Teresa Baranowska, Ryszard Gronet, Zenon F. Poławski - Monographic Series No 4
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Concept of land use map at a scale of 150 000 for the territory of Poland
Human needs necessary for its existence: food, place for living, work, leisure, transportation and safety have influence on management of Earth surface. Man’s activity is mostly related to development of built-up areas, transportation infrastructure and industry, which in consequence leads to spatial re-arrangements and to serious conflicts in natural environment. Unfortunately, it can be expected, that degradation processes of environment will develop more intensively. Therefore it is necessary to study relations man – environment and to monitor environmental changes.
Land use map can be one of the forms for studying relation man – environment. Cartographic comparison of land use and land cover forms with potentials and conditions of environment can give much information on level and intensity of management, as well as on rational/non-rational land usage at particular technical/social conditions. Land use image is the important basis for further studies and conclusions, concerning more rational use of environmental conditions.
Understanding of relations between man’s activity and its impact on environment is still insufficient, although distinct progress can be observed, as far as knowledge on environmental processes at global and local scale is concerned. Numerous international research projects, related to land use/land cover studies, can be the example of this progress.
Existing land use/land cover maps for the territory of Poland are not detailed and not updated. Hence, their contents can be use only for general purposes or for managing environment at European/ large region scale, but not at country scale or in case of smaller geographic/administrative units. Much more detailed and precise maps are needed for managing environment, with extended legend, which would take into account character and specific features of particular regions of Poland.
The aim of the research project was to prepared concept of the detailed land use map, especially concerning its legend and to produce exemplary maps at a scale of 1:50 000, on the basis of 1:26 000 PHARE colour aerial photographs. It was assumed to keep legend uniform for the whole Poland and at the same time to take into account specific features of different geographic regions of the country. Mapping of test areas was aimed at verification of the assumptions and at evaluation of graphical presentation of map contents.
Beginning the works it was assumed, that hierarchical arrangement of the legend and its level of detail will be comparable with the legends created at the other European countries. This assumption will be important in the near future, when Poland will access European Union.
Demonstrating results of the works conducted within the research project it was decided to present differences between terms „land cover” and „land use” and to make historical overview of land use maps, prepared so far in Poland (Poławski Z.F.: From land utilization map to land use map – CORINE Land Cover Level 4).
Term „land use” is related, according to numerous authors, to functional aspect of land, concerning its social and economic features, while term „land cover” concerns biophysical aspect of land, relating mostly to its physical features.
When making overview of various works, different approaches to these terms can be observed, from distinct division and analysis of land cover and land use separately, through aggregation of both types to joint, equivalent treatment of land use and land cover, as well as superior treatment of land use in relation to land cover.
Polish thematic cartography has over 70 years of experience in making land use maps, which resulted in numerous, significant elaborations in this field. At initial works on preparation of the method of the detailed land use mapping only basic elements of land use were considered. In mid-fifties proposal of the detailed land use maps was presented by team under supervision of K. Dziewonski. Thematic range comprised not only 7 main land use categories ( Level 1 of detail), but many sub-categories as well, i.e. 29 forms belonging to Level 2 and 58 forms belonging to Level 3.
Slightly different approach is presented at the next works, concerning the detailed land use map. Studies of the authors were concentrated on evaluation of conditions of geographic environment from economic point of view. Instructions prepared by J. Kostrowicki for the detailed land use map in 1959 and 1960 comprised 6 categories for Level 1. 19 categories for Level 2, 74 categories for Level 3 and 115 land use categories for Level 4.
Almost forty years later concept of the detailed land use map revived. CORINE Programme, conducted at the Institute of Geodesy and Cartography, was an impulse to new works in this field. CORINE Programme (COoRdination of INformation on Environment) was launched by the European Commission in 1985 (Baranowska T.: Analysis of contents of land use maps corresponding to 1:50 000 CORINE Land Cover map – Level 4 prepared at some EU countries). At first stage countries in Western Europe participated in this programme, but at the second stage ten Central- Eastern European countries were invited, including Poland. The main objective of the programme was to coordinate activities aimed at collection of information about state of environment in EU countries. As a result of joint activities geographic information system was created; its database comprises dozen or so layers, containing information on administrative boundaries, transportation network, drainage network, digital terrain model, land cover, as well as information about soil types, erosion hazard, sanitary state of forests and various elements influencing state of environment. The gathered information will be a basis for environmental policy in EU countries. In 1991 – 1993 CORINE Programme was implemented in Poland; the Institute of Geodesy and Cartography was responsible for coordination of the works concerning preparation of land use/land cover information layer (CORINE Land Cover). The works were carried out using PHARE funds.
