Morfometrijske značajke šireg područja Duvanjskog polja, Bosna i Hercegovina

The objects of this study are the hillslopes in the broader area of Duvanjsko polje (Bosnia and Herzegovina). Slopes can be defined as relief surfaces determined by geographical position, slope inclination (related with horizontal surface), aspect, and degree of curvature (profile and planar).Recent slope shapes can be defined as results of series of natural and anthropogenic factors during relief genesis and evolution. It is possible to correlate slope characteristics with geological structure and other natural geographic features (climate, soils, vegetation etc.) using geomorphometrical analysis. The main aims of this study are: a) analysis of morphometric relief indicators, b) analysis of relationships between morphometric indicators, structural and lithological features, and c) synthesis of all analyzed indicators in order to better understand exogeomorphological and morphostructural features of the investigated area. The final intention is to assess the extent and intensity of the dominant geomorphologic processes. Special attention was given to the detailed geomorphometrical analysis of morphostructures in the broader area of Duvanjsko polje in GIS environment based on DMR. The applied geomorphometrical relief analysis included the use of different methods for precise calculation of the investigated area’s numerical relief parameters, which enabled a mutual comparison of specified parameters and comparison with tectonic units and lithology maps. The aim of this approach is a more exact analysis and interpretation of morphometric relief parameters as indicators of the investigated area’s endogenous and exogenous processes’ characteristics.


Introduction
This paper focuses on geomorphometrical analysis of certain basic parameters of the broader Duvanjsko polje relief (slopes, aspects, profile and planar curvature) and their importance as endogenous and exogenous geomorphologic processes indicators. The analysis is mostly aimed at hillslopes of inclination > 2° located in the broader area of Duvanjsko polje mountainous rim, but also provides an insight into areas which correspond to the category of slopes with inclinations < 2°, which primarily refers to the Polje itself but also to some lesser terrain shapes outside the Polje.
Geomorphometry is the science of quantitative features of the Earth's surface (Pike et al., 2009). It represents an analytical and cartographic approach in the research of topographical features of Earth as well as an interdisciplinary field that mostly emerged from mathematics, natural sciences and informatics. Considering the object of geomorphometrical research, smaller terrain shapes are the object of specific geomorphometry while the terrain as a whole is the object of general geomorphometry. General geomorphometry is the basis for quantitative comparison of larger terrain shapes and includes methods that are not necessarily geomorphologic (MacMillan, Shary, 2009). This paper employs the principles and methods of general geomorphometry, which applies to computer-based GIS analysis of the broader area of Duvanjsko polje within its observed limits.
Contemporary geomorphometrical analysis, based on GIS methods, refers primarily to the analysis of a digital terrain model (Franklin, 1987;Jordan, Csillag, 2001;Ganas et al., 2005;Smith, Clark, 2005). A digital terrain model is a mathematical representation of the Earth's surface in either raster or vector shape, which also contains various strings of height values. Considering the spatial resolution, there are various raster terrain models, which directly influences the output results' quality and precision. For the purposes of this paper, a digital raster terrain model of Duvanjsko polje and its bordering hillslopes has been created by vectorization of contour lines from topographic maps scaled 1:25,000.
The objects of this research are hillslopes of the broader Duvanjsko polje area. Hillslopes can be defined as terrain levels defined by geographical location, inclination in relation to horizontal surface, aspect in relation to cardinal directions and the degree of curvature (profile or planar). Recent hillslopes' shapes are the result of various natural and anthropogenic factors that have occurred during genesis and evolution of the terrain. By means of morphometric parameters analysis it is possible to establish a relation between hillslope features and geologic characteristics, as well as other natural and geographical factors (such as climate, soil, vegetation, etc.). Numerically expressed morphometric parameters data observed in local context give insight into the effects of exogenous geomorphologic processes while, in the regional context, they give insight into the effects of endogenous (primarily tectonic) morphostructural processes (Marković, 1983).
