| Scenario |
Taiwan is surrounded by oceans and has a subtropical monsoon climate. The average annual rainfall is about 2510 mm which is the main source of water resource in Taiwan. However, the rainfall of distribution of time and space is not distributed equally. Even though the total rainfall is quite abundant, most of it is concentrated in summer and autumn. Consequently, the floods in rainy season and droughts in dry seasons are caused usually. Moreover, the change of the climate in recent years also deteriorates the unequal rainfall in Taiwan.
In order to observe the change of rainfall in Taiwan more effectively, Central Weather Bureau in Taiwan has used a stand-alone GIS system to deal with the rainfall data by dynamically facing, mapping, overlaying, and storing image, etc since 2005. The map data generated by the system have been the essential reference for the rainfall forecast and study in Central Weather Bureau.
However, the stand-alone GIS system cannot satisfy the increasingly need and data. Therefore, to improve the convenience of data providing and efficiency of system use, Central Weather Bureau planned to build a WebGIS system to centrally manage the rainfall data. As a result, the related staffs in the bureau can search, display, and save the rainfall map data via an internet browser.
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| Goals |
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| Climate Rainfall Map System interface |
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Central Weather Bureau builds a set of complete WebGIS system to raise the convenience of data providing and efficiency of system use. As a result, the related staffs can apply an internet browser to search, display, and save the rainfall map data. Furthermore, typhoon is another factor to influence the climate in Taiwan. Besides the strong wind damages the buildings, the instantaneous rainfall brought by typhoon also causes heavy rain. The unequal rainfall also results in floods and mudflows. Therefore, the bureau also builds the digital rainfall map data of land warning (2006-2008) for the staffs to search the historical typhoon rainfall data.
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| Challenges |
Since the system uses large quantities of data and complicated functions, how to integrate the key techniques, such as reading and changing the data in database, linking to the remote data, online data exchange, management functions, interface design, and analyze the current structure of database would be the key points to influence the performance of the system.
In addition, the system adopts SQL for attribute data search. However, users not only need to be familiar with the syntax but also need to know the data well. Therefore, in designing the search function, the developers should have the knowledge and capability of data analysis and also have enough experiences of data analysis so that the appropriate search functions can be provided.
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| Solutions |
Climate Rainfall Map System is a WebGIS system built up by map server. As to the structure of hardware, the system is built in a server. The data of accounts, rainfall map scheduling, etc are managed centrally in a database server. The structure is like the graph below.
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| The structure of the hardware |
In terms of the software, Climate Rainfall Map System adopts SuperWebGIS as the internet map server to provide mapping and GIS functions. Additionally, the database software uses Microsoft Windows SQL Server 2000, and the server software applies Windows Server 2003. As to the website development, the system utilizes ASP.Net, JavaScript, HTML, and CSS as the basic program languages.
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| Results |
Climate Rainfall Map System allows users to search, display, save the rainfall map data through the internet browser. Users do not need to download or install any system object and can link to the website to use. According to the function classification, the system can be divided in to the front-end for display and search and the back-end for management.
The front-end includes 4 main functions: Basic Map Manipulation, Rainfall Map Manipulation, Users Map Data, and Map Image Export.
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Basic Map Manipulation: |
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This system provides several map navigation tools for users to zoom the map to full-extent, zoom in/out, pan the map, etc. |
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Rainfall Map Manipulation: |
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Rainfall map scheduling is the main manipulation function in the system. The aim is to read the rainfall database in the bureau or the users’ rainfall data. Through the setting conditions and statistics, the system can draw the rainfall distribution map of a certain time and place within a specified period of time.
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| Users can draw the rainfall distribution map of a certain time and place through the setting conditions and statistics |
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| 3. |
Users Map Data: |
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To facilitate users to manage their own map data, the name of the folder will be changed according to the users' account. Moreover, each user has two folders; one is named "Finished Data" and the other "Unfinished Data." Since the rainfall map in the system is processed by scheduling, the system will automatically search the unfinished data regularly. If the data which has been assigned into the schedule has not been finished to map, the system will categorize the file to "Unfinished Data." On the other hand, the finished data are categorized to the "Finished Data." Users can gain the rainfall map results and basic information in each file. Additionally, each map file can be overlaid with other layers to be studied and analyze in the future. |
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Map Image Export: |
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The system supports to export the map file as the image of Lan file so that it will be easier for users to import the file and use the file in the stand-alone software. |
The back-end contains three parts, user management, schedule management, and background program management.
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User Management: |
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User management in the system includes "Add New Users" and "User List." To add a new user, users can apply by themselves or administrator can add a new user. Moreover, the "User List" mainly lists the information of the user, including username, name, priority, authority, number limit, etc. |
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Schedule Management:: |
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The Schedule Management contains "Rainfall Map Schedule Management" and "Rainfall Map Data List." "Rainfall Map Schedule Management" can facilitate administrators to view all of the users' processing status; the administrators can adjust the order of the schedule if the case needs. "Rainfall Map Data List" allows all of the users to view the rainfall schedule record and the thumbnails of the face results.
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Background Program Management: |
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The aim of the background program management is to set the map schedule. Through the management system, the administrator can know the second setting of the current schedule time and can modify the schedule second setting of the schedule time. |
Climate Rainfall Map System provides a cross-unit platform integrating geographic information data and system services. In addition to improving the convenience of data providing in the bureau, the cross-unit platform also raises the use of the rainfall data and enlarges the applicability. |
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