CollectHomepage AdvertisementContact usMessage

Most read

Published in last 1 year |  In last 2 years |  In last 3 years |  All
Please wait a minute...
For Selected: Toggle Thumbnails
Applicability study of CFSR,ERA-Interim and MERRA precipitation estimates in Central Asia
HU Zeng-yun,NI Yong-yong,SHAO Hua,YIN Gang,YAN Yan,JIA Chao-jun
   2013, 36 (4): 700-708.  
Abstract10168)      PDF(pc) (3323KB)(4096)       Save
In this paper,the applicability of three reanalysis precipitation datasets,CFSR,ERA-Interim and MERRA,in Central Asia was evaluated with the observed monthly precipitation data(OBS) during 1979-2011 from 162 meteorological stations by the correlation analysis,t test and the method of least squares.  Accuracies of the reanalysis datasets were quantified with mean bias error(MBE),correlation coefficient(R),mean absolute error(MAE) and root mean square error(RMSE). In addition,the variations of the three reanalysis precipitation accuracies at different months and altitudes are analyzed. The results suggest as follows:(1) All the three reanalysis datasets tend to overestimate the OBS precipitation. However,there exist obvious differences of the simulation results between CFSR,ERA-Interim and MERRA. For each reanalysis data,MERRA precipitation agrees most closely with OBSR=0.53,MBE=5.12 mm) than CFSR and ERA-Interim,the following is ERA-Interim with (R=0.53,MBE=17.75 mm) and the worst is CFSR with (R=0.50,AE=27.04 mm) although all of them significantly correlated with the OBS precipitations (p<0.05). This may be affected by the scarcity and uneven distribution of the meteorological stations,the complex topography in Central Asia. Furthermore,different assimilation techniques,data sources and models used in different reanalysis datasets can also cause the different simulation results. (2) CFSR,ERA-Interim and MERRA have the consistency trend in monthly precipitation change. Comparing with the OBS precipitation,the biggest magnitude overestimates appear in March and April for the three reanalysis datasets. While the smallest magnitude overestimates appear in August,September and October. The precipitation differences between the three reanalysis datasets indicate that CFSR precipitation values are bigger than ERA-Interim from January to May and from October to December with the average difference 16.33 mm,while smaller than ERA-Interim in the other months. The precipitation differences between CFSR and MERRA are positive for all the months during the year,and the corresponding average difference is higher than 21.9 mm. All the monthly precipitations for ERA-Interim are bigger than MERRA,and the biggest differences reach to 24 mm in May,June and July.  (3) For the three reanalysis datasets,the best precipitation accuracy appears in 500-1 000 m ranges. When the altitude is over 1 000 m,the precipitation accuracy is decreasing following the altitude increasing which shows that the simulation results of the three reanalysis are poor at high altitudes. From the above analysis,it was found that although there exists some uncertainties for the three reanalysis simulation results at different months and areas in Central Asia,the sufficient evidences show that the result from MERRA matching the OBS precipitation data is better than that from CFSR and ERA-Interim. Therefore,MERRA precipitation data can be used to study the precipitation spatial and temporal patterns in Central Asia. The results of the applicability study between the three reanalysis datasets and [OBS] can provide theory and technology for the rectifying of the three reanalysis datasets.
Reference | Related Articles | Metrics | Comments0
Meathod of determining CN value in the SCSCN method
FU Suhua,WANG Xiangliang,WANG Hongye,WEI Xin,YUAN Aiping
   2012, 35 (03): 415-421.  
Abstract7697)      PDF(pc) (802KB)(2287)       Save
Water shortages and nonpoint pollution caused by soil erosion have reached crises point in many regions. Hydrological model, soil erosion model and nonpoint pollution model have been used as the main technique tools which evaluate the risk of water resources, soil erosion and water pollution. Runoff calculation is an important part in the hydrological models and is the basic element in the calculation of water contaminants including sediment, nutrients and pesticides etc. Soil Conservation Service Curve Number (SCS-CN) method has been widely used in many countries and regions. Runoff curve number (CN) is an integrated parameter in the SCS-CN method, which reflects the effect of soil water content, soil type and land use etc. on runoff depth. But SCS-CN method may result in bad prediction accuracy in China because the values of curve number provided by USDA Soil Conservation Service can not be directly used in China due to the differences in landuse,hydrologic soil groups and slope gradient etc. Thus the purpose of this study was to compare the differences in determining CN value by using mean method, arithmetic-mean method, median method, S probability distribution method and asymptotic method and to compare the accuracy of runoff predicted by different CN value. Data of rainfall - runoff from three runoff plots at Shixia, Miyun, Beijing, with a period from 1993 to 2006, were used. Runoff depth was calculated by using SCS-CN method with different CN determining methods. The index of Nash model efficiency, correlation coefficient and acceptance rate were used to evaluate the accuracy of runoff depth predicted by different CN determining methods. The results show that the runoff depth predicted by five methods was significantly different from the measured ones. The asymptotic method had the best Nash model efficiency. But arithmetic-mean method provided with the best correlation coefficient and acceptance rate. Compared to asymptotic method, arithmetic-mean method is simple, thus we recommend that arithmetic-mean method be used to determine the CN value. The antecedent moisture condition had important effects on the results of runoff prediction. The acceptance rate under the AMCII was the best whereas that under the AMCIII was the worst. The results also indicate that it is necessary for further research on the initial abstraction ratio in Beijing area.
Reference | Related Articles | Metrics | Comments0
Application of five potential evapotranspiration equations in Hanjiang Basin
ZHANG Xiaolin,XIONG Lihua,LIN Lin,Long Haifeng
   2012, 35 (02): 229-237.  