The aims of this research are: a) the analysis of morphometric terrain indicators, b) the analysis of the relation between morphometric indicators, structural and lithological features, and c) the synthesis of all the analyzed indicators in order to gain better insight into the exogeomorphological and morphostructural features of the observed area, as well as enable an estimation of dominant geomorphologic processes' size and intensity. Special attention was given to a detailed geomorphometrical macro-morphostructures analysis of the broader Duvanjsko polje area in GIS environment by means of digital terrain model (DMR).

The researched area
Duvanjsko polje is a karst polje in the so-called "high karst zone" of Bosnia and Herzegovina (Čičić, 2002). Bosnia and Herzegovina is located in the central Dinaric Alps, and includes some 25% of the overall Dinaric Alps area. So far, as Čičić (2002) and Lepirica (2009)  Što se geotektonskog položaja tiče, situacija na istraživanom području vrlo je složena. Papeš (1985.) izdvaja devet velikih tektonskih jedinica na području "jugozapadne Bosne", od kojih se pet nalazi u neposrednom okružju Duvanjskog polja. Budući da u obzir nije uzeto područje južno od Duvanjskog polja, tektonska regionalizacija upotpunjena je iz Tumača OGK (list Imotski, According to this type of regionalization, Duvanjsko polje, together with its surrounding area, is a part of Outer Dinaric Alps, while the border between Outer Dinarides and Middle Dinarides passes between the Ljubuša and Raduša mountains in the vicinity of Duvanjsko polje. Although different sort of criteria are employed in tectonic units determination, what is unquestionable in the case of Duvanjsko polje is the fact that it is located completely within the region of Outer Dinaric Alps, that is to say within the "high karst zone" (Fig. 1).
Morphologically, the researched area is very heterogeneous. The relative height difference is 839 meters (the lowest point is the bottom of Duvanjsko polje at 855 meters, and the highest point is the Peak of Tušnica Mountain at 1,694 meters). In the surrounding terrain, the most evident formations are the flat and the parts of mountainous range ( Fig.  1). Between Duvanjsko polje and Buško blato at the southwestern part of the researched area Midena mountain is located. It represents a part of the wide Grabovica plateau, made up of various concave (dolines, uvalas and collapse dolines) and convex shapes (interspaces between concave forms) with prominent elongated ridges, stretching from the northwest to the southeast, to Mesihovina (Papeš, Raić, 1968). Southeast from Duvanjsko polje the Vran Mountain is located, with its characteristic west -east orientation and its steep slopes, which are a contact area with Duvanjsko polje.
Located to the south of Vran is the Lib Mountain. There is a very deep river shaped valley, formed after the ice had melted and the karst terrain had corroded, located between the Lib and the Vran Mountain, or between Kongora and Blidinje Lake. Tušnica Mountain is located along the northwestern rim of Duvanjsko polje (stretching from east to west, similar to Vran). The range of Ljubuša is positioned along the elongated northeastern side of the Polje, its slopes representing the contact area with the Polje. Borders between the Polje and its surrounding mountainous rim are not clearly defined at all points. This primarily refers to the hillside southwest from Tomislavgrad, southwestern slopes shaped by Cretaceous sediments at the contact point between Ljubuša and far western part of Vran, and the contact area between the southeastern part of Grabovica and the Polje (Fig. 1).
polje. Considering the fact that his regionalization did not include the southern part of the area researched in this paper, the regionalization has been complemented with Tumač OGK (list Imotski, Papeš, Raić, 1968). The criteria for tectonic units' selection are the following (Čičić, 2002): fault contacts, the shape of folds and faults, facial development of stratigraphic units of the same age, the number of stratigraphic units and their relation (continuity or discordance of sedimentation and stratigraphic voids). Based on the aforementioned criteria six tectonic units of prime importance for the researched area have been isolated: Dinara, Glamoč, Cincar, Malovan, Ljubuša and Zavelim (Fig. 2).
