The knowledge about the natural potential vegetation is important to ensure the ecological stability of the area in terms of the restoration of riparian vegetation. The natural generic and spatial arrangement of riparian vegetation helps to maintain aesthetic appeal and has a high biological value in the country. Therefore, this work analyses the qualitative stream characteristics. To classify the qualitative parameters of the stream the method of indexes was used. The following hydromorphological methods were used to assess the condition of the biotope: QBR method (Qualitat del Bosc de Ribera) that is based on qualitative analysis of riparian vegetation, the HMS method (Habitat Modification Score) that allows to examine the anthropogenic changes in the river, BEHI method (Bank Erosion Hazard Index) that is used to determine the vulnerability to erosion, RGA method (Rapid Geomorphic Assessments) that is used for assessing the stability and sensitivity of the stream in relation to sedimentation processes, and RCE method (Inventory of River, Channel and Environment) that is used to assess the physical and biological state of small currents. The above-mentioned methodologies reliably identify the extremes concerning the riparian and the accompanying vegetation of the rivers. The vegetation is an important parameter for assessing the quality of the stream and it point out the areas that should be restored as a priority. As expected, the qualitative and quantitative characteristics of riparian vegetation have shown better results in rural areas than in urban areas. The quality of the stream is degraded by anthropogenic interventions in urban areas as well as in rural areas, so the focus on the vegetation of the whole stream is substantial. The individual methods allow the restoration of data in case of more significant changes that could be caused, for example, by floods or more significant anthropogenic impacts. The importance of this issue is growing as the riparian vegetation represent a valuable element of ecological stability with multiple functions. The riparian vegetation care is set by the actual legislation at national and transnational level, regarding the admitted European strategic objectives and documents. The application of the methodologies reliably identifies extremes in riparian vegetation, which significantly affect the overall characteristics of the flow quality, and they should be the subject of the restoration. The biological, morphological and water state of ten representative parts of Slatina and Drietomica rivers were evaluated. The results show that these methodologies present an appropriate tool for assessing the quality of riparian vegetation and can be used for restoration measures.

The article aims at assessing the impact of hydraulic characteristics on the habitat quality of mountain and piedmont watercourses. The solution results from the Riverine Habitat Simulation model, where the quality of the aquatic habitat is represented by the weighted usable area (WUA), which is determined using brown trout as the bioindicator. Flow velocity and water depth are basic abiotic characteristics that determine the ratio of suitability of the instream habitat represented by the weighted usable area. The influence of these parameters on the objective evaluation of the habitat quality is the essence of the paper. The measurements were carried out during the summer period at minimum discharges for 17 mountain and piedmont streams in Slovakia. Three methods for assessing the habitat quality were tested, and differences in the results were found to be significant. The evaluation shows the optimum design methods for calculating the weighted usable area.

This study evaluated the relationship between abiotic flow characteristics and habitat quality. Habitat quality was assessed using the Instream Flow Incremental Methodology (IFIM), which uses bioindication. Brown trout was selected as a bioindicator because of its sensitivity to morphological changes and its occurrence in sufficient reference reaches. The correlation between the morphological characteristics of the stream and the area-weighted suitability (AWS), which represents habitat quality, was evaluated. Fifty-nine reference reaches of fifty-two mountain and piedmont streams in Slovakia were analysed. The correlation analysis demonstrated the strongest relationship between the AWS and the stream depth and width. The relationship between the water surface area and the AWS indicated that, for mountain streams, there is a significantly increasing trend of the AWS value with increasing surface area. Considering piedmont streams, the AWS variation with a change in the water-surface area was minimal. These results can form the basis for deriving regression equations to determine habitat quality. Such a procedure can significantly simplify the evaluation of the quality of aquatic habitat, making it much more accessible for design practice.

Forests represent the most natural means of retaining water in a basin. Assessing the impact of a forest on a hydrological cycle is a very current topic that hydrologists and water managers deal with. The differences between site conditions and a forest itself, together with various methods of exploring this issue, lead to inconsistent opinions on the extent of the ability of a forest cover to prevent or minimize surface runoff. This article is therefore focused on an assessment of the impact of changes in the composition of a forest under the effect of severe windstorms on runoff conditions in the selected river basin. The most severe windstorms in the last 25 years and their impact on changes in forest cover in the selected area of the Ipoltica River basin have been assessed in this article. The most significant severe windstorm in terms of its impact on changes in the forest communities was Filip, which occurred in the year 2007. Therefore, the impact of changes in forest cover on the given territory was examined for the period after the year 2007. The WetSpa rainfall-runoff model was used to assess the changes.

