GIS ASSIST IN THE FROST-RIVEN CLIFF INVESTIGATION. Aleš Létal 1, Marek Křížek 2

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1 Geographica 36, GIS ASSIST IN THE FROST-RIVEN CLIFF INVESTIGATION Aleš Létal 1, Marek Křížek 2 1 Department of Geography, Faculty of Sciences, Palacky University of Olomouc Head of department: Ass. Prof. RNDr. Miroslav Vysoudil, CSc. 2 Department of Physical Geography and Geoecology, Faculty of Sciences, Charles University in Prague Head of department: Prof. RNDr. Jan Kalvoda, DrSc. Received August, 5; accepted September 10, 2000 KEY WORDS: spatial modelling, DEM, frost-riven cliffs ABSTRACT Paper gives a concrete example to show how to apply GIS methods and to reveal possible interactions between certain relief forms presence and chosen relief characteristics. 1. INTRODUCTION More a wish than a reality is to involve GIS under our conditions into basic research, especially into geomorphology. This article gives a concrete example to show how to apply GIS methods and to reveal possible interactions between certain relief formations presence and chosen relief characteristics. In this case the SW part of the Hostýnské vrchy Hills Rusavská hornatina Mts. was chosen. Hostýnské vrchy Hills present the western part of the Hostýnsko-vsetínská hornatina Mts. Especially the steep northern slope, being formed by the Magura nappe being put on, is very marked (Fig. 1). Recently a detailed geomorphological mapping has been finished in this region. This mapping revealed an extensive occurrence of periglacial relief formations, we were especially interested in tor-like forms. In most cases these tor-like forms could be defined as frost-riven cliffs. Frost-riven cliff forms can be defined as a steep edge (bedrock step) with debris material which have been loosened from the underlying solid bedrock. These deposits are built out of frost-broken fragments (Fig. 2). These forms originated in the cold period at the end of the Pleistocene (Riss, Wűrm) and they witness intense periglacial processes taking place in Quarternary cold periods. Permanent contentions are still made on these formations, their classification, origin, development and other characteristics. From that reason we have decided to put these formations under a microscope, taking relief and bedrock features into consideration. The characteristics we have discovered might help explain more accuratelly these problematic forms occurring not only in our mountain ranges but also anywhere else in Europe and the world. Above all it is important to quantify the relief features which had a direct influence upon given formations during their rise and genesis. The initial question is what predetermines the landscape occurrence of these formations and also what factors and characteristics are responsible for their existence. These formations originated in the Pleistocene and recently in our latitudes they can be found as disharmonic formations not coresponding to existing humid climate. They have been remodeled by recent geomorphological processes corresponding to our temperate humid zone. In addition a lot of frost-riven cliffs were been influenced or even destroyed by anthropogenic activities. On the other side some activities can be observed among some frost-riven cliffs, especially those in higher altitudes i.e. in Hrubý Jeseník Mts., Králický Sněžník Mts. Such activities are linked with short-time periglacial conditions effect which apparent mainly in winters. For GIS analyzing processes we need a database, as precize as possible, as a source for future analyses. For the given purpose a spatial database consisting of individual layers with a particular phenomenon important for the detailed research was created. Spatial analysis software is substantial as well. For our analytical purposes we have used products made by ESRI (Arcinfo , Arcview 3.1, Spatial Analyst, 3D Analyst). The occurrence of frost-riven cliffs is conditioned by certain dependencies. Being the facts discussed, some dominant factors determining the existence of a formation were set. On the basis of these facts the spatial database necessary for creating a spatial model was established.

2 42 Acta Universitatis Palackianae Olomucensis Facultas Rerum Naturalium Fig. 1: NW part of the Rusavská Hornatina Mts. Photo by Marek Křížek Fig. 2: Frost-riven cliff (832 m a.s.l.) in the Rusavská hornatina Mts. Photo by Marek Křížek

