Geoscience Reference
In-Depth Information
BC E
1
q
L+
0.
5
A
D
F
0
0
1 …0
1
2
3
4
5
t =(t/t
s
)
buildup
decay
+
Fig. 6.5
Rising (AC) and receding (EF) hydrographs at the lower end
x
=
L
of a plane, obtained with the
kinematic wave approach (for turbulent flow with
a
=
2
/
3). The rate of flow is scaled with the
equilibrium rate of flow
q
s
L
=
iL
and the time is scaled with the time to equilibrium given by
Equation (6.20), so that
q
L
+
=
(
q
L
/
q
s
L
) and
t
+
=
(
t
/
t
s
). The area ABC represents the volume stored
on the plane under equilibrium flow conditions, and it is equal to the area DEF.
1
0.8
q
L
+
0.6
0.4
0.2
0
0
0.2
0.4
0.6
0.8
1
1.2
1.4
t
+
Fig. 6.6
Comparison between scaled rising hydrograph obtained with the kinematic wave approach (for
turbulent flow with
a
=
2
/
3) and scaled experimental data obtained by Izzard (1944) on a plane
covered with turf. The solid line represents
q
L
+
=
t
5
/
3
+
. The data points are derived from several
different experimental combinations, namely rainfall intensities
P
=
i
=
91.4 and 45.7 mm h
−
1
,
slopes
S
0
=
0.01, 0.02 and 0.04, and plane lengths
L
=
22, 15, 7.3 and 3.7 m. (After Morgali,
1970.)
