SPATIAL ANALYSIS OF POPULATION DATA BASED ON GEOGRAPHIC INFORMATION SYSTEM Liu, D. Chinese Academy of Surveying and Mapping, 16 Beitaiping Road, Beijing 100039, China. E-mail: liudq@casm.ac.cn ABSTRACT Population is an important information source about the situation of a country, especially for a country like China with about one-fourth-world population. It has paid an important part in the fields such as administrative management, population research, market analysis, etc. With the development of Geographic Information System (GIS), the spatial analysis about population becomes a more and more useful tool of population data mining. By the integration of spatial data from National Fundamental Geographic Information System and population data from the 2000 Population Census of China, the Population Geographic Information System is established. The paper will focus the spatial analysis in tow aspects, macro analysis in a country level and micro analysis in a city level. Population distribution has a spatial characteristic. Traditional method of population analysis is lack of abilities to combine the quantity and quality methods, data and graphic methods. By use of the powerful functions of display and analysis in Geographic Information System, the spatial characteristics of population data are exhibited in macro point of view in country level. The paper introduces the methods such as 3-D model display, Laurence curve creation, movement of population center of gravity in different periods and population potential analysis. In the micro point of view analysis in city level, an example of location distribution of retailing system is emphasized, the paper introduce the main factors for retailing system location, consistency of population distribution and location of retailing unit, affecting area of retailing unit analysis. The model to locating the retailing unit is proposed. Geographic Information System can pay an important role in the government and business decision-making process by the integration of spatial and population data. Based on the population data from 2000 Population Census in China, the Population Geographic Information Systems at national and city level are established. The methods to manage and analyze the population data in E-Government are presented. In nationwide approach, the characteristic of spatial distribution of population in China is analyzed, by the methods of 3-D model display, Laurence curve creation, movement of population center of gravity in different periods and population potential. The paper then discusses the application in the field of location distribution of retailing system in city level. consistency of population distribution and location of retailing unit and affecting area of retailing unit are analyzed, and the model to locating the retailing unit is proposed. Keywords: Population GIS, Population distribution, Population potential, Population center of gravity, Retailing System, Location distribution 1. INTRODUCTION Population Census is a basic way to obtain information on the status of the population. China conducted 4 population censuses during 1953-1990, and the results of the censuses played important role in the country s decision-making at macro level. The 2000 population census, as a key survey of the national conditions and strength conducted at the turn of the century, is of great significance. Rich information is available on the size of Chinese population, its sex and age composition, industrial and occupational distribution, composition of population with various education attainment, employment and unemployment, migration, marriage and fertility, urbanization process, living environment, etc. [1] With the development of Geographic Information System (GIS), the spatial analysis about population becomes a more and more useful tool of population data mining. By the integration of spatial data from National Fundamental Geographic Information System and population data from the 2000 Population Census of China, the Population Geographic Information System is established. Proceedings of the 21 st International Cartographic Conference (ICC) Durban, South Africa, 10 16 August 2003 Cartographic Renaissance Hosted by The International Cartographic Association (ICA) ISBN: 0-958-46093-0 Produced by: Document Transformation Technologies
The main functions of Geographic Information System in the population census can be summarized as follows:! Assistance of population enumeration. GIS can output the enumeration map of each enumerator to ensure no overlap and omission of enumeration geographic area.! Spatial basis for the integration of population data and geographic data.! Management assistance of population data. GIS can provide the tools to query, analyze, create thematic maps, charts and tables.! Establishment of analysis model for the help of decision-making in the government. The paper will focus the spatial analysis in tow aspects, macro analysis in a country level and micro analysis in a city level. 2. MACRO-LEVEL ANALYSIS OF POPULATION DATA Population distribution has a spatial characteristic. Traditional method of population analysis is lack of abilities to combine the quantity and quality, data and graphic methods [2]. By use of the powerful functions of display and analysis in Geographic Information System, the spatial characteristics of population data are exhibited in macro point of view in country level. The hidden geographic population information and internal relationship of population spatial distribution are revealed. The paper introduces the methods such as 3-D model display, Laurence curve creation, movement of population center of gravity in different periods and population potential analysis. 2.1 3-D Display of Population Data Digital Elevation Model is a digital representation of three dimensional terrain with the combination of spatial coordinates and its elevation as a attribute. The population density 3-D model of China is established using the same method as Digital Elevation Model with the substitution of elevation value as population density. Figure 1 shows 3-D model of population density of China in county level (No data in Taiwan province). The figure shows the spatial distribution of Chinese population and clearly reflects the difference between east and west part of china. The red line represents the AiHui-TengChong Line, which is brought forward by population geographer Prof. Hu Huanyong in 1933 [3], still clearly depicted with the east part having dense population and west part having sparse population. Figure 1. 3-D Model of Population Density. 2.2 Laurence Curve Laurence curve is a accumulated frequency curve. It has been used to measure the difference of fortune distribution in economics. In Laurence curve, the difference between the curve and the diagonal is the measurement of difference of two variable distributions. Superposition of the curve and diagonal means the even distribution of two variables. It can be used to analyze the pattern of population distribution. Figure 2 shows the Laurence curve between population and area. From the figure, we can see the population distribution of China is quite uneven with about 90% of population account for 50% of land.
