Water Resour Manage (2009) 23:2633–2653 DOI 10.1007/s11269-009-9400-y
Functional Structure and Data Management of Urban Water Supply Network Based on GIS B. Yan · X. R. Su · Y. Y. Chen
Received: 4 February 2008 / Accepted: 14 January 2009 / Published online: 3 February 2009 © Springer Science + Business Media B.V. 2009
Abstract This paper presents an urban water supply network system based on GIS technology. The system will adopt three-tier/N-tier architecture as the application logic structure. Thy system can be divided into six subsystems: the analysis subsystem, the aided design subsystem, the installation and maintenance management subsystem and the customer service subsystem serve data management subsystem. The data management of the system will adopt SuperMap. We present the details of the data management, such as basic data collection, structure framework of the basic geographic information bank, the process to construct GIS basic information bank of water supply network, data conversion and input into banks, data vectorization and input into banks, etc. Then the system database is designed in detail. We adopt object oriented analysis and design methods, and utilize Class Diagram of UML to represent the entity tables and their relations against the core data of the network system, that is spatial dictionary database and spatial database. According to Class Diagram, it can be directly mapped as the database structure and an example is given. Finally, the successful application of the system in Yiyang city of China is beneficial for water supply enterprises to utilize the existing water resource in time, rationally and effectively. Keywords Water supply network · Geographic Information System (GIS) · Three-tier/N-tier architecture · Data management · SuperMap
B. Yan (B) · Y. Y. Chen School of Economics and Commerce, South China University of Technology, 510006 Guangzhou, China e-mail:
[email protected] X. R. Su Hunan Waboo Technology Development Co. Ltd., 410015 Changsha, China
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1 Introduction Fast development of cities results in higher demand of water and fast expansion of the water network system. The network becomes more complex, and more data have to be processed. The manual managerial modes and measures cannot provide safe water utilization and high quality service for water supply enterprises. The strain capacity and efficiency of emergency treatment have to be improved too. Since the water supply system is invisible under the ground, the management, maintenance and future construction of the underground pipeline is very difficult (Dawoud et al. 2005; Babiker et al. 2007). Based on GIS, we propose a set of comprehensive management and decision analysis system for water supply network in this paper. With this system, the capacity of manufacturing and management of the city water supply will be improved greatly. Combing with the practice in Yiyang City, Hunan Province of China, this paper probes into the functional structure and data management of the urban water supply network GIS. A good overview of GIS and database as well as their application within the field of natural systems hydrology is found in Singh and Fiorentino (1996). Hellweger and Maidment (1999) developed an integrated application for delineating drainage basins and determine surface runoff in natural watersheds using the HEC–HMS (Hydrologic Engineering Center–Hydrologic Modeling System). Application of GIS in urban stormwater systems has been more limited due to the need for large, expensive and detailed spatial and temporal databases. Feinberg and Uhrick (1997) discuss integrating an infrastructure database in Broward Country, FL with a GIS and water distribution and wastewater models. Shamsi (1998) distinguishes three forms of information exchange between ArcView GIS and the EPA Storm Water Management Model (SWMM): interchange, interface and integration, listed in order of complexity. Shamsi (2002) applies GIS to the field of water, wastewater and stormwater engineering design.
2 The Functional Structure of the Urban Water Supply Network Based on GIS 2.1 Functional Requirements of Water Supply Network Based on GIS GIS system on the enterprise level should not only complete data processing, but also include other related business and functional systems. The water supply network based on GIS should provide the following functions: 1. to manage all information, including information of the network such as pipelines and valves, and information of the urban terrain, streets, residential areas, divisions, meters and so on. So the attribute database and graphic database ofx the network can be combined organically. The network data and attribute data should be stored in the standard GIS graphics format for easy conversion of data among different GIS platforms. 2. be able to browse, zoon, roam, query by conditions, query by regions, random statistics and analysis, to view any layer, to open or shut down layer display, and with eagle eye, index chart and other functions.
