Abstract

The paper presents the system design and the implementation of the digital national geologic database of Hungary in a pilot 1:100.000-scale area. Setting up digital national geological databases is one of the priorities in many geological surveys throughout the world. These projects raise a number of challenges. One of them is the elaboration of a uniform legend incorporating all geological formations occurring in the country. Not less important are defining the data structure of the results of exploration methods (wells, geophysical measurements, in-situ tests, laboratory data) supporting the interpreted geological formations and developing applications facilitating the query of the database as well as the creation of derived maps.
One of the central questions of the project is to organise the database in a way facilitating most the creation of applied maps and other interpreted products for practical purposes, like the composition of concession packages or environmental projects financed by the Ministry for Environment and Regional Policy.
The project started with the elaboration of a standard geological legend that was completed within 3 years. System design is basically finished this year and will be slightly modified to accommodate comments resulting from testing the system in a pilot area. The project is planned to be completed by 2002.
Digital data acquisition and pre-processing proceed in the Microstation environment. The GIS database is set up in the Esri ArcView 3.0 - Oracle system.
Themes of the database are organised in several views that can naturally be altered. They include:

• Geological map
• Geological layers
• Geological thickness maps
• Geological profiles
• Geophysical explorations
• Wells
• Aerial images

Apart from the functionality provided by standard ArcView tools a customised application was developed supporting the display of images representing

• Drawings of geological base profiles in exposures
• Description of base profiles
• General description of base wells
• Lithostratigraphic profile of base wells
• Pictures of well cores and thin sections.

INTRODUCTION

The Geological Institute of Hungary was founded in 1869 and it was almost 90 years ago that it could move into its present headquarters representing one of the most spectacular monuments in Budapest (Figure 1).

Figure 1
The headquarters of the Geological Institute of Hungary

During the 130 years of its activities the Geological Institute of Hungary has been responsible for the acquisition, processing and management of geological and geology-related data, the latter including disciplines like hydrogeology, engineering geology, environmental geology, pedology and geophysics.
One of the most important issue in the activities of the Institute is the management of basic geological information represented on geological maps. It can be used as the basis for processing derived maps tailored to the needs of potential customers including firms engaged in environmental management, exploration of mineral resources and water supply etc. In order to improve the quality of providing the customers with reliable geological information there has been an increasing demand for setting up the uniform digital geological database of the whole country with a surface of 93.000 km2 on the scale of 1:100.000.
The process of the standardisation of geological data and maps has already started a couple of years ago and involved a number of respected experts, but it was this year that the first unit of a pilot area has been completed using GIS. This paper describes the challenges met and mastered so far in this process as well as the data architecture, thematic layers and the experience gained during the project.

CHALLENGES

They were numerous and they can be summarised in the next hierarchy:

• setting up uniform legends
• defining database themes and structure
• defining the application environment
• ensuring flexible database handling procedures

Though it does not directly implicate GIS, setting up a uniform legend of the related themes was an indispensable prerequisite of the success of the project. In the language of GIS it concerned the definition of the attributes each thematic layer has in the geological database covering the whole country. It required an agreement between geological experts

• using slightly different, private approach in the geological mapping procedure
• having eventually different views on the evolution of certain geological formations
• involved in mapping of hilly or plain areas requiring different methodology
• specialised in mapping on specific scales (small, or large).

It has not been an easy process and it is still not quite clear whether a completely uniform legend can be used for hilly and plain areas. The results of the standardisation have been published in a paper [1] providing the basis for setting up the digital database.
Database themes have been selected upon their priority of furnishing useful data, availability and the possibility of their organisation in a standard database. Several specific projects supported the choice of the most important items that helped us pinpoint the most needed entities.
As of the application environment we were eager to set up a database that has a certain independence of the hw/sw environment but priority has finally been given to the ArcView - Oracle system.
ArcView 3.0 provides a number of easy and flexible tools for data management and representation helping us avoid the necessity of developing sophisticated applications. Nevertheless, a specific extension has been created for the management of some point data types as well as for representing related images and HTML documents.

TECHNICAL BACKGROUND, PROCESSING PHASES

As previously described the database has been set up in the ArcView - Oracle system under both UNIX and WINDOWS NT. Though the difference not large, first of all the developed application had to be slightly redesigned for flawless operation under both systems.
One of the basic aspects of the project was the design of the tabular database in the Oracle system. Priority was given to the relational aspect and simplicity.
The most important table is the MSTR_GEOLOGY (Table 1) including master information in unique records for each specific geological formation occurring in Hungary.

Table 1

Tables and views defined in the Oracle environment are related to this table when it comes to the definition of geological formations.
Table 2 represents processing phases of the graphic database with the formats and environment.

Table 2

DATABASE THEMES

After processing the above data types we have organised different themes in certain views that gives the best possible overview for potential users of the database. In the following list view names as well as themes and data types are indicated by bold italic and normal italic characters, respectively.

