Geoscience Reference
In-Depth Information
On the Kwisa River, upstream of the Złotniki reservoir, there is only one gauging
station located in Mirsk. For the analysis of the Złotniki reservoir operation, the
hydrological data fromMirsk gauging station were transferred, using recommended
hydrological methods, to dam cross section. Characteristic discharges in that cross
section are as follows (Polish abbreviations): minimum NNQ
0.214 m
3
s
1
,
¼
0.817 m
3
s
1
, mean SSQ
4.449 m
3
s
1
, average
average low flow SNQ
¼
¼
323 m
3
s
1
(1981).
Maximum discharges with a given probability of exceedance are
Q
50%
¼
94.07 m
3
s
1
, and maximum WWQ
maximum flow SWQ
¼
¼
85 m
3
s
1
,
198 m
3
s
1
,
Q
5%
¼
245 m
3
s
1
,
Q
1%
¼
351 m
3
s
1
,
Q
0.5%
¼
397 m
3
s
1
, and
Q
10%
¼
600 m
3
s
1
, respectively.
According to the regulations (Rozporz˛dzenie
2007
) valid in Poland, Złotniki
dam is classified into hydrotechnical structures of the first class of importance. For
such structures, not subjected to destruction due to their overflow, a probability of
exceedance for computational discharges should be set at 0.5% and 0.1%, but for
the higher discharge - with the upper extension at
t
a
¼
Q
0
:
1
%
¼
1 and confidence level 0.84.
For Złotniki dam cross section, the discharges are
Q
0.5%
¼
397 m
3
s
1
and
Q
0
:
1
%
¼
600 m
3
s
1
, respectively. Computational discharges significantly exceed the outlet
installation capacity ability of the reservoir, so model tests were carried out,
preceded by analytical computations for the reconstruction of outlet installation.
First, a side channel spillway was analyzed due to its possible significant over-
dimensioning (Machajski
2009
; Machajski and Olearczyk
2009
).
3 Analytical Calculations
Side channel spillway fulfills two parallel functions, that is, that of overflow part
and that of flume which is conducted parallel to overflow edge. This flume takes
over the water overflowing spillway and conveys it to installations that link the side
channel spillway with the downstream river section. Analysis of water movement
conditions within the reach of side channel spillway has changed gradually. At
present (Khatsuria
2005
; Novak et al.
2007
; Vischer and Hager
1998
; Tan
ˇ
ev
2005
;
¸ enturk
1994
), the analysis is available based on the law of linear momentum
conservation assuming that the only force ensuring flow of water in flume results
from slope of water level in the direction of water routing. Next, the energy of water
overflowing a spillway is dissipated as a result of its mixing with water in flume,
with simultaneous lack of influence on flow conditions in flume.
The same purpose of hydraulic computations of side channel spillway is the
determination of necessary length of spillway edge assuming exploitation condi-
tions on reservoir, and the determination of pattern of water-table lines in flume at
the assumed parameters of flume cross section, slope of its bottom, and steady
growth of discharge along the length of flume.
The spillway discharge was determined assuming that it will work in the whole
range of expected discharges as not-submerged. Calculations were carried out using
