Variations and trends of the freezing and thawing index along the Qinghai-Xizang Railway for 1966-2004

Annual freezing and thawing index of 7 meteorological stations along the Qinghai-Xizang Railway were calculated based on daily maximum and minimum temperature records for 1966-2004. Trends of annual freezing and thawing index were analyzed using the Mann-Kendall test and a simple linear regression method. The results show that: 1) The mean annual freezing indices range from 95 to 2300 degrees C.d and the mean annual thawing indices range from 630 to 3250 degrees C.d. The mean annual freezing index of the 7 stations exhibited decreasing trends with decreasing rate of -16.6- -59.1 degrees C center dot d/10a. The mean annual thawing index of these 7 stations showed increasing trends with the related decreasing rate is 19.83-45.6 degrees C center dot d/10a. 2) The MK trend test indicated the significant decreasing trends (significant at < 0.05 significant level) in the annual freezing index for most stations except for Golmud. The significant increasing trends can be observed in the annual thawing index for 4 stations except Golmud and Tuotuohe. Golmud was the only station with no trends in both annual freezing and annual thawing index

The spatial distribution and movement of the spring soil moisture in the hinter land of Junggar Basin

The exploitation of resources and an increase in civil engineering projects in the Junggar Basin has caused major environmental disturbance to the fragile desert eco-system. It is a serious problem that attracts global attention on how to restore and reconstruct the stable natural eco-system. Understanding soil moisture content and lateral water movement in and areas, at a shallow depth, is of practical importance. On the one hand, lateral flow can be expected to reduce the groundwater recharge rate. On the other hand, it may result in a strong variability of water resources over short distances, thus affecting the distribution and composition of the vegetal cover. The eolian soil moisture condition is the primary factor that affects desert plant-cover in the hinter land of Junggar Basin, especially in spring (from March to May). With neutron probe, through field calibration, the soil moisture changes in different terrain parts, which are the crest, slope, the foot of the natural and disturbed dunes and the interdune land were measured. The data shows that the spatial distribution of the soil moisture in spring is closely related to the sun radiation, the depth of snow in winter, landscape position, the depth of soil, plant cover condition (cover-degree, plant species), and human impact. The data also provides scientific information and instruction for restoring and reconstructing the eco-system that has been damaged by engineering disturbance

Digital regionalization of geomorphology in Xinjiang

This paper presents a method of geomorphologic regionalization for Xinjiang, with the use of Srtm-DEM (resolution 90 m) and TM images for 1990 (resolution 30 m). After interpretation and classification of geonnorphologic types, the present research focuses on the qualitative and quantitative distribution of different geornorphologic types based on geographical grid analysis. Then, by using system clustering analysis method, geomorphologic types are grouped into divisions. The resulting geomorphologic regionalization hierarchy of Xinjiang includes three levels, i.e., macro-landform divisions, medium-landform divisions, and micro-landform divisions, containing 6, 23 and 200 types, respectively. This method makes it possible to digitally delimit geornorphologic regions. Comparison and verification show that the spatial precision of the boundaries of geomorphologic subareas in Xinjiang is very high

Farmland management effects on the quality of surface soil during oasification in the southern rim of the Tarim Basin in Xinjiang, China

Oasification and desertification are basic geographical processes in arid areas, and both change the soil properties and quality. Recently, oasification has been obvious in the southern rim of the Tarim Basin of Xinjiang, China, and agriculture is the main land-use type. There has been little research on oasification involving farmland of different management types in extremely arid regions. In 2004, four experimental fields were established in the Cele Oasis, representing four typical land-use types of local farmers' tillage practices during oasification. Three experimental fields were situated in the desert-oasis ecotone: newly cultivated land (NEF), a field with normal manure input (NMF), and a field with high manure input (HMF); there was also another field in the oasis interior (OIF), to allow analysis of the management effects on soil properties and soil quality of farmlands. Additionally, the soil from an uncultivated control plot was analyzed for comparison. Both a Soil Quality Index based on soil properties and a Sustainable Yield Index based on yearly yield were used to assess the soil quality of the different farmlands. There were significant differences in seven soil indicators, including soil particle size distribution and soil organic matter, between the four locations. NEF had the lowest and OIF the highest values in all assessments among the five experiment plots. Fertilization of NMF and HMF had positive effects on soil properties and soil quality; however, the sustainable productivity of these farmlands was low. The results should be beneficial for re. ning agricultural management practices and improving sustainable land use in the oasification process

