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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.  
Abstract9962)      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.
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Review of radiometric cross-calibration
GAO Cai?xia,JIANG Xiao?guang,MA Ling?ling,HUO Hong?yuan
2013, 36 (1): 139-146.  
Abstract2770)      PDF(pc) (1338KB)(3507)       Save
With the development of quantitative remote sensing,interest in the radiometric calibration aspects of terrestrial remote sensing has been on the rise,and significant resources are being devoted to the relevant areas of research and development. The radiometric calibration of those sensors is a contributing factor to the success of application of remote sensing data. The calibration of sensors has relied on the preflight laboratory work as well as on in-flight techniques. At present,three kinds of in-flight radiometric calibration methods have been developed and widely used,namely,on-board calibration,in-situ calibration and cross-calibration. On-board calibrators,such as solar diffuser (SD) and solar diffuser stability monitor (SDSM),can be used for operational calibration;however,some satellites are not equipped with these due to power,weight,and space restrictions. In order to compensate for the limitations of on-board calibration systems,many methods have been proposed and used for in-flight radiometric calibration,such as in-situ calibration and cross-calibration. The problem with in-situ calibration is that it could be labor intensive,costly and time consuming.This typically limits the number of calibrations that can be performed. Cross-calibration is an alternative and potentially easier technique that can be used to acquire post-launch calibration coefficients. In comparison to in-situ calibration,cross-calibration can circumvent the strict requirements of atmospheric and surface variables;it is a cost-effective and convenient mean of calibration without the need of accurate synchronous in-situ measurements,compensating for the deficiencies of in-situ calibration. To date,many cross-calibration methods have been proposed with the same goal but different application conditions,advantages and limitations. Therefore,this paper aims to review these cross-calibration methods and to provide technical assistance for in-flight calibration. This paper gives descriptions of four cross-calibration methods,namely,ray-matching method,spectrum-matching method,radiative transfer modeling method and rayleigh scattering method. Besides,the advantages and drawbacks of these methods are also discussed in this paper. In practice,we can select the optimal cross-calibration methods in consideration of the scopes in these methods and the available datasets,promoting the development of quantitative remote sensing.
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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.  
Abstract4435)      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.
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Prospecting development of south Xinjiang: water strategy and problem of Tarim River Basin
DENG Ming-jiang
2016, 39 (1): 1-11.  
Abstract2344)      PDF(pc) (1479KB)(2891)       Save
Having terrain feature of two basins between three mountains,Xinjiang is divided into North Xinjiang, South Xinjiang and East Xinjiang. Tarim River Basin almost covers the whole of area of South Xinjiang, made by nine water systems such as Hetian River,Yarkant River,Akesu River and so on. The paper analyzes its current situation of geography,climate,environment,oasis economic characteristics,water resources and exploration& development. It researches current water problems,including further increasing the contradiction of water supply and demand,a new threat causing by pollution of surface water and ground water to water ecological environment protection,climate change and transboundary rivers water affairs conflict,etc. It predicts challenge that will face in the future,including more complex of water resources problems,entering a new phase of construction and management of water facilities,river basins'water function recovery becoming a long term work, implementing trans-basin water transfer,etc. It proposes tentative plan of construction works of New Qiuci Project and New Loulan Project,Ecological-type construction in Tarim River,Hetian River discharge water quantity replacement scheme,and arid inland rivers threshold value regulation & control management model,which means half water for environment and half water for economic development while 30% runoff is used for natural water cycle and the maximum utilization ratio of inland surface water is not more than 70% in which there is 30% for water consumption for artificial environment and 70% for social and economic development. It provides a new way for Tarim River Basin comprehensive treatment and South Xinjiang stable development in the aspect of inter-basin water transfer,enhancing carrying capacity of water resources and environment,optimizing social and economic development layout,constituting ecological and economic zone of Tarim Basin,ecological immigration, relieving resources pressure for environment caused by population in the oasis,pushing balance development of national reunification and so on.
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Evaluation of regional urbanization level based on new urbanization: a case of 10 provincial cities in Shaanxi Province
NIU Xiao-chun,DU Zhong-chao,LI Tong-sheng
2013, 36 (2): 354-363.  
