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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