Groundwater Dependent Ecosystems 2003
The immediate reason for the preparation of Map 05.07 is the Water Framework Directive, Directive 2000/60/EC of the European Parliament and the Council Establishing a Framework for the Community Action in the Field of Water Policy, adopted by the European Union in 2000 (WFD).
Besides this, a city-wide overview of groundwater-dependent biotopes is important as a basis for the control of groundwater. The goal here is to design a procedure for groundwater extraction which will be ecologically appropriate. Among other things, all Berlin waterworks are to receive new extraction permits which will also contain ecological stipulations.
The knowledge of groundwater-affected ecosystems also permits a determination as to which locations are suitable fore an environmental impact assessment (EIA) in case of a drop in the groundwater table.
The European Water Framework Directive
The Water Framework Directive imposes on the member states the obligation to first of all carry out a comprehensive ascertainment of resources in river areas. The basic requirement is to carry out a general description and to examine the effects of anthropogenic activities on ground and surface waters.
For the groundwater, groundwater-dependent land ecosystems and groundwater dependent surface waters, hereinafter known collectively as groundwater-dependent ecosystems, are to be ascertained.
The goal of the directive is to “prevent further deterioration, and protect and enhance the status of aquatic ecosystems and, with regard to their water needs, terrestrial ecosystems and wetlands directly depending on the aquatic ecosystems” (Article 1 a).
The good quantitative condition of the groundwater bodies, which is the goal of the WFD, precludes significant damage to land ecosystems which are immediately dependant on the groundwater.
The comprehensive ascertainment is designed to determine which groundwater bodies have a high risk of not fulfilling the goals of the Water Framework Directive. The delimitation of the groundwater bodies defined for Berlin is shown in Fig. 1.
The Berlin Situation
For over 100 years the waterworks have discharged groundwater from the groundwater bodies of the municipal area for drinking water production in Berlin. Groundwater extraction is also carried out by private water supply facilities, and in the context of construction water management and groundwater rehabilitation.
During the sixties and seventies, high groundwater extraction caused a city-wide drop in ground-water levels. Since the beginning of the nineties, the groundwater level has risen in the entire municipal area. Lower discharge quantities due to reduced industrial, commercial and household water consumption are the main cause. The raw water discharge of all Berlin waterworks dropped from 378 million cubic meters in 1989 to 226 million in 2003.
The situation in the immediate vicinity of the wells is somewhat different. Five small Berlin waterworks permanently discontinued production between 1991 and 1997. However, the most efficient waterworks which pump the highest-quality groundwater also are located in areas characterized by sensitive and valuable ecosystems. Environmental problems continue to occur in these areas.
The wells are primarily located in woodlands and wetlands of the Spree and Havel glacial spillway, which is naturally characterized by very high groundwater levels.
Due to the extensive drop in groundwater tables, almost all Berlin wetlands have been more or less strongly impaired. Landscape and species protection program adopted in 1994 by the State Parliament of Berlin therefore mandated the “drafting of special protection and development stipulations for the preservation of the ecological functionality of groundwater-dependent biotopes and vegetation stands.”
Almost 3000 hectares of groundwater-affected Natura 2000 areas (areas protected under the EU Habitats and Birds Directives) are also located in the sphere of influence of the wells. These areas already safeguarded as nature and landscape protection areas (Map 05.06) include transition and quaking-meadow mires, moor-grass meadows, tall forb fields, oak-hornbeam forests and alder-ash forests.
In the catchment area of the waterworks wells, broad and deep permanent sink-holes have developed. Moreover, sometimes considerable fluctuations of groundwater levels occur there, analogously to the discharge rates of most waterworks, which fluctuate over the course of a year.
Drops in groundwater table levels as a result of drinking water extraction have been a serious problem in the past. Once species-rich damp meadows have shown distinct desertification and over-use tendencies. Mires such as the Teufelsbruch (“devil’s swamp”) and the Great Rohrpfuhl have dried out, and mire vegetation receded before bush encroachment. Groundwater-dependent forest lands have sometimes shown considerable drought damage. The rare and very endangered swamp and alluvial forests have also been particularly affected.
Around the Müggel Lake, in the southeast of Berlin, 90% of the wetlands are existentially threatened (the Müggelheim Krume Laake, the Teufelssee Mire, the Neue Wiesen [“new meadows”] / Kuhgraben, the Most Pool, the Thyrn, and lower stretches of Fredersdorf Creek).
Extensive drops have also occurred in the Spandau Forest area, due to increased groundwater discharge by the Spandau Waterworks since the seventies. With the aid of a groundwater recharging plant brought into operation in 1983, the impairment of valuable wetland biotopes due to seepage is counteracted here by treated Havel water.