Abstract2638)      PDF(pc) (1043KB)(2839)       Save
As the current urbanization in China is facing many problems and challenges, it is imperative to take the new urbanization development path with Chinese characteristics: intensive and efficient, environment-friendly, urban-rural integrated, social harmonious. Based on the summing-up of the new urbanization theoretical connotations and features, this paper constructed an evaluation index system of the new urbanization, including six aspects: population, economy, infrastructure, quality of life, environment and urban-rural integrated development level. Using AHP method based on entropy technology the weight of each index was determined, and Shaanxi Province taken as an example.of empirical analysis. The evaluation results showed that 10 cities in Shaanxi Province are divided into five grades by the comprehensive level of new urbanization: the highest (Xi'an), high (Baoji, Yan'an, Yulin and Tongchuan),medium (Xianyang), low (Ankang, Hanzhong and Weinan ) and lowest (Shangluo). The new urbanization development level of the cities in northern Shaanxi is higher, lower in southern Shaanxi, and prominent in the center (Xi'an). Among the cities of Shaanxi Province, the differences of economic urbanization level are significant. The population and economic urbanization level of Xi’an are remarkably higher than that of other cities, but the advantage in quality of life and the fundamental facility level are relevant lower, the environment and the urban-rural integrated development level are even lower than that of the Ankang City and Hanzhong City; the quality of life in Baoji, the economic urbanization level and the construction of environment of Yan’an, the urbanization of population of Tongchuan, the economic urbanization of Yulin, the construction of environment and the urban-rural integrated development level of Ankang, the urban-rural integrated development level of Hanzhong are evidently higher than the equilibrium of the whole province. The economic urbanization of Tongchuan, Hanzhong and Weinan, the urbanization of population of Yulin and Xianyang, the economic urbanization and the urbanization of population of Ankang, the economic urbanization and the environment level of Shangluo are markedly lower than the equilibrium of the whole province. There are differences in the same evaluation factor of different cities and the different evaluation factors of the same city, development unbalanced. Therefore, it is obvious that the economic development is the main propelling factor in the urbanization of Shaanxi province. The development of population, the lifting of the quality of life, and the construction of the fundamental facilities are the main characteristics.  Ecological environment construction is unbalanced with economic development and urbanization process. It is needed to develop the new urbanization according to local conditions with overall conditions, in order to achieve comprehensive, coordinated and sustainable development.
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Wet-drought pattern and its relationship with vegetation change in the Qinghai-Tibetan Plateau during 2001-2010
WANG Min,ZHOU Cai-ping,WU Liang,XU Xing-liang,OUYANG Hua
2013, 36 (1): 49-56.  
Abstract2586)      PDF(pc) (3150KB)(2741)       Save
As one of the striking characteristics of global change,regional dry-wet climate variations and its effects on ecosystems has become one of the most important environment problems being faced by the world,and has been the focus and the advancing edge of global change study. Qinghai-Tibetan Plateau (QTP) is both a climate change frontier and natural defense of stable climate system of China and around the world. However,impacted by the global warming and anthropogenic activities,the ecological environment problems is showing up gradually,and the ecological shelter zone is seriously threatened. Vegetation is the most important and the most sensitive composition of climate change,and compared to other regions,the action of the vegetation system can have earlier and more obvious indicating effects of global change. The study of regional dry-wet status of the QTP and its relation to the vegetation changes will improve our understanding of the response and adaptation mechanisms of terrestrial ecosystems to climatic change,and also will have very important implications to the implementation of the scheme of ecological shelter zone and contribute to global ecosystem management activities. In this study,the model of RFE 2.0 and Penman-Monteith were used to estimate the precipitation and potential evapotranspiration of the QTP in growth season of the last ten years,respectively. Then based on the aridity index derived from the precipitation and potential evapotranspiration,the temporal and spatial character and the relationship between variations of regional dry-wet climate and vegetation change were explored and discussed. The results showed as follows:(1)Aridity index of QTP increased from SE to NW in general,with 67% of the entire plateau belonging to arid and semiarid regions. Over the ten-year period,about 25% of the area become drier,and obvious difference was detected between the north and the south for the drought trend;(2)The spatial pattern of [EVI] during the growing season were similar to that of drought,showing clearly defined boundaries for the western and eastern. About 25% of the area present obvious vegetation degradation during the last 10 years. (3)The degree of wet-dry has significant influence on the vegetation distribution of QTP,especially in the semi-arid areas which covered 44% of the whole plateau,the correlation coefficient between both was the biggest,the effect of Human disturbance on the vegetation distribution was not very apparent,but there was a relatively weak relationship between aridity index and EVI in the area with intensive human interferences;(4)In terms of the sensitivity of vegetation to the changes of wet-drought,The higher sensibility of EVI to aridity index of 96 meteorological sites during the growing seasons was distributed mainly in northeast and central plateau,and also along the upstream of Brahmaputra River,and as drought conditions worsen,the vegetation of more than 60% of those meteorological sites were degenerated in the nearly 10 years.
