Small erosional landforms are characterised by a dynamics closely related to the occurrence and changes in precipitation and water flowing down the slopes. Triggered by water, the erosion processes are controlled by the other environmental conditions like slope gradient, lithology, land cover and land use. Studying the changes in the topography gives information about the spatiotemporal dynamics of erosion and can contribute to a more effective assessment of erosion susceptibility and mitigation measures at the earliest stage of the process development. Usually in the initial stages, the changes in the topography are hardly noticeable and using high resolution digital terrain models (DTMs) is of high importance. In this relation, the aim of the current research is to determine to what extent the resolution of the models influences the results of delineating the flow lines, rills and gullies. For this purpose, a terrain survey was carried out and data was acquired by UAS (uncrewed aerial system) DJI Phantom 4RTK. DTMs in horizontal resolution of 0.05, 0.1, 0.2, 0.5 and 1 m are created and analysed. Special attention is given to the analysis of surface curvature as an indicator for flow convergence and divergence. The research is done on a slope area covered mainly by grass and some rare bushes and trees. Despite the observed variations, the results show a general trend of decrease in the flow length with decreasing DTMs resolution. Considering the plan curvature and concave areas, the differences are smallest between the models with cell size 0.1 and 0.2 m.

Erosion processes, triggered by water, occur and propagate on sloping surfaces and have a significant negative impact on the soil quality and vegetation, as well as cause a change of the topographic surface. In the long term, they can lead to an increase in sediment transport, siltation of dams, and higher flood hazard. The development of water erosion reflects on the slope profile and the specific landforms like rills and gullies. In this regard, the geomorphological features of the areas can be considered indicators of the spatial distribution of erosion and accumulation. The sediment properties give information about the conditions of the transport and the intensity of the hydrogeomorphic processes. The current study aims to analyse the short-term changes in erosion and deposition by application of morphometry and grain size analysis. Topographic wetness index (TWI) and cross-section profiles of two small gullies were analysed based on high-resolution digital terrain models (DTMs), generated from unmanned aerial system (UAS) data. Remote sensing was combined with field geomorphological research and sediment sampling. The results of the research show about average 2 cm change in erosion and deposition for the period October 2021 – November 2022. Despite TWI and cross-section profiles depending on the DTMs resolution, they are reliable indicators for erosion and deposition. The grain size analysis supports the morphometric analysis. Coarse to very fine sands are predominant in most cases of sediment sampling. The sorting coefficient shows very poorly to moderately sorted deposits which indicates transport in a more dynamic environment and temporary flow.

Three-dimensional (3D) photogrammetric modelling is a contemporary remote sensing method for generating digital models with their specific appearance and texture, which are used in various areas of life. The modelling of complex geometry objects, such as masonry bridges, is not an easy task, because of their specific features (the presence of arches and various niches). This determines the choice of an adapted capture method according to the individual characteristics of the object. The paper presents research aimed at generating a highly accurate three-dimensional model of a bridge, by combining terrestrial and aerial photogrammetry. A low-cost unmanned aerial system (UAS) was used for capturing the upper side of the bridge. This significantly optimised capture time. But its capabilities do not allow to capture the bridge arches from the bottom upwards, nor to obtain an accurate model of the bridge railing. Because of this, a terrestrial survey was made with a digital camera, thus complementing the information required to generate a comprehensive model of the bridge. The integration of aerial and terrestrial capturing using low-cost cameras and systems, along with the application of modern algorithms for processing, allow to create precise, accurate, and detailed digital models. It is all very important for future conservation, restoration, adaptation, and socialisation of such type of objects which are monuments of culture.

In the process of developing a coal deposit, significant amounts of data and extensive knowledge about the object of operation are accumulated. This data and knowledge may not be structured, not reliable, contradictory. In turn, for the further conduct of the entire complex of mining operations and the development of a coal mining enterprise, structured and reliable data and knowledge are needed. The aim of the study is to propose structuring knowledge about the process of sudden outbursts of coal and gas by presenting knowledge about the subject of research in the form of an elementary knowledge graph. The study is based on an ontological approach to solving the issue of safe mining, namely, to study the problem of sudden emissions of coal and gas from the standpoint of the fact that the release is considered before it has occurred. To solve the existing problem, it is proposed to create an elementary knowledge graph that takes into account geological, hydrogeological, geophysical, mining information about the subsoil use object, as well as geomechanical and geodynamic processes, and physicochemical mass transfer processes occurring in the coal seam and the accumulated experience and knowledge of miners using methods Data mining. As a result of the study, we can conclude that it is necessary to create a network of elementary knowledge graphs, and use other methods of knowledge extraction. For further analysis and refinement of data and knowledge about the process of sudden coal and gas emissions.

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