1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

RISCURI ŞI CATASTROFE, NR. XIII, VOL. 15, NR. 2/2014

1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA
RESERVOIRS

S. KOVÁCS1

ABSTRACT. – 1D hydraulic model in relation with the planned Tisza
reservoirs. The floodwaves of 1998-2001 and the year 2006 reached never before
measured heights on the river Tisza. The peak heights of the upper and middle
reaches of the river exceeded the maximum values by 130-150 cm. Such an
intense growth has never been experienced (the peak heights measured at the
Tivadar gauging station exceeded the values of 1970 by 149 cm and at the Szolnok
gauging station by 132 cm), not even after the river regulations in the XIX.
century. The new, critical maximum water levels urged the reconsideration of the
flood protection system’s development strategy alongside the river Tisza. Taking
the present flood-conveyance capacity with its declining tendency and the possible
reoccurrence of the latest (1998-2001) or earlier (1970, 1947/48, 1940, 1941,
1932, 1919, 1895, 1888) hydro-meteorological phenomena into consideration, the
success of a flood protection procedure can only be guarantied by the
improvement of the riverbed’s flood conveyance capacity and the concerted
operation of several reservoirs. The concerted and effective operation of the
reservoirs (6 to be built in the I. development phase and others to be constructed
later) have to be based on a complex and steering high-water operational model, a
constantly updated data-base and a well functioning organization. The river Tisza
demonstrated its power this year as well. The river exceeded the highest water
levels on a 270 km long reach from Tiszaug (Tiszainoka) down to the Danube
influx. Experiencing the flood of spring 2006, the floodwave of 2000, called to be
the floodwave of the millennium, is not exceptional anymore. It seems, that we
have to prepare for water levels 100-150 cm higher than the maximum levels of
the last, hydro-meteorologicaly similar period of 1960-1970. This statement is
based on the following: considering the data of the period 1901-2006, the 1%
water level calculated by traditional probability theory is 1059 cm, calculated by
intercept method is 1058 cm. For the accuracy of our forecasts, during the flood in
spring 2006 we combined the hydrodynamic model with our forecasts prepared for
the boundary cross-sections. In this study we present the hydrodynamic model
prepared for a 740 km long reach of the river Tisza and the combination of the
model with the forecast system.

Keywords: maximum discharge, Water discharge curves, 1D hydrodynamic
modelling, hydraulic engineering structures, calibration of the model
2

Middle Tisza Region Water Directorate, Szolnok, Hungary, e-mail: drkovacs@kotivizig.hu

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1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

1. Results of hydrological surveys
Because of its returning and gradually increasing, and sometimes
extremely high floods as well as recurring and lasting law waters the River Tisza is
considered to be the most variegated river of our country. Characteristics of the
river decisively originate from the shape of the drainage system, from the relation
of water output of tributaries to the main stream, from the considerable amount of
drift, from the small slope on the long lowland section and from the regulation of
both low and high water bed. Current length of the River Tisza is 945.8 km; its
catchment area covers 157.200 km2. According to the measurements of past
decades the maximum water discharge of the river at the Tivadar section (705,7
stream-km) exceeds the value of 4.000 m3/s, in the middle section, between
Kisköre and Szolnok it is between 2.600 and 2.900 m3/s, while in the lower section,
i.e. at Szeged (173,6 stream-km) it is over 4.000 m3/s.
water level
(cm)

TISZA, SZOLNOK Q=f(H) - Rating Curve

1050
2000. április
2006. április

1000

950

1999. március
1932. április

900
1970. május
850
1979. február
800

1895. április

750

700

650

600
900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

2800

2900

3000

3100

3200

3300

3400

discharge (m3/sec)

Figure 1. Water discharge curves on the River Tisza at the Szolnok section
(334,6 str-km)

Before the regulation works the River Tisza was a strongly meandering
stream with a small slope. Following the regulation works in the course of the
second half on the 19th century the length of the river decreased by 30 percent; its
103

