It was not just about comparing two maps
This project is an attempt to reconstruct nearly a century of spatial change in Czerwonak Municipality using a series of cartographic sources. Behind the contemporary interactive map are the georeferencing of historical materials, their vectorization, the standardization of land-use classes, and an analysis of changes carried out in a GIS environment.
1. Purpose of the project
The main objective was to conduct a methodologically consistent analysis of changes in the land-use structure of Czerwonak Municipality between 1933 and 2024 based on cartographic data. I was interested not only in what changed, but also where, to what extent, and at what rate these transformations occurred.
The analysis also aimed to answer whether cartographic materials from different periods and produced according to different standards could be brought into a common spatial model that would allow them to be compared.
The key assumption of the project was therefore to create a consistent method for comparing sources that were originally not created with such a comparison in mind.
2. Why Czerwonak Municipality?
Czerwonak is an area where different forms of land use meet within a relatively small space: extensive forest complexes, the Warta River valley, agricultural land, residential development, as well as industrial and transport areas.
At the same time, the municipality is located directly adjacent to Poznań. This location means that its contemporary landscape is strongly connected with the development processes of the metropolitan area. The study examined, among other things, the influence of settlement development, industrialization, economic changes and infrastructure expansion on the gradual transformation of the earlier agricultural landscape.
This does not mean, however, that every change visible on successive maps can be directly attributed to a single factor. Maps primarily show the outcome of processes, and their interpretation requires consideration of both the history of the area and the characteristics of the sources themselves.
3. Nine decades of cartographic sources
The analysis was based on six cartographic sources representing successive stages in the development of the topographic data archive. The sources differ in scale, level of detail, methods of depicting features, and principles of cartographic generalization. Their selection was driven by the need to maintain the most continuous possible time perspective while taking into account the availability of materials.
| Source | Period / currency | Scale | Role in the analysis |
|---|---|---|---|
| WIG topographic map | 1933 | 1:25 000 | Beginning of the analysed period and reference point for long-term changes. |
| “Powiatówka” topographic map | 1962 | 1:25 000 | Post-war stage of land-use transformation. |
| Map in the “1965” reference system | compiled in 1980 | 1:25 000 | Further stage of change, represented using a different cartographic standard. |
| Map in the “1992” reference system | later compilation | 1:50 000 | Period of significant settlement and economic transformations. |
| TBD | data current as of 2013 | 1:10 000 | Transition to considerably more detailed digital data. |
| BDOT10k | data current as of 2024 | 1:10 000 | Contemporary land-use situation used as the final point of the analysis. |
Important: The dates used in the analysis do not always represent the year in which a field observation was carried out. For some sources, they refer to a specific cartographic product, its reference system, or the currency of the data. Therefore, “1965” and “1992” should primarily be treated as source identifiers rather than direct observations made precisely in those years.
4. From an old map to spatial data
A historical map is not yet a directly comparable spatial dataset. To use it in the analysis, its position first has to be reconstructed within the current spatial reference framework, and the information shown on the map then needs to be converted into features that can be measured and analysed.
4.1. Georeferencing
The historical materials were georeferenced, meaning that they were aligned with contemporary geographic space. They were then clipped to the current boundaries of Czerwonak Municipality. This made it possible to compare the areas of land-use classes within the same reference area.
4.2. Vectorization
The information from the maps was converted into vector data in a GIS environment. This involved manually reproducing the boundaries of land-use units and assigning them to specific categories.
4.3. Standardization of classes
The individual sources did not use identical approaches to land-use classification. It was therefore necessary to create a common classification scheme that would allow data from different periods to be compared. The research process used 12 base classes, while the results presented here distinguish the most important categories, such as arable land, forests, green areas, built-up areas, industrial areas, water, cemeteries and wasteland.
4.4. Calculations
For each source, the percentage share of individual classes in the total area, absolute change, relative change and average rate of change were calculated. In addition, the Land Use Change Intensity (LUCI) index was calculated for the two extreme sources: the WIG map from 1933 and BDOT10k data from 2024.
5. What changed the most?
The most characteristic change is a clear decline in the area of arable land, accompanied by an increase in forests, green areas, built-up areas and industrial areas. This change was not uniform throughout the analysed period. The individual sources show different stages of this process.
LUCI – scale of change between 1933 and 2024
The LUCI index reached a value of 0.75. In percentage terms, this corresponds to approximately 75% of the area experiencing a change in land-use class between the two extreme sources. This does not mean that 75% of the municipality became built-up.