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Moving paths and nowcasting indicators of radar of hail cloud in Northern Tianshan Mountains
WANG Yun, XIE Xiang-yang, MA Yu, WANG Shi-gong
2017, 40 (6): 1152-1164.  
Abstract1999)      PDF(pc) (3279KB)(2603)       Save
In this paper,the variation characteristics of hail stone in the range of May to August from 2005 to 2014 were analyzed by using the observation records of meteorological stations on the north side of Tianshan Mountains,the records of artificial hailings,Karamay sounding data and detection data of four radars. The radar echo characteristics and the moving path of the hail cloud were studied and forecast index and radar warning index of the hail cloud are determined based on the percentile method. Moreover,the forecast and forecasting indexes were validated by the hail record data and radar detection data in the rage of 2015 to 2016. The results showed as follows: (1)Hail stone appeared on the north side of the Tianshan Mountains in the past 10 years,focused on the period from May to August and most appear in July,especially at 16:00-22:00 PM and most at 19:00 PM. (2)Echo tops (ET)of 7.0-13.0 km (average 10.34 km),40 dBz echo depth (ED)of 4.88-11.40 km (average 8.42 km),45 dBz echo depth (ED)of 3.86-10.65 km (average 7.44 km),50 dBz echo depth (ED)of 2.90-9.51 km (average 6.55 km). Maximum echo intensity of 51.4-65.8 dBz (average 57 dBz),combined reflectivity of 49-62 dBz (average 54.5 dBz)and vertical accumulation of liquid water content of 3.2-35.3 kg·m-2 (average 16.7 kg·m-2)are the radar characteristics for hail stone disaster from May to August. (3)Hail stone in the north of the Tianshan Mountains was formed in the Torrey Mountains (the west of Karamay City)and the Aiding Lake Valley (west of Wusu County). The three migration paths of hail cloud were northwest,northwest and west,southwest and west. (4)The potential forecasting index of hail cloud in the range of May to August is 0 ℃ layer height difference smaller than 3 872 m,freezing layer thickness is less than 3 236 m,K index is bigger than 23 ℃ and SI index is smaller than 3.85. (5)The Radar warning indexes of hail cloud in the range of May- August before hail 30 min are: the echo top height is bigger than 7.0 km,0 ℃ layer height difference bigger than 3.47 km. 40,45,50 dBz echo height is respectively greater than 4.96 km,4.38 km,4.18 km and the 0 ℃ layer height difference is bigger than 1.75 km,1.06 km,0.69 km. Moreover,the combined reflectance is greater than 42.9 dBz,vertical cumulative liquid water content is greater than 3.1 kg·m-2. The Radar warning indexes of hail cloud in the range of May-August before hail 15 min are: the echo top height is bigger than 8.0 km,and the 0 ℃ height difference is bigger than 4.81 km. 40,45,50 dBz echo height is respectively greater than 5.99 km,5.10 km, 4.80 km and the 0 ℃ layer height difference is bigger than 2.78 km,2.03 km,1.14 km. In addition,combined reflectivity bigger than 47.5 dBz,vertical cumulative liquid water content bigger than 4.54 kg·m-2,thickness of upwind zone in the radial wind field is exceeds 3km and existing wind cyclonic convergence in velocity field. The validation test of the forecast indexes and the radar warning indexes of the hail cloud in the rage of 2015 to 2016 shows that these indexed can play decisive role for forecast and early warning.
