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  • 2008 Volume 10 Issue 6
    Published: 25 December 2008
      
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  • ARTICLES
    Development of Digital Altitudinal Belts Identification System on .NET Platform
    SUN Ranhao, ZHANG Baiping
    2008, 10(6): 690-696.
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    Geo-info Tupu methodology is a new direction for geographic researches,and it's not only a way for presentation but also a method of analysis in geo-information science.Based on the idea of Geo-info Tupu and digital mountain altitudinal belts(digital MABs),the objective of this paper is to construct the models of multi-scales spatial patterns in altitudinal belts and develop the digital framework that identifies the horizontal and vertical differentiation from multi-source data.According to three patterns of digital identification,i.e.,single flank,single peak and multiple peaks,this paper develops different algorithms using the Matlab programme.Contrasting the identification patterns,we indicate the relative merits among them in digital identification and Tupu visualization,and show clearly their special scale for the study regions.Based on the VB.NET platform,we build a programming system,named "Mountain Altitudinal Belts Digital Identification System"(MABsDIS),which provides several modules with useful tool sets,such as data in-out module,data processing module and graphic plotting module.Using the MABsDIS software,the mountain altitudinal belts are identified from digital terrain models and digital vegetation data in the Helan Mountains,China.The study reveals that the digital identification of MABs could enrich the source materials of mountain researches and enhance the digital comparison and analysis method of MABs.And it also could reveal more geographical information than ever before and is an effective attempt for Geo-info Tupu practices.
  • ARTICLES
    Research on Simulation of the PAR Distribution in Tree Canopy
    WANG Zhangang, ZHUANG Dafang, MING Tao
    2008, 10(6): 697-702.
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    The common methods about research on the distribution of radiation in canopy are introduced.The principle of ray-tracing technology and its application in radiation transmission are described.A radiation transfer model is proposed for tree model based on forward ray tracing.The model hypothesis,processing flow and primary algorithm are expounded.Forward ray tracing is used to simulate transmission course of photosynthetically active radiation in tree canopy.Finally the special conversion method between HSV and RGB color space is adopted to clearly express distribution of radiation in canopy.On the basis of analyzing optical characteristics of leaves,the radiation transfer model is applied in the simulation of distribution of PAR in canopy.At the same time,we can get the reflectance rate,transmission rate and absorption rate.The simulative data have little difference with the actually measured data which indicated that the radiation transfer model based on forward ray tracing is effective.
  • ARTICLES
    Some Problems on the Application of Population Data in Geo-science
    DU Guoming, YU Fengrong, ZHANG Shuwen
    2008, 10(6): 703-709.
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    In recent years,quality and uncertainty of population data have attracted a mass of attention,but more attention was paid to uncertainty of population data itself and less to uncertainty that was results from inaccurate using.Population data that used in geo-science mainly includes modern population investigation data,population forecast data and historical population data.Different population data that come from different sources have different characters.When population data are used,attribute character,spatial character and temporal character of population data should be paid attention.As to attribute character,the main attention should pay to the differences of statistical indexes of population data,the differences of population data of statistical resources and the change of standard of setting up town or city.As to spatial character,the main attention should pay to illegibility and uncertainty of administrative borderline,adjustment and change of administrative regions and the difference between the study area and the statistical unit of population data.As to temporal character,the statistical time of population data should be cared for.When population data with different sources and time are used,they should be integrated firstly.The main measures include: reclassifying and recounting data based on different statistical indexes and standards of population data;recounting data based on adjustment of administrative regions,or spatializing population data;forecasting or calculating population data for special time based on accurate temporal character of population.
  • ARTICLES
    Research on Ecological Restraint of urban Expansion Model Construction and Its Application—— A Case Study in Nanning City
    LU Yuan, MO Jianfei, WEI Liangying
    2008, 10(6): 710-715.
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    Urban expansion is a complex spatio-temporal transformation process.It transfers different kinds of land use types into urban land,the results show that the scale of city expands increasingly.But land resources are limited,urban expansion simulation must be constrained by ecological security.So how to lead to healthy urban development and make good use of land is crucial to maintain human sustainable development.Based on the theories and methods of the complexity of science and ecological security,supported by the technique of CA and GIS,integrated with Tietenberg model,GEOMOD model,ecological applicability evaluation model,an ecological restraint urban expansion model(ERUEM) is constructed,and urban expansion simulation is researched based on the technique.According to the simulation,Nanning city expansion was predicted with the model.The results show that: ERUEM model effectively protects natural resources such as waters,paddy field,dry land and woodland.It also nurtures the urban ecosystem services and promotes urban ecological sustainable development;ERUEM model can be effectively applied to urban planning.The results are sensuous to the planners,and show how to develop the city by planning policy.The characteristics and innovation are that ERUEM model can overcome the limitation of simulating complex systems of urban expansion models constructed by CA model,and consider external factors in the macroscopic and microcosmic scale.
