The tendencies of hydrogeological mapping and problems of compiling maps of new generation
|Location||International Geological Congress,oslo 2008|
|Holding Date||03 September 2008|
The most important advantages of cartographic information include: its situational character and conformity between the mapped natural situation and factual data. From the informational point of view, in characterizing the hydrogeological conditions the map and the factual data compose an inseparable informational spatial-analytical unity. An insufficiency of any of these components in this unity negatively influences the information as a whole.
The Ministry of Natural Resources of Russia have developed the normative-methodical documents which orient the technologies of compiling hydrogeological maps to an unified informational-analytical system - unified GIS project, implemented on maps of a new generation which take into account the following widely-used hydrogeological regular factors:
- valleys of regional drains and the first-orders tributaries have often such hydrogeodynamic conditions, in which the thickness of free water-exchange zone (FWEZ) and zones of fresh water are minimal or absent at all;
- in the absence of an underlying regional aquitard, the separating boundary between zones of fresh water and water with an increased mineralization is very mobile and during artificial interference into it (e.g. due to work of water-extracting facilities) leads to radical changes in groundwater state;
- maximum thicknesses of the both zones are usually typical to areas of creating pressure heads;
- thickness of fresh groundwater zones in water-bearing formations of evaqporite basins are always less than of zones of free water exchange;
- zones of free water exchange of hydrogeological structures in sedimentation basins have, as a rule, several levels of draining and spring runoff at these levels shows a picture on stratifying conditions of distribution and localization of groundwater resources in each draining zone.
The hydrogeological Map of Russia on a scale of 1:2 500 000 is being compiled as a basic component of the GIS-project.
Most difficult is to map the boundaries of hydrogeological structures. As a rule, the boundaries of initial structure ranks are distinguished according to the geologic-structural basis, whereas of the final ones - taking into account the structures of water-exchange basins.
The current mapping with its powerful resources of information-capacious computer technologies can proceed from the precondition of the natural unity of hydrogeological structures, understanding of continuity of internal linkages and interacting processes both as particular hydrogeological bodies and systems, and their marginal interaction. Just on this principal basis it is not only possible, but also reasonable to create hydrogeological maps that would combine structural-geologic and water-balance (morphological and structural) approaches with zoning of the ground hydrosphere.