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Erosional Damages on Concave Banks of Directional Arcs in Natural Torrent Bed

Jakubis Matúš, Jakubisová Mariana

Journal of Ecological Engineering

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2022

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Vol. 23, nr 9

44--52

EN

The article deals with the research of erosive damages of concave (outer) sides in directional circular arcs in the natural torrent bed. The research was carried out on 22 reference circular arcs on the Hučava torrent in the geomorphological unit of Poľana (Central Slovakia). The relation between R/Wbkf ratio (radius of curvature R/torrent bed width inside the banks Wbkf) and the bank slope angle BA of the concave arc BA = f(R/Wbkf) was analyzed. The relationship between R/Wbkf ratio and the percentage of vegetation cover VEG on the concave bank of the directional arc VEG = f(R/Wbkf) was analyzed as well. At the same time, the relation between ratio R/Wbkf and the VEG/BA coefficient was studied, which simultaneously the influence of vegetation cover and bank slope in connection with its erosive damage VEG/BA = f(R/Wbkf). It was found that the determination index for the relation BA=f(R/Wbkf) has the value of R2 = 0.924, for the relation VEG = f(R/Wbkf) the value of R2 = 0.953 and for the relation VEG/BA = f(R/Wbkf) the value of R2 = 0.967.

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The Impact of Hydrologic Characteristics of Mountain Watersheds on Geometric and Hydraulic Parameters of Natural Torrent Beds

Jakubis Matúš, Jakubisová Mariana

Journal of Ecological Engineering

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2019

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Vol. 20, nr 3

13--23

EN

The aim of the paper is to determine the geometric and hydraulic characteristics of natural torrent beds and to propose a regional hydraulic geometry equations of mountain watersheds for the High Tatras region. The research was conducted in 26 natural torrents and their watersheds on the reference sections and profiles under the sediment source zones. Two different regression equations to determine the relationships of hydraulic geometry (hitherto used without asymptote and newly proposed with asymptote) were compared. The analyses showed a strong correlation relationship between watershed area Aw (km2) and bankfull geometric characteristics of natural cross-sections: width of the bed inside the banks Bbf (m), mean depth of the bed Hbf (m), channel cross-section area Abf (m2) and hydraulic characteristic – bankfull discharge Qbf (m3.s-1). The results were tested by t-test and Shapiro-Wilk test. The determination coefficient (R2) for the relationships without asymptote ranged between R2 = 0.919 and R2 = 0.972; p – values from Shapiro – Wilk test ranged between p = 0.0359 and p = 0.8027. The determination coefficient (R2) for the relationships with asymptote ranged between R2 = 0.952 and R2 = 0.974; p – values from Shapiro – Wilk test ranged between p = 0.0221 and p = 0.8617. Based on the analysis we found that the new equation with the asymptote provides very good results.

3

Morphogenesis of Torrent Beds in the Watersheds with a Different Geological Bedrock and Geomorphological Rock Value

Jakubis Matúš, Jakubisová Mariana

Journal of Ecological Engineering

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2019

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Vol. 20, nr 5

69--77

EN

The paper deals with the morphogenesis of natural torrent beds in two watersheds with different geological backgrounds and a different geomorphological rock value: Hučava (geomorphological unit of Poľana with geological bedrock: neovulcanites – pyroxene and hornblende-pyroxene andesites, andesite porphyry, rhyolites, rhyodacites, rhyolite tuffs, diorite porphyry) and Mútňanka (geomorphological units of Podbeskydská brázda and Oravské Beskydy with geological bedrock: flysh – claystones, sandstones, shales-thin bedded flysh, microconglomerates). The bankfull geometric characteristics of a natural reference cross-sections of these torrents: the width of the channel inside the banks Wbkf (m), mean channel depth Dbkf (m), channel cross-section area Abkf (m2) and the hydraulic characteristic, namely bankfull discharge Qbkf (m3.s-1) in relation to the watershed area Aw (km2), were analyzed and compared. The analyses showed a strong correlation between the watershed area Aw (km2) and the bankfull geometric characteristics of natural cross-sections: Wbkf (m), Dbkf (m), Abkf (m2) and the hydraulic characteristic Qbkf (m3.s-1). In the analyzed relationships, the coefficient of determination (R2) ranged from R2 = 0.905 to R2 = 0.962 in the Hučava torrent and between R2 = 0.912 to R2 = 0.958 for the torrent of Mútňanka. Using statistical testing, the significance of the differences between the absolute and as well as regression coeficients in the hydraulic geometry equations for these torrents and their watersheds of different geological bedrock were confirmed.