GIS Based Studies in the Humanities and Social Sciences - Chpater 5

5 A Method for Constructing a Historical Population-Grid Database from Old Maps and Its Applications Yoshio Arai and Shiro Koike CONTENTS 5.1 Introduction: Can GIS Deal with Historical Phenomena?....................72 5.2 A Preliminary Study on the Population Estimation Made for Around the Year 1890 in East Biwa....................................................73 5.2.1 Estimation Method..........................................................................73 5.2.2 Estimation Accuracy.......................................................................74 5.3 Derivation of the Historical Population-Grid Data for Around 1890 in the Kanto Plain...............................................................................76 5.3.1. Estimation Method..........................................................................76 5.3.2 Estimation Accuracy.......................................................................77 5.4 Derivation of the Historical Population-Grid Data for Around 1930 in the Kanto Plain...............................................................................77 5.4.1 Source Materials..............................................................................78 5.4.2 Estimation Method..........................................................................78 5.4.3 Estimation Accuracy.......................................................................78 5.5 Historical Population-Grid Database Covering the Period 1890–2000 in the Kanto Plain.....................................................................79 5.5.1 Integration of the 1890-, 1930-, 1970-, and 2000-HPD ..............79 5.5.2 Analysis of Population Change Using the 1890–2000-HPD................................................................................80 5.5.2.1 Spatial Patterns of Population Change in the Kanto Plain ........................................................................80 5.5.2.2 Population Change Along Railway Lines ....................80 5.6 Conclusion ....................................................................................................82 References...............................................................................................................83 71 Copyright © 2006 Taylor & Francis Group, LLC 72 GIS-based Studies in the Humanities and Social Sciences 5.1 Introduction: Can GIS Deal with Historical Phenomena? Owing to recent progress made in the refinement of geographic information systems (GIS), spatial analysis using GIS is penetrating human and social sciences, such as economics, sociology, archaeology, and human geography. However, many studies using GIS in these fields are concerned with rela-tively recent phenomena that have occurred in the last two or three decades. Few studies deal with long-term events, such as urban growth during the social modernization process of the past 100 years. Although it is considered that a detailed spatio-temporal analysis of the long-term development of urban areas provides some valuable insights into the nature of cities, severe difficulties are encountered using GIS to study this process. The largest problem is the lack of suitable detailed historical spatial data. Can GIS really deal with historical phenomena? The only way to make it possible is by digitizing contemporary maps and documents. A few studies have attempted to adapt historical data to be suitable for GIS. Pioneering work in this field was undertaken by Norton (1976), who reconstructed land-use data for a township in Canada. A recent example of research by Lee (1996) is a quantitative analysis of population distribution in Northern Ire-land during the 19th century. More recently, Taniuchi (1995) estimated the population-grid data for Tokyo around the year 1900, using various statistical materials. Siebert (2000) reconstructed with GIS the infrastructure patterns of pre–World War II Tokyo using old maps. These studies, however, have a limitation in that they generally focused upon a small area at one point in time and did not cover a much larger area over a long period. In this chapter, we propose a method for constructing historical population-grid data (HPD) from old topographical maps. The method is designed to overcome limitations found in previous studies. Topographical maps, which were made in accordance with an authorized format for survey publications, illustrate geographical features across a wide area. From them we can see the detail of urban and rural areas at the time of map production. Can we derive from these old maps numerical data on the population distribution in those days? Herein, we have attempted to assemble historical population-grid data from around 1890 (1890-HPD) and that from about 1930 (1930-HPD). These data, together with modern statistics, have been used to make a time-series dataset for intervals of less than 40 years, covering the 110-year period from the close of the 19th century. This dataset is valuable for spatio-temporal analysis of the changing pattern of population throughout the period from the beginning of the Japanese modern era to the present day. The chapter consists of six sections, including this introductory Section 5.1. A preliminary study in Section 5.2 gives a systematic sampling method