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Variation and evolution of groundwater chemistry in the middle and lower reaches of the Tarim River
ZHU Hai?yong,CHEN Yong?jin,LIU Jia?zhen,GAO Shan
2013, 36 (1): 8-18.  
Abstract2458)      PDF(pc) (1823KB)(2522)       Save
The change of the groundwater environment in arid areas has played a pivotal role in economic and ecological stability. And the groundwater water chemical type is a concentrated reflection of the groundwater chemical composition, is a system response of the way of the whole water and groundwater circulation characteristics. Then know about the distribution of the groundwater water chemical type not only can help to know the regional groundwater hydrogeochemical characteristics,but also have an important meaning for the further study about the regional groundwater circulation characteristics and the hydrodynamic field characteristics. While the characteristics of area underground hydrological geology and the properties of hydrogeochemical plays an important role in the direction and evolution of groundwater migration rule. So,to research the variation characteristics and the evolution law of groundwater water in chemical space and time can better reveal the interaction mechanism of the groundwater and the environment. Furthermore,it has a real significance for maintaining the ecological system’s healthy and stability in the arid areas. Based on the data of groundwater chemistry collected from 57 monitoring wells of 14 monitoring sections during 2006-2010,the temporal and spatial variation and evolution of groundwater chemistry in the middle and lower reaches of the Tarim Rive were analyzed. The results showed that the changes of groundwater salinity, TDS and concentrations of ions in the monitoring wells were greater than the pH, the ion contents of the groundwater samples were dominated by Na+and Cl-.Most of the higher salinity wells were Cl-SO4-Na-Mg type, in which the ions change little; and a few low-salinity wells were Cl-Na(Mg)type,in which the ions change much. Hydrochemical type of groundwater evolve from Cl-SO4-Na、Cl-Na-Mg and Cl-SO4-Na-Mg types to Cl-SO4-Na-Mg and Cl-Na types gradually in the middle reaches,from Cl-SO4-Na-Mg、Cl-Na-Mg to Cl-Na、Cl-HCO3-Na and Cl-Na-Mg type in the low reaches. The temporal variations in groundwater chemistry evolved from Cl-SO4-HCO3-Na to Cl-SO4-Na-Mg and Cl-Na in 2006,and from Cl-SO4-Na to Cl-SO4-Na-Mg then Cl-Na in 2010;In the low reaches,the temporal variations in groundwater chemistry evolve from Cl-SO4-Na to Cl-SO4-Na-Mg then Cl-Na(Mg)type water in 2006,from Cl-SO4-Na-Mg to Cl-Na(Mg)directly in 2010. All of the waters fall within the upper Gibbs boomerang envelope,suggesting that the chemical compositions of the waters in the middle and lower reaches of the Tarim River are controlled by evaporation and crystallization. The factors affecting hydrochemical characteristics formation were climate,hydrology,hydrogeology and human activity,including the projects of sluice,irrigation and sinking well.
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Transaction status evolution of sector nodes in industrial network of Beijing
WANG Mao-jun,LI Feng-wu,CHAI Qing
2014, 37 (2): 356-371.  