S. KOVÁCS

track has changed and also the bed slope has increased slightly. The slope of the
water surface is changing between 1 to 6 cm/km on the lowland section. There
have been embankments built alongside the river. Currently, the embankment
system of the Tisza lasts from Tiacev (Ukraine 887 stream-km) completely down
to the mouth and the “blond” river moves on the water and drift circulation
between these embankments, on a considerably smaller area than before the
regulations. The bed of tributaries on their lowland section was also regulated
similarly to the Tisza; there are embankments rising alongside the tributaries on
more hundred kilometres. The total width of the river changes between rather wide
limits, that is between 350 to 6000 m.
In the course of years between 1998 and 2006 such flood waves subsided
on the River Tisza which have never been experienced before. The values of
culminations have exceeded the previous maximum values by 130 to 140 cm.
These new flood waves of critical height resulted in the reconsideration of flood
prevention alongside the River Tisza. We can best and most accurate demonstrate
the water discharge ability of the bed by analysing of water outputs. We may
declare this despite the fact, that because of the slight bed and water surface slopes,
the back-swelling effects of the Hármas-Körös, the Maros and, to a certain extent,
also the Danube have impact onto the pass down of flood waves and onto the shape
of flood loop curves at the same time.
Table 1 indicates the maximum discharges measured at the Szolnok crosssection and water-level differences in relation to Szolnok-Csongrád and SzolnokSzeged. This table demonstrates the decline in the river’s water conveyance
capacity.
Table 1. Maximum water levels and discharges of the Tisza at the
Szolnok cross-section
Year
1895
1919
1932
1970
1979
1998
1999
2000.
2006

Hmax
Szolnok
(cm)
827
882
894
909
904
897
974
1041
1013

Qmax
Szolnok
(m3/s)
3317
3179
2450
2424
2161
2403
2608
2406

Hmax.Szolnok-HtCsongrád
(cm)

Hmax.Szolnok-HtSzeged
(cm)

221
264
232
239
369
384
352
312
240

465
509
492
492
650
714
677
633
512

An important question of analyses of water output measurements was
whether to accept or involve into the survey the historical measurement results
(from 1895 and 1932). We will see below, that these measurements must not be
104

1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

disregarded by all means. It is possible, only by the processing and analyses of
these measurement results, to find an explanation and to understand the phenomena
have been taking place in the regulated bed for 100 years.
Let us control the section of the Tisza at Szolnok. Fig. 1 demonstrates the
water output measurements on the occasions of floods with outstanding dimensions
in the years 1895, 1932, 1970, 1979, 1999, 2000 and 2006. It has to be mentioned,
that the measurements in 1895 and 1932 were performed not direct in the section at
Szolnok, but in the constrictions of Tiszapüspöki and Vezseny, however, the water
levels were related to the water measurement post at Szolnok already at the time of
measurements.
The measurement results obtained in 1970 (Hmax = 909 cm) and in 1979
(Hmax = 904 cm) were very resembling to each other considering both water levels
and water output. To the culminations that slightly exceeded the 900 cm there were
water outputs belonging over 2.400 m3/sec. Between 1932 and 1970, there were 38
years elapsing. (Almost exactly as many years as between 1895 and 1932)
However, the culminating water levels in 1970 and 1979 that slightly exceeded the
values of 1932 occurred at water outputs that were less by 400 to 500 m3/s.
One of the decisive elements of the Update of the Vásárhelyi Plan Program is the
knowledge of differences between the highest water levels and the authoritative
flood levels along the longitudinal section of the River Tisza (Figure 2).
Z
mB.f.

∆Η
(cm)

DIFFERENCES BETWEEN MAXIMUM AND DISIGN WATER LEVELS

123

130

121

120

119

110

117

100

LNV-MÁSZ

115

90

113

80

111

70

109

60

107

50

105

40

103

30

101

20

99

10

97

0

95

-10

93

-20

91

-30

LNV
(interpolált)

89

-40

87

-50

MÁSZ

85

-60

83

-70

81

-80

79

-90
700.0

600.0

500.0

400.0

300.0

200.0

100.0

-100
0.0

77
fkm

Figure 2. The difference between the highest water levels and the authoritative flood levels
on the River Tisza

105

S. KOVÁCS

Based on the figure the most critical sections can be designated alongside
the river and the sequence of interventions, like the reinforcement and
strengthening of embankments, regulations on the flood plain, construction of
reservoirs, can be determined.
In this paper we shortly summarize our 1D hydrodynamic modelling
activities serving as a base for further planning. The modelling has been
accomplished by applying the HEC-RAS software. When selecting the hydraulic
model, it was of fundamental importance to work with a program that operates on
good physical bases, and is easy to handle with short running time and displays the
results in a well structured form. In the decision process it was of outstanding
importance that the five countries on the catchment area of the River Tisza might
connect to the structured system or to a certain segment of joint interest of that.

