Hydrogeological overview map of Lower Saxony 1 : 200 000 - Base of the upper aquifer complex
Description
The map "Base of the upper aquifer complex" illustrates the large-scale distribution and depth (in meters to NN) of the upper supra-regionally important aquifer complex. Depending on the density of information, the information on the depth position is summarized more or less strongly. If further subdivisions within a color surface are only partially possible, this depth information appears as colored lines in the surfaces.
In this map, all sands (up to the fine sand range) and gravel with silt or clay content below 5% are classified as aquifers. For example, due to the layer description, a very weakly silty fine sand is still addressed as an aquifer, while a weakly silty fine sand is referred to as low water conductive.
In the loose rock areas of Lower Saxony, two superordinate aquifer complexes are distinguished on a large scale. The upper aquifer complex is composed of sands and gravel from the Pleistocene, as well as sands from the Pliocene and Upper Miocene. The lower aquifer complex consists of permeable sediments from the lower to mid-miocene, the so-called lignite sands. The two aquifer complexes are separated by the groundwater inhibitor Upper Glimmerton, which consists of silty-tony sediments from the Middle to Upper Miocene. In the areas where the upper mica clay is missing as a separating intermediate layer (groundwater inhibitor), only one aquifer complex is usually formed - considered on a large scale. This case occurs both in the area of deeply incised gutters, as well as in the area of highly raised salt domes. In the eastern part of Lower Saxony, the upper mica clay has been removed. In the map picture, therefore, only one aquifer complex is shown in these areas and referred to as the upper aquifer complex, although in these areas the permeable sediments of the lignite sands, which otherwise form the lower aquifer complex, are also attributed to it. The base of the upper aquifer complex thus forms either the upper mica clay or, in its absence, submiocene to oligocene clays and silts.
On the map, two areas are distinguished in the color scale: 1. Areas where the aquifer complex is unstructured because either the mica clay separator is missing or a lower sub-miocene aquifer is not formed. 2. Areas in which the aquifer complex is divided, i.e. the upper mica clay is widespread and separates an upper from a lower floor.
It is possible that regionally other low-permeability sediments, such as quaternary basin clays, can assume the function of separating interlayers, which then cause a spatially limited division of the aquifer complex into two or more aquifers. On the basis of the available data, however, too few statements can be made about the area-wide distribution of low permeable quaternary sediments, since they do not have a constant appearance over larger areas like the mica clay, but can also be formed very differently in their facies over short distances. Therefore, they cannot be included in this overview map, although they are often of great importance for regional groundwater hydraulics. The thickness of the upper aquifer complex is shown in a separate map.
Resources
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https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=134&Service=WFS&Request=GetCapabilities& |
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https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=134&Service=WMS&Request=GetCapabilities& |
Tags
- opendata
- inspireidentifiziert
- nibis-metadaten
- sgd_hydrogeologie