# ijege-13_bs-gavardashvili.pdf

*Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università*

*Editrice*

*DOI: 10.4408/IJEGE.2013-06.B-40*

**PREDICTION OF FLOODED TERRITORIES**

**IN CASE OF POSSIBLE BREAKDOWN OF THE SIONI EARTH DAM**

or knocking down of waterworks facilities, which on

their turn can be caused by different natural calami-

ties, such as earthquake, as well as by the accidents of

outdated hydraulic structures. Dam breakdown is also

possible through terrorist acts.

kind since the ancient times, evidenced by the water-

retaining facilities of different heights built in Babylon,

China, Egypt and Italy several thousand years ago.

son for dam failures with the second most widespread

reason being the overloading of an earth dam above

the acceptable level and so on.

ity of slopes. Earthquakes with the magnitude of over

5,5 are capable of causing the landslide of natural and

artificial slopes.

with large-scale destruction; the landslide in the ba-

sin of Vajont arched Dam in Italy in 1963 having

taken away the lives of 2.300 people (G

2006 with 2.000 victims.

Below, we report some dam failures in the world with

**ABSTRACT**

**1**

of the Sioni earth dam, the author has re-worked the

algorithm of the Volna-2”, which allows, in the case

of a possible breakdown of the dam, to calculate the

wave velocity, the run-out distance according to the

topography of river.

as the areas adjoining the Iori River comes under

great flooding.

**K**

**ey**

**words**

**:**earth dam, imitation of a flood, prediction,*break down*

**INTRODUCTION**

ties in the world. By the UN data, in the past century

(1900-2000) floods took away the lives of approxi-

mately 10 million people in the world if not talking

about the damages caused by them (G

*et alii*, 2009).

*1*

*Experience within the NATO SfP 983833 project entitled “Risk-*

*Based Security Analysis of the Hydraulic Systems in the River*

*Network in the South Caucasus Regions (Armenia, Azerbaijan*

*and Georgia)”*

*G. GAVARDASHVILI*

*International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013*

a natural calamity - wreckage of a dam and its result-

ant flood. Reduction of the damages and improvement

of the population safety need accurate forecasting of

floods and risk-factor assessment of natural calami-

ties, as well as continuation of the diagnostic and in-

tensifying the scientific-practical studies of the out-

dated hydraulic structures.

networks, topography of the study area, natural bar-

riers and factors capable of changing the hydrologi-

cal regime, as well as technical data of the outdated

hydraulic structures in the area are known in advance.

reservoirs on the entire territory of the country. As is

known, along with the basic economic purpose of res-

ervoirs, special role is assigned to dams as one of the

means of regulating natural disasters, including floods

and freshets.

planet, facilitating intensive melting of glaciers,

which in turn is one of principal causes of the forma-

tion of floods, freshets and many different types of

instabilities.

for the analysis of various types of hazard (a

*et alii*,

is assessed but it becomes possible to plan measures

for averting or mitigating the expected catastrophe.

With account of all these factors, loads are gradually

increasing on water-management facilities, includ-

ing obsolescent dams. Account should also be taken

of the studies started in 1969 by Acad. Tsotne Mirt-

skhoulava (M

dams, which reduces the reliable work of dams and

raises the probability of the risk of their collapse.

expected results of hydrodynamic calculations, by con-

crete tiles, and clay-loamy ground was placed in

the dam center. The dam accident took away the

lives of 239 people.

led and took away the lives of 2.500 people.

led and taking away the lives of 129 people.

ple died.

taking away the lives of 100 people.

sing the death of over 100 people.

Dam accidents also happened in the former Sovi-

of accidents were never published. Therefore, the in-

formation about the number of victims is unknown.

For instance, in 1955, an accident happened at Gorki

hydroelectric power plant dam; in 1956, there hap-

pened an accident with Luzhskyi dam (Leningrad

oblast), in 1958, an accident happened with Irkutsk

dam and so on.

2008 in China (Sichuan Province), thousands of

hectares of the area got flooded because of the

ground block-up in the riverbed.

lives of over 20 people.

