Extreme Runoff Simulation in Mala Svinka Basin
Pavol Miklanek, Dana Halmova, Pavla Pekarova
Institute of Hydrology SAS, Bratislava, Slovak Republic
Introduction
In the second half of the 1990s several catastrophic floods occurred in Slovakia, and central
Europe. It is also new, that the number of flash floods increases. The most catastrophic
rainstorm flash flood in history of Slovakia occurred in Mala Svinka basin on July 20, 1998.
Forty-eight people died during the flood, and the material damages were high as well. The
estimated rainfall depth over 100 mm during one hour is not the highest in the history of
meteorological observations in Slovakia. In Salka, 232 mm were gauged on July 12, 1957
during 65 minutes storm, and 162.8 mm were gauged in Trnava on June 3, 1951 during 2
hours (Samaj et al, 1985). These storms did not produce historical floods.
This paper includes the description of the Mala Svinka basin and of the flood on July 20,
1998, and simulation of the floodwave by the AGNPS model with distributed parameters.
Description of the Mala Svinka basin
Mala Svinka basin is situated in Bachuren mountains (1081 m a.s.l.) in Eastern Slovakia. The
spring of the stream is in 920 m a.s.l. and the confluence with Svinka river is in 320 m a.s.l.
Length of the stream is 23.7 km and the area of the basin is 61.21 km 2. Basic characteristics
of the basin are in Table 1. The scheme of the basin is on Fig. 1. The valley is narrow and
feather-like. The basin is in Neogene flysh area (flysh is a geological formation consisting of
alternating layers of sandstones and clay). Shallow soils and steep slopes cause erosion.
Table 1
Basic morphometric characteristics of sub-basins of Mala Svinka catchment.
River
Cross-section
Area
[km2]
1. Rencisovsky brook
Rencisov
2. Mala Svinka
Downstream Rencisov
3. Mala Svinka
Upstream Uzovske Peklany
4. Mala Svinka
Jarovnice
5. Mala Svinka
Outlet
Length A/L2 Forest River
Cover slope
[km]
[ %]
[%]
Q100
[m3s-1]
Min
elevation
[m a.s.l]
7.07
4.6
0.334
20
8.8
54.54
600
12.52
4.7
0.567
60
7.6
63.5
600
21.53
8.2
0.320
60
5.2
78.25
514
34.39
13.8
0.181
50
3.8
92.55
410
61.21
23.7
0.109
40
2.4
111.42
330
Results of the simulation
The hydrological part of the AGNPS model (AGricultural Non-Point Source Pollution Model)
was used to simulate the peak flows and runoff depths in Mala Svinka basin. The AGNPS is a
geographically oriented model. It models the floodwave, and both water and material flows
during a single rainfall-runoff event. The main input is precipitation depth and duration and
output is peak runoff. Model can be used for simulation of different runoff situations (dry and
wet conditions depending on antecedent precipitation). The land-use changes or farming
practices can be simulated as well (particularly important for the chemical part of the model).
Details are in the manual of the model by Young et al (1996).
LEGEND
1. Renčiš. brook - Renčišov
2. M. Svinka - downstream
of Renčišovský brook
3. Malá Svinka - upstream
of Uzovské Pekľany
4. M. Svinka - Jarovnice
5. M. Svinka - outlet
60 mm
100 mm
precipitation station
M. Svin
ka
3
1
Bachureň
1081 m
Renčišov
Renčiš
. b.
2
M
d
in
ž.
b.
Lipovce
62 mm
Uzovské Pekľany
4
Jarovnice
S
M.
A
RI
ST
AU
48
POLAND
CZECH
REPUBLIC
SL
O
K
VA
5 km
IA
a
49
k
vin
50
N
UKRAINE
HUNGARY
5
47
16
Fig. 1
18
20
22
24
E of G [degre]
Kojatice
Mala Svinka basin, rainfall depth on July 20, 1998.
Rainfall
The mean rain gauge density is about 1 gauge per 70 km 2 in Slovakia. Unfortunately, there is
no rain gauge in Mala Svinka basin. Eight rain gauge stations are situated around the basin.
The nearest station is in Lipovce, about 5 km far from the watershed. The rainfall depth was
“only“ 62 mm in Lipovce during the day of the flood (Fasko & Lexmann, 1998).
Major runoff depths were measured in Lipovce several times before: 81 mm on July 25, 1965
during the afternoon, 70 mm on July 13, 1973, and 93 mm on August 4, 1997 between 6 p.m.
and 7 p.m. The highest daily rainfall in the neighbouring basins was 97.4 mm and it was
gauged on June 29, 1958 in Brezovica nad Torysou. No significant flood was produced by
these extreme rainfalls.
Fasko & Lexmann (1998) noticed that the rainfall depth 62 mm in Lipovce represents 10years rainfall depth. They estimated that the rainfall depth over 100 mm occurres with the
probability of 200 years. Samaj et al (1985) estimated the N-years maximum daily rainfall
depths in Brezovica nad Torysou station (Table 2).
