This article contains an analysis of the hydromorphological state of mountain streams under contemporary human impact conditions. The subjects of the study are the Jaszcze and Jamne streams, located ...in the Polish Flysch Carpathians. The hydromorphological state of each stream reflects its habitat quality and depends on a number of natural and anthropogenic features. The research is conducted on the basis of a British method, the River Habitat Survey, which complies with the EU Water Framework Directive. The Habitat Quality Assessment and Habitat Modification Score indices are used to determine the diversification of natural features and the levels of human transformation of the streams studied. The research showed that the largest transformations in stream hydromorphology and habitat conditions occurred in those valley parts characterized by intensive development of building construction and hydrotechnical infrastructure.
The article presents the changes in the physicochemical properties (temperature, conductivity and pH) of the water in the Ropa River in the Polish Carpathians that were caused by the Klimkówka ...Reservoir, which was commissioned for operation in 1994. The study uses data mainly from daily measurements of the physicochemical properties of the water in the Ropa River. The measurements were taken during the period prior to the reservoir being built (1982–1993) and from the period after the dam became operational (1994–2006). The measurements were conducted 16 km downriver from the dam. The conducted analysis shows that the Klimkówka Reservoir radically changed the thermal conditions and the annual cycle for water conductivity in the Ropa River. The pH of the water in the Ropa River experienced the smallest changes.
The content of 19 metals (chromium, cobalt, nickel, strontium, arsenic, magnesium, barium, cesium, gallium, rubidium, uranium, vanadium, zinc, lead, copper, cadmium, iron, manganese, and aluminum) in ...sediment in three ephemeral streams (Nahal Sansana, Nahal Revivim and Nahal Pura) with reservoirs in the Negev Desert is studied herein. The study was done in September 2016. The samples were collected from the surface layer of sediment (up to 10 cm) in the reservoirs and in the channels upstream and downstream of the reservoirs. Silt, which on average, accounted for 72% dominated in the sediment. In the spatial distribution of the particle size, sand and gravel fractions were deposited in the reservoirs. Aluminum, iron, and magnesium accounted for 99% of all analyzed metals. The Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) showed that sediment in the Negev Desert channel upstream of the reservoirs had similar concentrations of metals. Similarities were also found between the analyzed reservoirs. The bottom sediment in reservoirs had higher concentrations of metals than sediment upstream and downstream of the reservoirs. The comparison of concentrations in upstream and downstream locations did not show any unambiguous trends because metal concentrations downstream from the reservoirs were not always lower than upstream of the reservoirs. The analysis of the sediment enrichment factor (EF) showed the highest value in the reservoirs and the lowest downstream of the reservoirs. The concentrations of most analyzed metals did not indicate the possibility of potential ecological risk (SQG).
A thermal regime of aquatic ecosystems determines the possibility of survival and development of aquatic biota. Thermal stratification of river water impounded by dam reservoirs can cause a permanent ...disturbance in the naturally existing water‐air temperature relationship downstream of reservoirs. This article aims at determining the role of dam reservoirs in the disturbance of naturally shaped synchronous behaviour of water‐air temperatures. The object of the analysis is the Carpathian river Dunajec downstream of a reservoir complex built in 1994–1997. Results of spectral analysis indicate that the annual scale is the main scale of water temperature (WT) variation, and this scale corresponds to the main frequency of phase synchronisation. However, following the reservoirs construction, the definite synchronous behaviour of interacting air and WTs was apparently distorted, because the response time of WT to changing atmospheric conditions has considerably increased in comparison with the predam period.
The hydromorphological state and habitat quality of the selected streams in the Negev Desert was taken under consideration in the paper. Field studies were conducted in September 2014 on selected ...500 m sections of streams (Nahal Be’er Sheva, Nahal Hebron) characterized by noticeable anthropopressure as well as on streams (Nahal Sansana, Nahal Yatir, Nahal Hatira) without visible human pressure. The survey of the hydromorphological state of selected streams was carried out using a British method, the River Habitat Survey (RHS). The hydromorphological state and habitat quality of the tested streams, based on the habitat naturalness indicator (HQA), as well as the habitat modification indicator (HMS), places the analysed streams of weak anthropopressure in class III—moderate (Nahal Yatir, Nahal Hatira) and IV—poor (Nahal Sansana). Bad hydromorphological state (class V) is the characteristic of the Nahal Hebron and Nahal Be’er Sheva streams with significant human pressure. However, it is important to verify RHS method and the classification of a hydromorphological state, especially the HQA index, and adapt them to the reference conditions in arid and semi-arid areas.
The article presents the results of an assessment of the hydromorphological state of selected Carpathian rivers in sections above and below the reservoirs. An attempt has also been made to assess the ...impact of reservoirs on the hydromorphological conditions and quality of river habitats. The research was based on the River Habitat Survey (RHS) method. The synthetic indices Habitat Quality Assessment (HQA) and Habitat Modification Score (HMS) were calculated on the basis of the gathered data for each section studied; this allowed the hydromorphological qualities of the rivers to be assessed numerically. The reservoirs interrupt river continuum, and they alter different biotic and abiotic elements of natural environment. However, this study has shown that the operation of reservoirs does not always negatively impact the hydromorphological conditions of rivers that reflect their habitat quality. The influence of reservoirs on a river's hydromorphological state above and below a reservoir's location may be neutral, but it also can improve the habitat conditions of a river.
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