Using old military survey maps and orthophotograph maps to analyse long-term land cover changes – Case study (Czech Republic)

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The underlying goal of the study is to further develop and refine an existing method for making a detailed analysis of long-term changes in land cover on the basis of old Military Survey Maps and on orthophotograph maps in the GIS environment. This method may contribute to a better understanding of the long-term landscape dynamics over a period of more than 250 years. The knowledge that is acquired can be applied in landscape planning procedures in order to provide relevant landscape management in the future. The study was carried out in the lowland area of Nové Dvory and Žehušice, Czech Republic, which comprises 21 cadastral units (a total area of 113 km2). The area is located in Central Bohemia, to the east of the town of Kutná Hora, which is a UNESCO World Heritage Site. The area of Nové Dvory and Žehušice is an intensively utilized agricultural landscape. The maps of the First (1785), Second (1851) and Third Military Surveys (1877) and the present-day orthophotograph map of the Czech Republic were used as data resources. They have been digitized, interpreted and analysed in the GIS environment. The changes in the main land cover categories correspond to the change trends in the agricultural landscape types in the Czech Republic as a whole. The most significant features of the dynamic landscape changes in the study area are a decrease in permanent grasslands (from 18% to 5%) and a decrease in water surfaces (from 6% to less than 1%), especially due to pond drainage at the end of 18th century and in the first half of 19th century, as a result of attempts to obtain more arable land. The growth of arable lands was the most remarkable change (from 53% to 67%). The Military Survey Maps provide a suitable basis for analysing and evaluating the development trends in the landscape macrostructure. However, the main shortcoming of the First Military Survey maps is that they suffer from some geodetic inaccuracy, and therefore support only an approximate quantification of the landscape changes between the First Military Survey and the other time horizons. The maps cannot be used for analyses of changes in the landscape microstructure, due to their inaccurate specification of landscape segments, and due to the scale of the original maps (scales ranging from 1:25,000 to 1:28,800), which makes them unusable for evaluating changes at the level of individual plots. When analysing the changes in the line segments on the Military Survey Maps, it is more appropriate to observe the changes in the development of the length characteristics, rather than the changes in the development of the area. Present-day orthophotograph maps are a suitable source material for surveying the state of the land covers, and for evaluating changes to them, over large areas. The legibility of the orthophotograph map depends on many factors, and these need to be taken into consideration. The method used for defining the land cover categories can have a distinct influence on the interpretation of the landscape development in the area under investigation.