Tomáš Mikita

Topographic Exposure and its Practical Applications

Topographic Exposure and its Practical Applications Topographic exposure is a topographic characteristic representing a degree of protection by a surrounding topography of a certain site. Detailed knowledge of topographic exposure has broad use in a number of applications ranging from studying forest wind damage through research on snow storage dynamics to optimisation in positioning wind power stations. This paper describes a method for creation of topographic exposure on the basis of a digital elevation model (DEM) using GIS. In combination with other climatic data on wind direction and speed, this factor is used to define the degree of terrain ventilation. Low terrain ventilation has, among other things, a significant influence on the creation of valley inversions and related vegetation zoning inversions. By combining the degree of terrain ventilation with DEM and forest vegetation zones in the area of the Training Forest Enterprise Křtiny, a clear relationship between the influence of topographic exposure, or terrain ventilation, and the creation of the vegetation zoning inversion was determined.

Visual Exposure Within the Dolni Morava Biosphere Reserve

Visual Exposure Within the Dolni Morava Biosphere Reserve Impacts on landscape character and tools for the support of decision making in the Czech Republic have always been important subjects in the sphere of landscape character and visual/environmental assessment. Only one publication could be found, however, that dealt with the use of landscape indicators for evaluating landscape character in the Czech Republic. In this study, we add to this by addressing the issue of visual exposure. In this project, we construct and compare two possible alternatives for computing visual exposure using GIS tools. The two alternatives differ in using a regular grid layer of viewpoints or of viewpoints based on actual use of frequented sites. The procedure was verified using the model area of the Dolni Morava Biosphere Reserve. The version based on most frequented sites produced a map with increased areas of visual exposure. This paper also goes on to suggest changes to the present regulations and other practical applications of the method.

Analysis of vehicle movement possibilities in terrain covered by vegetation

Movement in the space is one of the basic preconditions for the tasks fulfilment of armies and rescue units. However one third of European territory is covered by forests. Forest stand is generally considered as a movement obstacle, however there are situation when it is necessary to carry out the movement across it. It is essential to know the information about the trunk density, their thickness, height and other parameters to determine the cross-country movement possibility. The data obtained through the remote sensing methods data collection can be used to the determination of necessary attributes. Comparison of vegetation information acquired imagery and laser data shows that both methods can provide enough quality information for the forest throughput analysis processing.

Possibilities of Forest Altitudinal Vegetation Zones Modelling by Geoinformatic Analysis

Possibilities of Forest Altitudinal Vegetation Zones Modelling by Geoinformatic Analysis According to Zlatnik (1976) there are 10 forest vegetation zones on the territory of the former Czechoslovakia. These are at present being modeled by phytocenological studies using bioindicator species of plants. Their incidence is affected by many abiotic factors, like temperature, precipitation or influence of climatic-inverse locations. By effective modelling of factors affecting the site requirements of bioindicator species, it is possible to make a comprehensive modelling of vegetation zonation. For the process of modelling, however, it is essential to identify the abiotic factors influencing this phenomenon and determine the extent of their influence. Hence, all the selected factors were analyzed using geoinformation tools and then combined with a typological map, which describes, among others, vegetation zonation in forest stands. The outcome of this combination was subjected to discrimination analysis, which identified influential factors and determined the extent of their influence. For modelling forest vegetation zones two methods were tested, first maximum likelihood clasification and second classification function of discriminant analysis in three territories with different reliefs. Both methods create a new raster of vegetation zonation based on geospatial relationship of individual factors and vegetation zones. Match of result models and input typological dates reaches 70 % - 90 %.

Detecting Forest Road Wearing Course Damage Using Different Methods of Remote Sensing

Currently, a large part of forest roads with a bituminous surface course constructed in the Czech Republic in the second half of the last century has been worn out. The aim of the study is to verify the possibility and the accuracy of the road wearing course damage detected by four different remote sensing methods: close range photogrammetry, terrestrial laser scanning, mobile laser scanning and airborne laser scanning. At the beginning of verification, cross sections of the road surface were surveyed geodetically and then compared with the cross sections created in the DTMs which were acquired using the four methods mentioned above. The differences calculated between particular models and geodetic measurements show that close range photogrammetry achieved an RMSE of 0.0110 m and the RMSE of terrestrial laser scanning was 0.0243 m. Based on these results, we can conclude that these two methods are sufficient for the monitoring of the asphalt wearing course of forest roads. These methods allow precise and objective localization, size and quantification of the road damage. By contrast, mobile laser scanning with an RMSE of 0.3167 m does not reach the required precision for the damage detection of forest roads due to the vegetation that affects the precision of the measurements. Similar results are achieved by airborne laser scanning, with an RMSE of 0.1392 m. As regards the time needed, close range photogrammetry appears to be the most appropriate method for damage detection of forest roads.