Acta Univ. Agric. Silvic. Mendelianae Brun. 2020, 68(5), 841-849 | DOI: 10.11118/actaun202068050841

Estimation of Basic Geometric and Hydraulic Characteristics of Natural Torrent Beds

Matúš Jakubis¹, Mariana Jakubisová²

¹ Department of Forest Harvesting, Logistics and Amelioration, Faculty of Forestry, Technical University in Zvolen, T. G. Masaryka 24, 960 53 Zvolen, Slovak Republic

² The Borova Hora Arboretum of the Technical University in Zvolen, Borovianska cesta 66, 960 53 Zvolen, Slovak Republic

Many mountainous regions and their watersheds lack the mathematical description of their hydraulic geometry such as the High Tatras region in Slovakia. Therefore, the aim of the paper is to determine the geometric and hydraulic characteristics of natural torrent beds and to propose a regional equations of mountain watersheds for the High Tatras region. In the paper is also proposed a new equation to determine the relationships between the watershed area and the geometric characteristics of flow profiles. Derived regional equations can help in nature-friendly and ecological shaping and dimensioning of channel cross sections in torrent control designing. 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 regional relationships (hitherto used without asymptote and newly proposed with asymptote) were compared. The analyses showed a strong correlation relationship between watershed area A_w (km²) and bankfull geometric characteristics of natural cross-sections: width of the channel inside the banks B_bf (m), mean channel depth H_bf (m), channel cross-section area A_bf (m²) and hydraulic characteristic - bankfull discharge Q_bf (m³.s^-1). These relations were tested by t-test and Shapiro-Wilk test. The determination coefficient (R₁²) for the relationships without asymptote ranged between R₁² = 0.919 and R₁² = 0.972; p₁ - values from Shapiro-Wilk test ranged between p₁ = 0.0359 and p₁ = 0.8027. The determination coefficient (R₂²) for the relationships with asymptote ranged between R₂² = 0.952 and R₂² = 0.974; p₂ - values from Shapiro-Wilk test ranged between p₂ = 0.0221 and p₂ = 0.8617. At the same time, we tested and confirned the hypothesis that the correlation coefficients R₁ from equation without the asymptote are only randomly different from the correlation coefficients R₂ from equation with the asymptote and the difference between these coefficients is also random. Derived regional equations make it possible to the gradual creation of hydrologic landscape regions in the SR. They can be also used as a valuable input to the ecological cross sections designing in torrent control and revitalization for the regions with a similar natural conditions.

Keywords: bankfull characteristics, watercourses morphogenesis, High Tatras, Slovakia

Grants and funding:

This article was supported by the Grant Agency KEGA of the Ministry of Education, Science, Research and Sport of the Slovak Republic within the project No. 006TU Z-4/2018: 3-D functional models of landscape flood protection objects as a new methods and forms of university education.

Received: July 15, 2020; Accepted: September 25, 2020; Published: November 1, 2020  Show citation