3 Geographica 36, DATA STRUCTURE Geological data Aparently from the picture especially the geological component is substantial. From that reason basic geological maps (1:25 000) were transformed into their digital output. Digitalization was used as a method for such transformation and when the topology was set, the individual objects were given relevant codes according to the key. This procedure resulted in 2 layers, rocks (the polygon layer) and faults (the line layer). Topography and relief Concerning the area topography it was necessary to find as many relief features as possible that might have a possible influence ot the rock formation occurrence. One of these features were erosion grooves (ravine, gullies, terrain steps etc.). From a map we have created a layer of these formations by using the method of digitlization. From a simple analysis we have concluded that there was no connection between these landscape elements and the rock formations (frost-riven cliffs). These forms are much more younger and their location copies low resistance rocks occurrance. To get detailed relief characteristics we used morphometric relief features, such as slope, orientation, exposition or curvature. We have created a Digital Elevation Model (DEM) for these purposes. Resulting DEM (TIN) structure was generated out of contours (general interval 10m). It was necessary to provide a contours generalization because of the fact that some maps had due to the relief členitost contour interval 5 or in different cases 2 metres. For DEM we have created a coincident interval. The resulting TIN was transformed into grid format (2 meters resolution). Such format was chosen in consideration of the analysis width and the data visualization (histograms, zone statistics et.). Two metres resolution was also chosen with respect to the rock forms size. Climate Climatic factors were the leading factors without which the studied forms would not come into being. Although several authors suppose the winter climatic conditions in our mountain ranges to be the same or similar to those when these formations have been formed (J. Demek, 1969), there was not enough material to include such factor and only one feature analysis (aspect) was used. That is because it is rather difficult to define the Sun altitude and its daily sky movement with respect to the era when these forms came into existence. It is also necessary to take other Earth orbital elements into account because these elements resulted in a solar constancy change that caused climate fluctuations. Also this factor will certainly be analyzed in a detailed way and possibly included into the models. 3. SPATIAL MODELLING The procedure of modelling corresponded to basic methodic procedures of spatial modelling as being classified and defined by Yue-Hong Chou (1997). The spatial database, used as a background for the model, was described in the previous text. According to Yue-Hong Chou (1997) it is necessary to take into consideration several problematic questions and to set criteria and model components for the creation of the model itself. The author devides spatial models into 4 categories (ranks). Three of them will be used in our research. Single model types reassume during the modelling and this scheme will be followed. The first type is a descriptive model which helps to find out chosen variables parametres. First of all we have analyzed the spatial location of the objects in the given area. Descriptive model In the beginning of every modelling it is necessary to set units of the model and especially model borders and its resolution on the basis of the units. With regard to the size and space of the modelled phenomenon we have accepted for our model purpose metres as a general unit. The model borders comes from physical-geographical units borders set on the basis of water-shed lines completed with the border proposal. The complete acreage of the model area is 62 sq km as being found out by (polygon size without the use of DEM). 4. RESULTS FOUND OUT BY USING THE DESCRIPTIVE MODEL Geology Within the framework of the geological part the object occurrence in individual rock types was analyzed. The occurrence of these formations is linked with 4 rock types. Because of the legend being set together differently and also different rock types codes between the two used maps 1: the analysis was carried out for the northern and the southern part separately. In the northern part the formations prevail in the rocks of the rusavské vrstvy layers with sandostone and conglomerate beds, in a lower extent the hostynské vrstvy with pelite and psamitt beds. The occurrence of these formations in the deluvial loam-petrean sediments means either a wrong formation classification or geological map inaccuracy or another cause. This investigation must be verified by a field revision. Other objects will be selected out and they will undergo field comparison or reevaluation. Quite interesting might be found a certain dependency on the total occurrence orientation of the objects in space. As shown in Fig. 3 there is a direct connection with the main faults direction (SW-NE). This fact is completely clear in our case and it refers the relief formations to be predetermined by those structures and even copy slight curvatures.