The rainfall depths and intensities over the upper part of the basin were significantly higher
and they were estimated by the meteorological and radar observations as 100 mm/h, or more
than 100 mm depth. The duration of the storm was just about 1 hour. The approximate
isohyets are on Fig. 1 (according Fasko and Lexmann, 1998).
Table 2
N-years maximum daily precipitation in Brezovica nad Torysou and Lipovce
Station – Years
Brezovica nad
Torysou
Lipovce
2
5
10
20
30
50
80
90
100
200
37.8
51.6
60.5
69.7
74.9
81.1
87.0
88.6
90.0
98.3
62
>100
Simulation of the event by AGNPS model
The flood event was simulated by AGNPS model separately in two versions:
I. in the whole basin; and II. in the upper part of the basin.
The simulation results in four profiles (see Fig. 1) are in Table 3:
Profile 1.
Profile 2.
Profile 3.
Profile 5.
Rencisov brook in Rencisov;
Mala Svinka downstream Rencisov;
Mala Svinka upstream Uzovske Peklany;
Mala Svinka - outlet.
With respect to the rainfall depths estimated for the flood event by the Slovak
Hydrometeorological Institute, the simulations were done for the rainfall depths between 70
and 120 mm. The results are in Table 3.
Conclusion
Mala Svinka basin is an ungauged basin, therefore the floodwave and the peak flows were
estimated indirectly and post event by several authors. Svoboda and Pekarova (1998)
simulated the peak flows with different models (also AGNPS) with good coincidence with
estimated flow. The intention of this paper is to simulate hypothetical floods in this basin at
different rainfalls. The reliability of the model was tested by simulations with divers density of
grid cells (1 km and 500 m). The differences were negligible and grid area under 1 km 2 did
not influence the results.
Table 3
Simulated peak flows Q, yields qmax, floodwave volumes V and runoff depth R in
selected profiles. Simulations were done I. in the whole basin, and II. in the upper part
of the basin and rainfall ZR between 70 and 120 mm.
Area
ZR
70
80
90
100
110
120
Q
qmax
V
R
Q
qmax
V
R
Q
qmax
V
R
Q
qmax
V
R
Q
qmax
V
R
Q
qmax
V
R
m3s-1
m3s-1km-2
103 m3
mm
m3s-1
m3s-1km-2
103 m3
mm
m3s-1
3
m s-1km-2
103 m3
mm
m3s-1
m3s-1km-2
103 m3
mm
m3s-1
3
m s-1km-2
103 m3
mm
m3s-1
m3s-1km-2
103 m3
mm
Profile 1
6.7 km2
I.
II.
59
57
8.8
8.5
382
328
54
49
68
67
10.1
9.9
450
391
64
58
78
76
11.6
11.3
519
448
73
67
88
88
13.1
13.2
589
528
83
79
97
98
14.5
14.6
658
591
93
88
107
107
16.0
15.9
739
647
105
97
Profile 2
12.52 km2
I.
II.
92
79
7.4
6.3
696
598
56
48
107
93
8.5
7.4
820
712
66
57
122
106
9.7
8.5
942
814
75
65
137
124
10.9
9.9
1065
966
85
77
152
138
12.1
11.0
1186 1081
95
86
167
150
13.3
12.0
1288 1186
103
95
Profile 3
21.53 km2
I.
II.
124
100
5.8
4.6
1197
957
53
44
145
119
6.7
5.5
1413 1149
63
53
166
136
7.7
6.3
1631 1324
72
61
188
161
8.7
7.5
1848 1575
82
73
209
180
9.7
8.3
2071 1772
92
82
230
197
10.7
9.1
2289 1947
102
90
Profile 5
61.21 km2
I.
II.
222
3.6
3250
53
261
4.3
3856
63
300
4.9
4444
73
339
5.5
5056
83
377
6.2
5644
92
416
6.8
6231
102
AGNPS model is, in our opinion, a good tool for estimation and analysis of the rainfall-runoff
processes in the basin (particularly its graphical part).
References
FASKO, P. & LEXMANN, E.: (1998) The storm in Mala Svinka – the worst catastroph caused
by storm in Slovakia. (In Slovak.) SME/Smena, 3.8.1998.
SVOBODA A. & PEKAROVA, P. (1998) Catastrophic flood of July 1998 in the Mala Svinka
catchment – its simulation. (In Slovak.) J. Hydrol. Hydromech., 46, 6, 353-371.
SAMAJ, F., VALOVIC, S. & BRAZDIL, R. (1985) Daily totals of precipitation with extreme
intensity in Czechoslovakia during the period 1901-1980. (In Slovak.) Collection of
papers of the SHMI 24, Bratislava, 9-112.
YOUNG, R.A.–ONSTAD, Ch.A.–BOSCH, D.–ANDERSON, W. P. (1996) Agricultural NonPoint Source Pollution Model, Version 4.03. User´s guide. MPCA, Minnesota.
Acknowledgement: The paper was prepared with support of the VEGA grant 6008.