The southwestern border of the Polje, near Grabovica plateau, is stretched almost linearly; along the border, in its southwestern part, layers of limestone descend towards southeast, steeply in the middle section, and in the shape of terraces in the southwestern section. Due to the near-linear direction of the bordering area, as well as the existence of a steep cutoff in the middle section, it can be concluded that the bordering area of the Polje was created tectonically (by sinking); more recent denudation processes have only slightly changed it (Roglić, 1940).
Along the southeastern rim of the Polje, at the topographically clearly defined border, there is a contact between fresh-water limestone and marl layers from Miocene period (Papeš, 1967) covered by a thin layer of soil, along with Cretaceous limestone of Ljubuša. The limestone is covered in more recent layers only near Morkonog; in the middle section, at the Sazlivoda creek near Vedašić, light-gray dolomite from Early Cretaceous period appears along with limestone of the same age.
Borders of the polje at its northwestern and southeastern part are far more complex in terms or morphology and tectonic or petrographic features, with mountainous ranges and surrounding hills shaped like peninsulas protruding into the area (Lib Mountain in the southeast and the hillside near Tomislavgrad in the northwest). Tomislavgrad hills are made up of fresh-water marl, sandstone, clay with coarse sandstone and Miocene conglomerates (Papeš, 1967). These layers are fairly thick.
Tušnica Mountain is the most prominent section of the northwestern part of the Polje. Along with hard gray limestone of Late Cretaceous, Tušnica contains light-red limestone, marl, conglomerates and breccias, which make up its southwestern part. Significant amount of decay and breakage in the rock formations indicate that Tušnica had been an area of strong tectonic movements. The position of fresh-water marl indicates intensive geotectonic movements as well: the layers of Gromila slopes are inclined as much as 45°. The raising of Tušnica Mountain occurred before the second lake-formation period during the transition period between Late and Early Miocene (De Leuw et al., 2011). Water torrents from the zones made novijega poprečnog nabiranja i izdizanja koje je na veće visine izdiglo slatkovodne nanose koji imaju veliki pad prema dolini polja (Roglić, 1940.).
up of light-red limestone, breccias, conglomerates and the remaining marl have formed ravines and accumulated large amounts of rough material in the basins. This all indicates that the northwestern areas of Duvanjsko polje, especially those closer to Tušnica, are the areas of recent transversal folding and raising which elevated the fresh-water layers, which now fall steeply towards the base of the Polje (Roglić, 1940).

Data processing
Data processing was based on the digital terrain model analysis, which, for the purposes of this paper, employed the method of topographic maps' contour lines automatic vectorization. Nine papers of TK-25 maps made by the Military-geographic institution in Belgrade were used, some of which have been vectorized completely and other partially, depending on the shape of the researched area. A DMR of raster GRID structure was made, with a 25 meters pixel size. It is located within a square measuring 26 km from east to west and 26 km from south to north. Considering that the process of model generation usually experiences errors, a smaller error might have occurred in the output data, especially since the data have not been compared to that of other similar models. It is usually assumed that the vertical precision equals 1/4 or 1/5 of the equidistance (Ackermann, 1994), so the vertical precision of the current DMR model is 2-2.5 meters. According to Ackermann (1994), the distance between crucial points can amount to 40 meters at most.

Digital terrain model of the broader Duvanjsko polje area
For the purpose of the researched area's geomorphometrical analysis by means of GIS tools, it was necessary to develop a digital terrain model. The reasons for the DMR development are: unavailability of a more detailed DMR, better quality level compared to the available DMR 1 , and more precise output data. model), ovisno o tome prikazuju li samo reljef ili uključuju biotičke i antropogene sadržaje.
Korištenje alata GIS-a u analizi DMR-a omogućilo je stvaranje novih podataka i njihovu analizu, a izlazni podaci u konačnici su bili precizniji. Generally, a model is an object or a concept used to represent various entities in the geographic space, i.e. a smaller representation of the real situation transformed into an understandable form (Meyer, 1985, cf. Li et al., 2005. Various heightrelated digital terrain models are used for spatial analyses (DEM). Although there is a certain degree of misunderstanding in general terminology, they are usually divided into digital terrain models (DMR) and digital surface models, depending on whether they represent reliefs only or include biotic and anthropogenic elements as well.