Abstract7111)      PDF(pc) (1750KB)(2372)       Save
The Han River (Hanjiang) is the largest tributary of the Yangtze River and located in the geographical transitional zone between the north and the south of China. The climate in the basin is mild and humid, with an uneven spatial and temporal distribution of water resources. Evapotranspiration, as an important part of the hydrologic cycle, needs to be comprehensively analyzed to rationally utilize water resources. In this paper, the FAO56 PenmanMonteith equation and four temperaturebased equations were used to estimate the daily and monthly potential evapotranspiration in the Han River basin. The FAO56 PenmanMonteith equation is a synthetic method, which has been recommended by FAO and widely used all over the world. The four temperaturebased methods used in this paper include Hargreaves,BlaneyCriddle,Thornthwaite, and Hamon. These four methods require less meteorological observation data than the FAO56 PenmanMonteith equation,so they are simple in calculation and flexible in application. But each temperaturebased equation has an empirical coefficient to be calibrated, which limits their application across different conditions. The estimation of potential evapotranspiration was based on the daily meteorological observations from 14 gauging stations in Han River basin during the period from 1960 to 2009, while the areal mean potential evapotranspirations of the basin were calculated using the weighting method of inverse distance. With the results of FAO56 PenmanMonteith equation taken as a reference, the results of the four temperaturebased equations using original empirical coefficients were assessed. It has been found that, compared to FAO56 PenmanMonteith equation, large biases existed for the four temperaturebased equations when original coefficients were used. The maximum relative deviation was up to 41%; but for each decade of the study period, the mean annual potential evapotranspirations of temperaturebased equations were linearly related to the FAO56 PenmanMonteith’s results based on the Ftest. The value of the empirical coefficient of each temperaturebased equation was then calibrated to make its results of potential evapotranspiration estimates best approximate those of FAO56 PenmanMonteith. By using the calibrated coefficients,it was found that the relative deviation of the potential evapotranspiration estimates of each temperaturebased equation from those of FAO56 PenmanMonteith reduced significantly, and the maximum discrepancy was less than 0.1%. The simulation of all the four temperaturebased models improved, with similar variation trend and consistent peaks and troughs. The correlation between Hargreaves equation and FAO56 PenmanMonteith equation is the best, with the correlation coefficient of 0.94, and then the second and third are the Hamon and Thornthwaite equation respectively. The last one is BlaneyCriddle equation with a correlation coefficient of 0.76. Based on these analyses, the recommended temperaturebased method for estimating potential evapotranspirations is Hargreaves equation. This is the first time to compare the temperaturebased methods with the FAO56 PenmanMonteith in terms of potential evapotranspirations caculation in Han River basin, which should be useful for research on potential evapotranspiration methods.
Reference | Related Articles | Metrics | Comments0
Application of wind erosion prediction system in Minqin Desert Area
WANG Yan,WANG Ping
   2013, 36 (1): 109-117.  
Abstract4883)      PDF(pc) (1110KB)(2356)       Save
Wind erosion results in degradation of the land resources and destroys the ecological environment, which had stimulated a great deal research work in this region. How to predict the soil erosion and the changes of ecological environment aroused by the wind erosion has become an important problem, and it is necessary in the wind erosion control and sustainable use of the land. Based on the field observation of three sand storms in Minqin Desert,the paper investigated the application of Wind Erosion Prediction System(WEPS) in this area. The sand storms occurred on April 19, April 22 and April 23, April 30 of 2009, respectivly. Because there was a continuous wind on April 22 and April 23,the Aeolian sediments after the storm on April 23 was adopted and the two days’ storm was accounted as a sand storm. The paper applied the wind erosion submodel of WEPS to calculate the aeolian discharge in Minqin desert, aiming at exploring the adaptability of WEPS in China, or rather in this region. The results showed that there is a big difference between the practical measured aeolian discharge and the predicted wind-blown mass transport. For fields without natural vegetation and any other plant, WEPS gave a relative good estimation of Aeolian discharge, the maximum calculated value is about 2.2 times as the measured soil discharge mass, and the minimal value is just 0.47. For fields with natural vegetation at and around the research plot, WEPS overestimated the aeolian discharge mass. The maximum calculated value by WEPS is about 41 times as the measured, and the minimal ratio is about 6.7. So, if this model is used without any amendment, it will give a wrong aerolian discharge. Input parameters for WEPS such as wind speed, roughness length, vegetation cover, soil crust and soil diameter were measured to determine friction velocity and threshold friction velocity. Therefore,to want a good prediction of WEPS in China, a great deal of experiments should be conducted to measure these parameters under different means of land use and cultivation in areas where the wind erosion easy occured. A disadvantage of the current WEPS model is that it does not incorporate slope as a variable, more research is needed include field topography and parameters mentioned above in WEPS for better preiction of wind erosion. It is the first time to use the WEPS model to calculate the aeolian discharge in our country.
Reference | Related Articles | Metrics | Comments0
Interaction among climate change,fire disturbance and ecosystem carbon cycle
HU Hai?qing,WEI Shu?jing,SUN Long,WANG Ming?yu
   2013, 36 (1): 57-75.  