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3. to support data input in different forms and formats like AutoCAD, GPS and manual input, network detection, edition, alteration, maintenance, completion drawings input and other operations. The network should have an optimized system structure and perfect database system, easy to upgrade and maintain for future development. 4. to provide shutting, opening and optional programs on related valves in case of explosion and leakage in the water supply network, and regional analysis on water failure. 5. to provide hydraulic calculation analysis, i.e. to calculate the pressure, flux, velocity, direction, head loss, etc. for each pipeline segment node through certain mathematical model with telemetry data received from SCADA system and other auxiliary data. 6. to provide comprehensive information inquiry for both the inside enterprise and the public. 7. aided design. 8. to provide online office service, like online application, reception, examination and approval, and result notification of water application, design, project construction, network maintenance, etc (Schlüter and Rüger 2007; Vairawanoorthy et al. 2007). 2.2 Application Logic Structure of Water Supply Network Based on GIS The three-tier/N-tier architecture is the best choice for the water supply management information system because of its excellent operating speed, security, portability and augmentability. Thus the application structure will adopt three-tier/N-tier architecture. In the system, the GUI-based desktop application provides service for the design department and engineering department, and the browser-based web application for the decision-making sector, other users’ information inquiry and search. In the desktop application, for the interface tier, the GUI graphic forms are designed with VB, and the browser page is designed with ASP.NET for WEB based application, both of which can communicate and exchange data through XML with business logic tier of the server. The business logic tier will adopt the web service programmed with VB. The unified interface will be adopted, so the reuse and maintainability of the software can be improved greatly. The application logic structure of the water supply network based on GIS is shown in Fig. 1. The information integrated tier is also the data tier to store and manage all information in the enterprise resource databases, business information bank, production information bank, management database, SCADA database, geographic Information database, etc. This tier is the data foundation for the information service and application. The logic application platform is the core application system, including the core business processing component, the middleware to ensure system business processing ability and load balancing applications, etc. which is also the core service of the entire system software application. The information service platform is the application access to the entire information system. Both customers and internal staff can have access to the service provided by the system through the unified information service port. The outside user can obtain service through the customer service system in the business hall or on the
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Website Service
Customer Service
Basic Management
Decision Support Analysis
Information Service Tier
Data Input
Graphical Operation
Database Management
Security Management
External Service
Logic Application Tier
Enterprise GIS
Enterprise Information Integrated Database
Information Integration Tier
Business System Database
SCADA Acquisition System Database
Basic Information Bank
Fig. 1 The logic structure of the system application
enterprise portal website, while the internal staff can also process required business with the system via various internal application systems or desktop applications (Perez et al. 2005; Dangendorf et al. 2002; Vairawanoorthy et al. 2007).
2.3 Functional Design of the System 2.3.1 Overall Design of the System Function According to the requirements of the network system, the whole system can be divided into the following six subsystems: system management subsystem, customer service subsystem, data management subsystem, installation and maintenance management subsystem, aided design subsystem, analysis subsystem. The system modules are shown in Fig. 2. The relationship of the subsystems is shown in Fig. 3, which illustrates the content of data exchange among the subsystems. Among the six subsystems, aided design subsystem, installation and maintenance management subsystem and customer service subsystem provide service for the data management subsystem, while the system management subsystem is the control centre of other subsystems.
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System Management Subsystem Customer Service Subsystem
The Pipeline Network Management GIS System
Data Management Subsystem Installation & Maintenance Management Subsystem
Aided Design Subsystem Analysis Subsystem
Fig. 2 The functional module of the pipeline network GIS system
2.3.2 The System Management Subsystem The system management subsystem is the control center of the whole system, which constructs the framework of the whole system, integrates all other subsystems, and undertakes the security management and maintenance for the system. Specifically, its main function includes user login security, authority management, common connection of data sources, called by other subsystems, data backup and recovery, network security log management, etc. Its functional structure is shown in Fig. 4. All users login from the unified interface (Browser/GUI), and get access into the system functional main interface after security certification (role and password). Users choose functional buttons according to their purposes and tasks (the system will shield or turn on some functional buttons depending on different authorities), call other subsystems and share public components such as data source connection component at the same time, which makes the entire system a seamless organic whole.