The process of digital terrain model generation included the following steps: 1. Scanning of analogue topographic mapsturning maps into a digital format without a spatial reference.
2. Georeferencing and transformation -referential points were taken from topographic maps, which means that the maps were transferred to geographic space. Since the maps were scanned, an affine transformation of first-degree polynomial was used.
3. Vectorization of contour lines and addition of attributes (height data from topographic maps) -automatic vectorization included removal of noises, thinning, nodes improvement, and segment merging and topological reconstruction.
4. TIN development -a vector terrain model, which is made up of points, lines and triangles, and represents a base for raster terrain model development. Based on the crucial points (an integral part of a contour line), an irregular triangulation grid was constructed.
5. DMR development -a raster terrain model. Digital terrain model is a basic acronym used in literature that refers to GIS, remote research and similar fields. DMR represents the shape of the Earth's surface, but without vegetation or anthropogenic activity products. Therefore, DMR only shows the "basic" or "naked" Earth's surface, i.e. relief.
The usage of GIS tools in the DMR analysis enabled new data creation and analysis, while the output data turned out more precise.

Visualization of the calculated data
All the cartographic addendums represent visual results of the digital terrain model analysis. In this paper, a number of visualization techniques were used to display the results: 1. Color selection for individual classes 2. Optimization of the output data's cell representation within the raster, which employed the "cubic convolution" method 2 3. The obtained results' overlap (at 30% transparency level) and terrain shading in order to create a more plastic relief impression and determine relations between the quantitative parameters and terrain morphology.

Slope analysis
Relief can be defined as a combination of hillslopes of various inclination categories (Bognar, 1990). Large parts of the Earth's surface are made of various types of slopes created by both endogenous and exogenous processes. This research applied the comprehensive approach, i.e. morphometric analysis of micro-relief shapes was not as important as macro-geomorphologic relations within the complete researched area were. Spatial distribution and specific slope categories coverage analysis is important since they represent significant indicators of the size and intensity of morphostructural and exogeomorphological processes (denudation or accumulation). These processes have affected the slopes' morphogenesis during the paleo-geomorphological period and their analysis indicates future effects of the aforementioned processes on relations between terrain raising and sinking, i.e. denudation and accumulation and their characteristics (Tab. 1).
The change rate directed towards the x-axis for e.g. "h e " is calculated using the following algorithm: The rate of change towards the y-axis for e.g. "h e " is calculated using the following algorithm: By calculating the change rates in x-and y-directions, the "h e " cell inclination is then calculated as follows: Geomorphologic classification of slope inclination has been used in order to simplify data analysis and display (Tab. 1).
Slopes with less than 2° inclination are predominant in the largest part of Duvanjsko polje and therefore have the largest spatial coverage (35.2% of all the slopes, Tab. 2). However, smaller areas of identical slope inclination also appear in the bordering mountains. They are primarily present in the corrosion plateau of Podine, from Mokronoge to Lipa, at certain plateaus of Ljubuša Mountain, and on the Grabovica plateau (Fig. 5).
The second inclination category (2-5°, 13.58%) is mostly present at contact sections between the Polje and surrounding areas, where there is a mild transition from the Polje to steeper mountainous rim covered in colluvial and diluvial layers (Tab. 2, Fig. 5). At the edges of the Polje such inclinations appear most frequently north of Tomislavgrad, where the Polje gradually shifts into hillside, and in the bordering area near the village of Bukovica, where layers gradually rise into Midena Mountain. In addition, great portions of Ljubuša and Grabovica plateau belong to this category. These types of slopes are present in Ljubuša basins, which were seasonally populated and agriculturally used during the summer period in the past. Areas that also belong to this inclination category are the mildly inclined northwestern slopes composed of Cretaceous rocks near the contact area between Ljubuša and far western part of Vran Mountain, 3 Geomorfološka klasifikacija nagiba padina, temeljena na dominantnim morfološkim procesima koji se aktiviraju ovisno o veličini nagiba, kao i odgovarajućim reljefnim oblicima, prihvaćena je od IGU-a (International Geographical Union, 1968.).