Abstract4554)      PDF(pc) (782KB)(3444)       Save
Climate change have been drawn wide attention by the government,academic field and the public. Meanwhile,those issues have a significant effect on fire disturbance and forest ecosystem carbon cycle. Climate warming is one key issue of global change and plays an important role on carbon cycling in terrestrial ecosystems. Carbon storage of forest ecosystem is a basic parameter of studying carbon exchange between forest ecosystem and atmosphere,and an essential factor of estimating the absorption and discharge of forest ecosystem. Biomass burning is the burning of living and dead vegetation. Biomass burning is a significant global source of gaseous and particulate matter emissions to the atmosphere. Biomass burning has long been recognized as a significant source of a number of important trace gas species and particulate matter to the atmosphere. Forest fires are a major contributor of atmospheric gaseous and particulate pollutants. In forest fires are emitted significant amounts of gaseous and particulate matter pollutants into the atmosphere. Forest fires can play a significant role in atmospheric chemistry and contribute to climate change. Forest fire emissions can be important for local air pollution levels. The potential climate change mitigation benefits of carbon sequestration by forested ecosystems have garnered both national and international attention. Biomass burning due to anthropogenic activities has significant impact on the atmospheric chemistry,climate and on the global biogeochemical cycles. In many regions of the world,fires are an important and highly variable source of air pollutant emissions,and they thus constitute a significant if not dominant factor controlling the interannual variability of the atmospheric composition. This paper reviews the recent advance in our understanding of interaction among climate change,fire disturbance and ecosystem carbon cycle and underlying mechanisms. It also discusses the state-of-the-art in quantifying fire disturbance and ecosystem carbon cycle in modeling and its applications to carbon cycle assessment. The paper has described systematically mutual interaction among climate change,fire disturbance and ecosystem carbon cycle from the two aspects of the system. The focus of the paper is climate warming on the impact of fire disturbance and two-way feedback. The paper has described from the impact of climate change on fire disturbance and fire disturbance to climate change affects two aspects of the interaction relationship between the two aspects,fire disturbance and forest ecosystem carbon cycle interaction,respectively,from the impact of fire disturbance on forest ecosystem carbon cycle model in the simulation of fire disturbance on forest ecosystems in the carbon cycle affect two aspects of discourse fire disturbance on forest ecosystem carbon cycle and its quantitative evaluation model approach. The has elaborated fire disturbance in the context of climate warming on the carbon cycle of forest ecosystems. Fire disturbance on the atmospheric carbon cycle and fire disturbance on biomass carbon pool,atmospheric carbon pool,soil carbon pool and its turnover,forest litter carbon pool and its turnover were expounded,respectively. The paper has examined the model of fire disturbance on forest ecosystem carbon cycle. It found that the fire disturbance with the direct carbon emissions more perfect model approach,while the indirect effects of the carbon cycle model is not mature,and many methods are limited to qualitative description. The problem of cross-scale fire disturbance on carbon cycling should be further explored,focusing on integration of field measurements,remote sensing observations and model simulation scale conversion. Finally,under the background of climate warming and the fire disturbance to the forest ecosystem and the effect to carbon cycle,the paper has proposed the effective forest fire management the measures as well as the present need to strengthen in some research area and research direction.
Reference | Related Articles | Metrics | Comments0
Exogenic forces action mechanism in the development processof erosion landform on alluvial plains composed offluviallacustrine deposits in the Taklimakan Desert
LI Shengyu,GU Feng,WANG Haifeng,PANG Yingjun,,MU Guijin,LEI Jiaqiang,LIU Xiaolu,ZHANG Zhongliang,YAN Jian
   2012, 35 (03): 358-364.  
Abstract3758)      PDF(pc) (1690KB)(2042)       Save
Fluvial-lacustrine deposit is a kind of consolidation sediments that is one important geological basis for erosion landform. The erosion landform developed on alluvial plains composed of fluvial-lacustrine deposits is widely distributed. But its relevant studies, especially about the development process of erosion landform are very less. Based on the field survey information, theoretical analysis and some relevant articles, this paper comprehensively analyzed the exogenic forces action mechanism in the development process of erosion landform on alluvial plains composed of fluvial-lacustrine deposits in the Taklimakan Desert. The results show as the following:(1) These main exogenic forces including weathering, running water, aeolian erosion and gravity drive the erosion landform development on alluvial plains composed of fluvial-lacustrine deposits in the Taklimakan Desert. (2) Because aeolian activities in the Taklimkan Desert occur very frequent, so aeolian erosion plays a leading role in erosion landform development. (3)At the same time, weathering, running water and gravity also play important roles. Some records of summer strong rainfall events in the Taklimakan Desert indicate that the function of running water in erosion landform development can't be neglected. Rain infiltration and soil cracks, main weathering forms, loosen the surface soil structure, smash sediments to pieces, and make soil be eroded easily. Moreover, all these exogenic forces have different importance in different stages of erosion landform development. But they work co-operatively and mutually reinforce. Wind erosion breakthroughs can develop under aeolian erosion together with weathering and running water in the initial stage. A series of erosion landforms, including deflation furrow, wind erosion groove, blowout pit, wind erosion depression, erosion platform, wind erosion residual pier, and wind erosion plain, can rapidly develop under aeolian erosion together with gravity and weathering in the rest of stages. Sand wedges, composed of sand particles deposited in the wedge-shaped space of soil cracks, are of great importance in erosion landform development. Rainwater flows into sand wedges and is adsorbed by sand. Due to good penetrability of sand deposits, water can infiltrate quickly without evaporation loss and reach the bottoms of cracks. The deep soil can be destroyed by soil expansion of wetting and unfreezing; soil cracks widen and extend into deep soil further. Lateral erosion and undercutting are the main forms of wind erosion as well as sheet erosion, they make the sediments hang up. Lateral erosion, undercutting and sand wedges provide good conditions for gravity collapse and accelerate the negative erosion landform development on the sediments with nonhomogeneous texture. Collapse diluvium also can slow down the speed of wind erosion landform development.(4) The morphological characteristics of erosion landform depend on the special exogenic forces combination and the interbedded sedimentary structure of alluvial plains, namely, compact sediment and soft sediments are distributed in turn in vertical profile.
Reference | Related Articles | Metrics | Comments0
Ponder on the issues of water resources in the arid region of northwest China
CHEN Ya ning, YANG Qing, LUO Yi, SHEN Yan jun,PAN Xiang liang, LI Lan hai, LI Zhong qin
   2012, 35 (1): 1-9.  
Abstract3713)            Save
Climate change and water resources have been drawn wide attention by the government,academic field and the public. Meanwhile,those issues have a significant effect on the rapid development of economy in arid region of northwest China to some degree. The arid region of northwest China is featured by wide area,accounting for about 1/4 of the total area of the country,and plays an vital role in economic development as China[JP10]’[JP]s energy base. However,water resources system is very fragile and the climate change in arid region is sensitive to the global climate. Therefore,it is necessary to enhance the water resources system in arid region of northwest to address climate change and allocate limited water resources rationally. Based on the previous research results,this paper analyzes the influence factors of social and economic development and ecological security and the impacts of climate change on water resources in arid region of northwest. Moreover,the hot and difficult issues of climate change and water resources are explored,including water vapor source and climate changes,the change trends of glacial ablation and glacier water resources,water cycle process and simulation,and the vulnerability of water systems and water safety threshold,water resources allocation of “Water-eco-social economy”. Finally,the author probes into the impacts of the climate change on the formation and transformation of water resources and the future trends and the effects of climate change on water cycle process and water resource security in arid region of northwest.
