Abstract. The article is dedicated to the determination of the wash depth of mountain rivers in floods and overflows. As well-known, hydrotechnical equipment is exposed to destructive damages of the floods and overflows. The undersurface of
bridge basement and coast guards are washed away, the surface of drainage devices
in water supply and dams (Düker) at river crossings are opened up. Therefore, the
protection of the equipment against the destructive damage of the floods and overflows should be ensured. To this aim, first of all, the depth of the fortification of the
equipment basement in riverbeds and the width through which the river can flow
should be determined and the works of installing coast guards should be accordingly
implemented.
Since the flow regime of rivers due to floods in the course of mountain riverbeds
dramatically changes, the width, depth, roughness and cross-sectional area of the
riverbed also changes. To that reason, in the smallest case, calculation formulas includes the average width and wash depth of the riverbed in the course of the floods
and overflows, average diameter of undersurface soils, the slope of the location of
hydrotechnical structures, velocity due to the average diameter of the riverbed soils
and so on.
The article contains the analyses of theoretical and practical materials about the
floods and overflows in mountain rivers. For the rivers flowing through the southern
hills of Great Caucasus Mountains, the expressions for determining the riverbed parameters and hydrological parameters of rivers are used. According to the expressions, average width due to non-washing of the riverbed in floods in accordance
with flood flow and slope of the studied part of the riverbed, the average depth of
the riverbed crossing the flood, the average velocity of the flow and the wash depth
in accordance with them are determined. basing on all these, the determining method
of the wash depth of mountain riverbeds in floods have been worked out and determining the wash depth have been recorded. The studied methodology can be used
in determining the riverbed parameters in floods and overflows.
Keywords: Flood, riverbed deformation, mountain river, wash depth, average
diameter of undersurface sediments, riverbed stability, flood velocity