Abstract1880)      PDF(pc) (4461KB)(2440)       Save
The tendency of city economic growth and the development of industrial structure contains the process of market relationship conversion and the value flow shift between sectors of national economy. Each sector requires others’ outputs as production factors, meanwhile provides its outputs to other sectors as consumption. And then there exists interdependency and interaction of demand-supply relationship between sectors. This kind of complex relationship structure is similar to certain industrial network. Network analysis of the industrial structure is an important aspect in study area. The present studies focused primarily on two aspects: the determination of the network topology indicators. These analyses have a common characteristic: the vast majority of them are tending to explain industrial network as topology network. But they missed the point that the discussion of network nodes and rims’ actual significance. In this regard,there are three aspects worth to be analyzed. First,it is not meaningful to measure the connectivity of industrial network by average shortest path. Second,undirected treatment and unweighted treatment can’t reveal the true face of the industry network. Third,most of the studies did not carry out the discussion on self-loop. As an open and dynamic system,inter-industry relation in industrial network affects the development state of various industries,and in turn drives the evolution of industry network. For this reason,it is very necessary to find out the topology characteristics of industry network and figure out the evolution process of industry network. On the basis of the analysis of strengthen the weight of rim and node,in consideration of the random walk centrality, this paper attempts to answer two specific questions. First,what changes have occurred on industries’ position in network structure? Second,whether the network centralities rank of industries change significantly? If there are any change,dose this change reflects the direction of Beijing industrial restructuring?On the basis of the input-output tables of Beijing in 2002 and 2007,this paper constructs the industrial network of Beijing, and analyzes the evolution of the network features, then discusses the changing transaction status of sector nodes from 2002 to 2007. The results are as follows:(1)During the 5 years,following the network’s trading pairs of sectors increasing,the transactions have become more aggressive to promote the network and the network accessibility. (2)for transaction scale,the changes of trading centers’ status are different in 2002 and 2007,and the network structure roles of demand-supply center are also different. (3)there is a obvious change in the distribution of number of the trading markets, and the increasing rate of trading market number of tertiary industry is higher than secondary industry. It shows the trends of upgrading in industrial structure. (4)the strength of transaction linkage and the differences of sector trading have been expanded. However,the object of first trading sector is relatively stable,and the feature of self-loop trading is prominent. (5)the change in rank of sensitivity of tertiary industry and secondary industry is different,but the random walk centrality of producer services industry is steady.
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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.  
Abstract6810)      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.
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Water balance of Lake Bosten using annual water-budgets method for the past 50 years
LIU Li-mei,ZHAO Jing-feng,ZHANG Jian-ping,PENG Wen-fu,FAN Jing-long,ZHANG Tai-xi
2013, 36 (1): 33-40.  
Abstract2686)      PDF(pc) (1162KB)(2367)       Save
Lake Bosten, the biggest inland freshwater throughput lake in China, is located in the Yanqi Basin that is a semi-closed basin with rare precipitation surrounding by the Tianshan Ranges, The lake’s water supplies mainly depend on the rivers’ discharges that derived from surrounding mountains. Kaidu River as the largest inflow river to the lake, its east tributary is the unique inflow river that enables the water directly into the lake. Only Kongque River is an outflow river of the lake and its discharges into the river have been controlled by water pump since 1982. In the Central Asia, the lakes’ water resource is very important for the irrigation agriculture and the ecological environment. However, during the past several decades, the lake water level had decreased from 1 044.95 to 1 048.65 m. The water balance method had been used to study the reason of lake water level variation by many researchers, but their estimations about the water budgets were used to be offered as long-term averaged values (i.e. multi-years average) rather than a set of annual data year by year. In this paper, an annual water-budgets model of Lake Bosten is derived for the period 1958-2010. Calculation techniques are used to derive annual main inputs and outputs to the water balance, based on the data of lake rainfall, evaporation pan and rivers’ discharges during the historical period. This approach acknowledges that the water residual is produced here which is representative of the whole uncertainties to the lake, rather than just from individual flows of irrigation drainages and groundwater. The results indicate as follows:(1) During the period 1958-2010, the annual water inputs to lake totally were 14.34×108 m3/a, in which about 95% from river’s inflow; the annual water outputs from lake were 13.96×108 m3/a, about 43% by outflow and 57% consumed with lake evaporation; thus, the lake levels varied 1 047.01±0.94 m corresponding with the lake’s water storages of 71.57±3.92×108 m3/a. The water pump system built in 1982 has played a significant role on the water reconfiguration in the area around Lake Bosten. During the period of 1982-2010, the water outflows by this pump station were 8.07×108 m3/a, and the river’s inflows into the lake were 16.00×108 m3/a, it shows that the pump system has made the proportion of the outflow to the inflow from 31.7% to 50.4% than before. (2) For the extreme hydrological dry year in 1986, the annual inflow only accounted for 60% of the multi-year average; but the outflow from the lake was 155% of the average, it had lowered 0.94 m of the lake level which was the largest decline in historical records; for the wet year, the river’s inflow in 2002 was 2.62 times more than a normal year, which had caused 0.80 m of the lake level increased as being the highest rising records. (3) The alteration of the water residuals from ‘positive values’ to ‘negative values’ indicates that the water exchange between lake and groundwater is existing any time. In a word, when the water residuals of the year with a negative value, the lake water was recharging the groundwater, such as 2000 year and 2002 year; when the water residuals of the year with the positive value beyond of the drainages’ inflow magnitude, the groundwater was recharging the lake, such as 1975 year、1981 year and 1985 year. For the past 53 years, the lake water had recharged the surrounding groundwater with the net inflows about 0.87×108 m3/a totally.