Reference | Related Articles | Metrics | Comments0
Geographic distribution and ecology of C4 plants in Xinjiang
FENG Ying,DUAN Shimin,MU Shuyong,ZHAO Li,ZHAO Xinhua
   2012, 35 (01): 145-153.  
Abstract3691)      PDF(pc) (2133KB)(2287)       Save
All the C4 plants in the arid area of Xinjiang were identified according to the stable carbon isotope ratios contents and some related 1iteratures. There are 278 species of C4 plants from 66 genuses in 12 families. The taxonomy,life form,geographical element and the areal-types of genera were accordingly analysis. The results showed that the families with most species orderly from Chenopodiaceae,Gramineae,Cyperaceae,Liliaceae,Polygonaceae etc. Among which,the dicotyledon more than monocotyledon of angiosperm ,there is not C4 plants in the pteridophyte and the gymnosperm. Annual and perennial of C4 plant dominate in the arid area of Xinjiang. This reveals these species compete with a betteradapted and more powerful succession evolution. The dominant of C4 plants species occupy accounts for 10%. Among C4 plants 125 species grow in sand dune,103 species grow in salt and alkaloid environment,56 species grow in wet environment. Everything prove C4 plant might have higher tolerance to environmental stresses (dry and salting)and could make greater contribution to sand land restoration of botanic characters. Furthermore,The floristic composition of C4 plants is concisely enumerated and were found to belong to 10 categories,which the dominant element of the geographical composition was Mediterranea,W.Asia to C.Asia and there are 13 genera and 60 species in this region. The distribution of the florae reflects the dynamic climatic and geological changes during the species succession on a historical scale. Therefore,it is suggested to carry out the study on breeding,introduction and popularization of C4 plants and so as to solve desertification in the arid regions in northwest China.The complete investigation of the plant resources and their distribution and succession in the region will provide the scientific basis for protecting the plant resources in the region.
Reference | Related Articles | Metrics | Comments0
Ponder on the issues of water resources in the arid region of northwest China
CHEN Yaning,YANG Qing,LUO Yi,SHEN Yanjun,PAN Xiangliang,LI Lanhai,LI Zhongqin
   2012, 35 (01): 1-9.  
Abstract3629)      PDF(pc) (2301KB)(2138)       Save
Climate change and water resources have been drawn wide attention by the government,academic field and the public. Meanwhile,those issues have a significant effect on the rapid development of economy in arid region of northwest China to some degree. The arid region of northwest China is featured by wide area,accounting for about 1/4 of the total area of the country,and plays an vital role in economic development as China’s energy base. However,water resources system is very fragile and the climate change in arid region is sensitive to the global climate. Therefore,it is necessary to enhance the water resources system in arid region of northwest to address climate change and allocate limited water resources rationally. Based on the previous research results,this paper analyzes the influence factors of social and economic development and ecological security and the impacts of climate change on water resources in arid region of northwest. Moreover,the hot and difficult issues of climate change and water resources are explored,including water vapor source and climate changes,the change trends of glacial ablation and glacier water resources,water cycle process and simulation,and the vulnerability of water systems and water safety threshold,water resources allocation of “Water-eco-social economy”. Finally,the author probes into the impacts of the climate change on the formation and transformation of water resources and the future trends and the effects of climate change on water cycle process and water resource security in arid region of northwest.
Reference | Related Articles | Metrics | Comments0
International cooperation problems on transboundary rivers in Kazakhstan
DENG Mingjiang
   2012, 35 (03): 365-376.  
Abstract3589)      PDF(pc) (2535KB)(1673)       Save
Kazakhstan is a great nation in Central Asia area; it has transboundary water body relation with surrounding neighboring countries, 44% of the surface water from neighboring countries. Water resources development and utilization in transboundary rivers and ecological environment protection that are major strategic problems involved with national politics, economy, security and foreign overall situation. This article systematically analyzes distribution feature of the surface water in Kazakhstan, briefly reviews the cooperation with its neighboring countries in the aspect of transboundary rivers, profoundly analyzes the main countermeasures adopted for the anxious issue of water safety, analytically discusses the problems such as future cooperation path for the management of transboundary rivers, future distributive principle for water utilization of transboundary rivers, future solution for the water pollution of transboundary river between Kazakhstan and Russia, the prerequisites for solving crisis of Aral Sea among Central Asian States; it points out that the management of shared water resources can become a peace force in Central Asia, may also become accomplices of the conflict, the management for this interdependence resources is the international community today faces a major challenge of human development. The study on the issues of core interest point of view, cognition, adopting a different strategy used in the international cooperation of Kazakhstan transboundary rivers; therefore it is positive operation significance for dealing with the problem of transboundary rivers between China and Kazakhstan.
Reference | Related Articles | Metrics | Comments0
Glacier changes in Youyi Area in the Altay Mountains of  Xinjiang during 1959-2008
BAI Jinzhong,LI Zhongqin,,ZHANG Mingjun,GAO Wenyu,LI Kaiming
   2012, 35 (01): 116-124.  
