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Several methods allow accurate measurement of terrain surface motions. Global navigation satellite systems (GNSSes) and interferometry with synthetic aperture radar (InSAR) stand out in terms of measurement accuracy among them. In principle, both methods make it possible to evaluate a three-dimensional vector of the motion of points on the terrain surface. In this work, we dealt with the evaluation of motions in the up-down (U-D) and east-west direction (E-W) over underground gas storage (UGS) from InSAR. One crucial step in breaking down PSInSAR line of sight (LOS) measurements to U-D and E-W components is getting time series derived from individual tracks to the same time frame. This is usually performed by interpolation, but we used an innovative approach: we analyzed individual time series using the Lomb-Scargle periodogram (LSP), which is suitable for periodic noisy and irregularly sampled data; we selected the most significant period, created LSP models, and used them instead of the original time series. Then, it was possible to derive time series values for any arbitrary time step. To validate the results, we installed one GNSS receiver in the Tvrdonice UGS test area to perform independent measurements. The results show a good agreement in the evaluation of motions by both methods. The correlation coefficient between horizontal components from both PSInSAR and GNSS was 0.95 in the case of the E-W component, with an RMSE of 1.75 mm; for U-D they were 0.78 and 2.35 mm, respectively. In addition to comparing the motions in the U-D and E-W directions, we also created a comparison by converting GNSS measurements to a line of sight of the Sentinel-1 satellite to evaluate the conformity of InSAR and GNSS measurements. Based on descending track, the correlation coefficient between LOS from both methods is, on average, 0.97, with an RMSE of 2.70 mm. Web of Science 14 19 art. no. 4898

The space–time series carry information on temporal and spatial patterns in observed phenomena. The reported research integrates computational, visual and cartographic methods to support visual analysis of space–time series describing terrain surface movement. The proposed methodology for space–time series visualisation can support their analysts in investigating space– time patterns using transformation, clustering, filtration and visualisation. The presented approach involves spiral graphs for representation time dimension and cartographic visualisation through proportional point symbol map for representation of spatial dimension. The result is an intuitive visualisation of space–time series, conveying the sought-after spatio-temporal information. For practical tests, we used space–time series obtained by permanent scatterers interferometry (PS InSAR) to monitor the Earth’s surface movement above the underground gas storage (UGS) Tvrdonice, the Czech Republic. An UGS is characterised by periodic injection and withdrawal of natural gas, which induces periodic movement of the terrain above it. We have verified that our visualisation method provides the required pattern information and is easy to use. Web of Science 14 9 art. no. 2184

Pluvial flash floods are among the most dangerous weather-triggered disasters, usually affecting watersheds smaller than 100 km(2), with a short time to peak discharge (from a few minutes to a few hours) after causative rainfall. Several warning systems in the world try to use this time lag to predict the location, extent, intensity, and time of flash flooding. They are based on numerical hydrological models processing data collected by on-ground monitoring networks, weather radars, and precipitation nowcasting. However, there may be areas covered by weather radar data, in which the network of ground-based precipitation stations is not sufficiently developed or does not even exist (e.g., in an area covered by portable weather radar). We developed a method usable for designing an early warning system based on a different philosophy for such a situation. This method uses weather radar data as a 2D signal carrying information on the current precipitation distribution over the monitored area, and data on the watershed and drainage network in the area. The method transforms (concentrates) the 2D signal on precipitation distribution into a 1D signal carrying information on potential runoff distribution along the drainage network. For sections of watercourses where a significant increase in potential runoff can be expected (i.e., a significant increase of the 1D signal strength is detected), a warning against imminent flash floods can be possibly issued. The whole curve of the potential runoff development is not essential for issuing the alarm, but only the significant leading edge of the 1D signal is important. The advantage of this procedure is that results are obtained quickly and independent of any on-ground monitoring system; the disadvantage is that it does not provide the exact time of the onset of a flash flooding or its extent and intensity. The generated alert only warns that there is a higher flash flooding hazard in a specific section of the watercourse in the coming hours. The forecast is presented as a dynamic map of the flash flooding hazard distribution along the segments of watercourses. Relaying this hazard to segments of watercourses permits a substantial reduction in false alarms issued to not-endangered municipalities, which lie in safe areas far away from the watercourses. The method was tested at the local level (pluvial flash floods in two small regions of the Czech Republic) and the national level for rainfall episodes covering large areas in the Czech Republic. The conclusion was that the method is applicable at both levels. The results were compared mainly with data related to the Fire and Rescue Service interventions during floods. Finally, the increase in the reliability of hazard prediction using the information on soil saturation is demonstrated. The method is applicable in any region covered by a weather radar (e.g., a portable one), even if there are undeveloped networks of rain and hydrometric gauge stations. Further improvement could be achieved by processing more extended time series and using computational intelligence methods for classifying the degree of flash flooding hazard on individual sections of the watercourse network. Web of Science 13 15 art. no. 2943