In CORINE Land Cover Programme Landsat satellite images with 30 m ground resolution were the source of information. Land cover forms were determined on the basis of colour composites prepared from the processed satellite images, using visual interpretation. Hierarchical arrangement of the discriminated land cover forms was prepared, resulting from geometrical resolution of satellite images, which implied level of detail. For these works Level 3 of detail was assumed; it comprised 44 forms of land cover, existing on the whole territory of Europe. Thematic range and precision of mapping were related to 1:100 000 map. As it was already mentioned, Poland participated in this Programme and as a result of this participation land use map for the whole country was prepared, applying uniform technology and legend.
However in the course of these works it was revealed, that requirements for land use maps in particular countries are much higher. Hence, in many countries, extending the obligatory hierarchy of categories, the works were started in order to prepare Level 4 of land use/land cover categories. So, at the next stage of the work legends of land use maps at a scale of 1:50 000, prepared at various EU countries, were studied, as well as activities within CORINE Land Cover – Level 4 pan-European Programme were analyzed (Baranowska T.: Analysis of contents of land use maps corresponding to 1:50 000 CORINE Land Cover map – Level 4 prepared at some EU countries). This part of the work was very important, considering compatibility of the prepared map with similar maps created in other European countries.
The study work revealed, that despite of large amount of printed and internet publications, describing land use/land cover maps, prepared at various scales in EU countries, only a few authors present full legend applied for these maps, especially as far as specification of legend elements is concerned. In particular it concerns maps at 1:50 000 scale or at larger scales. Maps at smaller scales, especially those prepared within CORINE Programme (1:100000 scale) are discussed in details in many publications, including legends applied in various countries. However, in this case map contents is the result of international agreements and differences arise first of all from specific character of the area. For 1:50 000 maps in some cases solely number of the distinguished land use/land cover categories is given. Level of detail can be assessed only on the basis of type of map usage. These maps are in majority prepared for agricultural statistics and their legend contains first of all types of crops.
In case of using aerial photographs for obtaining information about land use for agricultural statistics, in some countries extrapolation methods of interpretation results are applied. They are based on combining results of interpretation at the selected points of photograph, most often at the corners of regular grid, to extrapolate these results to the determined area. Finally digital database is created, which contains information on land use and land cover, but it does not give possibility to prepare maps from these data. However, such databases enable analysis of changes in land use and land cover, aggregation of categories and graphical presentation of the results.
Despite of fact, that these databases do not create classic geographic information systems, methods of land use/ land cover classification applied in these works can be useful at initial phase of the research works, aimed at determination of level of detail, concerning distinguishing land use and land cover forms.
Analyzing the collected materials, originating from different publications and internet searches, it was found, that first of all the following projects should be considered:
– project of legend of land use map in the scale of 1:50 000, prepared within CORINE Land Cover – Level 4 (GISAT 1995, GISAT 1999);
– thematic range of databases and geographic information systems prepared in France, Belgium, Switzerland (European Commission, EUROSTAT 1998), Sweden (Syron M. 1999) and in Great Britain (European Commission, EUROSTAT 1998).
Special attention is put to programs conducted by EUROSTAT (EUROSTAT 2001) – organization of the European Union, which deals with statistical service. EUROSTAT itself does not collect any data; its task is to analyze statistical data sent by particular EU member countries and to make them comparable, i.e. to process these data according to the uniform methodology. Attention should be also given to four-level land use/land cover classification, applied within CLUSTER Programme (Classification for Land Use STatistics; Eurostat Remote Sensing Programme) (Beale L., College N. 1977; EUROSTAT 1997), although this classification is mainly applied for agriculture.
It can be seen from the presented overview, that among available classifications of land use and land cover prevail those designed for acquiring statistical data, mostly concerning agriculture. Second group of classifications concentrates mainly on defining types of utilization of built-up areas. These classifications are used first of all for fiscal-cadastral purposes. Classification of land use and land cover on the 1:50 000 maps for the territory of Poland should not be limited to these problems. So in practice, it was found, that the most useful for further works will be classification prepared within CORINE Programme – Level 4 and CORINE-derived classification utilized in Sweden (SLD – Swedish Land Cover Data), which also takes into account specific features of this country.