Abstract3572)      PDF(pc) (2012KB)(2136)       Save
Research on glacier change has been limited in Chinese Altay Mountains among the border of China, Russia and Mongolia, despite the fact that the number of glaciers in the Altay Mountains is less among all mountain ranges in China, and the glaciers in this region provide very important water resources for local economic development and drinking water for man use. Most of the research on glaciers in China is in Tianshan Mountains, Qinghai-Tibet Plateau and Qilian Mountains, but not in Altay Mountains. During the past several decades, most glaciers are in a state of rapid retreating due to climate warming. The glaciers of Youyi in the Altay Mountains were selected as the study area. Based on 1∶50 000 topographic maps in 1959,ASTER remote sensing data in 2008 and digital elevation model (DEM), the study area for glaciers was extracted by using the remote sensing image processing and analyzing method, and the changes of glaciers in the study area were analyzed under the support of the geographic information systems technology. The results indicate that the amplitude of the whole change of glaciers in the Youyi Area is large and glaciers in this area have retreated rapidly during the study period from 1959 to 2008. In the study period,the total area and number of the investigated glaciers(226) have reduced by 32.5%and 27.9%. At the same time, the results showed that glaciers average rate of change with area less than 1 km2 is -66.7% and glaciers average rate of change with area less than 0.5 km2 is -70%.Moreover,those glaciers with area from 1 to 5 km2 have reduced by 27.9%. The paper analyzed the reasons of the large change rate of glaciers, and the results indicate that the large change rate of glaciers is caused by the large proportion of small glaciers, whose glaciers smaller than 1 km2 account for nearly 75% in the investigated glaciers. Moreover, the results show that the larger the glaciers are, the higher the amplitude of the ablation is, but the reduced rate is lower. And those glaciers have the highest degree of response to climate change. The glaciers retreated by 253 m at a rate of 18.3%. The glacier changes exhibited obvious spatial differences, indicating that the reduction rate of glaciers to the south slope of the Youyi Area was larger than that of the north.
Reference | Related Articles | Metrics | Comments0
Estimating soil water in Northern China based on Vegetation  Temperature Condition Index (VTCI)
WANG Mingcheng,YANG Shengtian,DONG Guotao,BAI Juan
   2012, 35 (03): 446-455.  
Abstract3552)      PDF(pc) (3897KB)(1686)       Save
Drought is one of the main meteorological disasters in Northern China and it does great harm to national economic and agriculture of China.Soil moisture is an important parameter to study the characteristics of drought.A lot of methods were developed to monitor soil moisture both in field scale and macro scale regions,and there are too many limitations for these methods to monitor soil moisture.A nearreal time drought monitoring approach called Vegetation Temperature Condition Index (VTCI) integrates land surface reflectance and thermal properties and can invert soil conditions of land surface in macro scale region more accurately.It is calculated based on the triangular space of NDVI-Ts and closely related to soil moisture.On the basis of Terra-Moderate Resolution Imaging Spectoradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) products and soil moisture observation data during 2000-2008,we employed this method to monitor land surface soil moisture of northern China.Considering the complexity of geography environment and weather characteristics in northern China,we divided the study area into four division: the North region,the Northeast region,the Northwest region and the Qinghai region,and the soil moisture between 0-10 cm during 2000-2008 were calculated separately.We extracted the intercept and slope of the “Wet edge” and “Dry edge”and calculated VTCI,and soil moisture was calculated according to the linear relationship between VTCI and observation data.The results show that land surface soil moisture is various in different regions and different time:it is lower in the northern and western regions than that in the southern and eastern regions; it is greater than 0.2 cm3/ cm3 in the Northeast and the Qinghai region and less than 0.05 cm3/ cm3 in the desert region of Xinjiang;it is high in July and August and low in March and April,September and October due to the variety of rainfall and crop water requirement;it increased from 2000 to 2001,2001 to 2002,2005 to 2006,and decreased from 2002 to 2003,2004 to 2005 in most part of the study area;the changes of soil moisture are various in different years and regions,precipitation is highly correlated to the temporal and spatial distribution of soil water.Compared with ground measurements,it shows that the inversion based on VTCI method has good precision and can monitor the drought conditions in northern China more accurately.
Reference | Related Articles | Metrics | Comments0
Ecological features of phytoplankton community of Tangbahu Reservoir in Xinjiang
XUE Junzeng,BIAN Jiayun,WANG Qiong,CAI Zhen,ZHU Xinying;LI Zhouyong;LI Haifeng;WU Huixian
   2012, 35 (02): 254-259.  
Abstract3492)      PDF(pc) (1387KB)(1486)       Save
Tangbahu Reservoir is located in Xinjiang. It is one of the many reservoirs in Altay. The Tangbahu Reservoir stored up the thawed snow, and the snow water is the principal source of the reservoir. In recent years, the global climate become warming and the influence of human activity increased significantly, the glacier’s snow line has flinched 500 meters. It will make an impact in aquatic ecosystem. The phytoplankton which have an important impact on the plankton community, are major component groups of aquatic plankton. Phytoplankton community structure of Tangbahu Reservoir was investigated and analyzed in July 2008 (the flow period), October 2008 (the dry period) and May 2009 (the flood period). Results showed that a total of 97 phytoplankton species, belonging to 8 phyla were identified, of which 43 species were Bacillariophyta, 28 species were Chlorophyta, 12 species were Cyanophyta, 5 species were Euglenophyta, 3 species were Cryptophyta, 3 species were Xanthophyta, 2 species were Pyrrophyta and 1 species were Chrysophyta. The number of species for Bacillariophyta, Chlorophyta, Cyanophyta, Euglenophyta, Cryptophyta, Xanthophyta, Pyrrophyta Chrysophyta accounted for 45%,29%,12%,5%,3%,3%,2% and 1% of the total species respectively. The trends of species changing showed: the flood period (56 species)> the flow period (39 species)> the dry period (19 species), the flood period and the flow period was made up by 8 phyla, but the dry period was made up by 6 phylathe. The dominance analysis showed that the phytoplankton community structure was typical type of Chlorella-diatoms in this reservoir. A. oscillarioides, M. aeruginisa,C. minor,C. bodanica,S. bijuga,W. botryoides, C. vulgaris and T. oblonga were the dominant species in the normalwater season. In the dry season, dominant species were M. flos-marginata, C. minor, M. granulata, C. debaryana, S. bijuga, C. vulgaris and C. erosaerosa. But in the wet season M. incerta Lemm, M. granulate, A. formosa,S. armatus, C. vulgaris, C. minima, C. erosaovata and G. aeruginosum were the dominant species. The phytoplankton in Tangbahu Reservoir showed larger alternation of hydroperiod with the highest density (9.42±2.20×106 ind/L) in dry period, followed by the flow period (7.80±1.41×106 ind/L), the flood period was the lowest for 1.11±2.32×106 ind/L, it also had a very significant differences (p<0.01), the most obvious difference was in flood period. The cell density was the greatest in the dry season, and the wet season has the smallest cell density. The paper analyzed the ShannonWiener and evenness indexes of phytoplankton community during three periods in Tangbahu Reservoir. The diversity index showed as follows: the ShannonWiener indices ranged between 2.03 and 2.45, the Pielou indices ranged between 0.41 and 0.47, and the Margalef indices ranged between 0.78 and 2.74.Moreover, the phytoplankton composition, cell density as well as the diversity were closely related to the temperature and the water volume of Tangbahu Reservoir was also discovered.