3 Geomorphologic classification of slopes, based on dominant morphological processes which are activated in relation to inclination, as well as related terrain shapes, has been approved by IGU (International Geographical Union, 1968).
Most areas of Ljubuša Mountain and Grabovica plateau belong to this category as well. On Ljubuša Mountain, these slopes appear in uvalas, which in the past were seasonally populated and agriculturally used during the summer. Within this slope category are the low-inclined northwestern slopes of Cretaceous period in the contact area between Ljubuša Mountain and far western Vran as well as the contact area between southeastern part of polje and Vran, and the lower parts of Tablica 1. Geomorfološka klasifikacija nagiba  (Fig. 5).
Inclinations between 5° and 12° are the second most frequent, following the < 2° category and making up for 26.39% of the total surface (Tab. 2, Fig. 5). They are almost evenly distributed along the entire mountainous rim of the Polje, mostly at lower parts of the slopes or at limestone plateaus of Grabovica, Ljubuša and Lib Mountains (Fig. 4).
Regarding the highest inclination values, 32-55° inclinations most often prevail in higher parts of slopes near mountain crests (with the exception of areas with significant fault tectonics near Tušnica and Jelovača, where this category appears in lower parts of slopes as well) and near the canyon sides of Šujica. During the field research, highest category inclinations (> 55°) were recorded on a Lib Mountain cliff near Borčane (Fig. 5, Fig.  6) and, in places, on very steep sides of collapsed dolines on Grabovica plateau (Fig. 5).

Aspect analysis
Aspect can be defined as slope orientation in relation to cardinal directions. Orientation angle is usually measured clockwise from the north. Conceptually, the function of aspect is the calculated aspect value of a central pixel in relation to its eight neighboring pixels within a 3x3-pixel grid. The direction to which a surface is orientated represents the aspect of the central pixel (Burrough, McDonnell, 1998 Stopa promjene u x smjeru za ćeliju "h e " izračunava se sljedećim algoritmom: Stopa promjene u y smjeru za ćeliju "h e " izračunava se sljedećim algoritmom: Uzimajući stopu promjene u x i y smjeru za ćeliju "h e " ,ekspozicija se izračunava pomoću algoritma:
In accordance with the apparent motion of the Sun across the horizon during the day or different seasons, the intensity of shortwave radiation on hillslopes changes as well. On the northern hemisphere, most of the radiation is received by southern hillslopes and the least by northern. Generally, eastern and western slopes are less exposed than southern slopes but more than northern; eastern slopes receive most of the radiation in the morning and the western slopes in the dusk (Šegota, Filipčić, 1996). The influence of aspect on geomorphologic processes is very important since differently exposed slopes receive different shortwave radiation, which affects the climate elements as exogenous and geomorphologic agents.
In the researched area, aspects indirectly influence the changes in denudation, corrosion and sedimentation of slope material, as well as hydrological processes on the slopes. For example, an increased amount of shortwave radiation on the slopes exposed to the southern quadrant (southwest, south and southeast) directly influences evaporation and transpiration increase, which leads to water shortage during the dry season (especially on limestone-based areas), and the result is a decrease in the plants' number and size on the slopes, i.e. much scarcer vegetation. Scarce vegetation enables more rapid loss of water from the soil and greater surface drainage, which intensifies the denudation process. On northern slopes, the moist is contained in the soil for longer periods of time, which positively affects vegetation development and provides more acceptable conditions for creation and development of soils. Long term processes of soil wash, amongst other denudation processes, can result in increased inclinations in higher parts of slopes (more intense denudation) and decreased inclinations in lower dijelovima (pojačana sedimentacija) (Kirkby, 2004.), što se može uočiti na primjeru zapadno eksponirane padine na planini Lib iznad Borčana, uz JZ dio Duvanjskog polja (Sl. 6.).