Figure 2. Laurence Curve Between Population and Area. 2.3 Population Gravity Center The position of population gravity center is depended on the status of population distribution. If the population is distributed evenly, the position of population gravity center is in the gravity center of region s geometry. Shift from the gravity center of geometry will occur when the population is distributed unevenly. The meaning of calculating population gravity center is that changes and speed of changes can be shown from the track of movement of population gravity center in a period of time. Figure 3 shows the changes of population gravity center from 1953 to 2000 and Table 1 shows the speed of changes. Figure 3. Changes of Population Gravity Center from 1953 to 2000. Table 1. Speed of Changes of Population Gravity Center from 1953 to 2000. Period Speed (Km / year) 1953 1964 12.5 1964 1982 1.4 1982 1990 6.1 1990 2000 1.2
2.4 Population Potential Potential is also a concept of physics. There is potential between two objects. The closer the distance between the objects, the greater the potential. Population potential is affected by the status of population distribution. If the population is distributed evenly, the potential of every point in the region is the same whereas the region with greater population density will has greater population potential. Figure 4 shows the population potential contour of China (no data in Taiwan Province) and the status of population distribution is clearly depicted. Figure 4. Population Potential Contour. 3. MICRO-LEVEL ANALYSIS OF POPULATION DATA Population Geographic Information System can be used in many fields in micro-level analysis such as in city level application. We will take an example of location distribution of retailing system as analysis in the micro point of view in city level. 3.1 Main Factors for Retailing System Location The factors of location selection depend on quality of main body to be located [4]. The development of retailing unit is affected by producer and consumer. But in the city region, the dominant element is closely related to consumer. The factors for Retailing System Location is mainly represented as consumer oriented. The factors included market, transportation and competition environment. The market factor is composed of population scale and income. The scale of population directly determines the scale of market. The transportation factor is consist of spatial distance and transportation condition. Generally speaking, the shopping persons to certain retailing unit will decrease as distance from the person s house to retailing unit increases. The factor of competition environment is mainly related to the scale of retailing unit of the same kind and the distance between them. 3.2 Consistency of Population Distribution and Location of Retailing UnitT The following formula is used to calculate the index of consistency [5]. where X is the index of consistency, X i is the population of neighborhood, Y i is the number of retailing unit in the corresponding neighborhood, X,Y is total population and total retailing unit respectively. Figure 5 is the result of consistency analysis of population distribution and location of retailing unit in Tianjin city. The result shows the index of consistency is 80.53, which means that the pattern of retailing unit and population distribution in Tianjin city is highly consistent, but some space for new retailing units still remain.
Figure 5. Index of Consistency of Retailing Unit and Population. 3.3 the model to locating the retailing unit Locating a new retailing unit in a city is one of most important application of Geographic Information System. Based on the conditions in Tianjin city, 3 factors of location, which are market condition, transportation and competition environment, are considered. The basic criteria of location for a new retailing unit are:! market condition: affecting population larger than 5000 persons in 1200 meters radius;! transportation: less than 1500 meters to the main bus stop linked to the retailing unit, total distance less than 4000 meters;! competition environment: less than 2400 meters from the same kind of retailing units. Figure 6 shows the analysis result of locating a new retailing unit. Figure 6. Analysis of Locating a New Retailing Unit.
4. CONCLUSION In China, population is always an issue of overall importance. The large size of population is always an influential factor that has to be taken into consideration in all major decision-making process. With the valuable information from the 2000 population census, we can better understand the trend of change in the Chinese population in order to formulate sound population polices and programs for social and economic development by further control of the growth rate and improvement in the quality of population in the 21 st century. It also helps us in dealing with such issues as employment, urban development and management, development of education, environmental protection, improvement of the social security system, so as to promote the coordinated social and economic development and the implementation of the strategy of sustainable development. 5. REFERENCES [1] National Bureau of Statistics, Major Figures on 2000 Population Census of China, China Statistics Press, 2001 [2] Jianfa Shen, David Chu, Developing a Census Data System in China, International Workshop on GIS in Spatial Population Analysis & Regional Economic Development, 1997, Hongkong [3] Hu Chong-qing, Hu Huan-yong, Selection of Population Geography, China Finance and Economics Press, 1988 [4] Zhang Wen-zhong, Economic Location, Science Press, Beijing, 2000 [5] Xu Jian-gang, etc. Development and Application of Information Technology in City Planning, South-East University Press, Nanjing, 2000
SPATIAL ANALYSIS OF POPULATION DATA BASED ON GEOGRAPHIC INFORMATION SYSTEM Liu, D. Chinese Academy of Surveying and Mapping, 16 Beitaiping Road, Beijing 100039, China. E-mail: liudq@casm.ac.cn Biography Liu Deqin, Professor in Chinese Academy of Surveying and Mapping, China. The recent research topic is about the theory, establishment and application of a Population Geographic Information System.