Sayısal Jeoloji Haritaları Ve İlgili Veritabanının Oluşturulmasına Bir Örnek : Batı Karadeniz Bölgesi

Abstract

Bu çalışmanın temel amacı, sayısal jeoloji haritaları ve ilgili veritabanının oluşturulmasında Coğrafi Bilgi Sisteminin önemini vurgulamaktır. Ayrıca yerbilimcilerin karşılaştığı kompleks problemleri anlama ve çözümünde bilgi sistemi oluşturmanın gerekliliği diğer amacını oluşturmaktadır. Bu çalışma altı bölümden oluşmaktadır. Birinci bölümde, bilgi sistemi oluşturmanın gerekliliği ve çalışmanın amacı anlatılmıştır. İkinci bölümde, Coğrafi Bilgi sisteminin önemi, yararlan ve temel kavramlar irdelenmiş, Coğrafi Bilgi Sisteminin bileşenleri ve veritabanı gibi kavramlara açıklamalar getirilmiştir. Üçüncü bölümde ise jeoloji haritalarının tanımı ve yorumlanması kavramlarına açıklık getirilmiş ve jeolojide günümüz teknolojisine paralel gelişen yenilikler tanıtılmıştır. Ayrıca sayısal haritanın tanımı ve sayısal harita üretim teknikleri irdelenmiştir. Dördüncü bölümde, uygulamada kullanılan yazılımlar PC ARC/INFO ve Arc View incelenmiştir. Bu yazılımların uygulamalardaki yetenekleri ve vektöre dayalı bilgi sistemleri içindeki fonksiyonları ele alınmıştır. Beşinci bölüm de, Batı Karadeniz Bölgesi'ne ilişkin bir Coğrafi Bilgi Sisteminin tasarımı ve gerçekleştirilmesi irdelenmiştir. Bu uygulamada Türkiye'de ilk defa sayısal jeoloji haritası üretimi için bir teknik geliştirilmiş, Tüysüz ve diğ. (1998) tarafindan güncelleştirilmiş olan Sinop ve Zonguldak jeoloji haritaları temel harita olarak alınmıştır. CBS ile, büyük miktardaki jeolojik veri bu haritalara tablolar yardımı ile bağlanmıştır. Ayrıca, haritaların yapımında kullanılan kaynakların listesi, detaylı kesitler, fosil listeleri, bazı detay haritalar ve birimlerin saha görünümünü yansıtan fotoğraf vb. veriler haritalara bağlanmıştır. Tüm bu veriler bir CD-ROM içinde kullanıma sunulmuştur. Bu çalışmada hedeflenen amaçlar ve elde edilen sonuçlarla öneriler son bölümde sunulmuştur.