Customer service
Network analysis
Business flow data
Basic network data Business flow data Analytical data
Basic data management Basic data management
Aided design
Installation and repair data
Business flow data Control
Control
Control Control Installation and maintenance
System management Fig. 3 The relationship of the subsystems
Control
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User login interface
Main functional interface
Data backup and recovery program
Data dictionary & metadata dictionary component
Network log management
Data source management component
Choose functional buttons to call other interfaces
User authority management component
Database
Fig. 4 The functional structure of the system management
2.3.3 The Customer Service Subsystem The customer service subsystem has two modules: business hall and online. All operations like installation, maintenance and breakdown report can be executed through this subsystem. Relevant sectors in the water enterprises can also get information on pipeline segment, node and appendage, operation status of the network etc. online. The website service adopts three-tier architecture based on.NET. The client is a browser. When visiting the ASP.NET website, the HTTP request will be sent to the web server, which will be dealt with by the ASP in the web tier and C# in the business tier, and data will be exchanged with the database through the ADODB interface. XML pages can be converted into HTML pages, which can be displayed in the Internet Explorer by combining the support of XML and CSS or XSL, and displayed in the client ends after interpreted by browser. 2.3.4 The Data Management Subsystem The data management subsystem has several functional modules, including network foundational data maintenance, query and statistics and interface data management. The functional modules of data management subsystem are shown in Fig. 5. 1. The maintenance of network foundational data The main function of this module is to convert various file information of the network into GIS data. Background data management, network data management and attribute data management are all completed through this module. The background data management refers to the input, output of terrain data and data format
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Network data management subsystem
Network Foundational Data Maintenance
Interface Data Management
Query & Statistics
Marketing Interface
SCADA
Map Output
Regional Query
Combination Query
Classification Query
Statistics
Graphics & Text Query
Attribute Data
Network Data
Background Data
Fig. 5 The functional modules of the data management subsystem
conversion; the network data management refers to manage the input, edit and deletion of the network data such as file information, external detection information, pipelines, valves and fire hydrants information, to verify the rules of the network data, and to eliminate obvious errors through error check and special topic check; the attribute data management allows the input of non-spatial operation attribute data either in batches or in single mode by clicking the map element needed. 2. Query and statistics This module mainly completes the function of GIS data query and statistics. Query and statistics is the output of the system. The combination query on all data whatever obtained by all means or input manually. Statistics, and report forms are all shown in this module. The function of this module includes: graphic-attribute mutual query, classification query, self-defined combination query, regional query related to operation system and statistic report form output. The details are shown as follows: (a) Graphic-attribute mutual query, mainly for information on the network and the appendage. This kind of query can be divided into three types: x query graphics from graphics, to find other relevant graphic information through some part of the map. The typical example is to search the small scale maps (the detailed maps) on the large scale maps (the sketches), for which, a corresponding relationship between detailed maps and sketches should be determined firstly. y query graphics from attributes, referring to query based on attributes and display the related graphic elements. The system has two applications in this field: one is to locate the graphic elements according to the attribute data. For example, when we need to find the valve with the condition of “value No. = F0123”, i.e. to display the valve’s location in the map. Another one is to locate the geographic position by the street. z query attributes from graphics, which is to display relevant attribute information by specifying some elements.
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The query function allows graphic-attribute mutual query on information about the pipeline network and related auxiliary equipments of the water enterprises. Information on valves, fire hydrants, nodes, pressure-measuring points, flow-measuring points, and pipeline segment can be queried on different conditions, such as query against radius scope, rectangle scope, polygon scope, point-line-face, random expression or ambiguous conditions. (b) Network statistics, referring to statistic total number of graphic elements, summation, maximum, minimum, average of the field or classification, and the number of statistical graphic elements or tables according to some filed of selected file attribute (or table) or classification number appointed by the user and the scopes of each classification. The result can be presented in histogram or pie chart and saved or printed finally. (c) Classification query, to carry out instant query varying from different classification and emphasis in different layers. (d) Combination query, to carry out combination query based on customer attribute item on self-defined conditions. (e) Regional query, to query relevant information in designated geographic region scope, such as statistics and details of the equipment distribution, water use information statistics. (f) Output of the graphics and attributes, including output of the maps, spatial and attribute data of the network and related tables and cards. The system can perform page editorial processing, typesetting, and graphic grooming for various output data, and output to all kinds of devices (various printers, mapping devices, CD burners, etc.). Though query and statistics, the system provides several convenient and shortcut operational functions aimed at motion and zoom of graphics, such as graphics zooming, graphics roaming, full extent of graphics, graphics refreshment, layer control, proportional display, and Eagle Eye operation. 