IMPACT Project Breach Modeling Tests
Dam Failures Increasing (?) Worldwide
Some Recent Headlines
March 23, 1999 Chinese Dams Damned By Duncan Hewitt (BBC) in Beijing Thousands of Chinese dams have been described as "time bombs" by Chinese officials. They said more than one-third of the country's estimated 85,000 dams are defective and need urgent repairs.
Aug. 21, 2002Dam Bursts in Central India, 25 Feared Dead BHOPAL, India (Reuters) -- A dam burst under the pressure of heavy monsoon rains in central India on Wednesday, washing away at least 25 people, officials said.
August 16, 2002Dams Burst in Mexico, Killing 11By THE ASSOCIATED PRESSVILLA DE REYES, Mexico (AP) -- Heavy rains burst two dams and sent a wave of flood waters roaring over villages in central Mexico, where authorities said at least 11 people were killed -- including a 6-month-old baby.
Tuesday, 4 June, 2002Syrian Dam CollapsesDAMASCUS, Syria (BBC) -- Villages have been flooded in northern Syria after a dam collapsed. The state-run Syrian Arab News Agency (Sana) reported widespread damage and heavy casualties around the Zeyzoun Dam, near the town of Hama, about 350 kilometres (220 miles) north of Damascus.
Breach Model Tests
• A priori simulation of failure of two large-scale experimental earthen embankments from erosion by overtopping flows
• Two-dimensional depth-averaged flow and sediment transport model that models breach development and the resulting flood wave.
Governing Equations
0)](),([
QUGUFU
t
k
byb
bxb
kkk S
y
zgh
x
zgh
qC
ghh
qh
qqq
qCh
ghh
hC
q
q
h
1
10
2
12
1
2
222
21
2
1
21
221
1
2
1 QGFU
Sediment Transport (General)
)(
)(
**
**
depositionCCforCCw
erosionCCforCCwKp
S
kkkksk
kkkkskekk
k
6/1
*
5.1exp1
1
h
T
u
w
h
T
h
TK
askaa
ek
Total Load Equations
• Engelund-Hansen• Laursen• Bagnold (1956)• Yang (sand and
gravel)• Meyer-Peter and
Mueller• Others…
k
kb St
z)1(
Bed Composition Accounting
• Conceptual model of Bennett and Nordin (1977)
• Three layers• Active layer always• Deposition layer
sometimes• Armoring can occur
A c t i v e L a y e r A c t i v e L a y e r
D e p o s i t i o nL a y e r
O r i g i n a lB e d
M a t e r i a l
O r i g i n a lB e d
M a t e r i a l
T a
T d
T o
Embankment Erosion
cbs
dkk
KpS
Soil textural class
Detachment rate
constant, Kd
Detachment threshold bed shear
stress
(Kg/s/m2/Pa) (Pa)
Clay loam 0.0048 4.7
Loam 0.0085 3.3
Sand 0.0250 2.1
Sandy loam 0.0100 2.5
Silt loam 0.0120 3.5
Clay 0.0089 2.9
Silty clay 0.0120 4.8
Silty clay loam
0.0053 3.2
Soil Texture Classes
Finite Volume Formulation
0)()~
,~
(1
advi
jjRL
i
ni
ni t
A
tUQUUFTUU 1
0
0
)()(2
10
)~
()~
( bLbRRL zzhhgUFUF
k
by
bx
S
1
10
Q
Field Test #1 Mesh
Field Test #1 Mesh
Field Test #1 Embankment
• Homogeneous (maximum cohesive) soils:
– Clay = 25%– Silt = 60%– Sand = 15%
• Embankment:– Height = 6.0 m– Length = 36 m– Slope = 2:1 (horz:vert)
upstream and down
• Crest:– Elevation = 370.81 m– Width = 2.0 m
Field Test #1 at 1:00 h
Field Test #1 at 2:00 h
Field Test #1 at 2:30 h
Field Test #1 at 4:00 h
Field Test #1 Crest Profile
Field Test #1 - Dam Crest Profile
364
366
368
370
372
0 10 20 30 40
Crest Distance (m)
Ele
va
tio
n (
m)
0:00
1:00
1:30
2:00
3:00
6:00
Field Test #1Embankment Transect
Embankment Transect at Notch
364
365
366
367
368
369
370
371
0 5 10 15 20 25
Distance (m)
Ele
vati
on
(m
)
0:00
0:30
1:00
1:30
2:00
3:00
4:00
5:00
Field Test #1 Breach Hydrograph
Field Test #1 - Dam Breach Hydrograph
0
20
40
60
80
100
120
0 1 2 3 4 5 6
Time (h)
Flo
w R
ate
(m3 /s
)
• Homogeneous (minimum cohesive) soils:
– Clay and silt = 2%– Sand = 42%– Gravel = 56%
• Embankment:– Height = 5.0 m– Length = 36 m– Slope = 1.7:1
(horz:vert) upstream and downstream
• Crest:– Elevation = 369.81 m– Width = 2.0 m
Field Test #2 Embankment
Field Test #2 at 0:30 h
Bed elevation (m) : 0.500
364.00
364.80
365.60
366.40
367.20
368.00
368.80
369.60
370.40
371.20
372.00
Field Test #2 at 1:00 h
Bed elevation (m) : 1.000
364.00
364.80
365.60
366.40
367.20
368.00
368.80
369.60
370.40
371.20
372.00
Field Test #2 at 1:30 h
Bed elevation (m) : 1.500
364.00
364.80
365.60
366.40
367.20
368.00
368.80
369.60
370.40
371.20
372.00
Field Test #2 at 2:00 h
Bed elevation (m) : 2.000
364.00
364.80
365.60
366.40
367.20
368.00
368.80
369.60
370.40
371.20
372.00
Field Test #2 at 6:00 h
Bed elevation (m) : 6.000
364.00
364.80
365.60
366.40
367.20
368.00
368.80
369.60
370.40
371.20
372.00
F ie ld T e s t # 2 - D a m C r e s t P r o f ile
3 6 4
3 6 6
3 6 8
3 7 0
3 7 2
0 1 0 2 0 3 0 4 0
C r e s t D i s ta n c e (m )
Ele
va
tio
n (
m)
0 : 0 0
0 : 3 0
1 : 0 0
1 : 3 0
2 : 0 0
3 : 0 0
6 : 0 0
Field Test #2 Crest Profile
E m b a n k m e n t T ra n se c t a t N o tc h
3 6 4
3 6 5
3 6 6
3 6 7
3 6 8
3 6 9
3 7 0
0 5 1 0 1 5 2 0 2 5
D is ta n c e (m )
Ele
vati
on
(m
) 0 :0 0
0 :1 5
0 :3 0
1 :0 0
1 :3 0
2 :0 0
Field Test #2Embankment Transect
Field Test #1 Breach Hydrograph
Field Test #2 - Dam Breach Hydrograph
0
10
20
30
40
50
60
0 1 2 3 4 5 6
Tim e (h)
Flo
w R
ate
(m3 /s
)
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