Reference | Related Articles | Metrics | Comments0
Spatio-temporal distribution and temporal periodicity of annual precipitation in Shaanxi Province
LIU Wen,CAO Ming-ming,SONG Jian-xi,QIU Hai-jun
   2013, 36 (5): 865-874.  
Abstract3462)      PDF(pc) (2533KB)(1762)       Save
Using precipitation data of every stations located in Shaanxi Province during 1959 to 2009,applying the statistical methods such as the Mexican hat wavelet function,linear trend analysis and Mann-Kendall method,the features and trend of the annul precipitation temporal and spatial distribution of 51 years in Shaanxi Province was analyzed. It is very important for us to strengthen the research of climate change law under the background of the global climate change,for which helps us raise the prediction ability of short-term climate,this paper took the Shaanxi Province as an example,analyzed the temporal and spatial distribution and trend of the annual precipitation in Shaanxi Province during 1959-2009,revealed the complex structure of annual precipitation in Shaanxi Province in multiple time scale,analyzed the period and mutation point of precipitation sequence in different time scale,and identified the main cycle. The result showed as follows:(1)In 1959-2009,average annual rainfall of Shaanxi Province had three periods which are 3-7 years,10-17 years,17-30 years and the 10-17 year is most obvious;(2)In the 1959-2009 time series,average annual precipitation change in Shaanxi Province was relatively stable;(3)The three regions with an average annual precipitation changes are relatively stable,from an average annual precipitation view,the northern and southern Shaanxi presented slightly down trend,the Guanzhong Plain showed a faint rising trend;(4)No significant mutations in northern Shaanxi,the significant mutations of Guanzhong Plain and southern Shaanxi respectively were in 1993 and 1991;(5)The evolution of rainfall in each area had three kinds of cycle rules. The micro scale that is 3 to 8 years behaved messy and was not significant. In medium scale,the precipitation cycle in Guanzhong Plain and southern Shaanxi was significant that is 10-17 years,precipitation cycle in northern Shaanxi showed irregularly. In macro scale,precipitation cycle of northern Shaanxi was 23-30 years,precipitation cycle of Guanzhong Plain was similar to southern Shaanxi’s,18 to 25 years.
Reference | Related Articles | Metrics | Comments0
Characteristics of climate factor change in Yulin Region during 1970-2010
YANG Qiang,QIN Zhihao,WANG Tao,WANG Qianqian
   2012, 35 (5): 695-707.  
Abstract3422)      PDF(pc) (7913KB)(2010)       Save
Yulin locates on a typical agropastoral ecotone of North China between Loess Plain in Shaanxi Province and Mu Us sandy land in Inner Mongolia Autonomous Region. In order to understand the development trend and characteristic of climate change in Yulin region, the paper used spatial interpolation to analyze seasonal and interannual trend and characteristic of climate in Yulin on the basis of meteorological data in Yulin during 1970-2010. Five meteorological indexes (such as, average minimum temperature, average maximum temperature, precipitation, and solar radiation) were used for the analysis of climatic characteristics, for example, change trend, periodic variation, and abrupt change. Five meteorological indexes were interpolated into raster layers by using of Kring method, and further clipped by the administrative line of Yulin region. The average value of five metrological indexes in Yulin region were abstained from raster layers based on spatial overlay analysis at last. Then, regression analysis and moving average method were used for trend analysis, Mann-Kendall method and Moving [WTBX]t[WTBZ]-test technique for abrupt change, and wavelet analysis for periodic analysis. Through the analysis above, the results indicate that the average temperature in Yulin increased during 1970-2010. The temperature in spring and winter contributes relatively higher to the rising of annual temperature than that in summer and autumn. Annual and seasonal precipitation fluctuated obviously during this period. The precipitation in summer reduced relatively higher than that in other season. As well, the precipitation increased before 1990s, decreased at the beginning and middle of 1990s, and picked up since the late 1990s. The solar radiation in past 41 years had a downward trend, and reduction of the solar radiation in summer showed higher contribution to the decreasing of annual solar radiation. The periodic variation of five meteorological indexes was much stable in the lager time scale, such as 25-32 years. Precipitation and average minimum temperature in the four seasons owned obvious periodic characteristic at three kinds of time scale. In addition, except for precipitation in spring, the frequency of meteorological factors in other seasons during 1970-2010 had a rising trend, and the time interval decreased. Thus, the climate change was much active during the last 10 or 20 years in this region.
Reference | Related Articles | Metrics | Comments0
Measures for safe driving at violentwind section of Xinjiang Expressway
MA Yun juan,MA Shuhong ,ZHANG Yunhui ,GE Feng ,LI Jian,XUE Wanxin
   2012, 35 (02): 209-220.  
