Research On Ecological Environment Dynamic Changes And Ecological Water Demand In The Tarim River Basin Based On RS And GIS

With the development of science and technology and with the explosive growth of world population,the natural environment has been intervened and worsen on a large scale at an unprecedented speed,which has resulted to a severe succession of ecological problems such as soil and water erosion,land desertification, vegetation degradation,etc.threatening the human beings' lives,properties and their normal production. Therefore,the monitoring and then analyzing and researching the dynamic changes of the ecological environment in a given area has become one major concern of the hot topics in the concerning research fields. The Tarim River Basin is located in the arid inland with the rare rainfall in the western area of China,whose extremely fragile ecological environment resulted from the increasing human beings' activities and the excessively disorder development and ineffective utilization of the water resources constantly keeps itself in the foreground of the ecological stability of the oasis and the sustainable development of the local society and economy.It thus directly prevents the developing strategy from implementing in the west of China.In order to improve the local ecological environment,the Rarim River Basin Management Bureau and the relative departments started the Emergent Water Transportation Project in May 2000 and since then has provided six times of emergency water supplies till June 2004,on the basis of which great changes in the ecological environment have taken place in the local area.The multi-source remote sensing images data and the basic ground data of multi-type and multi-scale are collected before and after the emergent project.Five ecological factors such as land use,soil salinazation,vegetation coverage,vegetation type and land desertification are selected as the research objectives by means of automatically extracting remote sensing information,building databases of massive datum of more projection zones,dynamic monitoring the ecological changes of environment,and estimating the natural vegetation ecological water demand,and so on.The creative methods and the major conclusions of this research are summarized as:(1)The five indicative factors are chosen on the background characteristics of the Bason ecological environment and evaluated under the classification and grade scales system,the density slicing technology. The methods of system classification,interpretation marks setting,ecological conversion models building, automatically remote sensing information extracting,field investigations and knowledge base constructing, etc.are applied to automatically collect the multi-source images information from 1999 to 2004.The extraction accuracy of the target data mounts to 87.7 percent,up to 95.4 percent after calibration,which meets the practical needs for the production in the research zone.(2)The theory of the integrative spatial and attribute data,seamless integration of multi-source cata are used to build the massive databases in terms of the analysis of the actuality and the future developing requirements in the Tarim River Basin.The data are arranged and organized as their layers,classification and blocks and the cluster server frame of double PC in interback-up model.Ten massive databases namely Digital Line Graphic(DLG)Database,Digital Raster Graphic(DRG)Database,Digital Elevation Model (DEM)Database,Digital Orthophoto Map(DOM)Database,Hydraulic Engineering Database,Ecological Environment Database,Social Economic Database,Multimedia Database,Metadata database and the Result Database,have been firstly accomplished to integratively manage and research the spatial and attribute data since fifty years in the target research zone.The volume of the data stored in these bases mounts to 600 GB or so.(3)The thought of input with one key is put forward by virtue of ineffective of data storage and the complicated operation.Under this process,the Arc/info scripting language,spatial data engine(SDE) command and oracle command are combined with database structure design,data checking and configuration, database building scripting generating and others to form a encrypting batch file,which is then run to complete the automation data input and data tracking management.This one-key-input technology promotes the efficiency of data storage dramatically.(4)Based on the multi-source remote sensing special data and multi-scale basic geographic data,the five ecological factors are dynamically monitored and analyzed in the qualitative and quantitative methods,which reveal how the areas of the five factors change and their changing tendency before and after the eme(?)gency water supplies during 1999 and 2004.The ecological environment tends to improve after the eme(?)gency water project in the local basin as a whole.The Green Corridor is positively recovering in the lower reaches of the Tarim River.The population pressure and human beings' activities are the major driving forces degenerating the ecology of the target zone.(5)The concept of the ecological water demand for the natural vegetation and its quantitative model are put forward and established in terms of the corresponding analysis of the current situation in the mainstream of the Tarim River.The remote sensing(RS)and geographic information systems(GIS)technologies and the phreatic evaporation theory are applied to extract the current vegetation situation in the three periods of the remote sensing images in 1999,2002 and 2004 respectively and calculate their ecological water demand for the natural vegetation in the corresponding year.On the basis of it,the ecological construction mode is set up to secure the sustainable development of the target zone. The information technologies of RS,geographic positioning systems(GPS),GIS and SDE,etc.used in this research have favorable characteristics of high information extraction accuracy,convenient data management,excellent transplantation and strong operability,etc.which offer possible unified dispatch and management for the basin water resources,and the scientific guides for the ecological environment evaluation and economic sustainable development planning.Its theoretical and practical significance can be extended to other relative areas.