| Recently, due to the aggravation of atmospheric pollution, increasing deterioration ofglobal climate, constant extreme weather conditions and abnormal climate events, waterscarcity and drought occur in many regions. Facing up with the frequent occurrence ofdrought disasters, it’s necessary to monitor and warn drought and to reduce the effectsand disaster losses of drought by means of a regional drought monitoring and forecastingsystem. Computer information technology is used to achieve real-time informationcollection and transmission of the drought and it can provide basis for survey, analysis,decision of drought. It has a very important significance to the early identification ofdrought, drought resistance and drought risk assessment.Yantai City, located in the temperate zone of North China, belongs to continentalmonsoon climate, and has less precipitation in spring. Thus continuous droughts fromspring to summer happen frequently, which caused a great deal of influence on theindustrial and agricultural production. Drought monitoring and warning system in YantaiCity is a subsystem of drought monitoring and moisture prediction system. The systemhas a function of drought monitoring and the soil moisture forecast, and it’s a partinformation construction of flood control and drought release of Yantai City. It canprovide information support for scheduling of the production and living and ecologicalwater demand of Yantai City, and also can provide a basis for decision making of watersupply, water diversion and drought resistance.The innovative point of this paper lies in the visualization representation (GIS) ofwater regime information, mainly moisture information of Yantai City., Certain graphicalprocessing of the water regime of real-time and historical information of Yantai Citymakes the information more readable, the expression of the information content moreabundant. This paper focused on the graphical representation of the soil moistureinformation, using IDW interpolation algorithm as the main means together withreal-time and historical data from moisture stations as basis, to generate more abundantcontent of contour or contour maps for experts and decision-makers as reference waterallocation.Firstly, this paper introduced the basic situation of the area for study, the currentresearch status of domestic and international geographic information system software andthe organizational structure of the paper.Followed the introduction part, several key techniques used during the systemdevelopment process were briefly described, including the primary features of ArcGIS Engine, which was the main part of system architecture, the Microsoft.NET framework,C#programming language and SQL Server2005.Secondly, this paper analyzed the composition and logical relationship of the systemdatabase, the structure of the proprietary format for the ArcGIS Engine ShapeFile and itsrelationship with relational databases. Since graphical data are the basis for thedevelopment of GIS, the analysis of the underlying data will contribute to the systemdevelopment. This section of the paper focused on description and analysis of theorganizational structure of vector graphics and raster data of ArcGIS Engine, as well asthe relationship between vector graphics data and relational database, using this system asa prototype.Thirdly, this paper analyzed the generation algorithms of vector graphics and rastergraphics of the system, which were used by graphic displaying information. Theexamples includes IDW algorithm, GIDW algorithm, the grading color gradient renderingalgorithms, and the quadratic linear interpolation algorithm of grading renderingre-sampling algorithms for the raster graphics of soil moisture content and so on.Finally, this paper gave the design and functional logic structure of the system anddescribed in detail about the regional graphical query function, the operation of theregional graphic elements, the displaying of distributed water regime information and thedrought information query functions. |
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