The article focuses on adapting generalized depth preference and flow velocity characteristics from Brown trout (Salmo trutta morpha fario) to the Minnow (Phoxinus phoxinus). The results obtained were used to model habitat suitability with 1D and 2D models. Since 1995, research on assessing aquatic habitat quality has been ongoing on 77 mountain streams in Slovakia. This assessment employs a System of Environmental Flow Analysis (SEFA), which is based on the Instream Flow Incremental Methodology (IFIM). In most sections, Brown trout occurred in representative numbers. Brown trout habitat preferences were derived and generalized, and represented by suitability curves. Minnows were present in sufficient numbers for the derivation of suitability curves only on some streams, making direct generalization from the measured data unrepresentative. The measurement results showed that Minnow has similar depth and flow rate preferences to Brown trout. Therefore, it can be assumed that it is possible to adapt the generalised suitability curves from Brown trout to Minnow. This expansion enabled us to broaden the assessment of habitat quality using the SEFA model to mountain streams that are dominated by Minnows and where there is insufficient Brown trout presence. Verification of parameter adaptation from Brown trout to Minnow was conducted in 11 sections of mountain streams. We discuss the performance of habitat quality modeling, concerning the fundamental hydraulic characteristics of streams, using both 1D and 2D models. The results of the 2D modeling are presented for a sub-mountain stream.

Accurate representation of river channel geometry is a key prerequisite for reliable hydraulic and aquatic habitat modelling. Traditionally, detailed field surveys combining topographic and bathymetric measurements have been used for this purpose. However, such data are time-consuming, costly, and logistically demanding, and are often unavailable for long-term or spatially extensive applications. An alternative is publicly available airborne laser scanning (LiDAR) data, which provide topographic information with high spatial resolution and full areal coverage, but do not directly capture the submerged morphology of the river channel.Minimum flows represent critical hydrological conditions during which aquatic habitat availability and quality are strongly constrained by channel hydraulic and morphological controls. Under low-flow conditions, the spatial distribution of aquatic biota is primarily governed by water depth and flow velocity, together with the availability of morphological refugia that enable organism persistence during hydrological stress. Inadequate representation of the channel bed may therefore result in distorted hydraulic conditions and, consequently, in unreliable assessments of aquatic habitat suitability.For this reason, the present study compares river channel geometry derived from detailed field surveys with geometry based on publicly available LiDAR-derived topographic data, with the aim of quantifying geometric distortions arising from the omission of bathymetry and evaluating their potential effects on aquatic habitat modelling under minimum-flow conditions.The analysis was conducted on a selected reach of the Nitrica River in Slovakia, representing a small sub-mountain stream with pronounced morphological variability. Two sets of geometric inputs were compared: (i) reference geometry derived from a detailed topographic and bathymetric field survey conducted in 2019, and (ii) geometry based on LiDAR-derived topographic data from the national digital terrain model (DTM 5.0, spatial resolution 1 m, updated in 2025).The results indicate that, for small mountain and sub-mountain streams, the exclusive use of LiDAR-based topographic data leads to substantial underestimation of flow depth and distorted representation of key habitat features. Consequently, LiDAR data cannot replace detailed bathymetric surveys for accurate aquatic habitat assessment under minimum-flow conditions, when habitat quality is primarily determined by riverbed morphology.However, the question remains open as to the channel width and flow conditions at which water depth ceases to be the dominant factor influencing habitat suitability, even within mountain and sub-mountain streams. Identifying this threshold represents an important direction for future research, which would allow refinement of methodological guidelines regarding the applicability and limitations of publicly available LiDAR data for aquatic habitat assessment under varying hydromorphological conditions.Acknowledgement:This work was supported by the Slovak Research and Development Agency, under the contract No. VV-MVP-24-0208 and the VEGA grant agency under contract No. VEGA 1/0067/23.