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Application of wind erosion prediction system in Minqin Desert Area
2013, 36 (1): 109-117.  
Abstract4789)      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.
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Quality Assessment of the TRMM Precipitation Data in Mid Tianshan Mountains
JI Xuan,LUO Yi
2013, 36 (2): 253-262.  
Abstract2356)      PDF(pc) (2446KB)(2327)       Save
Precipitation has significant implications for the regional hydrologic cycle. Studying the spatial and temporal distribution of precipitation is important to the ecological environment and people's livelihood in northwest arid zone in China. Remote sensing precipitation products have the ability to reflect the spatial and temporal distribution of precipitation, and help with solving the problem of sparse meteorological stations in this region. The TRMM (Tropical Rainfall Measurement Mission) precipitation products as a satellite data are widely used in the humid tropics in recent years, and it is proved that the performance is good. However, the effect of the products in the arid and semi-arid area remains to be unclear. It should do a qualitative assessment before applying the products. This paper chose the mid Tianshan Mountains region as the study area, which locates in the inland arid zone. The quality of TRMM3B42 precipitation products was mainly evaluated for different time scale and different elevation scale based on observed data of 15 stations around the study area. The result showed that: the accuracy of precipitation events estimated by the daily products is low,and the accuracy is better in warm season than that in cold season, also the accuracy is better in small amount than that in large amount; Bias analyses of daily precipitation show that the estimated value tends to be higher than that of observed data on small precipitation events ,and to be lower on large precipitation events in warm season, but it has an opposite situation in cold season that higher on large precipitation and lower on small precipitation. For monthly precipitation assessment, the products perform well [(R2>0.85)] at the two stations (Bayinbuluke and Baluntai) on the southern slope of the mid Tianshan Mountains, it is quite different for the stations on the northern slope. On the northern slope, compared to the performance of the low plain, the monthly precipitation estimations is better in the mountain area; both the [R2] and RMSE changes with the elevation show a parabolic distribution, and have a positive correlation with annual average precipitation; also the annual distribution of the deviation is different in each elevation ranges, large deviation could be found in the spring and the autumn in low altitude area but in the summer in high altitude. In terms of yearly scale evaluation, it is clear that the TRMM estimated precipitation is lower than that of observed data at all stations, but the estimated value still can reflect the tendency of spatial distribution of precipitation,as the elevation increasing the deviation becomes larger, and gets maximum at the altitudes between 2 000 m and 3 000 m. Overall, the TRMM 3B42 precipitation data have the limitation in quality for arid and semi-arid climate environment, but the deviations have certain regularity. Calibration is indispensable and feasible processing of TRMM in the arid region.
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Spatial heterogeneity of Minqin Basin’s groundwater depth in recent 10 years
MA Jin?hui,HAN Jin?hua,ZHANG Yan?lin
2013, 36 (1): 1-7.  