2. 1D Hydraulic modelling of the water system of the river Tisza
2.1 The stream network
In its current structure, the database of the model includes the 740 km long
rives section between Tiszabecs and Titel, as well as the 8 tributaries mouthing into
the main stream, moreover, two branches (Borzsa and Lónya Canal) as
concentrated load. The total length of streams involved into calculations exceeds
1.500 km (Fig. 3). We have approached the stream system of the River Tisza and
its tributaries by more than 1.550 cross sections. We installed 84 bridges and 11
flood reducing structures into the model.
2.2 Cross section data
The HEC-RAS model (together with the other 1D models) is suitable for
inputting cross sections determined by the traditional distance-height point couples
as well as for operation of databases based on geographic informatics systems
(GIS). We presented the cross sections with the help of digital relief map on the
river section between Kisköre and the southern confines of the country. On the
strongly overgrown flood plain areas, in the line of channel bars, we corrected the
data of relief map by geodetic measurements. In the assembly of the river system it
was a great assistance from the part of Serbian water management professionals,
that they made the cross sections of the river between the southern boundary and
the mouth available for us.
2.3 Hydraulic engineering structures
The HEC-RAS model applied for the detailed description of the entire river
system provides an opportunity for taking into consideration the hydraulic
engineering structures, as well like bridges, barrages, culverts, overflow weirs,
floodgates, bottom stages, bottom sills, side overflows and gates, static reservoirs,
pump head stations and water intakes.
106

1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

r og

os
m

B

T

Sz
a

Fzsolca-Shidveg
Sajohi dveg
Shidveg-T ujvaros

Agerdomajor-Vnam

Delborsodi
T iszananai
Hanyi-Jaszsagi
Hanyi-T iszasul yi
s

Za g

Ti

za

Jasztel ek-Szoln

yv a

Nagykorui

T ujvaros-Szolnok
Nagykunsagi

Pocsaj -Szeghalom

T iszaroffi

o
tt y
e
Berettyo_tor
Kszakal-Kladany
B
Szol nok-Csongrad
Kettos-K-tor
Kladany-Fol yaser
Mergesi_tarozo
a s - Kor o s
rm
Szanazug-Ktarcsa
Gyoma-Csongrad
Kisdelta_tarozo
Fekete-K-tor
Ant-Remete
Malyvadi _tarozo

is

Ha

za

T

e

r

Szol nok

Ti

Olcsva-Vnameny

Olcsvaapati
T iszakaradi
T okaj
T becs-G.ugornya
Vnameny-T okaj
Vnameny
Szamoskozi
i s za T okaj-T uj varos
Szamos-Kraszna
T iszaujvaros
Csenger-Olcsva
od