  • ARTICLES
    A Study on Organizing and Managing Multi-source Seismic Active Fault Data Based on ArcGIS
    LI Ce, DU Yunyan, YU Guihua, XU Xiwei
    2008, 10(6): 716-723.
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    In order to meet the urgent need of building spatial data infrastructure for urban anti-earthquake defense,and to make decisions for urban developing planning,landuse planning and site analysis of major projects,this paper firstly applies a feature analysis on multi-source seismic data based on seismic probing data acquired from "National Seismic Active Fault Probing Technique System" program to depict data's major characteristics;secondly,a concept model is built respectively for active fault probing database and seismic risk assessment database;thirdly,considering the requirement of storing and managing original geo-physical,geo-chemical and geological survey data and associated log files,which may be attributes of spatial data in enterprise database as well as spatial data,a set of BLOB based archive tables and archive records to feature linkage principle are designed and developed;and then this concept database model is implemented using ArcGIS Geodatabase specification and UML tools;finally,we design and implement a series of work flow and conversion tool to import,transfer and re-construct probing source data into database schema.
  • ARTICLES
    Study on Adaptive Watermark of GIS Vector Data
    ZHANG Lijuan, LI Anbo, LV Guonian, LIN Bingxian
    2008, 10(6): 724-729.
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    Aiming at the current application and requirement of watermark technology on GIS vector data,this article proposes a double embedded auto-adapted watermark algorithm(DEAWA) for the vector digital mapping,which is based on the applied characteristic of administrative or physical division,and the various aspects of GIS vector data such as element style,data format and redundant initiation position.The DEAWA means that,once for point layer,the algorithm used for adaptive embedding and extracting is based on administrative(or physical) regionalization and for polyline or polygon layer,the algorithm is based on feature.This algorithm can automatically sense the carrier and adaptively adjust the intensity and the location of the watermark.However,because of the disordered point storage in GIS vector data,the watermark can be easily destroyed but the data precision keeps unaffected when the storage sequence of points is aggressively adjusted.Therefore,in order to avoid such invalid sequence,the DEAWA can be improved by using spatial relationship and position to arrange the point sequence in advance so that the watermark can be orderly embedded and extracted.Finally,according to the definition of difference,this article judges the imperceptibility of watermark algorithm for the GIS vector data through the operation of spatial analysis.The experiments show that the DEAWA possesses excellent imperceptibility and robustness.
  • ARTICLES
    A Novel Approach for Raster Data Vectorization
    ZHANG Xingyue, WANG Min, JIANG Sheng
    2008, 10(6): 730-735.
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    Raster data vectorization is one of the key techniques for the integration of remote sensing and GIS.Although it's a traditional problem with a lot of algorithm proposed,there still exist many defects including,e.g.,the problem of the "island",especially the multi-nested "island" in many vectorizing methods.In this paper,an improved algorithm for raster data vectoriation is proposed.This method includes four main steps.The first step is to extract the vertices and nodes.Moving through the image using a 2×2 template window,we can extract the vertices and nodes and their connection information.The second step is to construct the arcs.We use the connection information to construct the non-closed and closed arcs.The third step is to build the polygons.With left-turn algorithm,we can build simple polygons from non-closed arcs.Besides,since closed arcs correspond to simple polygons,we only have to convert a vertex of an arc to a vertex of a polygon.The last step is to deal with the "islands".We judge containing relationship among these polygons.Since a polygon may be contained by several parent polygons,we should find its minimal containing parent and then deal with the "islands".The main advantages of the proposed algorithm include the follows.1) Algorithm efficiency is relatively fast.2) It isn't sensitive to the size of raster data,but only sensitive to the number of the nodes and vertexes.3) It can build the correct topology and then solve the problem of multi-nested "island".Our method is validated with many successful experiments when applied in vectorizing the remote sensing classification imagery.