4 44 Acta Universitatis Palackianae Olomucensis Facultas Rerum Naturalium Fig. 4: Relationship between an exposition and a number of rocks Fig. 3: The location of faults and investigated forms in the SW part of the Hostýnské vrchy Hills (Rusavská hornatina Mts.) Morphometry Morphometric area characteristics are the most difficult part of the model for a dependency definition probably. General area parametre were counted up from TIN: horizontal area acreage 62 km 2 average altitude 510 m a.s.l. highest altitude 864,7 m a.s.l. lowest altitude 350 m a.s.l. the frozen-riven cliffs occurrance is limited by the lower limit 438 m a.s.l. Fig. 5: Relationship between a slope inclination and a number of rocks Also remaining layers defining the morphometric characteristic (slope, aspect). These layers were compared by using a simple analysis with the rock formation layer and results can be seen in Fig. 4, 5 In contrast to geology it is rather problematic to verify the data concluded from the created DEM. Recent discussions on methods for finding out the accuracy and the sensitivity of DET still take place. There are even several algorithms created just for these purposes. For the future research it will be necessary to evaluate the created model. The results will certainly be presented in a similar way. In the case of morphometric terrain characteristics the analyses were only focused on the orientation and inclination dependency. Grid layers with the same resolution (2m) were for the purpose of the study generated out of the created DEM as slope, aspect (3D analyst) and curvature of the Earth information (CURVATURE, ARCINFO ). All of these layers underwent so called summarize zone and the results are shown in Fig.4,5. By the analyses of the orientation and rock formation occurrence, we have found out slight prevalence of the object presence on the surfaces with no orientation. Also the sensitivity to E-W and neighbouring directions orientation is significant. Such dependency can be derived from the prevailing fault orientation (Fig. 2). It is directly supported in Fig. 4. As for the inclinations an interesting result have been made in the fact of a limited rock formations occurrance in the 5 15 degrees interval. To find out the curvature of the surface (acute, obtuse, flat) the CURVATURE command was used. We will not mention the methodology since being described by Moore (1977). The values reckoned in this way vary from 4 (extremely konvex) to 4 (extremely koncave). Values between are considered as flat. In our case we have extended the interval to 1 1 (keeping the same intervals).

5 Geographica 36, CONCLUSION By summarizing the achived results we can conclude that the geological conditions (structural dependency) are the main factor influencing the rock formation occurrence in the Hostynské vrchy Hills area. The data as being figured out of the DEM revaled a marked rock formations occurrance orientated towards the western and eastern quadrant. This phenomenon is conditioned by the course of ridges which is influenced by the Magura nappe. Considering the terrain inclination the occurance of these formations prevails in the inclination, the terrain curvation parametres revealed the rock formation occurence linked to acute shapes. The study has only showed the first degree of the possible spatial modelling without a greater use of statistic functions. This topic will be subjected to future research and from that reason it will be linked to the previous results. We will also verify some features in the field and incorporate the second degree into the modelling with the map background application (ZABAGED 1, digital geological maps), an explaining and especially predictive model. SUMARY Spatial modelling in GIS is the new dimension in the physical geography investigation. In our research we were applied GIS tools for spatial modelling. The main emhasis in our research was oriented to establish the predominant conditions for frostriven cliffs location. The results of this general research will be used as a base platform for the next stage of the spatial analyzing these phenomena. REFERENCES Demek, J., Novák, V., et al. (1992): Vlastivěda Moravská Neživá příroda, Muzejní vlastivědná společnost v Brně, 242 pp. Demek, J. (1969): Cryoplanation terraces, their geomorphlogical distribution, genesis and development, Rozpravy ČSAV-Academia, Praha, 80 pp. Demek, J. (1984): Fossil periglacial phenomena in Czechoslovakia and their paleoclimatic evaluation, Scripta facultatis scientiarum naturalium, Universitatis Purkynianae Brunensis, Univerzita J. E. Purkyně, Brno, Vol. 14, No. 7, p Embleton, C., King, Ch. A. M. (1975): Periglacial geomorphology, Butter&Tanner LTD., London, 203 pp. Křížek, M. (1999): Povrchové a podpovrchové jevy na Čecheru v Hostýnských vrších. Geografie Sborník ČGS, Vol. 104, No. 3, p Moore, I. D., Grayson, R. B., Ladson, A. R. (1991): Digital terrain modeling: A review of hydrological, geomorphological and biological application. Int. J. of Hydrological Process. Vol. 5, No. 1, p Yue-Hong C. (1997): Exploring Spatial Analysis in Geographic Information Systems, OnWord Press, Albany, 476 pp. Mgr. Aleš Létal Department of Geography Faculty of Sciences Palacky University in Olomouc Tř. Svobody Olomouc Czech republic LETAL@RISC.UPOL.CZ Mgr. Marek Křížek Department of Physical Geography and Geoecology, Faculty of Sciences, Charles University in Prague Albertov Praha 2 Czech republic KRIZEKMA@NATUR.CUNI.CZ Reviewed: Mgr. Jakub LANGHAMER, PhD. SOUHRN Prostorové modelování v GIS přináší novou dimenzi do fyzickogeografického výzkumu. V našem projektu jsme aplikovali především nástroje GIS pro prostorové modelování. Hlavní důraz byl kladen na zjištění dominantních podmínek pro výskyt mrazových srubů. Výsledky šetření budou následně použity v dalších stupních prostorového modelování těchto jevů. Acta Univ. Palacki. Olomuc. Fac. Rer. Nat. (2000), Geographica