za
Ti s

Gesztely-Shidveg

s

za

Cigandi
Fberecki-T okaj

Csongrad
T i s za

Gyuladuzz-Gyula
Csongrad-Szeged

Mako-Szeged

Szeged

T

zi sa

Szeged-T itel

Figure 3. Stream network of the River Tisza in the model

107

S. KOVÁCS

Figure 4. Detailed demonstration of roughness factors in the cross section

2.4. Roughness (smoothness) coefficient
For calculation of the water discharge capacity of the main bed as well as
for taking the flood plain cultivation branches into consideration we used the
roughness (smoothness) factors given in the Table 2 in the course of calibration of
the model. We determined the cultivation branches on the flood plain by aerial
photographs, i.e. by ortho-photographs, as well as by the results of on-site
inspections. The roughness factor was changed crosswise according to flood plain
cultivation branches. The roughness (smoothness) factor assigned to these was
determined on the base of the prescriptions of the Hungarian standard, as well as
on the base of values applied also by HEC-RAS and proposed by Chow (1959).
The smoothness factors assigned to individual cultivation branches overlap each
other as there is no possibility for making sharp difference between the categories
of “sparse thicket” and “dense thicket” (Fig.4).
The advantage of such calibration method is that in case of planning future
conditions the roughness factors to be changed can be given simply and bound to
the physics of the river system. In the course of planning works we performed
calculations by giving the horizontal roughness factor. However, in the course of
further development of the model there is a need also for vertical modification of
the roughness coefficient. This makes possible to model not only the extremely
high flood waves with the application of the same system on higher accuracy.
108

1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

Figure 5. Bird’s eye view on the bed of the River Tisza.

With the roughness factor we practically divide the flow zones of the river
into “layers”. The horizontal division of the roughness factor is definitely necessary
in case of rivers with broad flood plain. On the flood plain the vegetation, forests,
meadows and the different agricultural cultivation branches are located in an
intermittent pattern. The water discharge capacity of the river (the roughness
coefficient) is changing according to this pattern, too.
In the course of flood waves the depth of the main bed reaches 24 to 26 m
at many places, especially in river bends. In case of such water depths it is
necessary to divide the water movement, i.e. to create also vertical layers. As soon
as the water reaches the height of the bank edge, the branches of trees protruding
into the water are decreasing the movement or flow rate of the water. In the case of
meandering rivers with flood plain the flow conditions are modified vertically to a
great extent by the coinciding waters passing along the main bed and on the flood
plain (Fig. 5). The results of water discharge measurements in the course of flood
waves have proven the need of vertical modification of the roughness factor.
Hydrological basic data and limiting conditions.
2.5.Calibration
The calibration of the model was accomplished gradually, starting with the
shorter sections. We assembled together the individual section and then performed
the river section between Tiszabecs and Titel.
109

S. KOVÁCS

Tiszabecs_Titel_uj_F_T

Plan: Tiszabecs_Titel_2000_ujF_T

Geom: Tis zabecs_Titel_2000_uj_F_T
Tisza Szeged-Titel
120

110

100

Elevation (m)

90

T
i
s
z
a

T
i
s
z
a

C
s
o
n
g
r
a
d
S
z
e
g
e
d

S
z
o
l
n
o
k
C
s
o
n
g
r
a
d

Tisza Tujvaros-Szolnok

T
i
s
z
a

Tisza Vnameny-Tokaj

T
o
k
a
j
T
u
j
v
a
r
o
s

T
i
s
z
a

T
i
s
z
a

O
l
c
s
v
a
V
n
a
m
e
n
y

T
b
e
c
s
G
.
u
g
o
r
n
y
a

Legend
WS Max WS
Ground
Left Levee
Right Levee
OWS Max WS

80

70

60

50

40

0

100000

200000

300000

400000

500000

600000

700000

800000

Main Channel Distance (m)

Figure 6 The results of calibration on the river section between Tiszabecs and Titel

Figure 6 illustrates the results of the calibration process. The continuous
line (red, with a blue coloured field there under) in the figure represents the
envelope of calculated water levels (longitudinal section of culminations), while
red dotted line shows the maximum water levels measured at standard posts and
those at dam keepers in the course of the flood wave in 2000.
On the river section between Tiszabecs and Titel, in the culmination of the
flood wave the difference between the calculated water level and that of observed
was between 0 and 10 cm in absolute values, which can be considered as a very
good result.
2.5. Verification
In connection with the calibrated bed it has to be verified that it is valid not
only to that event onto which it has been calibrated (as in case of sufficient free
parameters to be calibrated the model can be calibrated to any flood wave), but can
be extended to discretionary flood waves, too. For this reason the verification of
the model has been performed by running of an independent event in such a
manner, that the parameters have not been modified in the meantime.

