GIS Realization In The Jilin Province Flood Warning Service System

It is necessary to establish the Jilin Province Flood Warning Service System for sharing flood warning information in the most possible range and extent,ensuring real-time and accuracy of pricipitation information in Jilin Province, and improving efficiency and effect of Jilin Province flood warning service. The system has combined the modern information-processing, and network with GIS technology.Through establishing engineering database, flood warning and engineering information can be queried automatically, and real-time pricipitation information can be monitored. The system has provided graphic display and outputed table for user by vivid and visualized mode, and it brings modern technology into flood warning service.The Jilin Province Flood Warning Service System is developed in operating system of Windows2000 Server(SP3)and Windows2000 Pro(SP3). IIS(Internet Information Service)5.0 is selected for web server. Internet Explorer6.0 is designed for client. Development software uses Visual Basic 6.0, Visual InterDev 6.0,and ArcIMS ActiveX component. Graphic tool software is ArcMap and Adobe PhotoShop5.0.Debugging tools is Ms Script Debugger.Database system is Sybase11.9. designing Data tool is Sybase PowerDesigner8.0. The system has Browser/Server network architecture,which has three layers. Browser/Server network architecture overcomes Client/Server architecture's shortcomings.Its codes are easily reused and the function's modification and addition can be realized in business logical layer.IIS security is used to set user's authorization. IIS security control IP address and user's account. Through IIS it can accept or reject specific IP address to access the web server.The system use WEBGIS mode, which enables publishing vector map on network. Every distribution map and quering and analyzing result can be displayed in the map. WEBGIS handles massive data and makes pictures which high compression ratio,then sends the pictures and attributive data to brower.It can reduce data quantity in the maximum extent and provide dynamic interactive display.The system publishes GIS message through network. ArcIMS is a new ESRI product based on internet.It allows a application for publishing GIS map and data. in a large extent and provide the information to intranet or internet users.It is easy to establish,design and manage a website. ArcIMS has client and server technology,which extend common website.It has free HTML and Java browser and support other client.The system contains eight sections: rainfall, reservoir water, river channel water,history, engineering,flood regime,management and maintenance for database.The following technologies are used:Active Server Page,active HTML,COM/DCOM,WEBGIS and Java Applet. The system use Visual Basic 6.0 to develope a class file for the specifical need of Flood Warning Service based on ArcIMS. The class file is compiled a ActiveX Dll file,which can run in server.The Dll file can be called by ASP and performance various oprations,such as scaling up or down map, querying information and analyzing data ,etc.Then the data is published by ArcIMS. The system has three main interface webpage:logging,main and Popup. The logging webpage includes system name,logging account,password.The main webpage includes varius operations for map,menu,etc. The databases contain rainfall database and engineering database. The rainfall database is foundation of the whole system.The both databases is desined according to national standard. The rainfall database is based on Sybase11.9 and the engineering database is based on SQL SERVER7.0.