Assessment of water retention function as tool to improve integrated watershed management (case study of Poprad river basin, Slovakia)

The concept for innovative Comprehensive Assessment of Lowland Rivers

Current river assessment methods focus on evaluating a single aspect (e.g. the physical and chemical quality of the water or its hydromorphological state) and usually do not integrate various factors. The lack of an interdisciplinary method makes it difficult to correctly assess the condition of a river as a complex ecosystem significantly influenced by humans. This study aimed to develop a novel Comprehensive Assessment of Lowland Rivers (CALR) method. It is designed to integrate and evaluate all-natural and anthropopressure-related elements that influence a river. The CALR method was developed using the Analytic Hierarchy Process (AHP). The application of the AHP allowed the assessment factors to be determined and given weights to define the importance of each assessment element. As a result of AHP analyses, the following ranks were determined for the six main parts of the CALR method: hydrodynamic assessment (0.212), hydromorphological assessment (0.194), macrophyte assessment (0.192), water quality assessment (0.171), hydrological assessment (0.152) hydrotechnical structures assessment (0.081). In the comprehensive assessment of lowland rivers, each of the six elements listed above is rated on a scale of 1-5 (where 5 means very good and 1 bad) and multiplied by an appropriate weighting. After summing up the obtained results, a final value is obtained, classifying the river. CALR can be successfully applied to all lowland rivers thanks to its relatively simple methodology. The widespread use of the CALR method may facilitate the assessment process and enable the comparison of the condition of lowland rivers worldwide. The research conducted in this article is one of the first attempts to develop a comprehensive method for evaluating rivers that considers all aspects.

New Empirical Model Using Landscape Hydric Potential Method to Estimate Median Peak Discharges in Mountain Ungauged Catchments

Designing hydraulic structures, such as culverts, bridges, weirs, and check dams, while planning new flood inundation areas, needs correct assessment of design discharges. In gauged catchments with long time series of discharges, statistical methods are commonly used based on fixed theoretical distributions and on empirical distributions. However, in ungauged catchments, this approach is not possible. In addition to more advanced methods, which are used today, e.g., rainfall–runoff models, much more simple approaches are still needed based on regionalization and empirical models. Thus, the objective of this work is to develop a new empirical model for calculating peak discharge expressed as the median of annual peak discharge (QMED). The innovative aspect of this paper is the use of a new parameter, named landscape hydric potential (LHP), as a descriptor of water storage in catchments. LHP has a crucial role as the descriptor of water storage in catchment and, thus, it has an influence on forming discharges. The work was done in the Upper Vistula basin in the Polish Carpathians. This study was carried out in mountain catchments located in the Upper Vistula basin, in the south part of Poland in in the Polish Carpathians. Results show that the proposed model could provide appropriate calculations in changing climate conditions, as well as when land use is changed. The proposed model is simple and effective; for calculating QMED, it needs only two parameters: catchment area and LHP. Since the model has a significant and high correlation coefficient, it could be used for assessing of QMED in ungauged mountain catchments. The determined form of the empirical equation finds application in the entire Upper Vistula basin, for catchments with a surface area from 24 km2 up to 660 km2.

Link between hydric potential and predictability of maximum flow for selected catchments in Western Carpathians

This study aimed to determine the link between a hydric potential of catchments (LHP) and the predictability (P) of maximum flow of selected rivers in southern Poland (within the Upper Vistula basin) and Slovakia. The LHP method refers to the ability of ecosystems to slow down runoff and retain water. The LHP method is focused on the analysis of the following indicators, shaping the geosphere at the catchment scale: hydrogeological conditions, soil conditions, meteorological conditions, geomorphological conditions, and land use. The predictability of river flows, calculated as one of the Colwell's indices, represents a measure of confidence with regard to the state of a flood event at a given point. To determine links between the LHP and P, a cluster analysis was used with the Ward method of agglomeration. The mean LHP varied between 1.2 for the Skawa River and 20.1 for the Vistula River. Only the Vistula River has very high LHP. The rest of the investigated rivers had medium and low values of LHP. The mean predictability of maximum flows for all rivers was relatively high (0.54), with the highest value obtained for the Wisłok River (0.69) and the lowest one for the Białka River (0.40). Cluster analysis showed that the studied catchments may be aggregated into four homogeneity clusters: first - catchments with high P and limited LHP, second - catchments with mean P and low LHP, third - with low P and average LHP and fourth - with very high P and medium and excellent LHP. The results are important for the management of catchments, especially for planning of any land use changes and investment projects related to water retention.