Some results of snow chemical surveys in the Kunnes River valley, East Tienshan mountains, China

Chemical surveys of snow were carried out in the upper reaches of the Kunnes River, a tributary of the Yili River in East Tienshan Mountains, China. Some surprisingly high values of sodium and potassium (K+ + Na+) ranging from 4.44 to 8.99 mg/l compared with other data from neighboring areas are detected. Moreover, some relative high values of SO42- with mean concentration 15.8mg/l for new snow and 14.40mg/l for deposited snow, ranging from 10.43 to 23.71 mg/l are also found. Therefore, it is inferred that the sodium and potassium (K+ + Na+) are in the forms of sulfate and that the sources of the sulfate are deserts and some dried lakes in Central Asia. It is also found that there is obviously spatial variation of ions such as K+ + Na+, Ca2+, SO42- and HCO3-. The concentrations of K+ + Na+ and SO42- and that of Ca2+ and HCO3- have similar spatial pattern. The temporal pattern of ion concentration of new snow is considered to be mainly controlled by the depth and area of snow cover in the study area and in the areas to the west. (C) 2002 Elsevier Science Ltd. All rights reserved

Decrease of river runoff in the Lake Balkhash basin in Central Asia

The decrease of river runoff draining into Lake Balkhash in Central Asia was investigated using hydrological and meteorological data over a long-term period. The data from the difference integral curves of the annual runoff from 1911 to 1986 suggested that a low-flow period began in 1970 in the River Ili, and in 1973 in the east rivers, continuing until 1986. Compared with the runoff before 1969, the decrease of runoff in the upper reaches of the River Ili was less than those in the middle and lower reaches. The decrease in the upper reaches resulted from natural variability, whereas those of the middle and lower reaches were due to a combination of the effects of climate and human activity. There are two reasons for this. First, after 1970, precipitation did not decrease uniformly across the entire basin. Second, in 1970, the Kapchagay dam started operating. As a result, the annual inflow into Lake Balkhash from the River Ili after 1970 decreased to 77% of the pre- 1969 mean. Similarly, after 1973, the inflow from the east rivers was 75% of the pre-1972 mean. The characteristics of the runoff in the growing season (April to September) and those in the non-growing season (October to March) were investigated for the upper, middle, and lower reaches of the River Ili. In all reaches, the runoff in the non-growing season remained unchanged both before and after 1969. However, from 1970 to 1986, decreases of river flow in the growing season were 2.0 to 2.5 times greater in the middle and lower reaches than in the upper reaches. This was primarily due to the impacts of human activity. In conclusion, it can be deduced that the decrease in runoff after 1970 in the middle and lower reaches was the result of human activity during the low-flow period. Copyright (c) 2006 John Wiley & Sons, Ltd

Magnification of flood disasters and its relation to regional precipitation and local human activities since the 1980s in Xinjiang, Northwestern China

Analyses of flood disasters were conducted using 1950-2001 data on the flood-damaged areas of cropland, the annual number of flood disasters and the direct economic losses in Xinjiang. There is an increasing trend in flood disasters in Xinjiang during the second half of the 20th century, especially since the mid-1980s. Results of a non-parametric Mann-Kendall test on the cropland-flooded index time series revealed an abrupt change in the mid-1980s. The reasons are discussed with respect to changes in annual precipitation and regional human activities, by correlating cropland-flooded area to annual precipitation and three socio-economic parameters (population, cropland area and GDP). The correlation coefficients between the flood-damaged area and the annual precipitation during the periods 1961-1998 and 1987-1998 were substantially higher than during the period of 1961-1986. The correlation coefficients between the flood-damaged area and the three human activity parameters, however, were relatively high for the whole period of 1961-1998, but generally not significant for the 1961-1986 and 1987-1998 periods, separately. These suggest that the occurrence of flood disasters could be mainly induced by local human activities before the mid-1980s, and thereafter mainly by abnormal precipitation in Xinjiang. Meteorological and hydrological records showed that the number of heavy rainfall events and the frequency of rainstorm flood disasters increased since the 1980s. In addition, siltation of reservoirs and loss of flood control structures are partly responsible for the increase of flood-damaged area. These results suggest that the increasing trend in flood disasters in Xinjiang since the middle 1980s could be attributed, at least in part, to an increasing trend in annual precipitation

