Geoscience Reference
In-Depth Information
Table 1 Compiled parameters characterizing the bedload in the Białka mouth area (
d
m
is the
mean size of grains covering riverbed,
d
i
are characteristic diameters of bedload fractions, and
d
is
the standard deviation of sieve curve
Location
Sample
number
d
m
(cm)
d
16
(cm)
d
84
(cm)
d
50
(cm)
d
(
)
Right riverbank
1
11
4.3
16
9.8
1.93
10 m upstream the river step
2
12.1
5.3
15.8
12.5
1.73
Shallow flow
3
12.9
5.6
20.5
10.3
1.91
Flow current downstream the step
4
30.2
11.6
42.1
28.5
1.92
Gravel bar
5
8.21
3.1
12.7
5.9
2.02
Flow current upstream
6
15.5
7.1
22.6
14.8
1.78
Fine material on the bank
7
6.4
1.7
10.7
5.1
2.51
Rough material on the bank
8
17.1
6.5
26.7
14.8
2.03
200 m upstream from the bridge
NB
35
14.6
43
37
1.72
carried out in Nowa Biala village on 18 November 2009. The material has been
mixed. No location was found with the bed armoring described by
d
of an approxi-
(
d
84
/
d
16
)
0.5
;
see Table
1
) pointing to the existence of armored bottom (Bartnik and Stru˙y´ski
1999
,
2002
).
Some differences were noticed in granulometric composition of the bedload.
The curves form two groups. Coarser material is situated downstream of the river
step in the current (sample 4). A similar bedload has been measured in the “NB”
locality situated 200 m upstream from the Nowa Biala-Krempachy bridge (about
10 km from the Białka mouth). On the gravel bars and midstream gravel banks
one can find both coarse and fine material (samples: 1, 2, 3, 5, 6, 7, and 8). The finest
grains (samples 5 and 7) are on the bank and gravel banks, although there are places
where much coarser bedload may be found on the bank (sample 8), similar to the
bed sample measured in the current (sample 6).
On the basis of sizes
a
,
b
, and
c
measured in Nowa Biala village on 18 November
2009, the shape factor SF was computed using the formula
mate value of 1.3 (where
d
is the standard deviation of sieve curve:
d ¼
c
ab
¼
p
SF
(1)
where
a
is the biggest,
b
the average (sieved), and
c
is the smallest diameter.
The grain size ranged from 2 to 49 cm. The grain shape factor fluctuated from
0.17 to 0.93 reaching the average value of 0.59. The grains measured in the mouth
reach in April and May 2,010 were characterized by the shape factor values from
0.4 to 0.7 with the value 0.6 describing the whole sample.
3.3 Hydrological Data
The course of the flood water in May 2010 registered by IMGW station in Krakow
is illustrated by observations from the Trybsz gaging point (Fig.
3
).