On the aspect map (Fig. 8) it is noticeable that most of the Duvanjsko polje area does not feature any significant aspect, meaning it is almost flat (with a very small downward slope from the northwest to the southeast, where the lowest point of the Polje, the Šujica river ponor, is located).
4 Increased inclination is evident in higher mountain areas and sedimentation in the lower areas. This is combined with prolonged processes of soil wash, creep and collapsing, enhanced by lithological features and significant daily and seasonal temperature amplitudes. 5 General aspect aptitude: N = cold aspect; NE and NW = moderately cold aspect; E and W = neutral aspect; SE and SW = warm aspect; S = very warm aspect. of the southern quadrant with warm and very warm orientation (southeast, south and southwest) make up for 46.22% of the total area. Those are the areas of Ljubuša Mountain, south and southwest slopes of Vran opposite to southeast and east slopes of Lib, southwest and south slopes of Lib, Mesihovina, large parts of Grabovica plateau, and southern slopes of Tušnica and Jelovača (Fig. 8).
A smaller portion (31.90%, Tab. 3, Fig. 8) refers to slopes with moderately cold and cold aspects (northwest, north and northeast), such as the far northeastern slope of Grabovica plateau, which mostly descends steeply toward the Duvanjsko polje. In addition, large areas with such aspect are present on the slopes of Vran, opposite to Ljubuša, the slopes of Mesihovina opposite to Lib and in some parts of Tomislavgrad hills, and Tušnica and the central part of Ljubuša (Fig. 8).
S matematičkog aspekta, zakrivljenost se definira kao odstupanje geometrijskog objekta 3. Slope curvature analysis The notion of slope curvature refers to its geometric shape. The shape of a slope is a result of denudation and accumulation processes caused by endogenous and exogenous geomorphologic factors.
Convex slopes (or their parts) are indicators of positive tectonic movements (rising), related to domination of denudation, the intensity of which increases with increase in slope length. Linear slopes or their parts indicate spatially balanced conditions for denudation, e.g. the slope retracts in a parallel way, or the material shifts evenly across the slope. Concave slopes (or their parts) are indicators of negative tectonic movements (sinking) related to increased amount of accumulated slope material (Dikau et al., 2004).
During DMR analysis a number of curvatures' values was calculated, from which three types of slopes were determined: concave, convex and linear. The choice of a method for defining curvatures represented a significant problem. Dikau (1989) considers slope curvatures of radius greater than 600 meters (k > 0.001666) on a 20 meter resolution model negligible and categorizes them as linear. Analogously, in models with resolution greater than 25 meters, slopes with radius greater than 750 meters are considered linear.
Limiting values are defined as follows: Curvature analysis points to characteristics and intensity of processes that cause changes in slopes' (or their parts) appearances. Such analyses, especially profile and planar curvatures analyses, indicate the areas in which changes in inclination values occur relatively fast. In geomorphologic research, these types of analyses can be employed to calculate and evaluate endogenous (raising or sinking) and exogenous geomorphologic processes' trends, such as soil wash and sedimentation (via planar curvature), enhanced denudation, and more resilient rock formations identification (via profile curvature) (Kennelly, 2009).
Profile curvature refers to slope (or parts of slope) curvature along the lines perpendicular to contours and it is used to define the inclination change rate for each pixel. Negative values point to a convex longitudinal slope profile, while positive values indicate concave profile. The zero value points to a linear slope (Fig. 9). Profile curvature influences the speed of water flow and the speed of detritus movement down the slope.