Abstract2184)      PDF(pc) (3125KB)(2320)       Save
Miqnin Basin is located in Gansu Province,northwest China where has the sharpest conflict of using water. Its total area is 5.2×103?km2,but the area of the oasis is just 1.5×103?km2 and is gradually reduced due to the shortage of water resources. Along with the population growth and the economic development,,groundwater in Minqin basin is excessively pumped, thus the groundwater depth is growing larger with the increasing span of time. In this paper,according to the data of monthly groundwater level from 1999 to 2008 provided by Minqin monitoring network,using the function of geo-statistical spatial analysis which is the part of Geographic Information System technique,the spatio-temporal patterns and spatial heterogeneity of groundwater depth is analyzed in recent 10?a. The interpolation results shows that the groundwater depth in Minqin Basin is growing larger yearly from 1999 to 2008. And the four funnel of groundwater depressions had appeared in 1999 and was gradually expanded and finally formed two biggest funnel of groundwater depressions when merging with nearby funnel in 2008. One-dimensional linear regression model has been established,and the results shows that the groundwater depth increases 0.52 meter every year. The values of C0/(C0+C)(Nugget/Sill) are far less than 25% in 10?a and this means the groundwater depth in Minqin Basin has a highly spatial relativity. The value of Sill increases every year which means that the Spatial heterogeneity of groundwater depth is increasing and the influence of human activities on groundwater has gradually became structural rather than random and will leading to the augmentation of the connectivity and frangibility of groundwater in Minqin Basin . The chief reason of this phenomenon is that the groundwater over-pumped every year. So in areas where groundwater has already been overdrawn,effective measures shall be taken,such as to readjust  the crop structure and enlarge the proportion of low water consumptive crops to protect groundwater resources in Minqin Basin.
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Snowmelt runoff model applied in the headwaters region of Urumqi River
HUAI Bao?juan,LI Zhong?qin,SUN Mei?ping,XIAO Yan
2013, 36 (1): 41-48.  
Abstract2731)      PDF(pc) (1060KB)(2287)       Save
There are seven glaciers and large-scale snow above the Zongkong hydrological station of Urumqi River,and the snowmelt runoff in Urumqi River contribute significantly in the glacier ice and snow melting period. It is therefore essential to simulate the snow-melt runoff of Urumqi River,and also meaningful for the utilization of the snow water resources in the whole basin or even in Xinjiang province. In this paper,the SRM was applied to simulate snowmelt runoff in the headwaters region of Urumqi River. It is currently based on a simple degree day method.The daily precipitation,air temperature and snow cover area are the input data. In addition to the input variables,a number of basin characteristics such as basin area,zone area and the area elevation curve are also needed. The Digital Elevation Model are used to divide different zones of the basin,and MOD10A2 data are used for the accumulation of snow. Besides,the meteorological and hydrology data observed from May to August in 2008 are also used for this model. The region is divided to three zones and we get the curves of snow coverage shrinking derived from the MOD10A2 snow products,and the recession coefficients are also calculated in detail. According to the simulation,a final simulation scheme is selected as the final decision.The simulation fit indexes of Nash-Sutcliffe coefficient(R2)is 0.702 and the volume difference(Dv)is 6.81% which are fitted to the accuracy of snow melt model,and it also indicates that the SRM model can be applied in the whole Urumqi River. In addition,this application suggests that Urumqi River will be necessary for snow-melt runoff to meet with the needs of irrigation supply and water supply. This is particularly important for utilization of Urumqi River water resources. Meanwhile,the research also shows that :(1)This study concludes that the snowmelt runoff model based on a degree day factor can efficiently simulate the daily discharge in the snow and glacier-fed catchments of the headwaters region of Urumqi River. Parameters which are sensitive to the results are degree day factor,recession coefficient K,the critical temperature value.(2)Air temperature and precipitation as the direct drive variables are more sensitive to the model. As the temperature and precipitation are not strictly comply with the temperature and precipitation gradient in headwaters region of Urumqi River,the IDW interpolation was used to solve this problem,thus,it provides a new train thought for the precision of the SRM model. (3)The degree day factor is not stable in different height belt while the degree day factor selection and adjustment is also very important to the simulation. While the snow density is closely related to the degree day factor,actual measurement snow density data are needed to measure in all the height belt. (4)SRM don’t take the infiltration,interception and evapotranspiration into account,so the simulation runoff is less than the measured runoff. Meantime,the study area in this paper is 28.9 km2;consider the resolution of MOD10A2 is 500 m×500 m,there is a certain error in the curves of snow coverage shrinking. There are some shortcomings in this research;we intend to do better in the future research.
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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.  
Abstract3602)      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.
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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.  
Abstract7332)      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.
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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.  
Abstract3254)      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.
