Hydrogeological map of Lower Saxony 1 : 50 000 - Groundwater surface location
Description
The position of the groundwater surface, or the groundwater pressure surface with tensioned groundwater, is usually represented by groundwater equals (isohypses). The map theme shows the groundwater surface of the first large-scale aquifer for all loose rock areas of Lower Saxony. Density differences were not taken into account. In the solid rock areas of southern Lower Saxony, this type of representation is not practicable, since a spatially coherent groundwater body spread over a large area usually does not exist there. The groundwater moves in the solid rock in gap and fault systems or karst cavities. Although the groundwater deposits in solid rock, e.g. in karst areas, can be quite considerable, they cannot be meaningfully represented with groundwater equivalents on this scale. These areas are marked on the map as solid rock.
In the coastal area of Lower Saxony, the groundwater levels are strongly influenced by the tide-related alternating height of the seawater level and by measures of artificial drainage (pumps, sieves). In the area of pumping stations and sub-pumping stations, the groundwater flow direction can run away from the coast towards the inland. In the immediate vicinity of the coastline, the groundwater flow direction changes depending on the status of the tide.
The groundwater levels are shown here only in a highly generalised manner.
For the construction of groundwater equals, groundwater level measurements at all measuring points are generally carried out at the same time (record-day measurements). The present presentation is based on reference date measurements from January 1993 and represents an average groundwater level of the time series from 1990 to 2000. The reference date measurements of the map series are based on groundwater level data from the Wasserkundliche Landesdienst, which were used with the permission of the Lower Saxony State Agency for Water Management, Coastal and Nature Conservation. In addition, some data was provided by water utilities.
As the grid from cut-off date measurements does not have sufficient evidence density, groundwater level measurements from other periods were added to the dataset as far as it seemed technically feasible. These data come from the drilling database or from archive documents of the LBEG. In areas with high fluctuations in the groundwater level, this supplement has not been made.
In the area of upwelling moraines, the groundwater distances show a great variability due to the very heterogeneous geological structure of these areas. Here, the groundwater equals can only represent the large-scale flow direction.
In areas with very low document point density, the actual water levels on site may differ from the map display.
In order to make the line representation of the groundwater equals more vivid, the surfaces enclosed by them are colored. The color areas indicate the location of the groundwater surface or the groundwater pressure area at intervals of 2.5 m in meters to NN.
The groundwater level plan is suitable for clarifying the flow directions and the potential gradient ratios of groundwater in the loose rock areas on a large scale. For detailed statements, maps with a higher document density of reference date measurements may be required.
Resources
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https://nibis.lbeg.de/net3/public/ogc.ashx?NodeId=200&Service=WMS&Request=GetCapabilities& |
Tags
- opendata
- inspireidentifiziert
- nibis-metadaten
- sgd_hydrogeologie