  • ARTICLES
    Discussion on the System of Digital Mapping Element Classification and Codes
    WANG Dali
    2008, 10(6): 736-740.
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    Nowadays geographical data working in GIS is mostly from digital map.The classification and encoding for the mapping elements on the digital map are very significant to building GIS,so the digital map data must be coincident with the geographical data which share GIS.The mapping elements are not equivalent to the geo-information features,or geo-information feature elements.The mapping elements and geo-information features are on different levels ontologically.To encode for the mapping elements,we must tell the difference of classification and codes for digital mapping elements from the geo-information feature's as well as give a system and encoding method of digital mapping elements which follows the geo-information feature's classification and codes.In the paper,the digital mapping elements are divided into two categories including "pure mapping elements" which are a set of mapping elements minus geographical feature elements,and "GIS′ elements" which are a set of mapping elements intersect the the geo-information feature elements;the concepts of virtual element,pseudo code and virtual code are introduced for the co-operation to the relations between the mapping elements and the geo-information features.The principle to design the classification and encoding method for the mapping elements on digital maps in the paper is to carry out the national standard of specifications for feature classification and codes of geo-information in the stage of digital mapping.The maneuverability of the classiication and encoding for the mapping elements in the paper is flexible and efficacious.The paper gives an example of the image from the mapping elements to the geographical features as well.
  • ARTICLES
    Research on The Method of Analysis and Evaluation of Landslide Disaster Based on Multi-source Data
    ZHANG Jun, ZAO Fangfang
    2008, 10(6): 741-748.
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    In order to prevent and reduce the expense of lives and belongings of people which coming from landslide,on the basis of the demands of disaster prevention and mitigation,this paper analyzes the research actuality of the evaluation of natural disaster losses.On the basis of traditional method of evaluating disaster losses,and analyzes the method that has been existed of evaluating disaster losses and puts forward a quickly evaluating method of coast disaster losses based on multi-sources geographical spatial data.This paper discusses integrative analysis method of coast disaster for multi-sources geographical spatial data.The method was demonstrated in Yanhua factory in Wushan,the Yangtse River Gerges,and summarizes the method of evaluating model of coast disaster losses.Finally,a comparison between two results of model calculational and traditional investigation was made,and the method of model calculation was demonstrated in its feasibility and applicability in multi-sources geographical spatial data.Depending on softwares such as ArcGIS,Oracle and ArcObjects,the paper carries out the method of establishing database based on multi-sources and the model of loss evaluation.
  • ARTICLES
    A Study on Remote Visualization of "Ocean Vector Field Data" Based on Web Service
    YANG Feng, DU Yunyan, SU Fenzhen, XIAO Ruling
    2008, 10(6): 749-756.
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    Nowadays,the visualization of GIS spatial data is in static manner,and the data is managed on the server side concentrically.So,it is difficult to satisfy the need for the multi-source and different structure data.At the same time,it also can't meet the need for the ocean environment information data,which has a strong attribute of dynamics.With the development of web service and grid computing technology and also with the utilization of these technologies in GIS,it is possible to realize the visualization sharing of spatial data in a uniform client and manage these data in a distributed way.So,firstly,the article analyzes the requirement of visualization sharing of ocean vector fields information on network in real time and its technologic difficulties.Then the article introduces the web service and network GIS technologies,which are the theoretical base of the systeam,and discusses the method and the system structure of ocean environment vector fields network visualization system in detail.Finally,the article took ocean current data as a case study,introduces the realization of network real time visualization platform of ocean current data with the support of network service of ArcGIS and visualization of ArcEngine.The experimentation has proved that the ocean current remote visualization system based on web service can meet the requirement of data access and visualization for vector fields in network.
  • ARTICLES
    Approach to Route Description in Chinese Natural Language for Electronic Maps
    ZHANG Xueying, LV Guonian, HUAN Jian
    2008, 10(6): 757-762.