Abstract3361)      PDF(pc) (2348KB)(1451)       Save
In order to improve driving safety and efficiency of different types of cars on expressway in violent wind weather conditions, a combined method was used of meteorology, fluid mechanics, wind monitoring technology, road engineering, aerodynamics and probability theory to carry out informatization and standardization integration,based on the recent 50 years (1961-2010) violentwind days materials of more than 100 weather stations along Xinjiang “five vertical and seven horizontal” expressways and highgrade highways, choosing 50 years(1961-2010) average maximal wind speed and wind direction, maximal instantaneous wind speed and wind direction for 10 minutes violentwind materials of 50 weather stations with their own record, 1 year monitoring data of seven“six elements”(temperature,humidity,wind direction,wind speed,precipitation,air pressure)and fivelayer (0.15 m,0.5 m,2.0 m,3.0 m,4.0 m)gradient wind of more than seven elements, 10 wind tower gradient and recent 10 years(2001 - 2010) monitoring data of 30 winds stations. On base of abundant and detailed materials, applying the meteorological model and the extremum Ⅰprobability model to calculate the different probability design values of 10 min average maximal wind speed in 1 km×1 km space gridding points along highway; through combining strong wind coefficient[WTBX] K[WTBZ]1, of spatial distribution and highway, embankment height and bridge height speedup coefficient [WTBX]K[WTBZ]2 and power exponent [WTBX]K[WTBZ]3 under different underlying surface features, set up a forecast model of different probability design values of maximal instantaneous wind speed in any 100 m×100 m space gridding points with 4m height from the ground; through a strongwind rose diagram, determine the horizontal wind guard region along the highway. Its innovative point lies in that it can predict any maximal instantaneous wind speed beyond the wind monitoring points along the highway(a region without anemometer).The integrated data is combined with topography, roughness, embankment height, bridge height and other parameters of different expressway sections, establishing maximum wind speed spatial distribution, vertical distribution and horizontal distribution along the expressway. Based on above work, this paper used threelevel regionalization index system and equalprobability partition theory to divide the wind damage zone along the expressway into 5 major areas, Ⅰmajor high risk area, Ⅱmajor strong risk area, III major risk area , Ⅳ risk area, Ⅴ low risk area. Based on above work, this paper made safe driving protection measures at Xinjiang Expressway Violentwind Sections composed of earlywarning monitoring technology and wind fence protection technology. And wind damage equal partition limiting value (threshold) from earlywarning driving monitoring technology is verified with onsite violentwind monitoring result. When instantaneous wind speed <12.0 m/s, different types of vehicles can run normally; 12.0 ≤ instantaneous wind speed 25.0 m/s, buses and trucks outage. It puts forward that measures for protecting safe driving in the horizontal region of highway consist of wind disaster prevention and control information management technology and windproof bar protection technology. It institutes wind disaster prevention and control management technology rule and pre-warn standard under the strongwind weather in Xinjiang Highway in order to provide reasonable driving speed limit instruction. It uses the form of different levels of probability risks to reflect the discipline of the maximal instantaneous wind speed in the highway; and it covers maximal risks in recent 50 years. It provides theoretical support for safe driving of vehicles in highway and highway disaster prevention and control technology.
Reference | Related Articles | Metrics | Comments0
Response to drought disaster in North America and their experiences to China
WANG Qing,,YAN Denghua,WENG Baisha,,FENG Jing,,SHI Xuan,
   2012, 35 (02): 332-338.  
Abstract3356)      PDF(pc) (1864KB)(1641)       Save
In the context of global climate change, extreme weather events are growing up. Among them, the flood and drought disasters influence our life most deeply. There are various climate types over North America, and its latitude location and sealand position are generally similar to Eurasia. Besides, most places over North America locate in the arid areas. With the growing impact drought made in the whole world, increasingly attention turns to reducing the risk of drought disastersthrough a variety of mitigation actions and plans to improve the operational capabilities,in order to reduce the risk of drought events. At present, the general trend of the international drought management evolves from the passive emergency droughtresistant and crisis management to the proactive risk management. In the longterm response to drought disasters, North America countries evolved fairly complete coping strategies against drought disastersthrough legislation, drought risk management, drought planning, engineering /nonengineering measures, drought subsidies and insurance, watersaving management in drought period, national integrated drought information system and other means to reduce the losses caused by drought. Facing up to the serious drought situation, the action policy in China which puts much emphasis on droughtresistant rather than drought prevention shows its drawback gradually, and becomes difficult to meet the demand of droughtresistant in the new period. This paper mainly used document searching and reviewing, combining some websites information of North America droughts[HJ1.85mm] to introduce the drought condition, then analyzed the main causes of the droughts and summed up their responding experiences, coming up with some advises specific to the lack of drought management in China, in order to put forward ideas and inspiration on risk management and mitigation measures in China. The primary enlightenments are as follows: (1)Transforming the passive droughtresistantoriented management mode in the past to the proactive drought risk management gradually is the main trend in China to respond to drought disaster.(2)To strengthen the construction of drought risk management in Chinaas to the macroscopic level, we should pay attention to the construction of drought legislation, drought management institute, drought prevention programs, national drought information system, material reserve of droughtresistant, watersaving management in drought period and the system of droughtresistant service. On the part of the microlevel, the details of the drought risk management must be spread out and put into practice in terms of legislation, economy, administration and other patterns. The concrete measures must be taken to regulate drought risk management. (3) On the one hand, we should improve water resources planning and management, on the other hand, making some suggestions on hydraulic engineering project in reason is also imperative. (4)Promoting the comprehensive utilization of economy, legislation, administration, technology and other ways to manage and complete droughtresistant work. (5)To enhance the basic research on drought disasters. For one thing, the conclusion of this paper is based on a large number of related drought researches, for another, it took the actual situation of our country into consideration. In general, the study and conclusion of this paper has some practical significance in drought risk management and comprehensive response to drought disasters in China.
Reference | Related Articles | Metrics | Comments0
Several caculations of parameters of windsandmovement at Guaizi Lake area of Inner Mongolia
HE Qing,HU Wengfeng,YANG Xinghua,Ali MANTIMIN ,ZHAO Congmin,
   2012, 35 (02): 187-192.  
