DIGITALNA ARHIVA ŠUMARSKOG LISTA
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ŠUMARSKI LIST 13/2005 str. 61 <-- 61 --> PDF |
V. Tlapak. J. Ćaska, J. Hcrynek: THE INFLUENCE OF FORESTS AND VEGETATION ON EROSION Šumarski list SUPLEMKNT (2005), 51-60 ween rainfall infiltration speeds (v;) and rainfall transformation factor (Wk) by equation of Horton type: y = (a-b) exp (-nx)+b (2) or by scheme at figure 2: v, (WJ = (vi0 - v,J exp (-n-W^v, (3) Vj = actual speed of infiltration (m.s-1) vi0 = initial speed of infiltration (m.s1) vjv = steady actual speed of infiltration (m.s-1) (4) Ht(t) = viv t + nw, nw,. is = rain intensity (m.s-1) High of water column of rainfall which created surface runoff (H0) from the beginning of rain (t = 0), respectively from time ts to time t 1 i, - v. (5) H0(t) = (is t + - + V;„ - V, nw. Maximal surface runoff Qmax can be evaluated from equation: HS0",, (6) «wnax H0 = high of water column of rainfall in surface runoff (m) Sp = area of watershed (m2) tk = time of surface runoff concentration (s) Time of concentration is evaluated from empiric equations for Sp = 0.8 km2 (Kirpich, 1940) f L ^ (7) 1,169 Vvi J RESULTS AND Retention of forest soils can be raise by: sequential conversion of coniferous monocultures at mixed stands with better hydrological effect by application of silvicultural systems which pro tect and uphold quality of forest floor (its thickness, optimal form, loose, integrity) n = exponent (J.rrf ) Wk = cumulated areal density of rainfall kinetic energy (J.rrf2) High of water column of rainfall which infiltrated into soil (Hi) from the beginning of rain (/ = 0) to the time t; ts = time of beginning of surface runoff t, = time of rain K-v;„ V,0-Vn exp(-nwkt)nw, ViO~Vn i,. -v„ exp(-nwkt) nw, L = maximal length of runoff distance at watershed (m) J = average slope of runoff distance H (8) J for 5=5 - 50 km2 (Kerby,V.S.) L (9) 86,5 n = roughness coefficient (pavement 0.02, soil 0.10, grass 0.30, lawn 0.80) By the upper mentioned method we can determinate beginning of surface runoff, its quantity and maximal volume of surface runoff or other runoff hydrological characteristics. DISCUSSION by application of environmentally friendly transport technologies which minimize compaction of soil horizons and soil surface design, built and maintain forest transport network with technical parameters adequate to natural and technological conditions |