Abstract

The Bavarian Geological Survey is responsible for statewide geoscientific data collection, their evaluation and availability to the public. Today GIS technology is used for data analysis and the deduction of thematic maps in almost every department of the survey. Also the cartographic production of the geoscientific standard maps is now carried out by digital methods.
Of increasing importance is the establishment of a general soil information system for interdisciplinary evaluation, prediction of dangers and risks and working out proposals for soil protecting actions. A common database of point data and related laboratory measurements was already set up. A database for spatial data is under development.

INTRODUCTION

With an area of approximately 70.000 km² Bavaria is the largest state of the Federal Republic of Germany. The Bavarian Geological Survey is one of the oldest institutions of its kind and responsible for statewide systematic geoscientific data collection, their evaluation and availability to the public. The size of the area in combination with new challenges and decreasing personal resources stresses the need for efficient use of technical tools for spatial data analysis.

THE USE OF GIS-TOOLS IN SELECTED DEPARTMENTS

In the framework of a research project on erosional risk evaluation Esri’s ArcInfo was used in 1991 for the first time. In the meantime the use of GIS technology became a standard tool for the production of thematic maps in almost every department (regional geology, hydrogeology, mineral resources, engineering geology, soil science). Examples are given below.

Soil science
The use of GIS-tools has become a standard procedure within this department. Besides the computation of erosional risk, there is a wide range of applications. A main focus is the production of soil maps at the scale of 1: 200,000 which are generated in a semi-automatic way using GIS- based conceptual maps (64 maps 1: 25,000 for each map sheet 1: 200,000). A very important part of this project is the establishment of a general map legend for all soil maps. Another project focuses on the data acquisition immediately in the field. For this purpose rugged field computers with GIS functionality are used. They allow the user to orientate himself with a digital map, collect profile descriptions and perform basic tests on the plausibility of the data which can then be uploaded into the common data base of the survey.
Other GIS based projects concern city soils and the programming of specific evaluation methods (mainly with AML).

Soil protection
For soil protection, the spatial coverage and visualisation of relevant parameters is of extreme importance. By detailed analysis of existing data a map series of background values of anorganic substances (e.g. heavy metals) in Bavarian soils could be produced. This atlas contains maps of the interpolated content of 12 different elements in 3 soil layers (Scale 1: 1,300,000; publication in preparation).

Figure 1
Part of a map of natural lead-content in bavarian soils.

Hydrogeology
Using ArcInfo, a map series was started, displaying the protective function of the groundwater covering strata. The working scheme is explained and illustrated in Diepolder (1995, 1996). Another essential result of this work was the deduction of a hydrogeological reference legend for use within the whole information system.

Mineral deposits
ArcView is used to visualize the data material acquired during reconnaissance trips and laboratory analysis. An application was prepared using Avenue to inform the user, about objects which provide additional information and allows easy access to this material via hot-links.

Figure 2
ArcView-Screen with photographs of outcrops and drill cores.

Geological mapping
The regional geological mapping (scale 1: 25,000) is the classical task of the survey. At present, the preparation of the field map is still done the traditional way, but more and more digital information is available at the geologist’s desk. The aim is, however, to start with the digital mapping already in the field, where additional information is provided to the geologist.

GIS AND CARTOGRAPHY

During the last years the cartographic production of the geoscientific standard maps was shifted towards digital methods.
1993 the Bavarian Geological Survey started a project „digital geological maps of Bavaria". The first completely digitally produced map was a sheet of the 1: 25,000 map series (Bayerisches Geologisches Landesamt, 1995). Then, as a major milestone, in 1997 the „Geological Map of Bavaria 1: 500,000" was published. It was produced exclusively with ArcInfo. This very ambitious and complex map with more than 22,000 single areas and over 120 different legend units clearly demonstrated the capabilities of ArcInfo for high-end cartography (Geiss et al., 1995; Bayerisches Geologisches Landesamt, 1996). In the meantime almost all new geological maps of the survey are produced digitally from the geologist’s manuscript map to the color separations for printing.

Figure 3
Part of the geological map of Bavaria 1:500,000.