Geographic information systems (GIS) are being used by thousands of companies and universities for the storage, update, manipulate, analyze and display of spatially (geographically) referenced data. Nowadays most geologists have heard of Geographical Information Systems (GIS) but few have made serious use of them. The popular perception that GIS technology has only appeared in the last few years is inaccurate as its origin can be traced back twenty years or so, though it is currently undergoing a period of rapid growth (Wadge and Pearson, 1991). The importance of geographic information systems (GIS) in geological map production has increased recently by the use of the capabilities of information systems. Geological maps show geographic extent of lithologically and chronologically classified rock units. These maps also show different contact relations between the "map units" and their structural features such as strike and dip of the planar and linear features, folds, faults etc. Some other special geological data can be shown on these maps such as age of the map units, engineering properties of the rocks, fossil contents, porosity, permeability, organic and inorganic geochemical analysis, petrographic descriptions etc. In addition to attach such data to the maps in a digital environment, GIS programs allow to produce hardcopy maps. These systems provide powerful tools for integrating and analyzing large data sets of various kinds and origins. On the other hand, such systems allow for the manipulation of data in a scale independent manner. In addition, GIS software includes utilities for placing information into a common projection (i.e., universal transverse mercator [UTM] and datum). One of the most complex and costly data sets to incorporate into these systems is surface geological information (geological maps), which require intense and time-consuming effort to digitize, characterize, and check for quality (Walker, et.al. 1996). If entered thoroughly, that is with each geological contact, rock unit, and structural measurement recorded and assigned explicit geologic attributes, the resulting data sets is accessible to both casual and expert users. In addition, the attributes allow for detailed analysis of the geology. For the last 40 years detailed geological maps have been produced, most of them being 1:25.000 scaled. A considerable information has accumulated, but the task of compilation of 1:500.000 maps is not still accomplished. This project is aimed to update 1:500.000 scale Sinop and Zonguldak sheets in the light of modern data and to produce them as digital geological maps by using GIS programs (PC ARC/INFO and ArcView). A digital geological map is a map which geographic details and explanatory data are recorded in a digital format that is readable by computer. Digital methods are faster and more efficient for the production of geologic maps. Digital maps can easily re-drawn at a different scale or projection than the original, and features on the maps can be easily added, deleted and updated. Geologists are usually concerned with using the digital representation of the geological maps to produce the hardcopy of the geological maps (Raines et. al., 1995). In particular, digital geologic maps are interactive electronic documents that put the geological issues into geospatial frameworks. They blend data display with results of interpretive research. In addition, digital maps can be integrated more easily with other digitally stored data facilitating the application of computer-based analysis techniques. The principal information base for geology consists of geological maps that are used for a wide range of application. In the light of increasing demand for geological information or data which would help fulfill future requirements for geological information or data. The purpose data model for digital geological maps is to provide a structure for the organization, storage, and use of geological map data in a computer. The data model formally defines the grammar of the geological maps. This grammar is independent of the vocabulary of geological maps (Raines et. al., 1995). The basic model for vector GIS breaks down the perceptual and physical reality into three basic data types: l)points, 2)lines and 3)polygons. Map and geographic-related in formation has been organized and grouped in many ways (Dangermond, 1988). A major part of a GIS is the acquisition and conversion of data into coverages. Many times, how the data are to be used in the analysis is not apparent until after the coverages have been created and the limitations determined. The accuracy of the data is one of the factors that determine usability. Every map has inherent error that can compound in the conversion to digital format. Errors can be introduced from the map projection, drafting errors, instability of the media, and the digitizing method. For this project many sources and scales of data were converted to digital format, each with its own accuracy limitations. Increasingly, field geologist are using portable computers to record and store geological data, facilitating generation of working geological maps in the field and, on return to the office, importation of the data into the central database for map production and analysis (Broome et.al., 1993). To maximize the potential benefits of computerization, the geological data must be consistent internally in nomenclature and symbology to allow comparison and analysis of the work of different geologists. Analysis and interpretation of geological data are required for geological mapping, land-use studies, mineral exploration and natural resource management. Digital data management in combination with digital cartography allows rapid map production and revision which in combination with a "maps on demand" distribution system results in map products that reflect the most current geological data and interpretations. Access to digital geological data from a central database also encourages the use computerized analysis and display techniques by facilitating data input thus permitting more time to be allocated to analysis rather than data acquisition and registration. In this study, the design and implementation of GIS has been completed in three stages;. Creation of the geographic database,. Executing query and analysis,. Presenting the results Creation of the Geographic Database The geological maps of Sinop and Zonguldak sheets was taken from Tüysüz et.al. (1998) and they digitized. All the map units were stored as separate coverages. The coverages are; Lithostratigraphic map units as separate layers, faults, folds etc. and topographic data as grids, rivers, roads, points and settlements (Figure 1). The main software package used in this study was PC ARC/INFO,by ESRI (Environmental Systems Research Institute,Inc). For this project, PC ARC/INFO version 3.4 was run on a PC DOS compatible microcomputer. In addition, PC ARC/INFO 3.4 was used for digitizing, editing, and preliminary analysis of data. Manual digitizing was carried out on Calcomp 9500 series digitizing tablets. Other software used in the manipulation of data include the ArcView 3.0, a database manager. Digitizing errors were removed by subsoftware of PC ARC/INFO. This coverages were converted, using the project command, from geographic coordinates to selected map projection coordinate systems supported by PC ARC/INFO. The most common projection used for regionwide covareges of Western Black Sea Region is Universal Transverse Mercator (UTM) zone 36. Errors removed in the coverages have set up topology. Then, all maps were translated into ArcView 3.0 environment. The geologic data were attacted to these maps as tables and links. Color, legend etc. of the all maps were prepared by using ArcView 3.0. Executing Query and Analysis The map databases consist of ARC coverages and supporting INFO files, which stored in a UTM projection. The content of the geologic database can be described in terms of the lines (arcs), areas (polygons) and the point locations (points) that compose the map. After the geographical coverages have been completed, they linked each other. Later, the conditions for the query were determined and the query outputs were obtained. The outputs were stored to form a library for later use. This table was developed by ArcView 3.0 software. Interrogated examples in this study are offered below. You can produce a map that display the shallow marine limestones Createceous age. You can classify magmatic rocks such as environments. You can produce a map that demonstrate the volcanic rocks distribution Permian age Queries can be increased in parallel to above. Queries can be do to used logical operations. Presenting the results All maps were also colored and published by using ArcView 3.0 final maps (Figure 2) and data were presented on a CD-ROM. Results of the study is plotted the requiring scales from plotter. Results of the query can be display on monitor and can be interpreted. The purpose of the thesis is to illustrate the stages of the producing of digital geological map and related database by using PC ARC/INFO and ArcView software, problems faced and their solutions. GIS provides a convenient platform for data collection, organization and research with multidisciplinary data sets. Such a database platform will significantly affect the way we conduct research, teach, and educate future generations of earth sciences. This application can respond timely to a customer's request with the most up-to-date geological map information in either printed or electronic format. 1 ılı JJt i I? Is SMl İ II k|f Kİ n ı!l! 1 T" j.ııiüİ!,, 11*1 UM i mmmw Trr^îTTTl alı M ııiıiiı e iti DBESÎBiIİMDE »illi I J|}JJ ««»-« mas.] nffli 1 ! i I I § ı1 f icllf 1 1 ili lil 01 BDHimFfMiUbWIIMilli H ca § I o o '5b o S 00 Q es t-.