Geoscience Reference
In-Depth Information
Fig. 3 Changes of flow observed at the Trybsz station during flood flow on the Białka River in
May 2010
The station is located 10.6 km upstream from the Białka mouth. In this reach the
catchment is narrow, which causes a slight increment of the immediate catchment,
but the river station does not register the outflows from the Trybska River and its
tributary - Czarnog´rska River, with their mouth just below Trybsz village. In
result, the station monitors a 25 km
2
smaller catchment. Taking into consideration
the catchment increment causes that the maximum of expected flow might have
reached the value of 147 m
3
s
1
. According to the IMGW data, the flow occurred on
17 May 2010 at 5.00 a.m. According to Punzet equation (Carpathian formula) it is a
flow of a 30% occurrence probability. In the hydrological sequence for the years
1995-2004 the minimal flow on Trybsz 2 station is 1.24, the maximum is 174.15,
and the mean flow is 4.76 m
3
s
1
(Kulesza et al.
2004
). The 174.15 m
3
s
1
flow
occurred in the summer season.
4 Computer Modeling Using CCHE2D Program
CCHE2D is a two-dimensional computer model, making computations using finite
element method (Zhang
2006
). It makes it possible to compute water flows in open
channels considering logarithmic velocity distribution. It enables computations of
slow- and fast-changing flows.
Moreover, it is possible to conduct the computations of bedload and suspended
load transport and changes of the bottom configuration (Wu
2001
). The authors of
the program calibrated the computations of bedload transport for coarse fractions
using Wu, Wang, and Jia's equation (Wu et al.
2000
)
"
#
2
:
2
32
=
n
0
n
t
b
t
ck
f
bk
¼
0
:
0053
1
(2)