The easy use makes the classically printed map still irreplacable for field work. Therefore, it will certainly be published in the traditional way with a high quality claim over the next years.
On the other hand an important field of activity will be the publication of our maps on electronic media. The digital geological map 1: 500,000 (along with explanations) on CD-ROM will be released this autumn.
Much time has still to be invested to generate the specific symbols and shadesets for the maps. It is our aim to establish a standard legend for the cartography, that is closely related to the general geological key used in our database system. However, as long as it is not possible to import complex shadesets directly from ArcInfo into ArcView, much double work is necessary to ensure the same familiar appearance of the maps in different systems.
There is still a great demand for digital vector data – topographic data from the land surveying authority as well as geological data and others. To reduce this problem, the published topographic and geoscientific maps were scanned and are now provided to our internal users as georeferenced raster maps.
An important and yet unsolved issue is the close relationship between the mapping of the geoscientific content and the topographic base map at the time of the field work. While a traditional printed map merges the two information layers inseperable, a digital information system allows and facilitates the combination of - possibly incompatible - data sets. To make the potential user aware of possible problems, a careful and detailed documentation of each information layer (metadata) is necessary.

THE BAVARIAN SOIL INFORMATION SYSTEM – STATUS AND PLANS

Of increasing importance is the establishment of interactive information systems. In 1988 the Bavarian Government decided to create a „soil information system" to collect data on soils and the deeper underground for interdisciplinary evaluation, prediction of dangers and risks and to work out proposals for soil protecting actions. As a first response the Geological Survey set up a common database of point-data and related laboratory measurements. This database and its applications provide users of every department with all necessary information (base data, profile descriptions) on point locations (including wells, boreholes, outcrops) and related analytical data.
At present the database for spatial data is under development. The aim is, to use this tool for structuring the geo-data, establish the data base for attributes and organize the geometries. An important functionality of the system will be the management of data history and interpretations. This is of fundamental significance for geoscientific data sets and was successfully implemented within the data base of point and laboratory data.
A further task for the future will be the integration of the large amount of information that is presently located in traditional paper and microfilm archives. First attempts to integrate complex, descriptive data (graphics, photographs) have been successfully made with ArcView.
The use of GIS systems will more and more spread out to untrained, occasional users. Therefore the user interface is gaining increasing importance. The systems must become more user friendly, allow access to all kinds of data (including metadata) and provide standardized methods as well as tools for individual analysis. Another requirement is the possibility to comfortably create reports and maps.
Today, the common GIS-frontend at the Geological Survey is ArcView, but other solutions (using Internet/Intranet techniques) are also under consideration.
Our experience showed, that the interdisciplinary unification of the data model and processing methods is necessary. Due to the longevity of most of the geodata, quality assurance is an important task. Therefore meta-data have to be provided to inform potential users on the basic properties of geo-objects (e.g. spatial extent, time and quality of registration, history of modifications, data source).
In general, we observe a continuous change of the focus of information systems. While in former years people concentrated on using the geopotential, today the main orientation is towards the protection of the geopotential. Our soil information system is part of Bavaria’s Agenda 21 and plays a major role in soil protection laws, that will take effect in 1999. This implies also, that our information system in no longer only a tool for internal use, but will be more and more in the focus of the public. Geoscientific data and information – presented fast, appropriate and clear - will be increasingly used for far-reaching decisions. GIS tools will play a major role in achieving this aim.

REFERENCES

• Bayerisches Geologisches Landesamt (ed.), (1995), „Geologische Karte von Bayern 1:25 000, Blatt Nr. 7234 Ingolstadt." Bearbeitet von H. Jerz und H. Schmid-Kaler, München.
• Bayerisches Geologisches Landesamt (ed.), (1996), „Geologische Karte von Bayern, 1:500 000", München.
• G.W. Diepolder, (1995), „Schutzfunktion der Grundwasserüberdeckung. Grundlagen – Bewertung – Darstellung in Karten." In: GLA-Fachberichte, Bd. 13, p. 5 – 79, 4 App.
• G.W. Diepolder (1996), „Protective Function of Groundwater Covering." In: Esri (ed.): Esri Map Book, volume eleven, pp. 36 & 37, Redlands, USA.
• E. Geiss, E. Poitner, M. Mehren & A. Schneider (1995), „The Digital Geological Map of Bavaria at 1: 500,000." In: Esri (ed.): Esri Map Book, volume ten, p 34, Redlands, USA.