17 people (the newspaper “Vzgliad”) and so on

(G

*et alii*, 2009).

dam happened on the night of May 14, 1987, in set-

tlement Tskneti, near Tbilisi. The dam height was 11.9

m. The catastrophe happened 30 years after the dam

was built as a result of a 3-hour-long downpour. 3 peo-

**PREDICTION OF FLOODED TERRITORIES IN CASE OF POSSIBLE BREAKDOWN OF THE SIONI EARTH DAM**

*Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università*

*Editrice*

scheme, as well as the duration of the passage of the

wave through the indicated sites (

*T*), equal to the sum

of time of rise of levels (T

(s

*H*

*R*

*S*

*R*

*h*

*G*

*М*- is the parameter describing the form of river

cross-section, assumed according to Fig. 3;

*B*

*W*

*h*

*G*

*h*- water river

was re-worked, allowing calculating the rate of the

wave in case of collapse, the run-out distance and,

acteristics, the calculation models for the considered

area have been designed. As for the assessment of the

risk-factor of a natural calamity, this was done by con-

sidering various cases of different degrees of damage of

hydraulic structures (0.25%, 0.50% and 1.0%).

dam with the destruction coefficient of 1.0%.

**METHODOLOGY FOR ESTIMATING**

**THE LOSSES IN THE CASE OF AN ACCI-**

**DENT AT THE SIONI EARTH DAM**

movement) and the duration of flooding.

siderable height of crest and rate of movement, pos-

sessing a great destructive force and energy.

on the surfaces of large reservoirs, has the capacity

to transport in the direction of its movement large

masses of water. Therefore, a breach wave should be

considered as a definite mass of water moving down-

stream the river and continuously changing its form,

dimensions and rate. A longitudinal section of such

wave is schematically shown in Fig. 2.

ture, hence in order to determine the engineering situ-

ation it is necessary to define its parameters: the height

of the wave (

*H*

*w*

*H*), rate of

points of the wave (front, crest, tail) at the calcula-

*Fig. 1 - General view of Sioni earth dam upstream wall*

*Fig. 2 - Diagrammatic longitudinal section of a breach wave*

*Fig. 3 - Values of the parameter M related to the form of*

*the cross-section of the river-bed*

*G. GAVARDASHVILI*

*International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013*

*Tab. 1 - Initial data on the hydro scheme*

*W*

*R*

*A*- is the co-

calculation it is assumed to equal 2;

*µ*- is the pa-

rameter characterizing the shape of the river-bed;

*В*

*i*

*m*;

*H*- is the depth of the

*L*

*V*

*V*

sequent sites, an analogous method is used. According

to the results obtained of the breach wave at all sites, a

graph of movement of the breach wave is built.

**FORECASTING SIONI EARTH DAM AC-**

**CIDENT BY CONSIDERING THE RISK-**

**FACTOR**

Sioni, Tianeti Region (70 km from Tbilisi), in the val-

ley of the river Iori. An earth fill dam is built across

the river Iori, at an elevation of 415 m above sea level,

with its upstream wall faced with concrete tiles. Data

of the dam are reported in Tab. 1 (h

inundated territory.

into consideration in constant values do not depend on

any condition; as to variable values, they depend on the

degree of the destruction of the dam, flood, and so on.

should not exceed 3 points on one side of the river axis

(in all 6 points on both sides).

sections, the distance between which should be given

on the topographical map in advance.

*V*) flooding in the tail-race of

(G

*V*

*V*

*H*

*H*

*V*

*H*

*H*

The degree of destruction of the dam (

*E*

*P*

*E*

*p*

*F*

*w*

*F*

*F*

*w*

*F*

*E*

*P*

section along the river, the distance between the sec-

tions (

*km*), width of the river bed (

*m*), the rate of the

water stream in the river bed (

*m*/

*sec*); the width of bed

of the river (

*m*), etc.

**ORDER OF CALCULATIONS OF THE PA-**

**RAMETERS OF THE BREACH WAVE**

*H*

*BI*

*H*- is the depth of the reservoir at the dam

(

*m*);

*h*

*G*

*m*).

complete emptying of the reservoir; s

**PREDICTION OF FLOODED TERRITORIES IN CASE OF POSSIBLE BREAKDOWN OF THE SIONI EARTH DAM**

*Italian Journal of Engineering Geology and Environment - Book Series (6) www.ijege.uniroma1.it © 2013 Sapienza Università*

*Editrice*

10

possible accident of Sioni dam, the cross-sections near

the settled areas were selected (Fig. 4).