Underground gas storage facilities are an important element of the natural gas supply system. They compensate for seasonal fluctuations in natural gas consumption. Their expected lifetime is in tens of years. Continuous monitoring of underground gas storage is therefore very important to ensure its longevity. Periodic injection and withdrawal of natural gas can cause, among other things, vertical movements of the terrain surface. Radar interferometry is a commonly used method for tracking changes in the terrain height. It can register even relatively small height changes (mm/year). The primary aim of our research was to verify whether terrain behavior above a relatively deep underground gas storage can be monitored by this method and to assess the possibility of detecting the occurrence of anomalous terrain behavior in an underground gas storage area such as reactivation of faults in the area. The results show a high correlation between periodic injection and withdrawal of natural gas into/from the underground reservoir and periodic changes in terrain height above it (the amplitude of the height changes is in centimeters), which may allow the detection of anomalous phenomena. We documented special behavior of storage structures in the Vienna Basin: the areas adjacent to the underground gas storages show exactly the opposite phase of vertical movements, i.e., while the terrain above the underground reservoirs rises as natural gas is injected, the adjacent areas subside, and vice versa. Based on the analysis of geological conditions, we tend to conclude that this behavior is conditioned by the tectonic fault structure of the studied area. Web of Science 12 2 art. no. 271

One of the current tasks of disaster management is to effectively counter toxic accidents on traffic communications. The paper demonstrates the procedure of the use of geographic data and knowledge with GIS technology for the operational mitigation of accident impacts on the traffic communication with leakage of toxic substance. A simulated leakage of toxic liquid substance on a highway in the Czech Republic was chosen as an example. The process is divided into two units. In the first preparatory block, data on soils and the geological environment are analysed and purpose oriented pre-processed. The data layer generally describes the expected movement of pollutants, e.g. predominant surface runoff, or predominant infiltration and/or a balanced combination of both of them. In the second operational unit, a location of the accident is precisely identified and the estimation of possible routes of pollutant runoff is performed with respect to the current status of the territory. Key points on these routes are identified with the aim to select mitigation measures and optimum access routes modelled for intervention techniques to reach key points in order to prevent contamination of water bodies. Web of Science 14 1 64 49

Natural disasters have occurred for a very long time, virtually on all continents, and it is obvious that in the areas where human’s social, economic and cultural activities are concentrated, their impacts are more severe. The Laboratory for Modelling and Simulations of Hazardous Situations, operating at the VSB-Technical University of Ostrava, works on a long-term basis on a project called FLOods REcognition On the Net (FLOREON) aimed at development (to meet the needs of the Moravian-Silesian Region) a system for modelling, simulating, monitoring and if appropriate even predicting crisis situations caused by both adverse natural, and possibly human effect. The paper describes principles which the FLOREON system is built on, a conception of the entire system and the first results achieved. In conclusion its further development is outlined, and focused on an extension of the system by next hazardous phenomena such as the modelling of dangerous substance leakage, monitoring of traffic situations and others. So a system occurs denoted as FLOREON+. The plus sign in the name means the system will deal not only with floods, but also with other phenomena in the territory. Přírodní extrémy se objevují od nepaměti, prakticky na všech kontinentech, a pokud zasáhnou oblasti, kde se koncentrují ekonomické, sociální nebo kulturní aktivity lidí, mohou být jejich dopady velice vážné. Laboratoř pro modelování a simulaci krizových situací na Vysoké škole báňské – Technické univerzitě Ostrava pracuje na dlouhodobém projektu nazvaném FLOREON (FLOods REcognition On the Net) a zaměřeném na vývoj systému pro monitorování, modelování, simulaci a pokud to bude možné, tak i predikci krizových situací, způsobených jak nepříznivými přírodními, případně i lidskými vlivy. Článek popisuje principy, na nichž je systém FLOREON budován, koncepci celého systému a první dosažené výsledky. V závěru je nastíněn jeho další rozvoj, zaměřený na rozšíření o další krizové jevy, jako je modelování úniků nebezpečných látek, monitorování dopravní situace a další. Rozšířený systém je označován jako FLOREON+. Znaménko plus v názvu vyjadřuje, že systém již nebude pracovat jen s povodněmi, ale i s dalšími jevy v území.