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Characteristics and comparative analysis of reconstructed drought/flood grade sequence in the eastern Northwest China from 1470 to 1912
BI Shuo-ben, QIAN Yu-jun, CHEN Chang-chun, LI Xing-yu, XU Meng-ya
2016, 39 (1): 12-21.  
Abstract2201)      PDF(pc) (2373KB)(2236)       Save
In recent years,under the background of global climate anomalies,drought and flood disasters occurred frequently in China. The historical climate research is an important content of international Climate Variability and Predictability Program. In recent decades,some scientists had made great progress in reconstructing the sequences of drought and flood based on historical documentary files,however,most of these rebuild sequences of drought and flood were mainly concentrated in Eastern China. Due to lack of early data,there were few research and analysis of historical flood and drought in northwest China. Collecting and classifying the data of drought and flood disasters in the eastern Northwest China from 1470 to 1912,and according to the criterion of drought and flood grade,this paper reconstructed the sequence of drought and flood grade. The change characteristics of drought and flood disasters including the decade and century frequency,periodic and mutability,periodicity over the past 443 years in all the regions were analyzed by using the moving average,accumulative anomaly, moving t-test technique,and wavelet analysis. Finally,in order to test and verify the reliability of this sequence, regional long-term trend was analyzed by comparing the Huashan precipitation reconstructed sequences and D/F index in Longxi,and further compared drought and flood grade curve with the stable oxygen isotopic record both from typical provinces. Results showed that drought disasters took place frequently and seriously in the eastern Northwest China. The alternate phenomenon about drought and flood was obvious. Probability of drought and the partial drought were higher than flood disasters,and the probability of flood years was the lowest. The drought and flood disaster which had obvious phases features could be divided into four stages:1470-1540, 1541-1615,1616-1796 and 1797-1912. Based on the four stages,we could further divide them into twelve drought-partial or flood-partial periods. Using moving t-test technique,we found that there were 12 abrupt changes on decade scale and 5 abrupt changes on 50 years scale. The reconstructed sequences displayed a periodic variability in multiple scales,which were comparatively obvious on the timescale of 130-110 a,70-80 a,50-52 a and 28 a,10-15 a,5 a,especially on the timescale of 10-15 a and 28 a. The first four periodic oscillations,from high to low,were in 28 a,15 a,73 a and 5 a. According to the comparison analysis,reconstruction of drought and flood grade sequence has high consistency with other precipitation sequence,showing multiple similar trends that peaks and troughs appeared at the same time,and corresponds to stalagmites oxygen isotopes records during the same period. All these could be an indirect proof of reliability and feasibility of our recovered historical flood and drought grade sequence based on the historical document data. The results have important practical significance for the development of disaster prevention and mitigation measures in eastern Northwest China. The study will be very important to discover the changing rules of drought and flood disaster and make accurately forecast for the future climate.
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Desertification assessments of Hexi regions in Gansu province by remote sensing
HAN Lan?ying,WAN Xin,FANG Feng,ZHANG Zheng?cai
2013, 36 (1): 131-138.  
Abstract2378)      PDF(pc) (2444KB)(2207)       Save
the Hexi region lies in the arid and semiarid regions of China, its fragile ecological environment and severity desertification were caused by natural environments change and humanity influences. With the development of remote sensing and GIS, it provides an effective method to research desertification. In this paper, MODIS data between June and August in 2002 and 2008 were used to analyze desertification, and five indexes {including MSAVI (Modified Soil-Adjusted Vegetation Index), Surface Albedo, LST (Land surface temperature), FAVI and TVDI} were used to assess degrees of desertification. The results indicate that the desertification land in Hexi region is larger and occupies more than 50% land in total land. The desertification land was decreased by 6431.64 km2 in 2008, the non-desertification land and slight desertification land increased by 2.25 and 0.26%, respectively; moderate, severer and extremely severer desertification land decreased 1.4, 1.09 and 0.31%, respectively. Summery, the reverse rate of land desertification is larger than development rate, and shows that reversing is common tendency but part region is in desertification development. In the study region, it mainly is slight desertification land, 23.64 and 23.90% in 2002 and 2008, respectively, and then belongs to moderate, severer and extremely severer desertification lands.
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