3. The interface data management The function of interface with sectors and units within the enterprise is very important for the efficient share and utilization of information. It mainly refers to interfaces with the SCADA remote data collection system and the marketing management system. The interface with the marketing system is to read the water meter information in the marketing system, and relate it with the water meter thematic maps, so as to meet the need of the customers for query attributes from graphics; the interface with the SCADA remote data collection system is to receive current status data of the network sent by monitoring terminals and display on the screen with GIS maps for the user in the control room to know the actual status of the network in real time (Dangendorf et al. 2002; Cech and Montera 2000). 2.3.5 The Installation and Maintenance Management Subsystem The installation and maintenance management subsystem consists of two function modules: installation management and maintenance management. 1. The network installation management module
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The function of this module includes: (a) Capacity enlargement program making, to make capacity enlargement program according to the installation plan, line chart and capacity enlargement application. (b) Payment management, which is the basis of the network installation, to manage the payment of capacity enlargement applications of users, including payment information input and query, etc. (c) Construction progress management, to make installation plan based on the network installation plan and capacity enlargement program, and output project status information and installation completion data. 2. The network maintenance management module The function of this module is to manage the network maintenance information, including equipment and facility assets management, and equipment maintenance management. The equipment and facility assets management refers to manage the equipment, facilities assets of the network, to perform statistic, query, classification and summary of equipments and facilities on certain conditions, and to display the results in charts for analysis and statistics. The equipment maintenance management refers to manage the equipment installation information, and its function includes: Task registration and dispatch management: task registration refers to the registration, input, edit and query of the repair work, and dispatch management refers to input, edit and query of the dispatching work. Leak detection management: to complete the plan-making, approval of detection, and registration, modification and query of the results. Patrol road management: to complete the plan-making, approval of patrol road work, and registration, modification and query of the results. Planned repair management: to complete the plan-making, approval of repair work, and registration, modification and query of the results. Repair results: to record and manage information on different valves with workers sent and repair results of pipeline segment (staff labour, materials, quality control, compensation, etc.). Basic information input: to manage the input of information on the enterprises, staff and valve maintenance related to the repair work. 2.3.6 The Aided Design Subsystem The function of the network aided design subsystem includes: 1. Data input, to input the permission bill of design, the network geographic information, the network technological standards and norms, the capacity enlargement application, the line chart and other information. 2. Pipeline pavement. The system allows connections among each node and the network appendages, with different thickness for pipelines, and different color for the materials of pipelines; in addition, the system can support real-time length calculation and display throughout the process to provide reference for the design.
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3. Set nodes and the network appendage. The system provides various graphic symbols in common use according to the characteristics of the water industry for valves, nodes, meters, etc. and the selected symbol will be added to the corresponding position on the map with clicking the mouse. 4. Additional attribute data, to connect the designed nodes with the attribute database. 5. Optimizing design scheme and making drafts. 6. Construction design generation, to generate and print the construction design chart. 7. Budget estimation management and program comparison. A budget estimation report will be generated automatically according to the appendage, pipeline length and material, price of equipments and pipelines, construction man-hour, construction quantity of earth and stone, etc., and sent back to the users. After paid by the users, installation will begin. 2.3.7 The Analysis Subsystem This subsystem is the core of the system. With the purpose of “scientific management, quick query and analysis, and aided decision”, analysis and decision must be efficient. All basic data are obtained, treated and served for analysis and decision. The network analysis includes measurement and calculation of random distance or area, collision analysis, valves shutting analysis, water cutting-off analysis, hydraulic adjustment calculation, etc. 1. Measurement and calculation, to measure and calculate the distance of the appointed one or more lines and area of randomly-appointed region, to measure and calculate the pin length, angles, perimeter and area on the map, and to display the graphic scope of full map, a graphic layer, or the window. 2. Collision analysis, to ensure the shortest distance between two spatial objects in the network. 3. Hydraulic adjustment calculation, to establish a certain data model based on the network optimization and figure out flow pressure of nodes, etc., to provide reliable basis for water dispatch and the design of the network. 4. Pipeline explosion and water cutting-off analysis, to find the best valve shutting program and determine the water cutting-off area according to the network information based on certain strategy when water leak occurs due to pipeline segment or node accident (Kesavan 1972; Kalivas et al. 2003).