On the profile curvatures map (Fig. 10) it is noticeable that convex slopes dominate higher parts of mountains, especially near the ridges and some parts of hillsides (Lib, Mesihovina, western part of Vran Mountain, Tušnica and tertiary Tomislavgrad hills), near the steep cliff peaks of the Grabovica plateau at the southwestern part of the Polje, and on the entire Grabovica plateau. In the case of Tušnica, correlation with geological data indicates intensive positive neotectonic movement, which is supported by fresh-Slika 9. Profilna zakrivljenost (URL 1) Figure 9 Profile curvatures (URL 1) Tablica 4. Tipovi i prostorni obuhvat profilne zakrivljenosti Za razliku od konveksnih, konkavne padine dominiraju na nižim dijelovima padina, uz rasjedne linije na cijelom istraživanom području, te uz niže dijelove bočnih strana jaruga planinskih masiva (Sl. 10.). To se može uočiti na nižim dijelovima uz kanjon Šujice, uz rasjednu liniju water Miocene marl position in higher areas. Morphological processes' characteristics, shapes and inclinations of slopes are in accordance with the aforementioned. In addition, relatively large areas of convex slopes are located in southeastern parts of Ljubuša Mountain, following the tectonic structures curve from northwest -southeast to west -east direction. An especially prominent zone of convex slopes stretches along higher parts of the linearly elongated "Greda" (The Wall) along the southeastern part of Duvanjsko polje, and along higher parts of Šujica canyon sides in the northern part of the researched area (Fig. 10).
Unlike convex slopes, concave ones mostly dominate lower parts of slopes, along the fault lines in the entire researched area and in lower parts of mountain valleys lateral sides (Fig. 10). This is particularly noticeable in lower parts of Šujica Slika 10. Karta profilne zakrivljenosti padina Figure 10 The map of profile slope curvature koja razdvaja Tušnicu i Jelovaču, uz rasjed između sjevernih dijelova zapadnih padina Vran planine i Ljubuše i uz rasjed koji se lučno proteže cijelim središnjim područjem Liba u smjeru SZ -JI.
Profile linear slopes are most frequent near the geologically new, Tertiary Tomislavgrad hills closer to the Polje at all the observed height levels i.e. they do not show a specific pattern of vertical occurrence (Fig. 10). They can also be found in the far southeast part of the Grabovica plateau, which gradually descends towards the Polje, on lower levels of Lib Mountain western slopes and the lowinclined (2-5°) northwestern slopes of Cretaceous period at the contact between Ljubuša and far west end of Vran Mountain.
Planar curvature denotes a slope's curvature on the secant line perpendicular to direction of the greatest inclination. A positive value indicates a convex shape of the slope, while negative indicates a concave shape. A zero value indicates a linear slope (Fig. 11). If the given direction is perpendicular to the direction of the greatest inclination (the horizontal secant line of a contour line), then, using the slope curvature model, it is possible to evaluate divergence (convex slopes) or convergence (concave slopes) of a hypothetical water flow (and, by extension, local water flow features and soil humidity) (Antonić, 1996). Convergent flow is related to water, soil and detritus accumulation processes, while divergent flow is related to the processes of soil wash, creep, sinking and gully erosion.
From the data that refer to the planar curvature (Tab. 5) it is evident that convex and concave slopes dominate, when compared to linear ones, in all of the researched area. Convex slopes are predominant (52.10%), even compared to concave slopes (44.04%). Linear slopes make up a very small portion of only 3.86%. This means that Slika 11. Planarna zakrivljenost (URL 2) Figure 11 Planar curvatures (URL 2) cijelog područja prisutna dominacija divergentnog u odnosu na konvergentno otjecanje površinske vode odnosno denudacijskih procesa u odnosu na akumulacijske.
Areas of pronounced divergent flow are noticeable on the planar curvature map (Fig.  12). This primarily refers to peaks and ridges between gullies on mountains slopes on all the observed height levels. Wider areas of planar convex curvature are especially pronounced around Tomislavgrad hills dating from Tertiary and southern slopes of Tušnica, which can be related to their lithological structure. In fact, in their base these areas consist of conglomerates, sandstone and marl, marl with conglomerates, and marl limestone from Paleogene and Neogene, which are more susceptible to denudation. Also, wider areas of this planar curvature type are found in western areas of Lib Mountain, in higher parts of far southeast slopes of the Grabovica plateau oriented towards the Duvanjsko polje (in which 32-55° inclination category prevails), and on Vran Mountain.
