitude. Statistical analysis shows that altitude and vegetation type are the principal environmental factors in the upper reaches of the Heihe River, which affect the distribution of bacterial community. Cultivable number of bacteria has negative correlation with altitude, and the diversity of bacteria increases firstly and then decreases with altitude, which is primarily controlled by plant biomass and cover degree. Besides, the diversity of cultivable bacteria is also correlated with some soil physicochemical properties (e.g., organic material, total organic carbon, salt and available K).
The changing trends in culturable microbe amount and its affect factors in the soils along the Qinghai-Tibet Highway were investigated in this paper. Along the highway, the amount of culturable microbes in the soils was in between 0.77×106 cfu·g-1dw and 2.44×107 cfu·g-1dw. Along the highway from south to north, the amount of culturable bacteria and fungi in the soils decreased first and then turned to stationary, while the amount of culturable actinomycetes decreased first and then increased. At the same time, the total nitrogen, total organic carbon and moisture content in the soils decreased, while the soil pH value increased gradually. The ratios of fungi/bacteria and C/N showed similar changing tendency, that is, increasing firstly and then decreasing. Correlation analyses between the environmental factors and the amounts of culturable microbes in the soils indicate that the microbial quantities in the soils are closely related to latitude and soil physicochemical properties. The microbial quantities have significant negative correlation with latitude and pH value of the soils, and have significant positive correlation with total nitrogen, total organic carbon and moisture content of the soils.
Net primary productivity (NPP) is the core of terrestrial carbon cycle research. Estimating NPP is not accurate in high altitude regions owing to lack of meteorological data. Based on the WRF model meteorological data and SPOT-VEGETATION remote sensing images, the grassland NPP of Qinghai Lake basin was estimated using CASA model from 2000 to 2010. The simulated results were validated by observed data and other simulated data, and then the temporal and spatial variations of NPP were analyzed. The analyses show: 1) WRF meteorological data might be applied well to CASA model, perfectly simulating grassland NPP. 2) The annual grassland NPP was 2.71×10m12 gC·a-1 and the NPP per unit area was 145.71 gC·m-2·a-1 on average, and spatially, NPP showed an increasing from southeast to northwest with elevation increasing, but NPP per unit area reached a maximum at the altitude of 3 200~3 500 m. 3) The inter-annual variation of NPP was obvious and an increasing tendency could be seen from 2000 to 2010. Around Qinghai Lake there was a main NPP increasing area. The NPP changed month by month significantly; most of them (57.36%) took place in summer. 4) Correlation analysis between NPP and meteorological data, including solar radiation, air temperature and precipitation, shows that the main factor affecting NPP is air temperature.
Statistical analysis on the water consumption, standing biomass, net primary production, water use efficiency and their correlations with the vegetation in Haibei alpine meadow from 2001 to 2011 showed that the water consumption from May to September was 416.30 mm, the aboveground net primary production (ANPP) was 393.07 g·m-2, the belowground net primary production (BNPP) was 945.26 g·m-2and the total net primary production (NPP) was 1 338.33 g·m-2, and the ratio of BNPP to ANPP was 2.404, the standing crop biomass at the end of Augustreached 3 422.92 g·m-2, of which the ANPP and BNPP was 411.07 g·m-2and 3 011.85 g·m-2, respectively, with the ratio of BNPP to ANPP of 7.327. This demonstrates that the current vegetation had huge standing stock and great ability to return the soil carbon. NPP had a poor correlation with the water consumption but had a significantly positive correlation with the air temperature averaged from May to September, indicating that water condition in the alpine meadow could meet the demand for the plant growth, and the synchronous air temperature was the principal factor to improve the NPP. Water consumption averaged over the 11 years shows that the water use efficiency for BNPP, ANPP and NPP was 0.958 g·m-2mm-1, 2.326 g·m-2mm-1and 3.284 g·m-2mm-1, respectively, indicating that the vegetation in alpine meadow had a higher water use efficiency.
The sapwood/heartwood boundary of the Picea crassifolia in the upper reaches of the Heihe River was determined with staining method and Heat Pulse Meter SF-300 made in Australia, respectively, and the spatial pattern of the trunk liquid transfer of the Picea crassifolia was studied by Heat Pulse Meter SF-300. It is found that both the staining method and the trunk flow method are able to determine the sapwood/heartwood boundary of the Picea crassifolia trunk. However, the staining method is more convenient and more rapid. There is an exponential relationship between diameter at breast height and sapwood width determined by the staining method. The trunk liquid transfer velocity of the Picea crassifolia gradually increases from the outer edge of sapwood inwards to a maximum and then decreases smoothly. The spatial pattern of the trunk liquid transfer of the Picea crassifolia is symmetric distribution in the main.
A new explanation of virtual water strategy is presented in this article. Based on the discussion of inadequacy of Allan's standpoint, the concept of virtual water strategy is redefined and its connotation is extended. In fact, Allan's virtual water strategy is suit for extremely water-deficient areas. In those areas, the virtual water strategy is an effective route to improve regional water security and people's living standard by allocating water resources optimally (both entitative water and virtual water). In other areas, the core of virtual water strategy is selecting an appropriate route to develop the secondary and tertiary industries that leads water resources flow to industry and service sectors by dint of positive feedback ring. Based on the analysis of the ecological economical development in Zhangye Municipality, it is found that the ecological economical strategy practiced in the city is an innovative virtual water strategy.
Eco-compensation is an innovative way to protect environment. It transforms the outside of ecosystem services and non-market value into the inherent power of environment protecting. Taking the Qinghai Lake watershed as a case, the impact of land use change on carbon storage is modeled by natural process model Carnegie Ames Stanford Approach, while supply costs of carbon storage are estimated by social survey. Upon these work, the natural process and economical process are included in an integrated model framework by cost-benefit analysis and minimum data approach to explore the spatial targeting and compensation standard in eco-compensation program. Results of the case study show that the efficiency cost ratios of the four counties in the watershed are: 0.5353 in Haiyan County, 0.5549 in Gangcha County, 0.5549 in Tianjun County and 0.4353 in Gonghe County. Regarding to the efficiency cost ratios, the cost order should be: Tianjun County, Gangcha County, Haiyan County and Gonghe County. To achieve the goal of restoration of grassland, the compensation standard order should be: Haiyan County (328.5 yuan·hm-2 per year), Gangcha County (250.5 yuan·hm-2 per year), Tianjun County (181.5 yuan·hm-2 per year) and Gonghe County (478.5 yuan·hm-2 per year). According to the compensation standard, the carbon storage will increase in all counties of the watershed as follows: 1.7×107 kg per year in Haiyan County, 5.25×107 kg per year in Gangcha County, 18.52×107 kg per year in Tianjun County and 2.86×107kg per year in Gonghe County.
The Heihe River basin is the second largest inland catchment in Northwest China and the researches involved this basin have strengthened in recent decades. By using the detailed bibliographic data from CNKI, ISI and EI databases, the publication tendency of articles focused on the basin is analyzed in this paper. Through quantitative statistics on the amount of published articles, key research organizations, core-author groups, research hotspots, major periodicals, main foundations, etc., it is found that the amount of articles has increased rapidly in recent years. Among the key research organizations, the Cold and Arid Regions Environmental and Engineering Research Institute, CAS, has preponderant contribution; The key words presented frequently are water resources, remote sensing, arid land, groundwater, climate change, land use, ecosystem, etc., which represent the hotspots and emphases in this field; establishing integrated watershed model is the recent research direction; the financial sources are various, but the National Natural Science Foundation of China is the first and foremost.