Simulating spatial distribution and varying patterns of population in Urumqi, China - art. no. 67900A

Taking Urumqi as a case, a simulation of urban population spatial distribution is proposed based on urban land use and population statistical data using GIS, and population spatial distribution patterns are analyzed by the raster population surface. As a result, generating raster population spatial distribution surface is more accurate and natural than the traditional choropleth map of population density in Urumqi. Concerning the population spatial distribution of Urumqi, the population density declines from south to north and the population distribution mainly presents "T-type", the population distribution presents polycentric agglomeration and the population distribution of the districts shows different features. The population density varies significantly with the increase of the distance from CBD. Finally, this paper finds that the development history of districts, terrain and traffic road are main factors influencing Urumqi's population distribution. This paper tries to provide more accurate data of population distribution for the plan and management of urban land, traffic and public facilities in order to enrich the researches of urban population distribution

Hyperspectral indices for leaf and pixel chlorophyll estimation in open-canopy tree - art. no. 675222

In this paper, the goal is to found indices; best for Cab estimation with leaves and heperion pixels. There are several indices chosen, which showed best results for Cab estimation at both leaf and canopy levels in other studies. Forty-eight typical leaves were sampled in middle and lower reach of the Tarim River, Xinjiang, China. Leaf reflectance and Chlorophyll of leaves collected. Result demonstrated that Indices such as red edge and derivative indices R750/R710, R740/R720, (R734-R747)/(R715+R720), Blog(1/R737), D715/D705,(R734-R747)/(R715+R726), (R694-R680)/(R732-R760) were shown to be the good indicators for Cab estimation at leaf. Hyperion data were acquired for Aqike section in the middle reaches of the Tarim River in Nine 28, 2006. Field data were collected at same day to coincide with the Hyperion, including Chlorophyll of each tree, LAI, green vegetation cover. LAI derived from scanopy 2006. Inventory field plots were 120mx120m quadrants, and Chlorophyll of pixel is deduced from field data of 360 trees. Generally good results are found for Cab estimation at pixel level with indices such as, (R734-R747)/(R715+R726), Blog(1/R737), (R694-R680)/(R732-R760), TCARI, TCARI/OSAVI, MCARI/OSAVI and so on. It was found that (R734-R747)/(R715+R720), Blog(1/R737), D715/D705, (R734-R747)/(R715+R726), (R694-R680)/(R732-R760),R740/R720 were successfully test on leaves and piexls. On the other hand, the "modified" indices (TCARI, MCAVI, TCARI/OSAVI, MCARI/OSAVI) already give good results at. the piexl level

Ecological water demand of natural vegetation in the lower Tarim River

We have appraised the relationships between soil moisture, groundwater depth, and plant species diversity in the lower reaches of the Tarim River in western China, by analyzing field data from 25 monitoring wells across eight study sites and 25 permanent vegetation survey plots. It is noted that groundwater depth, soil moisture and plant species diversity are closely related It has been proven that the critical phreatic water depth is five meters in the lower reaches of the Tarim River. We acquired the mean phreatic evaporation of different groundwater levels every month by averaging the two results of phreatic evaporation using the Qunk and Averyanov formulas. Based on different vegetation types and acreage with different groundwater depth, the total ecological water demand (EWD) of natural vegetation in 2005 was 2 4x10(8) m(3) in the lower reaches of the Tarim River. Analyzing the monthly EWD, we found that the EWD in the growth season (from April to September) is 81% of the year's total EWD. The EWD in May, June and July was 47% of the year's total EWD, which indicates the best time for dispensing artificial water. This research aims at realizing the sustainable development of water resources and provides a scientific basis for water resource management and sound collocation of the Tarim River Basin