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    Natural language route description represents path information using the ways of linguistic and thinking in people's daily life.Route description in visualization and natural language provides path query service with both pictures and explanations.With the increasing of electronic maps in mobile equipments and Internet,natural language route description becomes one of the significant services for the popularization and humanization of electronic maps.Natural language spatial relations play an important role in route descriptions,which are related to psychology and cognitive linguistics.This paper aims to solve the problems of generating natural language route description in Chinese way-finding systems,on the basis of datasets of geographical information systems and natural language generation technology.Firstly,based on the introduction of the shortest path algorithm,this paper describes the classification of terms for Chinese route description.Secondly,four unit syntactic models are presented to describe different path units.The combined syntactic model is proposed to describe one complete path by means of linear integration of path units,which focuses on the solution of the problem of limited syntactic models in the previous approaches.Furthermore,the algorithms are discussed for the extraction of additional information such as road names,landmarks and orientations according to a given path,in order to improve the understandability of route descriptions.Finally,one prototype system is developed to implement the proposed approach with the case of naming electronic map.It indicates that our proposed approach can achieve satisfactory performance.This system can simultaneously visualize the shortest path and generate its natural language description based on query requirements.
  • ARTICLES
    Research Development of GML in China
    ZHANG Shuliang, LV Guonian, MIAO Lizhi, GAN Jiayan, HUANG Jiazhu
    2008, 10(6): 763-769.
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    Due to its opening and self-described format system,abundant spatial data expression technology,flexible application mode generation method,GML quickly plays an important role in many GIS research and application directions such as spatial data modeling,transmission and exchange,integration and sharing after several years of development.This paper deeply analyses research development of GML in China on aspects of domestic GML related research project,doctoral and master's degree thesis as well as published Chinese papers by core journals.In addition,this paper proposes challenges confronting domestic GML research and application and crucial problems to be resolved in the direction of GML development from three aspects: GML specification research,GML technology research and GML application research.From the analysis of research subject,the focus of GML research has changed from the initial expression of GML data,spatial data modeling of industry,spatial data conversion and integration and visualized research of GML,to GML's internal mechanism which based on the principle of the core technology of GML,the way to realize GML and interoperability between applied technologies.From the analysis of doctoral and master's degree thesis and the Chinese papers published on core journals,we can see that the research of GML was emphasized on application before 2004 but at of GML technology and combination between it and space services after 2004.The research of GML application was mainly concentrated on the support of WebGIS framework,spatial data sharing and interoperability and so on,while that of GML technology focused on GML's storage,index,query,compression and pattern matching and so on.Papers and studies on GML put forward the challenges and urgent problems in domestic GML research and application from three aspects: the GML specification,GML technology and GML application.In GML norms aspect,China should promote the institution of national relevant sharing standards based on GML.In technical research aspect,domestic researchers should strengthen the technique and method's study on GML resolution,GML storage,GML query,GML index and GML compression and transmission.In applied research aspect,it is very necessary for professionals in GML field to establish professional application mode,fractionize the applied layers of spatial data,and improve the shared obstacles in GML application system.
  • ARTICLES
    Preliminary Study on Further Development of Google Maps
    CHEN Yuanyuan, JIAN Ji, YANG Wunian, ZHANG Min
    2008, 10(6): 770-775.
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    As the web platform continues to mature,we see an increasing number of amazing technologies that take Geographic Information Systems(GIS) visualization applications to new levels of power and usability.By integrating new powerful technologies into GIS systems,we get higher performance results with additional functionalities.The most recent development capturing the attention of the browser-based-application developers is the component development technology based Google Maps and Joomla.In this paper,the authors describe the recent situation of Google Maps and analyse its realization application in Joomla site,then provide a set of Google Maps design frame and four modules in Joomla.The component is implemented by using PHP and Java script language based on Joomla framework and Google Maps API.With the component,we can embed Google Maps in own web pages simply,draw markers and lines on the map fleetly,and build sophisticated applications with our own objective easily.
  • ARTICLES
    Comment on the Enhanced Water Index(EWI):A Discussion on the Creation of a Water Index
    XU Hanqiu
    2008, 10(6): 776-780.
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    This paper analyzes a newly proposed remote sensing index—the Enhanced Water Index(EWI),by Yan et al.(2007) and discusses the creation of a water index.The EWI was constructed by the ratio of the green light band to the sum of the near infrared(NIR) band and midddle infrared(MIR) band,i.e.,EWI=[(Green-(NIR+MIR))/[(Green+(NIR+MIR)).The evaluation of the EWI was through the application of the index in two images,one without atmospheric correction and the other with the atmospheric correction,and then the comparison of the results of the two enhanced images.Furthermore,the EWI-enhanced water images were also compared with the MNDWI-enhanced water images.The evaluation shows that the EWI failed to effectively enhance and extract the water features in the atmospheric-corrected image,while the MNDWI can work effetely in either corrected or uncorrected images.Many small open water bodies,such as ponds,lakes and city inner rivers,were omitted in the EWI-enhanced/extracted image.Obviously,the neglect of the atmospheric effect on the image resulted in the failure.In addition,the construction of the index is not reasonable.The increase in the concentrations of the suspended solids and algal chlorophyll can notably raise the reflectance of the NIR and MIR bands by water.Therefore,the difference in the reflectance between the green bands and the sum of the NIR and MIR bands can be significantly reduced and the EWI values of many such water bodies can be close to zero or even can be negative.Consequently,instead of being enhanced,these water features were depressed and even removed from the EWI-enhanced image,and thus resulted in the omission of the water features in the extracted EWI-water images.Therefore,in order to avoid uncertainty,any new water index to be created should be tested using atmospherically-corrected image beforehand.Moreover,the water components have also to be taken into account when constructing a water index.