for estimating population from an area occupied by housing. By modifying Copyright © 2006 Taylor & Francis Group, LLC A Method for Constructing a Historical Population-Grid Database 73 this method, the 1890-HPD is made for the Kanto Plain area in Section 5.3. Section 5.4 constructs the 1930-HPD in the same area, but the manner of derivation is further modified, because the source materials were different. Section 5.5 integrates the 1890-HPD and the 1930-HPD with the population-grid data published by the Statistical Bureau of Japan for 1970 and 2000. Section 5.5 also shows two applications of the integrated 1890-2000 HPD to population studies. The chapter ends in Section 5.6 with suggestions for further work. 5.2 A Preliminary Study on the Population Estimation Made for Around the Year 1890 in East Biwa To derive the historical population-grid data (HPD) for the Kanto Plain between the years 1890–2000, we carried out the preliminary study for East Biwa shown in this section. 5.2.1 Estimation Method The means of estimating population from topographical maps published in 1890 is based on the method proposed by Arai and Koike (2003) and Koike and Arai (2001). It is assumed that in 1890 almost all the buildings in villages shown on the maps were single story, and that the family structure was not very varied among settlements. In consequence, the total area occupied by buildings and the number of residents in a village were closely related. From these assumptions, we derived the hypothesis that population P can be expressed as a function of the area of buildings A, appearing on topograph-ical maps, i.e., P = f(A) (5.1) To measure the area of buildings efficiently, the systematic point-sampling method was used. We overlaid a scale grid of 20-meter intervals on a map and regarded the lattice points as systematic sample points. The number of such points included in the area of buildings was counted (Figure 5.1). Let N be the number of sample points included in the area of buildings. As N is proportional to A, A is substituted by N and Equation (5.1) is written as P = f(N) (5.2) Let us see if the relationship of Equation (5.2) really holds, using empirical data. The study area is fully named the “East-Biwako Area” located in the central part of Honshu, the main island of Japan. Old Seishikizu topographical Copyright © 2006 Taylor & Francis Group, LLC 74 GIS-based Studies in the Humanities and Social Sciences 0 100 200 m Circles represent sample points FIGURE 5.1 An example of point-sampling. maps cover the whole area at a scale of 1/20,000, and these show the geo-graphical features existing in 1890. Shigaken Bussanshi, a statistical report, was made at almost the same time as the maps. Actual population numbers by village are given in this report. We related the number of sample points included in the area of buildings to the population data. The relationship between the actual population of each village P, and the number of sample points within the mapped build-ings in that village N, is shown in Figure 5.2. This figure shows a clear correlation between N and P. A regression analysis provided the following equation: log(P) = 1.3008N 0.1634 (5.3) The fact that the squared correlation coefficient for this regression equation was 0.8304 is positive evidence that there is a close relationship between P and N, represented by Equation (5.2). The spatial unit used in Equation (5.3) was a village area, but any spatial unit can be used. In the HPD in East Biwa, square 1 km2 cells are used, and these are also employed in the Basic Grid-Square (BGS) system, which is now extensively used for GIS-based spatial analysis in Japan. 5.2.2 Estimation Accuracy The accuracy of the population estimation made above is next examined. We obtained the actual population of each square cell directly from the historical report. As a result, the estimated and actual population of each cell was available for comparison. Figure 5.3 shows the distribution of errors. The percentage of cells having an error within 20 percent was more than 60 percent of the total. Copyright © 2006 Taylor & Francis Group, LLC A Method for Constructing a Historical Population-Grid Database 75 4 log (P) = 1.3008N0.1634 R2 = 0.8304 3 2 1 00 0.5 1 1.5 2 2.5 3 log (N) FIGURE 5.2 Relationship of N and P in logarithmic scale (taken from Arai and Koike, 2003). 150 100 50 0 Estimation error FIGURE 5.3 Distribution of the error rate in the estimated grid population (taken from Arai and Koike, 2003). An uneven geographical distribution of error was found. The error rate seemed to differ between individual map sheets. This unevenness was caused by an arbitrary cartographic representation of villages or of buildings, resulting from a lack of standardization in map ornament at the time of map drafting. We attempted to reduce the uneven errors by considering the statistical characteristics of the Chinese lettering size used for village names written on the maps, and this adjustment allowed us to reduce the error rate. The detail of this technique is seen in Koike and Arai (2001). The percentage of cells with an error within 20 percent was increased to 70 percent of the total, and the percentage of cells with an error of more than 40 percent was significantly reduced. Copyright © 2006 Taylor & Francis Group, LLC ... - tailieumienphi.vn