3 The Data Management of the Urban Water Supply Network Based on GIS 3.1 The Data Organization Design of the System 3.1.1 The SuperMap Data Organization This paper adopts SuperMap of Beijing SuperMap GIS Technologies, Inc. as the GIS platform software. Different from other GIS products, all spatial and non-spatial information are stored in the database, and can be called by SDX, a spatial database search engine. Dataset is the basic unit of spatial data, and one dataset for one map
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sheet in general. Each record in the dataset indicates a certain spatial element, which can include non-spatial information either or not. The dataset becomes a graphic layer when called and displayed in the map window, so the graphic layer is a kind of visual definition for dataset. The graphic layer can be regarded as a transparent film in the map window, while the map is formed by a set of superposed films. There is one graphic layer for one dataset in general. The status and style of the graphic layer can be controlled via certain programs, e.g., to be set as displayed or hidden, editable or fixed, and the sequence of the graphic layers can also be changed. The relation between the dataset and the graphic layer is shown in Fig. 6. According to the difference in data structure, dataset can be divided into three types: vector dataset, grid dataset and compound dataset. Dataset like points, lines, areas, three-dimension and other dataset all belongs to vector dataset. Valves, fire hydrants, tee branches and other network GIS data, processed by the network system, are all designed as vector dataset. Grid dataset is used to store lattice or image data. The city geographical map in the network GIS is presented with grid dataset, and always used by loaded to the map window as background reference of network vector data. Compound dataset can be composed by different objects, used to store points, lines, areas, text and other geometric objects such as pipelines. 3.1.2 The Content of Data Management According to the demand analysis and conditions of the system, the final data in the system should include three types: spatial data, non-spatial operation attribute data and managerial maintenance data. 1. Spatial data. Spatial data is data with public geographic position base. For this system, there are two types of data: one is basic spatial data shared by all internal departments inside the water supply company, such as the administrative map and geographical map; another is applied spatial data for all systematic application departments, such as the network maps and planning drawings. Basic spatial data can be regarded as the core for position of the whole system, but the existing of business spatial data is necessary, which is tightly related with basic spatial data. It is business spatial data, but not basic spatial data to be utilized in
Data Source of Network GIS
Map Window Fire Hydrant
Graphic Layer 1
Pipeline Dataset
Graphic Layer 2
City Terrain Dataset
Graphic Layer 3
Fig. 6 Dataset and graphic layer
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the direct application. At this time, business spatial data has become the core for application analysis. Thus there is a kind of layer-by-layer support relation from basic spatial data to business spatial data, then to operation application analysis within the system, while any layer cannot be ignored. 2. Non-spatial operation data. Non-spatial operation data is attribute data in the nature, including tabular data, documentary data and multimedia data. Nonspatial operation data can be divided into two types according to the logic structure: structural data and non-structural data. The former refers to data with certain structure, and can be divided into fixed basic elements, displayed in the tabular form, and expressed in tables and views of relational database, such as various application and examination and approval tables; the latter refers to those data without obvious structure that cannot be divided into fixed basic elements, such as application information, various documents, laws and regulations, and other documentary and multimedia data. 3. Managerial maintenance data. Managerial maintenance data is generated mainly for the stability and maintainability of the database. In this system, all content related with data management will adopt the database management means to maintain the facility and integrity of database management. Managerial maintenance data includes metadata, classified encode data, various standards and so on. The metadata is the data about data, i.e. explanation, definition and description of the existing data, such as illustration of database tabular structure and field name, and stratified manner of spatial data. It is the metadata to provide an obvious structure for database management and maintenance among huge data storage. The metadata is not original data, just abstracted from the existing data. With the same importance as the metadata, classified encode data is also secondary-processed data, with function to provide organization for various data with fixed value (Wu et al. 2008; Patil et al. 2008). 3.1.3 The Data Layout According the above analysis, data in this system can be divided into two types: spatial data like network objects, network objects editorially-input data, geographical map data, etc., and relation data, including network objects’ attribute, equipment and facilities, project management dictionary, system dictionary, and so on. The spatial data is managed by application program with SuperMap SDX, while non-spatial operational data and managerial data are managed by relational database. Hereinto, non-spatial operational data plays a role to explain and describe spatial data, and we can describe their relations in the manner of key word ID correlation. 3.1.4 The Collection of Basic Data 1. The structure framework of basic geographic information bank The basic geographic information bank contains two graphic banks respectively for city plane graph and water supply network elements. The graphic bank of the city plane graph is constructed according to the block and layer concept of SuperMap. Horizontally, the city plane graph can be divided according to logical administrative area, for example, to divide the city into N districts, with framing manner of management. Vertically, the city surveying and
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mapping information can be divided according to element factors, so that there will be a certain element factor for each layer, and be managed in a stratified manner. According to the characteristics of SuperMap spatial data organization, and combing with the graphic formula of the geographical map, the graphic data can be divided into eight layers: buildings, water system, traffic, boundary, control point, boundary address point, independent ground objects, public facilities and green area. The construction of water supply network elements graphic bank mainly includes network characteristic points and pipelines. The network characteristic points can be divided into valve, air or pollution evacuation valve, fire hydrant, water tower, pumping station, knick or tapered point, water meter point, tee branch, and double tee, each of which has its own attribute expression. The structure framework of the basic spatial information bank is shown in Fig. 7. 2. The process to construct GIS basic information bank of the water supply network Figure 8 shows the process to construct the network basic bank. The city basic information, administrative boundary information and standard framing information will be input into the bank as background geographical information; after topologic treatment and check on topological structure, network vector map will be input into the bank as final network data; the existing attribute data in the basic maps will be transferred into the data base with geographical data, while those attribute data that need to be added or modified can be input and modified manually after the input of network data. 3. Data conversion and entry into banks For the network system, there is always problem for the existing systematic data to be transferred into a new system. In the computer graphic management system of some water supply enterprises, the graphic data are stored in DWG format of AutoCAD, while network attribute data is managed with Access database. With the development of the enterprise, it is in urgent need to transfer graphic data and attribute data to a unified relational database for centralized management.