Interchanging zones of convex and concave planar curvature can be found in great portion of the researched area, with approximately the same ratios. This is especially evident on the Grabovica plateau and in parts of Ljubuša Mountain closer to Duvanjsko polje (Fig. 12).
Domination of concave slope curvature is characteristic for limestone plateau area between the Lib Mountain central ridge and its northeastern slope, and for the limestone plateau area in the eastern part of Ljubuša Mountain located farther away from Duvanjsko polje. The reason for this Tablica 5. Tipovi i prostorni obuhvat planarne zakrivljenosti probably lies in greater density of dolines and lesser number of uvalas in such areas (as opposed to the Grabovica plateau, which features a greater number of spacious uvalas as well as dolines), which results in a smaller number of convex surfaces with divergent water flow in between dolines (Fig. 12).
Planar linear curvatures show similar spatial distribution as profile curvatures, i.e. they can be found in Tertiary areas of Tomislavgrad hills (primarily near the areas closer to Duvanjsko polje), in far southeast parts of Grabovica plateau, on lower levels of western Lib Mountain, and on northern slopes of western Vran Mountain, near the contact zone with Ljubuša (Fig. 12). Slika 12. Karta planarne zakrivljenosti padina Figure 12 The planar slope curvature map

Discussion
The morphometric terrain analysis used in this research included a number of different methods for precise calculation of the researched area's numeric relief parameters, which enabled relative correlation of those parameters as well as correlation with the map of tectonic units and geological map. The aim of this approach is a more exact interpretation of morphometric terrain parameters as endogenous and exogenous processes indicators in the researched area.
The researched area is dominated by slopes with < 2° inclination, which are the result of mostly flattened terrain of Duvanjsko polje. Smaller, isolated areas belonging to this category are found within the mountainous rim of the Polje, on corrosion terraces, plateaus, higher parts of mountains and mountain ridges, and, finally, dolines. The portion of 5-12° and 12-32° categories, which can primarily be found at mountain slopes (especially near the contact zones with the polje), is rather significant. As the height increases, categories of 12-32° and > 55° occur more frequently. Near dominant active fault lines category of > 55° sporadically appears and can be found on canyon slopes (Šujica canyon and southeast Kongora area) and along sides of karst dolines and uvalas (the Grabovica plateau).
Domination of southern slope aspects (southwest, south and southeast) due to higher daily and seasonal temperature amplitudes points to positive conditions for exogeomorphological destructive processes emergence and development in most of the researched area. In addition, long-term shortwave radiation on southward exposed slopes indirectly affects evaporation and transpiration increase as well as water shortage (especially in areas with limestone in their base), which results in the decrease of plants' size and number on the slopes, i.e. scarcer vegetation.
As for planar curvature characteristics, domination of convex slopes is even more evident in comparison to concave ones, which indicates intensified activity of exogenous morphological destructive processes in comparison to accumulation processes. Areas with greater proportion of planar convex curvature are most prominent around Tomislavgrad Tertiary hills, Tušnica and Vran Mountain, which leads to conclusion that in those areas exogenous destructive processes are very prominent. This is further reinforced by the areas' lithological structure i.e. large proportion of dolomite (Tušnica and Vran) and marl conglomerates (Tomislavgrad hills), along with greater inclinations (Tušnica, Vran) and/or the southern quadrant aspect. Similar to profile curvature characteristics, the planar curvature is also rather complex in the entire researched area and requires further analysis and comparison at smaller orographic and structural units' level.

Conclusion
Applicability of morphometric analysis used in this research is based on its synthetic character, since all the morphometric, lithological and structural parameters, as representatives of endogenous and exogenous morphological processes' influences, have been mutually related. This enabled the identification of certain areas of various endogenous and exogenous morphological processes, while correlation with geological and lithological maps enabled additional verification of the results related to the aforementioned processes' features. In this manner, it is possible to evaluate the recent condition of the relief's dynamic stability, which can be of great practical importance for almost all aspects of anthropogenic activities in the researched area.