  • ARTICLES
    Land Cover Remote Sensing Classification Framework Design Based on ISO Extensible Metadata Model
    WANG Juanle, JIA Wenchen
    2008, 10(6): 781-786.
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    Land cover information plays an important role not only in social-economic development but also in scientific research area.With the development of the information technology,remotely sensed images provide main data sources for land cover information and knowledge extraction in real time.While there are lots of land cover classification systems in the world facing to different research targets and objectivities and with the crossing of multi-disciplines and expanding of the research area,more and more land cover classification systems are designed.This causes the difficulties for datasets' exchange,integration and fusion which use different classification systems.The problems facing land cover classification systems are similar with the problem of metadata standards.Faced with this problem,ISO TC211 designs an extensive metadata standard framework for geographic data,and draws up the ISO Metadata Standard 19115.Enlightened by the ISO 19115 metadata extensible framework,the paper brings forward the land cover extensible classification framework.The framework is composed of 3 tiers,i.e.,land cover core classes,schema classes and application profile classes.The core classes are derived from the main international land use/land cover classification system.Schema classes inherit and extend core classes.Extensive principle and methods are designed in this framework.This ensures many application classification profiles can be extended from the core classes and schema classes easily while the designed extensive land cover classification system should be tested and perfected through more and more real applications.
  • ARTICLES
    The Influence of Bandwidth's Variety on Estimating Chlorophyll-a Concentration of Lake Waters: Taking Taihu Lake as an Example
    JIAO Hongbo, JIN Jiye, LIU Zhenmin, ZHA Yong, LI Sihai, LI Yunmei, HUANG Jiazhu
    2008, 10(6): 787-791.
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    In order to study the influence of different bandwidth's remote sensing data on estimating chlorophyll-a concentration in waters,this paper analyzes and calculates the correlation coefficient between normalized reflectance of different bandwidth and chlorophyll-a concentration based on real-measurement hyperspectral reflectance.With constant increase of bandwidth in a scope of 75.93nm,it has found that the maximum correlation coefficient decreases by degrees,the maximum positive correlation band moves to long wave,the maximum negative correlation band moves to short wave while estimating chlorophyll-a concentration in waters.As the bandwidth changes in the scope of 31.60nm,both the maximum positive correlation band and the maximum negative correlation band will keep a relative stable state.Finally,through contrasting the mean and standard deviation of different bandwidth's correlation coefficient,we think 723.51nm~33.00nm is the best band range for estimating chlorophyll-a concentration.This will provide important reference value for band setting of remote sensing sensor and band choosing of real chlorophyll-a estimation by remote sensing in water.
  • ARTICLES
    Forest Fuel Types Classification and Change Detection by Remote Sensing in Zhangping City
    CHEN Yunzhi, CHEN Chongcheng, WANG Xiaoqin, TANG Liyu
    2008, 10(6): 792-797.
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    Forest fuel type's spatial distribution is one of the key factors to be considered during forest fire spread and fire-fighting visualization modeling and simulation.Based on review of the status of the study on forest fuel type classification,a classification method considering tree types was put forward.According to the attribute of predominant tree types of 2003 forest stand layers,four forest fuel types,i.e.,bamboo forest,broad-leaved forest,Chinese fir forest,and Masson pine forest and their spatial distribution in Zhangping was acquired firstly.The object-oriented classification technology,which using the techniques of image segmentation to construct objects containing information of size,shape,topography and class hierarchy besides spectral information,and involving procedures of segmentation,construction of class hierarchy,and classification,was then applied to the ASTER images to detect interior and exterior change of each type's.Accuracy assessment of the classification result indicated that by the technology of object-oriented classification,both the spectral features and class-related features were used,and the accuracy was improved in terms of area,reaching 89.3%.Because thematic layers were involved during the image segmentation,the boundaries of objects did not get across the boundaries of each thematic layer,this makes the updating of the existing layers become very convenient.Finally,the vector format data of remote sensing classification result was used to update the original forest stand layer in order to get the available inputs of fire visualization modeling.This study not only provided up-to-date input layers of forest fuels types for fire visualization modeling,but also detected the areas which have been changed without changing the boundaries of the original forest stands.For forest resource managers,it provided target areas for validation by field survey.