Seamless Spatial Database Zoning and Framing District 1
District 2
District 3
District 4
District 5
Buildings Water System Traffic
Fig. 7 The graphic organization of the city plane graph
Layering
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Data Preparation
City Basic Information
Boundary Information
Standard Framing Information
Network Graph Vectorization or data transfer
Input Attribute Data
Input Plane Graph and Network Elements Information Incorrect Graphic Topological Structure Check Affirmation
Input Network Graphic Data Input Road and River Data Output of Maps and Reports Fig. 8 The construction process of the basic geographic bank
The purpose of data conversion is to transfer data from Access database to spatial database in order to obtain more powerful functions. Data after conversion are uniform with database layout requirements, and graphic data will be stored separately as point, line and poly. In the conversion process of attribute data related with space, ADO will be adopted as the data interface. ADO applications call on data in the database through OLEDB provider. When transferring attribute data related with spatial information, attribute relational empty tables, street tables, valve tables, water meter data tables, fire hydrant tables with the same structure as Access will be established in the SQL server database, and then two links with Connection objects: one to link with Access database, and another to link with SQL server. Therefore, when Access data are called on, data will be written into SQL server at the same time, that is, to write a field in another database when calling on a field until the Recordset directing to empty. 4. Data Vectorization and input into Banks (a) The process of scanning vectorization Figure 9 shows the process of scanning vectorization. Paper map will be transferred into graphic files after scanned, and finally into graphic vector data that can be processed by the GIS platform after treatment by vector software and a series of operations like correction, joint and so on. (b) The Principle of scanning vectorization of network map Vectorization operations include vectorization of graphic content, addition on graphic attributes and sheet lettering. According the requirements of the GIS management, the graphic content can be divided into buildings, water system,
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Vector Software
Image Enhancement, Correction and Joint
Vector Graphic Data
Data Check and After Treatment
Data Editing
Fig. 9 The process of scanning vectorization
traffic, boundary, control point, boundary address point, independent ground objects, public facilities, green area and so on. The general principle for vectorization operation is to keep the accuracy, precision and integrity of the original map, that is to select accurate codes for ground objects, to encode by superposition for multi-attribute lines, to capture the point position exactly, and to apply those tools in software skillfully that can improve data precision. The data collection should be laminated in categories to protect the integrity of ground object information, and to reach the basic standards of GIS for data collection. (c) Vectorization content of network map The vectorization content mainly includes: vectorization of graphic content, addition of graphic attribute, and sheet lettering. (d) Some key technology for quality control in the network map vectorization In order to keep the integrity, precision and accuracy of vector graph of the network map, it is necessary to pay attention on the following technical problems: rectangularity of buildings, treatment on suspension points, treatment on superfluous points and lines, closure of polygons, enclosing walls, benches and some other ground objects. The sign orientation after vectorization is relevant with the vectorization direction, and the sequence of points should be noticed in data collection. 5. Data refreshment and maintenance Some certain methods like field surveying and mapping and data transfer-in are adopted in the data refreshment and maintenance for the data refreshment and backup of historical data. After the completion of this system, the future daily basic surveying and mapping will be conducted in a fully numeralized way, so how the data is collected, and what equipments will be used in the basic surveying and mapping are also very important. (a) Basic survey data collection. The way for basic survey data collection includes electronic flat plate, all-stand devices with memory, all-stand devices with no memory, electronic handbook, field map, and so on. There are two manners for field data collection: brevity code and rough draft. The brevity code model can be adopted when the ground objects are normalized: firstly, to custom made brevity code for field operations based on certain encoding rules; when making the field exploration survey, to input brevity codes for the ground object point in the electronic note or all-stand device at the time of ground
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object measuring; coordinates data files with brevity code formula can be changed to internal code that can be identified by the computer through identification of brevity codes; then the plane graph can be automatically drawn by the program, and after attribute input, graphic edit and modification, text lettering and other editorial work on the basis of the initial drawings, all drawing work in the brevity code manner will be finished. The rough draft model can be adopted when the ground objects are not normalized, to make drawings based on the point number or its coordinates according the rough draft. The relevant attribute of the network can be input during the drawing process or after the finish of the maps. (b) Other manners. There are also some other ways for the data refreshment, such as lead-in of new data, so the system should support multi data format like usual electronic flat plate and point coordinates data formats in the data interface (Kimmance et al. 1999; Venkata et al. 2008). 