As it was already mentioned, within CORINE Land Cover Programme common range of map contents for all participating European countries was established. This fact obligates for applying the international agreements. However, from the other side, specific land usage in Poland implies application in some cases of more detailed classes, as it was in the case of Sweden. Satisfactory level of detail in distinguishing land use/land cover forms must be maximally adjusted to local, characteristic features of environment, land cover and land use.
The next article presents basic assumptions of concept of map legend, general characteristics of land use/ land cover categories – Level 4, as well as definitions of these categories and rules/ methods of selection of test sites, which were chosen for preparing exemplary land use maps (Poławski Z.F.: Concept and thematic range of the detailed land use map at a scale of 1:50 000).
As it was mentioned, the aim of the research project was to prepare detailed land use map at a scale of 1:50 000, and especially its legend. It was assumed, that thematic range of 1:50 000 land use map for the territory of Poland will correspond with hierarchical division applied in CORINE Programme, relating to Level 4 of detail, while colour aerial photographs at a scale of 1:26 000 will be the basis for mapping. Area of commune – the smallest administrative unit in Poland – was considered as a basis for preparing detailed legend for land use map in Polish conditions.
As a result of analyses, five communes were selected; they have so differentiated land cover, that they can be representative for CORINE – Level 3 categories and serve as a basis for preparing detailed legend of 1:50 000 land use map. The following communes were selected: Bytom, Nowy Korczyn, Piechowice, Suchowola and Wolin.
The assumptions accepted for distinguishing different forms of land use and land cover, as well as results of analyses done on the basis of aerial photographs for five pilot communes allowed to make initial project of thematic range of land use map much more detailed. Final legend of the detailed 1:50 000 land use map comprised 92 categories.
Comparing with thematic range, applied within CORINE Land Cover Programme – Level 3, number of categories was three times larger.
26 categories, out of 33 existing on the 1:100 000 land use map, were made more detailed. It means, that thematic extension was applied to over 85% of Level 3 categories. Only in case of 7 categories they were not made more detailed.
Anthropogenic areas were subject to the most significant changes, as far as level of detail is concerned. Number of the distinguished categories increased in this case from 11 to 40. Agricultural categories also increased more than three times; all 5 categories distinguished within Level 3 were made mode detailed. Land use categories forming group of forests and semi-natural ecosystems also were extended. This extension was not so distinct, as in case of previous categories, but 8 out of 10 categories were made more detailed. Relatively smaller changes appeared for wetlands and water areas.
Verification of concept of the detailed land use map was based on mapping land use in five above mentioned communes with diversified natural and economic character, using colour aerial photographs (Gronet R.: Aerial photographs as a source of information in preparation of land use and land cover maps at a scale of 1:50 000). These photographs were taken in 1996 and 1997. Interpretation of stereo images was done on colour prints at a scale of 1:26 000. Such a scale enables to distinguish surface elements w minimal area of 4 x 4 mm (about 1 ha). In case of line elements minimal width of the distinguished object was ca. 1 mm.
Results of interpretation were converted to digital form through scanning interpretation overlays; next geometrical data were transformed to „1942” coordinate system. This system is most often used in Poland for collecting and storing data in geographic information systems.
After all activities, necessary for obtaining full, correct digital form of land use and land cover map, editorial works, aimed at map printing, could be started. Process of map printing is preceded by preparation of colour map legend. Large number of land use/land cover categories (92 classes) does not allow for applying classic differentiation of these categories with the use of colour. From the other hand, in the legend of CORINE Programme the definite set of colours was assumed. Therefore, it was found useful to keep this set of colours also in the Level 4 legend.
However, in this case there are three times more categories than in Level 3. Sometimes for one Level 3 category there are six Level 4 categories, so there is no possibility to make them different with the use of shade of colour.
Hence, it was decided to use basic colour from Level 3 category and to make different Level 4 categories by application of line patterns. Owing to this map contents was much more readable.
The conducted works confirmed the accepted assumptions and proved, that thematic range and level of detail of land use/ land cover maps, prepared on the basis of colour aerial photographs, can be basic information on many aspects of environment. These maps can serve for institutions and organizations dealing with monitoring, protection of environment and physical planning at commune level or at larger-scale administrative units – districts (also for geographical regions). They can represent the most updated image of the state of environment, serving as a basic information material for making plans of spatial management; they can be also used by institutions and organizations dealing with environmental protection and monitoring.
Cartographic projection system uniform for the whole country and consistent method of map making enables to combine maps of particular communes of their fragments in order to prepare maps, which would be of interest for the end-user at any region of the country. Digital form of the map can be a basis for creating geographic information system to the selected area.