Flood risk from dike failure

Dr. László Nagy BUTE Geotechnical Department

Budapest, Hungary

Where we are ?

Topography of Carpathian-Basin

Inundations before the river regulation and dike constructions

Inundation map in the middle ages

Mean discharge of rivers entering and leaving Hungary

Hungarian answer:Large scale dike construction from 1846

4200 km dikes in Hungary11000 km dikes in the Carpathian basin

arable land 40% railways 32 %main roads 15 %communities 646population affected 2,3 millionstotal value at risk 2,5×GDP

Facts about the Hungarian flood control

Carpathian Basin

Duna-valley 547 dike failures

Tisza-valley 1269 dike failures

More than 2200 dike failures in the last 200 years

Dike failures in the Carpathian basin in the last 200 years

0

20

40

60

80

100

120

140

160

180

200

befor

e 180

0

1806

1813

1820

1827

1834

1841

1848

1855

1862

1869

1876

1883

1890

1897

1904

1911

1918

1925

1932

1939

1946

1953

1960

1967

1974

1981

1988

1995

piec

es

1846< 1000 km dike

1900

1888

1876

Carpathian basin dike breaches by ten days period

0

50

100

150

200

Jan. Febr. Mar. Apr. Maj. Jun. Jul. Aug. Sept. Okt. Nov. Dec.

Tisza valleyDuna valleyCarpathian basin

Tisza-valley dike failures distribution by ten days period

0

10

20

30

40

50

60

70

80

90

100

jan. feb. m arc. apr. m aj jun. jul. aug szept. okt. nov. dec.

ice jam 88 piecessnow melt 393 piecesrain 304 pieces

Duna-valley dike breaches distribution by ten days period

0

10

20

30

40

50

60

70

80

90

Jan. Febr. Marc. Apr. Maj. Jun. Jul. Aug. Sept. Okt. Nov. Dec.

ice jam 54 %snow melt 13 %rain 33 %

not well identified13%

rainfall and snowmelt

14%

snowmelt26%

rainfall27%

ice jam flood20%

Origin of the flood causing failure

After 1816 data

Distribution of dike failure mechanism

overtopping 68,2%

subsoil failure 7,8%

wave scour 0,6%

structure 4,6%

dike stability 6,3%

other known 3,4%

deliberate cut 7,6%

From 1168 data

After 19 dry years in the Tisza-valley large floods were in 1998–2001:

1998. November - Upper-Tisza1999. March-April - Bodrog and Middle-Tisza1999. June - Tarna, Zagyva, Ipoly and Tarnoca2000. April-May - Bodrog and Middle-Tisza2001. March - Upper-Tisza

Flood defencework

Inundations due to the dike breaches in the Upper-Tisza basin in the vicinity of the Ukr-Hun border

TúrSzamos

Tisza

Borzsa

Very old dike, very loose dike

Failed cross section

Slope slides along Tisza right bank, Tarpa-Tivadar section in 2001

16 Slope slidesoccured in a 2,700 m section

in 3,5 hrs!

Flood defence work

Dike breach, River Tisza right bank,Tarpa - Tivadar section, 54+650 and 55+350 tkm

Dike breach on river Tisza at Tarpa 2001

Dike breach on river Túr 2001

Tákos (Hungary) 2001

Bagolyszállás (Ukraine)

Damages at 2001 year flood in Hungary

Inundated territory 209 km2

Endangered villages 20 Inundated villages 8No. of evacuated people 11 000 personDamaged properties 3071Reconstruction cost 490 million €

Safety strategy

Need dike construction

Safety strategy

Need dike constructionSame elevation dike

Safety strategy

Need dike constructionSame elevation dikeSame cross section dike

Safety strategy

Need dike constructionSame elevation dikeSame cross section dikeSame safety factor

Safety strategy

Need dike constructionSame elevation dikeSame cross section dikeSame safety factorSame failure probability

Safety strategy

Need dike construction Same elevation dike Same cross section dike Same safety factor Same failure probability Same risk

Thank you for your kind attention!

Dangers in Hungary according to water