3.2 Design of the System Database 3.2.1 Overall Design of the Database The network system has many data sources and business data types, such as customer service data, dictionary data, geographical data, attribute data, business data and so on. The characteristics of data are also different, including both spatial data (vector, grid or image) on network geographical resources and non-spatial data (data statistics, data input, and so on), so there must be some certain principles and unified standards for the scientific storage. 1. Principles for the database design According to the characteristics, types and usage of data, relevant national and industrial standard, and considering the correlation among spatial data, or spatial data and non-spatial data, we set the following principles for the database design based on general relational database framework: (a) The primary principle for the database design is to improve performance and expandability of the database system based on relevant technical specifications of database. (b) To design the database with object oriented technology, define entity (or class), non-entity (or class) and correlated classes, and follow the three standard frameworks for database design. UML language, specifically represented by Class Diagram is used for model building. (c) Spatial objects are constructed mainly with spatial attribute class of SDEDatabase, following simple spatial characteristic standard based on SQL of Open GIS. The rules, domains, and correlation class of SDEDatabase are maintained with programming by the developer, so the system can be developed with more flexibility and better expandability. (d) Through constructing time varied relational tables among the important entities, to solve the storage problem of historical data of important entities. The design of spatial database must be normalized to reduce data redundancy and keep the consistency of data.
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(e) To handle the design problem of centralized and distributed database well, and to improve the calling efficiency of the long range system with some basic or public data in distributed database. (f) To establish normalized and detailed metadata and data dictionary. 2. The general structure of the system database Data is the blood of the information system, also the basis for the run of system applications. Based on the above principles, the system database can be divided into system management database, customer service database, business database, spatial data dictionary database, spatial database and so on according to the sources, characteristics of data and business. Figure 10 shows the general structure of the system database. The system management database provides frame data for the service of the whole system: staff data for the setting of the enterprise institutional system and staff; journal data for the record and assessment of the system usage status of users, authority data for users to operate all functional modules of the system under certain authority control, dictionary data for unification of codes for common fields in the system, and collocation data for management of the database link, interface and other individual operations. The customer service database serves for the customer service subsystem, including customer data, business application data, business circulation data, notification and feedback data, complaint and suggestion data and other types of data. Each data category includes several data tables. For example, customer data includes customer basic data table, customer variation data table, and business circulation data includes business nodes data table, business circulation data table, and so on.
System Database Customer Service Database
System Management Database
Business Database
Spatial Data Dictionary Database
Spatial Database
Customer Data
Organization and Staff
Installation Data
Category
Background
Business Application Data
Journal Data
Maintenance Data
Graphic Layer Catalogue
Pipelines
Circulation Transaction
Authority Data
Payment Data
Attribute Catalogue
Valve
Notification and Feedback
Dictionary Data
Charge and Fee Data
Field Catalogue
Fire Hydrant
Complaint and Suggestion
Collocation Data
Business Circulation
Style Data
Pool
Other Data
Other Data
Other Data
Other Data
Monitoring Point Other Data
Fig. 10 The general structure of the system database
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Business database covers installation, maintenance, and aided design data, runs in a flow manner, and includes business node data and real-time operation flow data with the core of business flow data. Spatial data dictionary database and spatial database are the core database of the network system: the latter is the real physical representation of space geography and attribute database, while the former is dictionary database to describe the relation of spatial physical databases, all of which are the basis for data management of the network system and network analysis. 3.2.2 Design of the System Database in Detail During the process of detailed design of the system database, it is necessary to analyze the special requirements and limitations of the selected DBMS sufficiently, and make necessary adjustment according to the reality of enterprise management to guarantee the reliability, security, high-efficiency and convenience of the database. Moreover, we should consider whether all key fields requested for process and treatment are included in the data logic structure or not, and the relationship among data units, and analyze the usage frequency of every data unit to determine its position in the logic structure. With regard to relational logic data model, the objective phenomenon is reflected by relations. In this paper, we adopt object oriented analysis and design methods, and utilize Class Diagram of UML to represent the entity tables and their relations against the core data of the network system, that is spatial dictionary database and spatial database. According to Class Diagram, it can be directly mapped as the database structure (data tables and their correlation). 