Data Management of Urban Water Supply Network Based on GIS

Bo Yan1, Xiaorong Su2, Yiyun Chen1 1 School of Economics and commerce, South China University of Technology, Guangzhou,

Guangdong, 510006, China 2 Hunan Waboo Technology Development Co.Ltd, Changsha, Hunan, 410015, China

yanbo@scut.edu.cn

Abstract After designing data organization including SuperMap

data organization and the content of data management and data layout, this paper probes into all aspects in the data management of the urban water supply network, such as 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, data refreshment and maintenance, and so on., then the system database in designed. Experience in Yiyang indicates that the development of the water supply network system in this paper has achieved expected effect.

1. Introduction

In recent years, with the fast development of the cities,

the water supply network becomes more and more vertically and horizontally interveined, and alters faster and faster, resulting in bigger and bigger network system, with more and more data to be processed, and more and more complexity for management. Therefore, the traditional management models of water supply network has become unsuitable for the modern urban water supply management, so it is very important to strengthen the data management of urban water supply network GIS [1]. Combing with the practice in Yiyang City, Hunan Province of China, this paper probes into the data management of urban water supply network GIS.

2. Systematic data organization design

We adopt SuperMap of Beijing SuperMap GIS

Technologies, Inc. as GIS platform software. Different from other GIS products, all spatial and non-spatial information are stored in the database for SuperMap, 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 sheet in general. Each record in the dataset indicates a certain spatial element, which can include non-spatial information either or not.

2.1. SuperMap Data Organization

The dataset becomes graphic layer when called and

displayed in the map window, so graphic layer is a kind of visual definition for dataset. Graphic layer can be regarded as 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 such as to be set as displayed or hidden, editable or fixed, and the sequence of the graphic layer can also be changed. The relation between the dataset and the graphic layer is shown in Figure 1.

Figure 1 Dataset and graphic layer

According to the difference in data structure, dataset

can be divided into three types: vector dataset, grid dataset and compound dataset.

Dataset like point, line, area, three-dimension and other dataset all belongs to vector dataset. Valve, fire hydrant, tee branch 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 point, line, area, text and other geometric objects such as pipelines.

2.2. The content of data management

Data Source of Network GIS Map Window

Fire Hydrant Dataset

Pipeline Dataset

City Terrain Dataset

Graphic Layer 1

Graphic Layer 2

Graphic Layer 3

2008 ISECS International Colloquium on Computing, Communication, Control, and Management

978-0-7695-3290-5/08 $25.00 © 2008 IEEE

DOI 10.1109/CCCM.2008.370

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2008 ISECS International Colloquium on Computing, Communication, Control, and Management

978-0-7695-3290-5/08 $25.00 © 2008 IEEE

DOI 10.1109/CCCM.2008.370

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2008 ISECS International Colloquium on Computing, Communication, Control, and Management

978-0-7695-3290-5/08 $25.00 © 2008 IEEE

DOI 10.1109/CCCM.2008.370

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According to demand analysis and specific situation 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-type data: one is basic spatial data shared by all internal departments of the water supply company, such as administrative map and geographical map; another is applied spatial data for all systematic application departments, such as network maps and planning drawings. Basic spatial data can be regarded as the core for position of the whole system, but it is necessary for the existing of business spatial data, which is tightly related with basic spatial data. It is business spatial data, but not basic spatial data to engage in 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 relationship from basic spatial data to business spatial data, and then 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. Non-spatial operation data can be divided into two types by the logic structure: structural data and non-structural data. The former refers to data with certain structure which can be divided into fixed basic elements, displayed in the tabular form, and represented with tables and views of relation 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 database management to maintain the facility and integrity of database management. Managerial maintenance data includes metadata, classified encodes data, various standards and so on [2].

2.3. 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.

2.4. Basic Data Collection 2.4.1. 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 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 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 [3]. 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 Figure 2. 2.4.2.The process to construct GIS basic information bank of water supply network

Figure 3 shows the process to construct 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 [4].

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Figure 2 The graphic organization of the city plane graph

Figure 3 The construction process of the basic geographic bank

2.4.3. Data conversion and entry into banks

For the network system, there is always problem for the existing systematic data to transfer 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, and network attribute data are 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.

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 unified 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. 2.4.4. Data Vectorization and Entry into Banks (1) The Principle of scanning vectorization of network map

Figure 4 is the flow chart of scanning vectorization. Paper map will be transferred into graphic files after scanned by the scanning instruments, and finally vector graphic 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.

Figure 4 The process of scanning vectorization

(2) The Principle of scanning vectorization of network

map Vector operations include vectorization of graphic

content, addition on graphic attributes and sheet lettering. According the requirements for GIS management, the graphic content can be divided into buildings, water system, 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

Scanning of Original Map BMP Picture Vector Software

Image Enhancement,

Correction and Joint

Data Editing

Data Check and

After Treatment

Vector Graphic Data

City Basic Information

Boundary Information

Network Graph Vectorization or data transfer

Input Attribute

Data

Input Plane Graph and Network Elements Information

Graphic Topological Structure Check

Input Network Graphic Data

Input Road and River Data

Output of Maps and Reports

Incorrect

Affirmation

Standard Framing

Information

Data Preparation

District 1 District 2 District 3 District 4 District 5

Buildings

Water System

Traffic

Zoning and Framing

Layering

Seamless Spatial Database

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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.

(3) Vectorization content of network map The vectorization content mainly includes:

vectorization of graphic content, addition of graphic attribute, and sheet lettering.

(4) Some key technology for quality control in 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]. 2.4.5. 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 history 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.

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. 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 [6]. 3. Design of System Database 3.1. Overall design of 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.

Data is the blood of the information system, also the base for the run of system applications. 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 5 shows the general structure of the system database.

System

Database

Customer Service Database

System Management Database

Business Database

Spatial Data Dictionary Database Spatial Database

Customer Data

Business Application Data

Circulation Transaction

Notification and Feedback

Complaint and Suggestion

Other Data

Organization and Staff

Journal Data

Authority Data

Dictionary Data

Collocation Data

Other Data

Installation Data

Maintenance Data

Payment Data

Charge and Fee Data

Business Circulation

Other Data

Category

Graphic Layer Catalogue

Attribute Catalogue

Field Catalogue

Style Data

Other Data

Background

Pipelines

Valve

Fire Hydrant

Pool

Monitoring Point

Other Data

Figure 5 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.

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. Design of the System Database 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

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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). 3.2.1. 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 special map, we can use special map operation tables and fields to describe the spatial data attribute table related with the graphic layer dataset [7].

The dictionary database class is shown in Figure 6.

Figure 6 UML class of spatial data dictionary database

3.2.2. Spatial database The spatial database includes two-type 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 network 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.

4. Conclusion

How to adopt advanced GIS technology to raise

utilization ratio of water resource and management level of urban water supply enterprises is brought forward. For supply water 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. 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.

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[3] Li Haijun, Layout of Underground Pipelines and City Subterranean, Underground Pipelines Management, Apr. (2000).

[4] Xu Jingyi, Investigation Report on the Status of Water Supply Technology, July (2000).

[5] Buckler, Michael, Scheurer, Wolfgang. Documentation for waterplants, network and branch connection in an integrated GIS-system, Water Supply. 18(4), (2000) 8-15.

[6] McKinney, Daene C., Cai, Ximing. Linking GIS and water resources management models: an object-oriented method, Environmental Modelling and Software. 17(5), (2002) 413-425.

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