By considering the sections selected across the

of Sioni earth dam, volume of the water reservoir and

topographic characteristics of the river, “Volna-2”

program algorithm was used (s

flooded area on the right and left sides off the river,

wave speed, depth of water, etc. in case of an accident

of Sioni dam across the river Iori.

given in Tables 3 and 4, and the graphs of the flooded

cross section are referred to in Figs 5-13 showing the

data of Sioni dam accident with the degree of the facil-

ity destruction of

*E*

*p*

geometric dimensions of the territories flooded in the

river bed and adjoining territory are given in Tables

(see Tabs 3 and 4). The transverse view of Sioni dam

at the initial section is shown in Fig. 5-13.

The calculated geometry of the flooded area was plot-

ted on the map shown in Fig. 14.

Thus, by considering the degree of destruction of

Sioni earth dam (E

river Iori and its adjacent area, where is possible water

mass flooding.

*Fig. 4 - Location of the area (a) and of the estimated*

*cross-sections (b)*

*Tab. 2 - Statistical and calculated indices of wave*

*Tab. 3 - Data calculated for the case of breach of Sioni dam*

*Tab. 4 - Data calculated for the case of breach of Sioni dam*

*G. GAVARDASHVILI*

*International Conference Vajont 1963-2013. Thoughts and analyses after 50 years since the catastrophic landslide Padua, Italy - 8-10 October 2013*

**CONCLUSION**

analysis of the statistical data of dam accidents

*Fig. 5 - Initial section of Sioni hydro scheme*

*Fig. 6 - Section N1 - v. Nakalakari.*

*Time of arrival of wave front: 8 min; time of flood-*

*ing: 117 min; max. height: 22 m; max rate: 10 m/s;*

*mark of under flooding sea level: 1011 m a.s.l.*

*Fig. 7 - Section # 2 - v. Bochorma.*

*Time of arrival of wave front: 18 min; time of flood-*

*ing: 205 min; max. height: 21 m; max rate: 11 m/s;*

*mark of under flooding sea level: 961 m a.s.l.*

*Fig. 8 - Section # 3 - v. Sasadilo.*

*Time of arrival of wave front: 29 min; time of*

*flooding: 279 min; max. height: 12 m; max rate: 7*

*m/s; mark of under flooding sea level: 891 m a.s.l.*

*Fig. 9 - Section # 4 - v. Paldo.*

*Time of arrival of wave front: 40 min; time of*

*flooding: 340 min; max. height: 10 m; max rate: 7*

*m/s; mark of under flooding 844 m a.s.l.*

*Fig. 12 - Section # 7 - v. Mughalno.*

*Time of arrival of wave front: 70 min; time of*

*flooding: 474 min; max. height: 6 m; max rate: 5*

*m/s; mark of under flooding 715 m a.s.l.*

*Fig. 13 - Section # 8 - v. Sartichala.*

*Time of arrival of wave front: 77 min; time of*

*flooding: 499 min; max. height: 5 m; max rate: 4*

*m/s; mark of under flooding 694 m a.s.l.*

*Fig. 10 - Section # 5 - v. Ujarma.*

*Time of arrival of wave front: 59 min time of flood-*

*ing: 423 min; max. height: 8 m; max rate: 7 m/s;*

*mark of under flooding 766 m a.s.l.*

*Fig. 11 - Section # 6 - v. Khashmi.*

*Time of arrival of wave front: 63 min; time of*

*flooding: 443 min; max. height: 7 m; max rate: 6*

*m/s; mark of under flooding 737 m a.s.l.*

**PREDICTION OF FLOODED TERRITORIES IN CASE OF POSSIBLE BREAKDOWN OF THE SIONI EARTH DAM**

*Editrice*

recasting the risk of possible catastrophes of old

earth dams in Georgia.

its adjacent area were specified by considering the

major dynamic and hydrological characteristics of

a wave and topographic and time factors.

ventive measures for the population, which, if

realized, will significantly reduce the number of

possible human victim in case of the wreckage of

Sioni earth dam.

*Fig. 14 - Layout of the areas flooded as a result of Sioni*

*earth dam accident (scale 1: 1 000 000)*

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