110

1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

3. 1D Model surveys
It has been emphasized on more forums that the fundamental aim of
regulations of flood plains consists in the possible restoration of water discharge
ability of the River Tisza prior to the year 1970.
Kiskore_Zenta

Plan:

1) Vezs-kerese

Geom: KiZe_RfVe_toltath050n
Riv er = Tisza Reach = Szolnok-Csongrad RS = 307.978
.
0
6
6
5

90

.
0
2
7
3

.093

.0665

.05
Legend
WS Max WS
Ground

88

Levee
Ineff
86

Bank Sta

Elevation (m)

84

82

80

78

76

74

72

0

1000

2000

3000

4000

5000

6000

Station (m)

Figure 7. Regulation of the flood plain

On the river section between Kisköre and the southern confines of the
country, within the framework of transformation of land use on flood plains we
plan to clean out the high water run-off stripe, the so called hydraulic corridor, the
demolition of summer dikes, the formation of hollow-chamfers that follow the
track of drift line and improve the water discharge performance. Similar
interventions have been planned on the Upper-Tisza section in the region at
Tivadar. In the Figure 7 we demonstrate the flood plain regulation in the Vezseny
bend on the basis of cross section.
Following the survey in connection with interventions on flood plains we
accomplished the examinations related to reservoirs, or groups of reservoirs with
and without flood plain interventions. Within framework of the first cycle of the
“Update of the Vásárhelyi Plan” program there are 6 reservoirs designated. We
performed the survey of reservoirs both for the authoritative historical flood waves
and for the synthetic, so called generated flood waves, too. The number of model
runs exceeded the 300.
111

S. KOVÁCS

The survey with and without flood plain interventions (related to the
authoritative conditions of the past) of the 6 reservoirs designated for the first
phase of the development will be discussed in what follows:
KORMÁNYHATÁROZAT 6 TÁROZÓ HULLÁMTÉRRENDEZÉS NÉLKÜL ÉS
HULLÁMTÉRRENDEZÉSSEL 2000. ÉVI ÁRHULLÁM

∆Z
(cm)

(Szamos-Krasznaközi, Cigándi, Hanyi-Tiszasűlyi, Nagykörűi, Nagykunsági, Tiszaroffi)

40
30
20
10
0
-10
-20

hullámtérrendezés
n=0,100; k=10

-30
-40
-50

Kormányhatározat 6 tározó
hullámtérrendezés nélkül

-60
-70
-80
-90
-100
-110

Kormányhatározat 6 tározó
hullámtérrendezéssel

-120
-130
-140
-150
-160
-170
-180
0

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

X (fkm)

Figure 8. Effect of the 6 reservoirs, designated in the government decree, with and without
flood plain regulation in case of the flood wave in the year 2000.

We accomplished the survey related to the flood plain interventions and
their possible effect on reservoirs with flood waves of different character. In this
paper we introduce only those runs that were accomplished for the flood waves of
the years 1998 and 2000. As it already has been mentioned, in the year 1998, there
was an extremely high flood wave on the Upper-Tisza, while in 2000, the water
level raised above the authoritative value on the Middle-Tisza section. According
to this, the flood plain interventions and the flood decreasing effect of reservoirs
have demonstrated differences. In the course of current calculations in question we
used that version in which the value of the roughness factor was n = 0,100; k = 10
in the 600 m wide and 240 km long “hydraulic corridor”. In the case of the flood
wave of the year 1998 the maximum decrease of water level would be close to 100
cm as a result of flood plain interventions and the effect of opening the reservoirs.
In the case of the flood wave of 2000 the degree of water level decrease
would reach 160 cm as a result of joint effect of reservoirs and the flood plain
regulations. With putting the flood reservoirs into operation we can compensate the
water level increasing effect of flood plain regulations on the lower section of the
Tisza, below Algyő.
112