1. The spatial dictionary database Spatial data are represented as data tables in the database. These tables are operated by SDX, the search engine of spatial database in SuperMap through application programs, which cannot operate on the spatial data tables directly. This application manner is determined by the self-maintainability of the platforms based on spatial data, but it can also result in much more difficulty for the application programs to demonstrate the relations of spatial data tables, which can be solved through designing spatial data dictionary database to describe the relations among spatial data tables. The basic principle is to set class diagram table for classification and class management on graphic layers according to the reality of the map graphic layer; then design spatial dataset dictionary table according to different map classes to describe every graphic layer dataset within the system; with regard to background graphic layer, design map sheet for detailed explanation; while for the special map, we can use special map operation tables and fields to describe the spatial data attribute table related with the graphic layer dataset. The dictionary database class is shown in Fig. 11. Hereinto: Map class table describes the basic type of the graphic layer, always can be divided into background maps and special maps, while the latter can be divided into pipelines, valves, nodal points, air evacuation valves, mud valves, fire hydrants, water meters, water meter wells, users, water source, pools, other pipeline points, manometric points and so on according to demand.
Functional Structure and Data Management of Urban Water Supply. . .
1
Map Class
File Class
ID
ID
Name Father Class
n
1
Graphic Layer Dataset Class DSID Map Class ID File Class ID Chinese Name Father Class Name of Original Map
1
n 1 0…n
Map sheet Class DSID
0…n
Map Number Map Sheet Name
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Name …
Special Map Business Class DSID Business table Name Chinese Name Table Type
n
Special Map Field Class DSID Sequential Number Field Name Type Length …
Fig. 11 The UML class of spatial data dictionary database
File class describes the format attribute of the graphic layer, while the attribute of points, lines and network are different. Graphic dataset dictionary table describes all spatial dataset in the network system, and DSID field denotes the ID number of dataset, correspondent with physical table name of spatial database. Map sheet table is detailed description of the background map, recording related surveying and version information of the map sheet, and is the basic information table for drawings print. Special map business table and field table describe the correlation between spatial database managed by SDX and spatial business data managed by ADODB, and the relations of which can be conveniently managed by these two related tables. 2. The spatial database The spatial database includes two types of data tables: geographic type and special map business type. The geographic data table describes the geographical characteristics of the network elements, and is constructed and managed by SDX of SuperMap. The special map business table is business data to describe related network elements in the correspondent geographic type data table, and is constructed and managed by application programs, while the correspondence between them can be defined by spatial data dictionary database. For example, as for valves, one type of the network
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Valve Business Class
Valve Class SMID
1
0…1
Coordinates Geographic image …
ID Burying Depth Materials Well Type …
Pipeline Class
Pipeline Business Class
SMID
1
0…1
Coordinates Geographic image …
ID Caliber Materials Burying Depth …
Fire Hydrant Class
Fire Hydrant Business Class 1
SMID Coordinates Geographic image …
0…1
ID Materials Burying Depth …
elements, the geographic coordinates, map image and other information will be recorded in the geographic table, while the burying depth, materials, well depths, manufacturers, construction institutions and other information will be recorded in the business table. Some class diagrams of the network element spatial data table are shown in Fig. 12.
4 Conclusions This paper presents an urban water supply network based on GIS technology. The whole system is divided into six subsystems: the analysis subsystem, the aided design subsystem, the installation and maintenance management subsystem, the customer service subsystem, and the data management subsystem. SuperMap is adopted for the data management of the system. We present the basic data collection, the structure framework of basic geographic information bank, the process to construct GIS basic information bank of water supply network, data conversion and entry into banks, data vectorization and entry into banks, and other details of the data management. We analyze the functional structure and data management of the urban water supply network based on GIS. The urban network MIS stated above has been
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implemented in some cities of China, while the test run of Yiyang water supply network system indicates that the development has achieved scheduled target and established a solid basis for subsequent development and further research. For the water supply enterprises to utilize the existing water resource in time, rationally and effectively, for accelerating the urban construction and economy development, it had general practical significance.
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