  • ARTICLES
    Analyses of Phase Synchronization on InSAR System Based on Formation-Flying Satellites
    TANG Xiaotao, LOU Liangsheng, LIU Zhiming
    2008, 10(6): 798-801.
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    The InSAR system based on formation-flying satellites is a multi-radar system,which depends on the satellites formation to form the baselines needed by the interferometry.For this system,time synchronization,phase synchronization and space synchronization should be established by the cooperated radars with each other.The precision of three synchronizations will influence the systematic function and performance of the InSAR system.The error of phase synchronization among the three synchronizations will affect the phase error of SAR SLC image directly,and influence the elevation measurement precision sequentially.In this paper,the requirements on phase synchronization are analysed based on the need of the SAR imaging under the condition of formation-flying satellites,the influences on the elevation measurement precision due to the loss of phase synchronization are also given.The results show that the requirements on phase synchronization include two facets,firstly,the carrier frequencys of master/slave radars should keep certain relationship within synthetic aperture to assure the SAR imaging to be done successfully,and the carrier frequency difference must be restricted to a determinate range which depends on different slant range resolutions.Secondly,the phase synchronization error can not overrun a limit which is requested by elevation accuracy demand during the whole interferometric data acquirement time.
  • ARTICLES
    Monitoring Fire from Crop Residues Burning with MODIS Data in North China Plain
    HU Mei, QI Shuhua, SHU Xiaobo, CHEN Liangfu
    2008, 10(6): 802-807.
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    Based on the fire pixels brightness temperatures characteristics and their difference with background,the fire-points from crop burning were picked up by fire detection algorithm with MODIS 1B data for the North China Plain.The fire-points from crop burning detection algorithm uses the neighboring pixels to estimate the radiometric signal of the potential fire pixel.The brightness temperatures were derived from the 4-and 11-μm channels.Together with geographic data and fire information,the fire distribution map of the North China Plain was got with the MODIS 1,4 and 3 bands reflectance product.The intersect operation was used to count number of fire-points from crop residues burning in North China Plain on Jun.17th and Jun.18th of 2007 with ArcGIS.The results show that the fire-points from crop residues can be found for these two days,and most of the fire-points were detected in Henan and Hebei provinces;and the number of fire-points has an increasing trend in Henan and Shandong provinces.Remote sensing can be used to detect the fire-points from crop residues burning at regional scale.It will improve the efficiency of prohibiting crop residues burning.
  • ARTICLES
    Research on Spatial and Temporal Changes of Riparian Vegetation Cover in the Three Gorges Dam Area Based on NDVI
    WANG Jingjing, BAI Xue, DENG Xiaoqu, WANG Mingcui
    2008, 10(6): 808-815.
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    The Three Gorges Dam Area was chosen as the study area in this paper.The destruction of the project on vegetation in the ecosystem is obvious,especially near the riparian zone.The vegetation fraction was calculated based on NDVI.Resorting to the comparisons of vegetation coverage in buffer areas along the dam area among three different phase remote sensing images of 1978,1999 and 2006,we detected the dynamic vegetation changes before and after impoundment in September and analyzed the distribution of vegetation cover of each year as well as the areal changes through grade analysis.A nonparametric two-sided t-test,Wilcoxon rank sum test,was used to evaluate significant differences between vegetation changes in different land use types between 1978 and 1999,1999 and 2006,and 1978 and 2006.The results showed the changes are significant.The research concluded that there was a high degree of vegetation damage between 1978 and 1999,the withal drop of vegetation cover area by 3.31km2,but between 1999 and 2006,in the case of 8km2 being inundeted,the area of vegetation cover only dropped by 1.57km2,indicating an evident vegetation restoration.On the whole,during the nearly 30 years,the vegetation cover hes shown an increasing trend.