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Berlin Environmental Atlas

02.11 Water Conservation Districts (Edition 2009)

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Criteria for the Delimitation of Water Conservation Areas

According to the stipulations of §51 WHG and §22 BWG, drinking water conservation areas are to be subdivided into zones with different protective regulations. The goal of the structure by conservation zones is to take the principle of proportionality into account. Since the danger for the groundwater used decreases with the distance of the source of danger from the wells, the zones are subjected to increasingly weaker restrictions the further they are from the wells.

Under the older regulations, applicable in Beelitzhof, Kladow and Tiefwerder, no differentiation was made within the remotest conservation zone, Zone III. In the water conservation area ordinances issued since 1995, Conservation Zone III has been subdivided into III A and III B.

The basis for the measurement and certification of drinking water conservation zones is the Technical Regulations of the German Technical and Scientific Association for Gas and Water (DVGW). The basis for the measurement of the breakdown into conservation zones in modern water conservation area ordinances is the isochronic concept. Isochrons are lines showing equal flow times of the groundwater. These are ascertained with the aid of hydrogeologic investigations, and "projected" onto the terrain surface, taking the hydrogeological, hydrological and geological conditions into account. The conservation area boundaries of the conservation zones II, III A and III B are established, with additional consideration for local conditions within a technically acceptable framework (e.g. housing, infrastructure). To make as clear as possible a determination, the actual delimitation is carried out along existing lot boundaries, pathways, streets or other markings.

Flow times to the point of withdrawal for the modern certification of conservation zone boundaries in Berlin:

  • conservation zone II: 50 days
  • conservation zone III A: 500 days to 10 years
  • conservation zone III B: 2500 days to 30 years
Due to the great expanse of the catchment areas of the waterworks considered - they extend far into Brandenburg - additional considerations were required in Berlin in order to resolve the conflict between a generally stricter groundwater conservation system on the one hand and an urban development with economic interests on the other. Here, it was possible to use the concept developed by Lühr & Schulz-Terfloth 1992, so as to distinguish between inner-city catchment areas with a dense population, and rural catchment areas with a silvicultural character. The main criterion is that despite all safety precautions, an accident or disruptive incident involving water-endangering pollutants cannot be excluded, and that the conservation zones must therefore be extended at least far enough to provide sufficient time allow the implementation of effective defensive measures for the protection of discharge wells. Thereafter, different flow times were used as the basis for delimiting conservation zones (Schulz-Terfloth 1998) in the urban-type areas than in those with a silvicultural character (see Table 2 and Fig. 3).

Tab. 2: Concept for conservation zone certification in Berlin
Inner conservation zone (Conservation Zone II) Outer conservation zone (Conservation Zone III)
  Municipal catchment area Silvicultural catchment area
  III A III B III A III B
50-day isochron 1000-day isochron 12-year isochron 10-year isochron 30-year isochron
Tab. 2: Concept for conservation zone certification in Berlin (Schulz-Terfloth 1998)

Fig. 3
Fig. 3: Structure of the water conservation zones under the isochronic concept

Zone I is defined by a radius of at least 10 m around the wells.

The conservation zones stipulated by the older water conservation area ordinances were established with consideration for then-current hydrogeological investigations and assessments of the subsoil, according to surface distances.

The conservation zones according to § 4 of the Order of 8 October 1946 were defined according to aboveground radial distances from the wells (100 m for the inner conservation zone, 500 m for the outer conservation zone). Here too certain use restrictions apply.

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