Surface sealing
Surface sealing or soil sealing refers to the covering of the natural soil with buildings made by humans. Surface sealing is used because no more precipitation can penetrate the soil from above and so many of the processes that normally take place there are stopped. Structures that are not visible under the earth's surface are also included in the sealing, such as B. Lines, channels, foundations and highly compacted soils .
Problem
Soil sealing has a very negative effect on the natural water balance , as the soil no longer serves as a buffer. The surface runoff is increased and the groundwater donation is reduced. This can lead to a lack of drinking water, increased drought damage and more severe flooding. The groundwater pollution and substance concentration can increase, as less nutrients and pollutants can be filtered in the soil when the precipitation seeps away.
"Underground seals" such as tunnels or particularly deep cellars can have a negative impact on the flow behavior of the groundwater, especially on slopes.
If, as a result of the construction of roads , asphalt paths and squares, houses, commercial and industrial facilities , including in the context of redensification , large open areas are sealed, significantly less rainwater can seep away. In cities and surrounding settlements, large parts of the soil are often sealed.
Seals absorb a lot of energy from solar radiation, as mostly dark surfaces (asphalt) are created; so it comes to a strong warming of the city on hot days. Along with the lack of shadow effect of the plants and their lack of water evaporation is the microclimate adversely affected.
The sealing has a massive impact on the natural fertility of the soil . Since the soil is permanently sealed off from air and water, the soil organisms perish; This means that the soil loses the ability to build, convert or dismantle fertile soil .
After all, unsealing the soil is time-consuming and expensive, and the soil structure remains permanently disturbed, for example by foreign substances such as concrete or asphalt chunks, plastic fragments or pollutants . The original soil fertility declines only slowly and over long periods of time; the previous quality can often no longer be restored.
Countermeasures
In order to counteract the sealing, government agencies use spatial planning and urban planning instruments . In Germany, for example, the regional planning law and zoning plans regulate which areas can be built on.
Ecological compensation areas should be created for construction measures with large areas of surface sealing. Interventions in nature and the landscape can thus be compensated elsewhere. Here, the sidelines are hedges and neglected grassland planted areas, wetlands created and rehabilitated streams. These biotopes are very valuable from a nature conservation point of view because they are very species-rich.
Surfaces actually sealed
It is very difficult to ascertain the actual built-up area. The surface sealing is not collected by the statistical offices. The Federal Office for Building and Regional Planning and the Federal Environment Agency estimate that around 50% of the settlement and traffic areas in the Federal Republic of Germany are sealed.
The Monitor of Settlement and Open Space Development (IOER Monitor) of the Leibniz Institute for Ecological Spatial Development offers one possibility to show the proportion of sealed areas . The indicator “degree of soil sealing” is made available for the periods 2006 and 2009 and 2012 on different spatial reference levels (excluding marine areas). The data are based on satellite data provided by the European Environment Agency. Among other things, the proportion of sealed area through buildings, traffic areas and other structures in the area, i.e. the degree of surface sealing, can be displayed. This is characterized by an urban-rural divide, but also a difference between the old and new federal states.
Old industrialized regions such as the Rhine-Ruhr or Rhine-Main areas or large city regions such as Hamburg, Stuttgart or Munich stand out due to a higher proportion of sealed surfaces. In East German industrialized regions, on the other hand, only moderate degrees of soil sealing are recorded. The north-east of Germany (Uckermark district, Brandenburg: 1.9% soil sealing), the east of Lower Saxony (Lüchow-Dannenberg district: 1.7% soil sealing), the Eifel (Rhineland-Palatinate and North Rhine-Westphalia) and the Bavarian region achieve particularly low values Forest and the rural areas of the Alps. The lowest value could be determined for the district of Bayreuth (Bavaria, 1.6% soil sealing), the highest for the city of Herne (North Rhine-Westphalia, 47.9% soil sealing). The mean degree of soil sealing for the whole of Germany is 5.5%.
The settlement and traffic area in turn is recorded by the statistical offices in the statistics of actual land use. The settlement and traffic areas include:
- Buildings and building-related areas for uses such as residential, retail, services, trade, industry and waste disposal,
- Recreational areas (sports fields, campsites),
- Traffic areas: streets, paths, squares, railway areas, airports,
- Business areas without mining land (heaps, storage ...) and
- Graveyards.
These areas cover a total of around 12.5% of the land area in Germany, of which 50% are sealed according to the above estimate. In addition, there are other sealed areas that are not included in the settlement and traffic area (for example forest or agricultural buildings).
Land use and surface sealing
A common mistake is to equate settlement and traffic areas with sealed areas. For example, the “buildings and open spaces” not only contain sealed areas, but also house gardens. To date, no method has been generally accepted for the exact survey of the sealed surfaces. In this context, it should be noted that the daily land consumption of approx. 69 hectares does not mean that 69 hectares are sealed every day, but that 69 hectares of agricultural or natural land are converted into settlement and traffic areas every day. As a result of this conversion, there is a different degree of sealing, but this is less than the land consumption.
Flood
Der Spiegel asked on the occasion of the floods in Central Europe in 2013 Is the asphalting of the ground to blame? and came to the conclusion
"Barely. Precipitation that causes large rivers such as the Elbe or Rhine to rise flows from an area that is almost as large as half of Germany. But only a tenth of the area in Germany is artificially sealed with asphalt or buildings. A look at the landscape reveals the real problem: the rain itself seals the ground, fields and meadows are currently flooded by vast lakes.
The cause was the heavy rainfall in a short time: in many places more than 300 liters fell in four days, the water is then 30 centimeters high, provided it does not run off. The rain fills all the pores in the earth so that further rain cannot seep away - the water flows directly into rivers and streams. According to the Center for Disaster Management and Risk Reduction Technology (Cedim), 40 percent of Germany's land area had new soil moisture records at the end of May. In many places, May is one of the wettest since records began around a hundred years ago. "
Web links
- Background paper: land use, an environmental problem with economic consequences - background paper land use (UBA, July 2004; PDF file; 215 kB)
- www.corine.dfd.dlr.de - The CORINE project for measuring land use
Footnotes
- ↑ Soil sealing. Federal Environment Agency, February 12, 2020 .
- ↑ Schleswig-Flensburg nature conservation as a task
- ↑ IOER Monitor: Soil Sealing Degree (2012) ( Memento of the original from October 9, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , accessed September 27, 2016.
- ↑ Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety: Land use - what is it about? , last amended on December 1, 2015, accessed on September 27, 2016.
- ↑ Causes and prognoses: Ten facts about the flood , spiegel.de June 6, 2013.
- ↑ June floods 2013 in Central Europe - focus on Germany. As of June 3, 2013 , cedim.de (PDF; 4.1 MB) (7 pages).