1D HYDRAULIC MODEL IN RELATION WITH THE PLANNED TISZA RESERVOIRS

A flood level reducing reservoir is a basic construction that meets the main
target, i.e. the flood level reduction, by appropriately constructed engineering
works, and provides also conditions for regular water supplement for land
management and ecological purposes, and later for the restoration of water.
For determination of flood level reducing effect of individual reservoirs
and reservoir combinations as well as for optimal selection of water intake
engineering constructions a great number (close to 30) of variations have been
controlled. In the course of control of this great variety more assumptions proved to
be correct that were based on empirical and approximative theoretical
considerations and were proposed in more preparatory studies: Certain parameters
of individual engineering structures, location of water intake structures, threshold
level of floodgates and spill-over, have been determined in the course of the
engineering process. Other dimensions of engineering structures (like the
maximum spill-over length, number of floodgates) have been corrected upon the
calculations for the preliminary hydrodynamic modelling and the opportunities of
technical realization. In the course of surveys the determination of theoretically
“optimal” openings of reservoirs has not been the aim, but only approximately
optimal openings have been applied.
Q
3
(m /sec)

HEC-RAS MODELLEREDMÉNYEK SZEGEDRE

H (cm)

3000

1000

H (1.1 érkező Q)
Szeged H

MÁSZ = 971 cm
2500

950

előrejelzés kezdete

extrapolálás kezdete

Kisköre-a. Q
2000

1500

1000

900

850

1.1 érkező Q

Makó Q

500

800

750

Gyoma Q

Jásztelek Q
0

dátum

Figure 9. Result of modeling and forecasting stage hydrograph, Tisza, Szeged.

113

2006.04.28

2006.04.27

2006.04.26

2006.04.25

2006.04.24

2006.04.23

2006.04.22

2006.04.21

2006.04.20

2006.04.19

2006.04.18

2006.04.17

2006.04.16

2006.04.15

2006.04.14

2006.04.13

2006.04.12

2006.04.11

2006.04.10

2006.04.09

2006.04.08

2006.04.07

2006.04.06

2006.04.05

2006.04.04

2006.04.03

2006.04.02

2006.04.01

2006.03.31

2006.03.30

2006.03.29

2006.03.28

2006.03.27

2006.03.26

2006.03.25

700

S. KOVÁCS

4. Application of the 1d hydraulic model during the flood in 2006
The first time we used the hydrodynamic model in practice was during the
flood in spring 2006. The model was calibrated to the year 2000. We uploaded this
version with the data of the year 2006. In order to simplify the calculation we run
the model on the Kisköre-Titel reach of the Tisza. We integrated three tributaries,
the Zagyva, the Körös (4 branches) and the Maros. The boundary condition in the
upper cross-sections were function Q=f(t), in the lower cross-section at Titel were
Z=f(t). The boundary conditions of the model were extended by a 6-day discharge
forecast. In case of Titel we downloaded a 4-day forecast from the Serbian website.
In order to give a peak-forecast on the Tisza, we extended the 6-day forecast to 12
days. The results are demonstrated on Figure 9.
5. Summary
The HEC-RAS model – following its merging with the hydrographical
information system and with the forecasting model of water levels and water
outputs – may serve as a base of high water management system of the River Tisza.
Current calibration of the model will change; in case of actual use of
reservoirs their effect on water level reduction will not be equal with the results of
current simulations. The parameters of the model have to be upgraded according to
the consequences of technical interventions accomplished in the meantime, as well
as with the results of the new geometrical surveying. For the sake of the cause, the
model and the related database require a continuous maintenance.

REFERENCES
1.
2.

3.

4.
5.

Kovács, S. (2003), Improvement of the flow carrying capacity of the flood-channel,
Dutch-Hungarian workshop, Szolnok, Hungary October 2003.
Kovács, S. (2004), Experiences in Application of HEC-RAS Model under Circumstaces
of Flood Waves, NATO Advanced Research Workshop, Ostrov u Tise, Czech Republic
October 2004,
Kovács, S. (2005), Modelling the River Tisza by using one-dimension hydro-dynamic
model, Third International Symposium on Flood Defence, Nijmengen, The
Netherlands, May 2005,
Kovács, S., Ivaskó, L., Tóth, I. (2006), Das Hochwasserschutzkonzept an der Mittleren
Theis, WasserWirtschaft, Organ der Deutschen Vereinigung 3/2006.
Kovács, S. Hegedüs, P. (2005), Using HEC-RAS for Complex Flood Control Project,
FMA 2005 Annual Conference, Sacramento, USA September 2005.

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