Abstract3355)      PDF(pc) (1390KB)(2251)       Save
Dust storms are disastrous weather phenomena frequently occurring in spring (March-April-May) in North China. Since 2000, the dust weather has frequently occurred in this region, resulting in serious environmental problems and disruption of social & economic activities. In recent years, due to the impact of desertification in China, dust storms appear to have aggravated. Besides, domestic and foreign scholars have noticed that the aerosol in atmosphere has recently been increasing due to wind erosion and it has become a hot topic in the research field. What is more, wind erosion, a very complex physical process, acts as a key progress of basic research on aerosol in the atmosphere. As to wind erosion, theoretical and experimental studies by the domestic & foreign have established a lot of mathematical models on dust emission. A case in point is the research in Guaizi Lake. Guaizi Lake, located in the northern margin of Badan Jaran Desert, is one of Chinese major centers of dust storms. Apart from that, as the north path of Chinese dust storms, Guaizi Lake usually raised dust in the region, which may affect the whole northern China. With the limitation of natural conditions and experimental equipment, it is difficult to do experimental research in Chinese major centers of dust storms for a quite long time. Fortunately, the “National Scientific and Technological Support Project” advocated establishing the Guaizi Lake wind observation site in order to further study the dust storms. The experimental system consists of a 2m high meteorological tower, a piezoelectric saltation sensor (Sensit) and a big Spring Number Eight (BSNE) sampler station. The piezoelectric saltation sensor (Sensit) can continuously record the occurrence and intensity of saltating particles, while the BSNE station consists of five BSNE samplers with the lowest sampler at 0.05 m and the highest sampler at 2.0 m above the soil surface, thus getting the monitoring data about the dust storms. The research on dust storms was strengthened by observations, several characteristics of sand movement were studied,calculated by using the classical formula and analysing the records of the site actual measurement as well. The conclusions are as follows :the critical sandmoving velocity at 2 m height is 4.55 m/s; the critical friction velocity is about 0.318 m/s; the average surface roughness is about 9.42 mm; the sandmoving average friction speed of April 5, 2011 is about 0.371 85 m/s; the friction velocity is positively correlated with the wind speed . The results indicate as follows: the threshold of sandmoving wind velocity, the roughness and the critical friction velocity are extremely small, which is one of the main reasons of sanddrifting activities. To sum up, it is very significant to calculate the parameters mentioned above for the sand storm control in Guaizi Lake area and this study fills the gap in some related parameters about windsand movement in this area.
Reference | Related Articles | Metrics | Comments0
Characteristics of land use and cover change in Central Asia in recent 30 years
   2012, 35 (6): 909-918.  
Abstract3349)      PDF(pc) (1791KB)(1225)       Save
Information on the patterns of land use and land cover change in Central Asia is scarce, and most of the resources used are outdated and unsystematic, which make it difficult to meet the needs of ecology and environmental change research in Central Asia. In this context, compiling the Global Land Cover Characteristics datasets in Central Asia is of great significance in theoretical and practical aspect. In addition, different organizations/institutions develop multiple sets of land use/land cover datasets with various classification systems on global scale depending on their purpose. Those datasets are almost unable to conduct rigorous verification and direct comparison. However, by merging classes based on the classification connotations, these datasets can be used to achieve the purpose of analyzing the macroscopic characteristics of land use and land cover change. In this paper, firstly, the UMD, GLC2000, DISCover, and GlobCover datasets with different land cover classification system are used to extract the long term land cover information in Central Asia. Secondly, all the land cover types are categorized into four classes: arable land, natural vegetation, water bodies and others, to analyze the characteristics and trends in land use and land cover change over the past 30 years in Central Asia.
The results show that there are various types of land cover types in Central Asia which was dominated by grass, bare land, arable land and shrub. Because of the Soviet Union collapse in 1991, arable land decreased sharply from early 1990s to 2000. In comparison with arable land, natural vegetation showed the opposite trend, which indicated a mutual transformation between arable land and natural vegetation area. The area of water bodies fluctuated resulting from the changes in lake area which was influenced by climate fluctuations and human agricultural activities. Urban area experienced an increasing trend, especially during 2000-2009, due to the rapid economic development and the increase of population.
Although the classification system of different Global land cover datasets in Central Asia is not uniform, the pattern of land use and land cover change can well characterized. This shed a light to the LUCC research in Central Asia to some extent. The macroscopic characteristics and trends of land cover in Central Asia can be depicted from the datasets after merging relevant class.Drawn on results of the paper, the land use and land cover pattern has been changed due to the climate changes and human activities in Central Asia. This will bring out a series of environmental issues including soil salinization, serious shortage of water resources, land desertification and other ecological problems, which should be the future direction of land use change research in this area.
Reference | Related Articles | Metrics | Comments0
Snowfall estimation of maximum possible snow melt in midsummer in Kumalake River basin
FU Hua,JIA Lihong ,XIAO Ji dong,YANG Zhihuan,LI Cong
   2012, 35 (02): 193-199.  
Abstract3327)      PDF(pc) (1512KB)(2144)       Save
Snowcover coverage, snowcover depth and snowmelt water volume of the Kumalake River basin were calculated using EOS/MODIS satellite data form June to September of 2002-2008. The paper also analyses the following three aspects with meteorological and hydrological stations data: first, the relationship between the change of snow cap and meteorological factors during snowmelt periods in 2002-2008; second, 15 effective temporal intervals of maximum temperature during the period of flood peak of 1990-2008; third, effective temporal intervals influenced by 12 hours precipitation. In the 7 flood peaks (2002-2008), 4 of them are type of snowmelt dominance (2003, 2006, 2007, and 2008) and 2 of them are type of snowmelt secondary dominance (2002, 2005). In the flood peaks of 2002 and 2005, precipitation is the dominant factor in 2002 while snowmelt is the dominant factor in 2005. Based on former analysis, following results were obtained: Firstly, snowmelt is the dominant factor in flood peaks during 2002-2008. When the snow cap in the mountain area was over 0.55 billion m3 and the height of 0 ℃ layer raised up to 4 500 m for more than 4 days, the snowmelt water from Kumalake River Basin reached up to 0.18-1.03 billion m3. The change of 0 ℃ level height of the Kumalake River Basin in summer indicates snowmelt flood well; Secondly, the snowmelt water of real snowcover in Kumalake River Basin in 2002-2008 reached up to 9.88×108 t, and the maximum possible snowmelt water was less than 11.18 ×108 t on hypothesis that all of the snowcover in the Kumalake River Basin was melted. The theoretically maximum possible snowmelt water was 17.55 ×108 t in this historical period. The snowwater equivalent produced by all of snowcover was melted was less than 17.75×108 t. The estimation of snowmelt water equivalent obtained from actually observed data and theoretical calculation can supply the support for estimating the maximum flood amounts due to snowcover melt in this mountain area.
Reference | Related Articles | Metrics | Comments0