Data on impervious soil coverage for Berlin have been available in the Environmental Atlas since the beginning of the ‘80s. At first, this was true only for the western part of the city. Since the political change in the East, a full-coverage data stock has been built up and maintained over the course of a number of shifts of emphasis and updates.
In cooperation with the Berlin University of Technology, the Humboldt University and the company Digitale Dienste Berlin, a new procedure for ascertaining impervious coverage was developed for Edition 2007. It has been partially re-adapted and used for editions 2012 and 2017. The databases for impervious coverage of editions 1993 and 2004, which had existed previously had been based on non-uniform ascertainment methods, for which reason a direct comparison with these editions is not possible. The present reuse of this ascertainment method now permits an overall comparison of degrees of impervious coverage of the years 2005, 2011 and 2016.
The following specialized information and geo-data, as well as satellite-image data, have been used:
The Urban and Environmental Information System,
Block Map 1 : 5,000 (ISU5) and Land Use Data
The spatial reference of the City and Environment Information System (ISU) is oriented toward the structure of the statistical blocks of the “Regional Reference System” (RBS) of the Statistical Office for Berlin-Brandenburg. However, each block may be further subdivided into homogeneous-use block segments. Each of the approx. 25,000 areas of the ISU5 structure, is stored in a database, in which information on both area size and use is stored.
A total of 52 area types with homogeneous use and spatial structures are distinguished.
For the impervious coverage mapping, ISU5 (as of 31.12.2015) was used in the analysis process to delimit the areas that were examined. The use data was incorporated into the rule-based classification system of the satellite-image data.
Official Property Cadastre Information System – ALKIS
Since December 1, 2015, data of the Register of Land Properties has been recorded in the Official Property Cadastre Information System ALKIS and no longer in the Automated Book of Properties (ALB) and Automated Map of Properties (ALK) (SenStadtUm n.d.). Therefore, ALKIS data was used for the first time in mapping impervious coverage in 2016, replacing the ALK data used thus far. The following data was used dating from April 2016:
- All buildings above ground excluding underground parking from the layer “Area-like buildings and construction elements”,
- A selection of building uses from the layer “Buildings areas”.
The ALKIS layer “Sport, leisure, recreation” was also used for the first time to record artificial surfacing.
Non-ALK Buildings
As part of the “Ascertainment of Building and Vegetation Heights in the Area of the City of Berlin” (DLR 2013) commissioned by the Senate Department for Urban Development and the Environment, approximately 73,000 buildings were now included, which had not been part of the underlying ALK (i.e. “Non-ALK buildings”). For the impervious coverage mapping, a selection of this data base was therefore integrated into the analysis process in addition to the ALKIS buildings. The data current as of September 2009 and September 2010 improves the ALKIS building stock, especially in regard to allotment gardens.
Map of Berlin 1 : 5,000 – K5
The map of Berlin by the State Mapping Agency at a scale of 1 : 5,000 (K5) is drafted by the Berlin boroughs on the basis the Berlin ALK (now ALKIS). The above-ground railway lines shown in the K5 Map were used for the impervious-coverage maps current as of August 2014.
The lot-precise recording of track areas was used primarily for the mapping of the shaded railway lines in forests, such as that north of Müggel Lake.
Orthophotos
The full-coverage digital RGBI orthophotos used were taken from material shot on April 2 and 3, 2016. They are available in a resolution of 0.20 m, and were used for the following work steps:
- Ascertainment and delimitation or review of reference areas,
- Ascertainment and delimitation of areas to be corrected (e.g. water bodies not recorded).
Data on Impervious Soil Coverage of the Berlin Water Utility
In the process of the evaluation, so-called corrective factors for ascertaining the degree of impervious coverage were used for certain area types. The purpose was to correct the view from the air, in which the impervious coverage is often largely obscured by trees, with certified information on impervious coverage. The ascertainment of corrective factors was carried out on the basis of the current impervious coverage information of the Berlin Waterworks (BWB). Starting in January 2000, this data was collected in connection with the changed calculation of the precipitate-water fees. The BWB aerial photography and the ALK served for the initial recording of the impervious areas of the properties. Moreover, the checked information of the property owners was incorporated (WTE 2004). The lot-precise data was aggregated at the ISU block and block segment level, and was available for evaluation, current as of 2001. Only the details on the non-built-up impervious areas were used. Lot-precise local observation and recording permitted a very high degree of precision of data on impervious soil coverage to be obtained. The corrective factors developed and tested in the 2007 mapping process were used again for the current mapping.
Multi-Spectral Sentinel-2A Scene
Multispectral data from the Sentinel-2A system were used for the first time in the impervious coverage mapping (Edition 2017). As part of the Copernicus Earth Observation Programme, the European Union (EU) and the European Space Agency (ESA) are developing a modern and powerful infrastructure for earth observation and geoinformation services. The aim is to provide current and reliable information based on earth observation data for decision-making processes in politics, the economy and science. The data is available free of charge (Copernicus n.d.)
Both the spatial and spectral resolution of the selected channels are comparable to the corresponding properties of SPOT5 scenes used in editions 2007 and 2013. For the preparation of the impervious-coverage map, it was possible to use a multi-spectral Sentinel-2A scene of May 2, 2016 as a data set. The original ground resolution of the scene is 10 m x 10 m and was refined to up to 2.5 m x 2.5 m during the analysis process. It was a more or less cloud-free image. The foliage is largely complete. The predominant phenology of the time of recording can be compared with that of the scene of the last impervious coverage mapping (Edition 2012). The proportions of shaded areas are also similar.