An Analysis of Hydromorphological Index for Rivers (HIR) Model Components, Based on a Hydromorphological Assessment of Watercourses in the Central European Plain

Abstract

Assessing the hydromorphological conditions of watercourses is a requirement of the Water Framework Directive (WFD) and national river status monitors (e.g., in Poland,the State Environmental Monitoring, and Water Monitoring coordinated by Chief Inspectorate of Environmental Protection). This paper evaluates the hydromorphological status of 10 watercourses (30 measurement sections) in Poland based on the multimetric Hydromorphological Index for Rivers (HIR). A new approach to the delineation of the river valley (small watercourses) is proposed. An analysis of the influence of river valley management on the value of HIR and its components was carried out using statistical methods (basic statistics, Mann–Whitney U Test and Ward’s cluster analysis). In addition, the relationship between the components of the HDS (Hydromorphological Diversity Score) and HMS (Hydromorphological Modification Score) was analyzed (Spearman’s Rank Correlation Coefficient). HIR values for the watercourse sections ranged from 0.553 to 0.825. HDS values ranged from 27.5 to 75.5 and HMS from 2.0 to 17.5. The results of the basic statistical analyses showed slight differences between the two river valley delineation methods. The Mann–Whitney U Test showed a significant difference in the test significance level of the HDS, HMS and HIR for the river valley delineation methods. Spearman’s rank correlation analysis showed that most of the HDS and HMS parameters components had a low degree of correlation. The juxtaposition of the two methods for delineating a river valley and its influence on the HIR allows for a better understanding of the interdependence between its parameters.

Methodological Framework for Assessing Hydromorphological Conditions of Heavily Modified and Artificial River Water Bodies in Croatia

“…Studies of hydromorphological alterations in rivers and/or their impacts on biodiversity are numerous [33][34][35][36][37][38]; however, few papers explicitly deal with HMWBs and AWBs and use adapted assessment methodologies (e.g., [39]). For example, the Polish hydromorphological assessment methodology presented in Garbowski et al [23] does have lower score thresholds for AWBs, but it does not determine MEP or take into consideration mitigation measures, as we did in this study. In Croatia, the designation of an HMWB and an AWB is made by Croatian Waters, the main state water management institution and the main decision-maker regarding feasibility of mitigation measures.…”

“…Results of the hydromorphological assessments show the current state of the river channel and, paired with analyses of past states and changes, can allow future projections [43]. In this way, it is possible to identify potential problem areas, river sections with increased flood or bank erosion risk as well as sections with a need for restoration or different management practices [23,38].…”

“…Since there is no common methodology for assessing MEP or GEP in the European Union [15], Member States use various methodologies to assess the hydromorphological conditions of their water bodies [16][17][18][19], e.g., the River Habitat Survey [20] or the CEN standard [21], which are primarily developed for natural water bodies. However, these methods are mainly used only to assess hydromorphological alterations, not to define MEP (e.g., [22,23]).…”

The impact of the geographical environment on the hydromorphological conditions of watercourses in southern Poland

“…It is observed in the case of geographical conditions such as altitude, type of geology and anthropogenic conditions, which are manifested by human activity in watercourse catchment areas. Garbowski et al (2023) showed significant differences between hydromorphological conditions in watercourses across two different regions of central and northern Poland. Both in their study and this one, the variables influencing hydromorphological quality were parameters related to natural morphological elements of banks and the valley.…”

“…River valleys, due to their different natural character (depressions and terrain indentations) and the different role they play in natural systems, cause some trouble in physico-geographic regionalisation (Garbowski et al 2023). Hydromorphological assessments of watercourses can vary depending on the assessment methods used (Belletti et al 2015), but such a parameter seems to be most differentiated by spatial and environmental variables.…”