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Summary:
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Posiva and the University of Turku Laboratory of Computer Cartography (UTU-LCC) agreed in 2010–2011 to conduct a joint research project about the development of the landscape of Eurajoki municipal. The prodject included transformation of digital historical cadastral maps into spatial data that can be analyzed and visualized with desktop GIS (Geographic Information Systems). Posiva is going to use the historical spatial data created in this project in their next Biosphere Description –report. Titta Koistinen (BSc) from the department of Geography and Geology produced and analyzed the data and docent Niina Käyhkö (Univeristy of Turku), Jani Helin (MSc) and Ari Ikonen (MSc) supervised the work. The used methods and fundamental results of the project are represented in this report. The research about the transformation of the rural landscape of Eurajoki is going to continue in the Master’s Thesis of Titta Koistinen.
When studing scenarios and possible future landscapes of an area, the past landscape has an integral role. In addition historical maps have a key role in landscape transformation studies because they offer spatial data, information about the landscape features and land use of man, from the earlier decades and centuries. In Finland cadastral maps span as far as to the 17th century. Unfortunately this time scale covers only part of the country. Transforming of historical cartographic data into digital spatial data includes many concerns and requires caution. However when the process is conducted well, historical spatial data can provide new possibilities in analyzing, modelling and visualizing of the landscape change and dynamics. In addition transformation to digital spatial data is the only way historical landscape information can be used together with modern spatial data products.
In this report the whole transformation process of the digital cadastral maps into vectorized spatial data is depicted. This includes interpritation of the used maps, vectorizing of the selected elements, standardizing of the heterogeneous spatial data and analyzing and estimating of the quality of the produced data. In addition report includes description of used landscape change study methods and visualizations of the produced spatial data and change analysis results. The future possibilities and restrictions of the data are also discussed. Main challenges for the use are thematic differencies and inconsistencies between the original map products. Different scales and geometric errors cause also some concerns for the future use. The spatial data produced from the more general map products can however turn out to be useful for example as approaching maps. The time scale of the study starts from the 1840’s and ends in 2007.
The maps used in this project turned out to be very varying in their consistency and reliability. This alternation was evident also between the landscape elements. Fields, meadows and buildings were depicted in the most consistent manner between the maps, altough meadow as a concept has somewhat changed during the research period. Most of the meadows in Eurajoki disappeared by the 1903–1904 as most of them were ploughed into fields. Measuring the changes in small lakes between the historical spatial data and the modern land use information was more challenging as precision of depiction was so different between the products. Comparing wetlands was also very difficult task because the way of classifying and depicting of them varied from one historical map to another. The basic structure of settlements has maintained during the whole study period although the housing in different parts of the municipal has somewhat changed it’s emphasis. The basic composition of roadnetwork has also remained throughout the study period. The only clear new feature in the landscape is the highway that was built in 1950’s.
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Keywords:
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Land use, landscape, geographical information, historical map, transformation analysis, Eurajoki.
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