Changes in the land use of urban catchments and the discharge of stormwater to rivers are causing surface water pollution. Measurements were taken of the quality of discharged stormwater from two areas with different types of development: a residential area and a residential–commercial area, as well as the quality of the Sudół River water below the sewer outlets. The following indicators were studied: TSS, COD, N–NO₃, N–NO₂, TKN, TN, TP, Zn, Cu, Hg, HOI, and PAHs. The influence of land use on the magnitudes of flows in the river was modeled using the SCS–CN method and the Snyder Unit Hydrograph Model. The results showed an increase in sealing and a resulting increase in surface runoff. Concentrations of pollutants in stormwater and analysis of the potential amounts of loadings contributed by the analyzed stormwater outlets indicate that they may be responsible for the failure to meet environmental targets in the Sudół River. Environmental risk assessment shows that the aquatic ecosystem is at risk. A risk factor indicating a high risk of adverse environmental effects was determined for N–NO₃, Zn, and Cu, among others.

Machine learning models facilitate the search for non-linear relationships when modeling hydrological processes, but they are equally effective for automation at the data preparation stage. The tasks for which automation was analyzed consisted of estimating changes in the roughness coefficient of a mountain streambed and the extent of floods from images. The Segment Anything Model (SAM) developed in 2023 by Meta was used for this purpose. Images from many years from the Wielka Puszcza mountain stream located in the Polish Carpathians were used as the only input data. The model was not additionally trained for the described tasks. The SAM can be run in several modes, but the two most appropriate were used in this study. The first one is available in the form of a web application, while the second one is available in the form of a Jupyter notebook run in the Google Colab environment. Both methods do not require specialized knowledge and can be used by virtually any hydrologist. In the roughness estimation task, the average Intersection over Union (IoU) ranges from 0.55 for grass to 0.82 for shrubs/trees. Ultimately, it was possible to estimate the roughness coefficient of the mountain streambed between 0.027 and 0.059 based solely on image data. In the task of estimation of the flood extent, when selecting appropriate images, one can expect IoU at the level of at least 0.94, which seems to be an excellent result considering that the SAM is a general-purpose segmentation model. It can therefore be concluded that the SAM can be a useful tool for a hydrologist.

Currently, an active debate is underway among the academic community, urban planners, and policymakers regarding optimal models of urban development, given that the majority of the population now resides in cities. One concept under discussion is the 15 min city, which posits that all urban residents should be able to reach key, frequently used services within a 15 min walk or cycle. Although the literature suggests numerous potential benefits, debate persists about whether such cities would be optimal from the standpoint of sustainable development objectives and residents’ quality of life. The ongoing discussion also concerns the extent to which existing cities are capable of aligning with this concept. This is directly linked to the actual spatial distribution of individual services within the city. The literature indicates a research gap arising from a shortage of robust case studies that would enable a credible assessment of the practical implementation of this idea across diverse cities, countries, and regions. This issue pertains to Poland as well as to other countries. A desirable future scenario would involve comprehensive mapping of all cities, with respect to both the spatial distribution of specific services and related domains such as the quality and coherence of linear infrastructure. This article presents an analysis of the spatial accessibility of basic urban services in the context of implementing the 15 min city concept, using the city of Koszalin (Poland) as a case study. This city was selected due to its representative character as a medium-sized urban centre, both in terms of population and area, as well as its subregional functions within Poland’s settlement structure. Koszalin also exhibits a typical spatial and functional layout characteristic of many Polish cities. In light of growing challenges related to urbanisation, climate change, and the need to promote sustainable mobility, this study focuses on evaluating access to services such as education, healthcare, retail, public transport, and green spaces. The use of Geographic Information System (GIS) tools enabled the identification of spatial variations in service accessibility across the city. The results indicate that only 11% of Koszalin’s area fully meets the assumptions of the 15 min city concept, providing pedestrians with convenient access to all key services. At the same time, 92% of the city’s area offers access to at least one essential service within a 15 min walk. Excluding forested areas not intended for development increases these values to 14% and 100%, respectively. This highlights the extent to which methodological choices in assessing pedestrian accessibility can shape analytical outcomes and the interpretations drawn from them. Moreover, given this article’s objective and the adopted analytical procedure, the assumed pedestrian walking speed is the key parameter. Accordingly, a sensitivity analysis was conducted, comparing the reference scenario (4 km/h) with alternative variants (3 and 5 km/h). This approach demonstrates the extent to which a change in a single parameter affects estimates of urban-area coverage by access to individual services reachable on foot within 15 min. The analysis reveals limited integration of urban functions at the local scale, highlighting areas in need of planning intervention. This article proposes directions for action to improve pedestrian accessibility within the city.

Determination of theoretical flood waves, commonly known as hypothetical waves, is still a difficult problem to be solved. Most frequently hydrological modelling is used for this purpose. However, there are no methods for verifying the obtained calculation results. The assumption applied, that...

Currently, most mobile devices can capture geotagged photos—i.e., images to which the location of capture is assigned. Despite extensive literature on the use of geotagging, there is a limited number of studies addressing the accuracy of the recorded locations. Therefore, this research was undertaken to assess the positional accuracy of geotagged photos, defined, among other metrics, by the mean unit error of the assigned coordinates. This article presents the results of test measurements conducted using various mobile devices to determine situational coordinates within the applicable coordinate system. The study discusses the satellite systems currently in use, as well as the measurement technologies that influence geolocation accuracy in smartphones and cameras equipped with a geotagging feature. Test measurements involved comparing the coordinates embedded in geotagged photos with those obtained using a high-precision GNSS receiver. Depending on the device and technology used, the mean unit location errors ranged from 4.0 metres to nearly 50 metres. These findings highlight the low precision of such devices in determining exact positions. To explore ways of improving accuracy, additional tests were carried out using various features and applications available on different devices, assessing their impact on location determination based on geotagged photos. Notably, the use of the GPS Test application for position stabilisation reduced mean unit errors by nearly 45%. The results of this study led to the development of recommendations aimed at enabling the determination of a mobile device’s X and Y coordinates with an accuracy of several metres. This level of precision may be sufficient for many practical applications and presents a cost-effective alternative to expensive GPS receivers, which require specialised geodetic knowledge for professional use.

The aim of the study was to assess the sedimentation of the Klimkówka reservoir using topographic differencing (TD) analysis of digital elevation models (DEMs) created for two periods: before the reservoir was filled and after30 years of operation. The archival model was developed from a scanned and calibrated analogue large-scale (1:5,000) topographic map with contour lines and elevation points. The current model was obtained by integrating unmanned aerial vehicle (UAV) photogrammetry and bathymetric measurements with a GNSS-positioned dual-frequency echo sounder. The accuracy of both models was analysed in detail, taking into account cartographic errors, map shrinkage, the scanning and calibration process, and the heterogeneous accuracy of the archival elevation data. Based on the DEM difference, the estimated sedimentation volume was considered unreliable. A detailed analysis of selected cross-sections revealed local accumulation processes in the backwater zone and slope erosion, but did not permit a reliable assessment of the siltation of the entire reservoir. The authors conclude that the reliable application of the TD method requires comparing two models produced with similarly high accuracy (e.g. UAV + bathymetry), while analogue cartographic materials from the 1970s do not meet current accuracy requirements for this type of analysis.