Assessment of shoestring gully erosion and basic regularities of mudflow hazards in mountain regions

The structure hydrographical network of the two regions: Central Asia and Kazakhstan, south-east of Western Siberia. The laws of the structure of river systems, installed R.E. Horton and modified A.N. Strahler, are described Yu.B. Vinogradov as a system: 1) The law of the spatial density flows: а = s(i)/s(i-l); s(i ) = s(l)CTⁱ⁴; s(k n) = s(l )(cⁿ-l)/(ir-l), where a - the ratio of channel network densities; s (1) - channel network density of first order, i.e their number per unit area;s (i) and s (l; n) - the same thread i-th order, and orders from l to n-th; 2) The law of the lengths of streams: X = l(i)/ l(i _- l); l(i)= l(l) X¹ -l, where X - the ratio lengths of streams; l(l) and l(i) - the average length of streams l and i-th order; 3) The channel network density - l-th order: ф() = l(l) s (l); i-th order: ф (i) = l(i) s(i) = l(l) s(l) (X а)^-l ; all orders up to and including n-th: ф (l; n) = l(l) s(l) [(X a)ⁿ -1]/ (X а -1) ; 4) The area law: (p = f (i) / f (i -1); i-th order: f (i) = f (l) ^p-l ; where ф - the ratio of catchment areas; f (l) and f (i) - the average area of watershed streams l and i-th order; 5) The acclivity law: p = tga{i)/tga (i _-l); tga{i) = tga(l) p^i-1 ; where в - the ratio of slopes; a (l), a (i) - average angles overland flow l and i-th order. For the Altay landscape of mudflow origination site minimum length is in the range 0,022-0,108 km (highlands) and in the range 0,150-0,270 km (Anuj and Peschanai basins, district Teleckiy lake). The average length mudflow channel in the range of l,57-l,79 km (Cocsa, Katun rivers) and 0,80-l,l2 km almost all mudflow basins. In the Altai area representative debris basin is 9-ll km² (average height of 1890-2400 m above sea level) and 5-6 km² (average height of 920-l080 m). Here within mudflow basins ratio between the area of watershed streams and their length is described by a power function l = 0,96 F⁰'⁶⁷ with closely connected to the empirical data R² = 0,89. The central part of the northern slope of the Zailiyskiy Alatau length mudflow channel proportional to the area basin level 0,76. Then a representative of their area is 9-l0 km². Dependence of length channel of denuded area of basin Gavasay approximated expression l = 2,83 F^{0 62} . In Chust-Pap adyrs thalwegs core length 2-fold higher than those for conditions of the Altai region. This is closely connected to the different grain-size classification soils.

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