Wells (Figure 2)

• Well_archive - Archive wells without geological layers (point)
• Well_mafi - Archive, reinterpreted wells with description of geological layers (point)
• Well_base - Base wells (point)
• Well_hydro - Hydrogeological base wells (point)
• Geo_bn - Map sheet boundary of the geological map (poly)

Geophysical exploration (Figure 3)

• Elec_te - Telluric geophysical measurements (point)
• Elec_mt - Magnetotelluric geophysical measurements (point)
• Elec_tem - Transient electromagnetic sounding (point)
• Magnetic - Magnetic geophysical measurements (point)
• Seismic - Seismic profiles (line)
• Topo_bas - Topographic base (line)
• Topo_bal - Annotations of the topographic base (DGN)
• Geo_bn - Map sheet boundary of the geological map (poly)

Geological map (Figure 4)

• Geol_tek - Tectonic lines of the geological map (line)
• Geol_sol - Polygons of the geological map (poly)
• Geol_dip - Dip of geological layers (line)
• Geol_bn - Map sheet boundary of the geological map (poly)

Geological layers

• Kain_bli - Tectonic lines on the map of the Cainozoic basement (line)
• Palb_sli - Tectonic lines on the map of pr-Albian surface (line)
• Kain_bas - Map of the Cainozoic basement (poly)
• Palb_sur - Map of the pre-Albian surface (poly)
• Geola_bn - Map sheet boundary of the geological layer maps (poly)

Figure 2
Structure of the view Wells

Figure 3
Structure of the view Geophysical exploration

Figure 4
Structure of the view Geological map

Figure 5
Structure of the view Aerial images

Geological thickness maps

• Pola_thc - Isolines of the united thickness of Polány and Jákó marls (line)
• Ugod_thc - Isolines of the thickness of the Senonian Ugod Limestone Formation(line)
• Pola_tht - Tectonic lines of the map of the united thickness of Polány and Jákó marls (line)
• Ugod_tht - Tectonic lines of the map of the thickness of the Senonian Ugod Limestone Formation (line)
• Geola_bn - Map sheet boundary of the geological layer maps (poly)

Geological profiles

• Bas_prof - Location of geological base profiles (point)
• Geol_bn - Map sheet boundary of the geological map (poly)
• Geola_bn - Map sheet boundary of the geological layer maps (poly)
• Aerim_bn - Boundary of the area covered by aerial images (poly)

Aerial images (Figure 5)

• Kalimed.img - Mosaic of 8 aerial images
• Topo_bas - Topographic base (line)
• Topo_bal - Annotations of the topographic base (DGN)
• Aerim_bn - Boundary of the area covered by aerial images (poly)

The pilot area covers 2240 km2. As it can be seen from the above list geological map, geological layer maps and aerial images for the pilot area cover different surfaces. Topographic base has been included in views that are not overcharged with other data.
Joins and links have been applied for acquiring detailed data of the geological profiles of wells as a function of the one-to-one, many-to-one or one-to-many relationship of database records, respectively.

APPLICATION DEVELOPMENT

A specific Avenue application converted to an extension has been set up for representing written documents, tables and pictures attached to geological base profiles and wells. It enables the user to acquire the functionality of a view window for viewing well profiles and photos of well core samples. Clicking on the respective feature on the map for viewing written documents and tables launches the Internet Explorer application featuring the related document in HTML format. Table 3 displays database themes and the related information and format that can be acquired directly through launching the extension.

Table 3

CONCLUSION

The standard 100.000-scale digital geological map database of Hungary set up for the first pilot area is presently being tested by experts inside and outside the Geological Institute of Hungary. On the basis of the comments the final database design of the project will be set up. Certainly, several corrections will be made in order to arrive at the most optimum solution concerning data organisation.
ArcView is a product, very strongly represented in the GIS market first of all because of its ability to GIS data representation, management and analysis on low cost. Maintenance of basic geological data is the responsibility of the Geological Institute of Hungary, therefore it is not our objective to stimulate our customers to modify e.g. the configuration of geological boundaries or the attributes of geological formations. Though the 3.0 version of ArcView supports both, it is primarily foreseen as a tool for analysing existing data. In summary, the philosophy of ArcView supports best our objectives to disseminate and eventually commercialise geological and geology-related data managed in a standard uniform digital geological database.

REFERENCES

• L. Gyalog, F. Síkhegyi et al. (1996) A földtani térképek jelkulcsa és rétegtani egységek rövid leírása (in English: Legend of geological maps and short description of stratigraphic units), Special publication of the Geological Institute of Hungary 187, p. 171. [1]
• P. Scharek, T. Tullner and G. Turczi (1994) - Die Nutzung geographischer Informationssysteme in der regionalen und angewandten Geologie - Zeitschrift für Angewandte Geologie Vol. 40/2 pp. 87-91, Hannover, Germany [2]
• P. Scharek, T. Tullner and G. Turczi (1995) - GIS for Environmental Management in the Little Hungarian Plain (Kisalföld), JEC '95 Conference Proceedings, Vol. 1. pp. 361-367, The Hague, The Netherlands [3]
• P. Scharek, T. Tullner and G. Turczi (1995) - Digging deeper: Hungary’ s Geological Survey increases its GIS activity - GIS Europe Magazine May 1995, pp. 28-30. [4]
• G.Turczi, R. Szeiler, T. Tullner and I. Marsi (1996) - Information support of the radioactive waste disposal site exploration, Annual Report of the Geological Institute of Hungary, 1996/II. (1997), pp. 333-342. [5]