Largest changes in individual classes
Forest area increased from 2557.67 ha in 1933 to 3797.19 ha in 2024, an increase of 1239.52 ha (48.46%). Arable land decreased from 4822.65 ha to 1729.62 ha, representing a decline of 3093.03 ha (64.1%). Built-up area increased from 105.96 ha to 754.83 ha, while industrial area increased from 6.15 ha to 229.09 ha.
However, these values should not be interpreted independently of the characteristics of the source materials. Differences in scale, level of detail and cartographic generalization affect how individual features are represented and may influence the resulting area measurements.
6. How did the landscape change between 1933 and 2024?
The successive sources reveal not a single transformation, but a long-term process of landscape change. Two phenomena are particularly clear: the declining share of arable land and the gradual increase in areas associated with forests, green spaces and built-up development.
Arable land covered 4822.65 ha, representing approximately 58% of the analysed area.
Compared with 1933, the share of arable land decreased, while forests and built-up areas, among other classes, increased.
The source shows a further reduction in arable land and the development of several other land-use classes.
Between the “1965” and “1992” sources, the largest increase in built-up area in the entire analysed series was recorded.
Between the “1992” source and TBD, the largest decrease in arable land and the largest increase in green areas among the analysed intervals were recorded.
The final picture is characterised by extensive forest areas, developed built-up areas and a substantially smaller share of arable land than in 1933.
7. What is behind these changes?
The changes visible in the maps are the result of several processes that took place simultaneously over the course of several decades. They cannot be attributed to a single factor.
Expansion of settlement
The area of built-up areas increased substantially between 1933 and 2024. This reflects the gradual expansion of settlement and the transformation of previously agricultural areas into residential and other developed land.
Industrialisation
Industrial areas also increased significantly. Although they still occupy a relatively small share of the municipality, their growth is one of the clearest relative changes recorded in the analysed data.
Location near Poznań
Czerwonak Municipality is located directly north of Poznań. Its proximity to a large urban centre has influenced settlement development, land-use changes and the gradual transformation of the surrounding landscape.
Infrastructure development
The development of transport and technical infrastructure has accompanied the growth of settlement and economic activity. Roads, railway infrastructure and other elements of the transport network form an important part of the contemporary spatial structure.
Forests and the environment
The increase in forest area is another important element of the long-term transformation. The changes visible in the maps reflect both changes in land cover and differences in the way individual source materials classified and represented wooded areas.
8. Not everything visible on the map represents a real change
Historical land-use analysis always involves a certain degree of uncertainty. A difference between two maps does not necessarily mean that the landscape itself changed by exactly the same amount.
Scale and cartographic generalisation
The analysed sources were produced at different scales and with different levels of detail. Small features may therefore have been omitted, simplified or represented differently depending on the source.
Georeferencing
Historical maps had to be fitted to contemporary geographic space. Errors introduced during georeferencing may affect the position of individual boundaries and consequently influence calculated areas.
Classification
The source materials did not use identical land-use classification systems. Some categories had to be combined or interpreted in order to create a common classification scheme for the entire study period.
Limited availability of supporting materials
The analysis is based primarily on the available cartographic sources. A complete set of historical aerial photographs, cadastral materials and other auxiliary datasets was not available for every period. Such materials could provide additional information and help distinguish actual landscape changes from differences resulting from cartographic representation.
9. Why is the analysis still useful despite these limitations?
The purpose of the analysis is not to reconstruct every historical land-use boundary with centimetre-level accuracy. Its main value lies in showing the long-term direction and scale of landscape transformation.
The same classification framework was applied as consistently as possible to all analysed sources. This makes it possible to identify the dominant trends: the decline of arable land, the growth of forests and green areas, and the expansion of built-up and industrial areas.
The results therefore provide a broad spatial and temporal picture of how Czerwonak Municipality has changed over more than nine decades. They can also serve as a starting point for more detailed analyses based on higher-resolution historical materials.
10. Basis of the project
The project is based on the master's thesis:
“Cartographic analysis of land-use changes in Czerwonak Municipality between 1933 and 2024”
The thesis developed the methodology used to compare historical and contemporary cartographic sources and analyse changes in the structure of land use within the municipality.
The project website presents selected results of this research in an accessible, interactive form. The complete master's thesis is not publicly available for download, but its existence and academic status can be verified through the University of Adam Mickiewicz in Poznań.
11. What next?
The analysis presented here can be extended in several directions. More detailed historical materials, aerial imagery and additional spatial datasets could help refine the reconstruction of land-use changes and distinguish actual landscape transformations from differences caused by cartographic generalisation.
The project can also serve as a basis for further analysis of individual parts of the municipality, selected land-use classes or specific periods of particularly intensive change.
The website itself may also be expanded with additional datasets, maps and visualisations as the project develops.