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Colorado State University
Training for Technical Planning of Small DamsDiponegoroUniversitySemarang, Indonesia
May 28, 2018
Part I. Reservoir Sedimentation
Part II. Sediment Management
3
Part II – Sediment Management
1. Sedimentation problems near dams
2. Density currents in reservoirs
3. Dambreak impact
4. Multi-objective dam operations
5. Socio-economic considerations
4
Sediment can be Flushed
12
Part II – Sediment Management
1. Sedimentation problems near dams
2. Density currents in reservoirs
3. Dambreak impact
4. Multi-objective dam operations
5. Socio-economic considerations
5
Discharge water through hydro power plant
13
/3714
Imha Reservoir has suffered from turbidity problems since 2002.
• Watershed area covers 1,361 km2
• Three major tributaries
In a deep reservoir, the density is determined by the result of solar heating of surface water which produces thermal stratification
15
(Imha Reservoir, July 2006)105
115
125
135
145
0 10 20
EL.m
O C
Temperature
997 998 999 1000kg/m3
Density
• Relatively warm, and• active mixing zone• Steep temperature
gradient zone
• Deep and cold zone
6
At IMHA BasinTyphoon Total
RainfallDuration
RUSA(8. 2002) 183㎜ 27hr
Meami(9. 2003) 185㎜ 31hr
Dianmu(6. 2004) 220㎜ 57hr
Ewiniar(7. 2006) 160㎜ 55hr
- Typhoon : triggered landslides and lots of sediment transport into reservoir
X
Plunge flow Underflow Inter flow
Plunge depth
Separation depth Interflow
depth
Plunge point
Separation point Interflow thickness
TE
W
Ti
Ti
TH
Epilimnion
Metalimnion
hypolimnion
17Discharge water through intake tower, 8/28/20068/28/2006
8/28/2006
18
II. Numerical Model
• Momentum (with Boussinesq approximation, non-hydrostatic ) :
)uux
U(
xdx
x
g
xg
x
P1g
x
UU
t
U
nsfluctuatioturbulentandforceViscous
3
1jji
j
i
j
gradientpressure'baroclinic'
ortionStratifica
z3
i0
gradientpressure'barotropic'
orsurfaceFree
i
gradientpressurechydrostatiNon
i
nh
0forceGravity
i
onacceleratiConvective
j
i3
1jj
onacceleratiLocal
i
• Scalar transport equation :
)ux
(x
)U(xt i
3
1j jj
3
1j jj
i
j
j
it x
U
x
U
it
x
3,2,1i:
t
tt Pr
0x
U
x
U
x
U
3
3
2
2
1
1
• Continuity :
7
/37
Inlet point0 km 4 km
Unit : kg/m3
/37
Inlet point0 km 4 km
Unit : kg/m3
21
Real-time gaging stations were installed at five stations to monitor turbid density currents propagating from each tributary into to the reservoir
Real-time monitoring system for Imha Reservoir; installed and has been operating by K-water since 2006
8
- Geomorphology and geological features of Imha Reservoir basin : Soil particles not easy to sink
Factors inducing turbid density currents
<Suspended Particle Sedimentation Test (After 48 hours)>
Other Site
DaeGok YongJunBanByeon
Imha Dam Basin
/3723
3-D Model simulation view at El. 141m
/37
0 10 200 10 20
0 200400 600800
0 10 20
24
July 11, 08:00 July 11, 12:00 July 11, 16:00 July 11, 18:00 July 11, 04:00
0 10 20
0 200 400600800 0 200 400 600 800 0 200 400 600 800
Observed
Simulated
105
115
125
135
145
0 200400600800
NTU
105
115
125
135
145
0 10 20
Temp.
Water Intake
9
/3725
26
Part II – Sediment Management
1. Sedimentation problems near dams
2. Density currents in reservoirs
3. Dambreak impact
4. Multi-objective dam operations
5. Socio-economic considerations
ResultsResultsIV.IV.
27
38th Annual AGU Hydrology Days38th Annual AGU Hydrology Days
21 Mile Dam, Elko County, NV, Feb 8, 2017
How does the flood wave propagate downstream?
10
Bento Rodrigues Town,6 November 2015
Gesteira Town6 November 2015
Doce River at Governador Valadares City
11 November 2015, C ≈30,000 mg/l
Coast, 21 November 2015C ≈1,500 mg/l
Candonga Dam, 6 November 2015C ≈ 700,000 mg/l
28
Observed hydrographs in Doce River after the Fundão Dam break (ANA,2015).
29
Space and time steps: ∆x 500 , ∆t 900
Reservoir: The reservoir routing can be solved using the Level Pool Routing
→2
∆2∆
Where:
reservoirstorageasfunctionoftime; Inflow; Outflow;
30
Reach
S (m/m)
L (km)
W (m)
D (m2/s)
Manning n Ce (m/s)
A 0.0005 204 217 922 0.037 1.20
B 0.0005 133 377 531 0.032 1.04
C 0.0008 34 624 336 0.025 1.40
D 0.0002 108 725 328 0.020 0.60
11
31
The one-dimensional advection-dispersion equation is applied on the evaluation of transport ofsuspended load in open channels (Fischer et al., 1979; Julien, 2010).
Analytical solution for a constant spill in finite time interval is given by (Chapra,2008):
,2
Γ
2
Γ
2
Γ
2
Γ
2
Where: Γ 1 4 and
The error function complement, erfc, is equal to:
1 12
32
C is the concentration;is the flow averaged velocity; is the longitudinal dispersion
coefficient; is the settling rate.
33
12
34
Part II – Sediment Management
1. Sedimentation problems near dams
2. Density currents in reservoirs
3. Dambreak impact
4. Multi-objective dam operations
5. Socio-economic considerations
/3735
Thank you!Questions?Sangju Weir, SK
from Hwayoung Kim
/37
Other Issues besides sedimentation
36
• It is hard to change reservoir operation rules for sedimentation problems because we have many other issues to deal with.
Flood control
Water supply
Turbidity
Stream ecology
Riverside environment
Hydropower
13
/37
10-3
10-2
10-1
100
101
0
0.2
0.4
0.6
0.8
164
|SC|Cobble
32|VCG
16|CG
8|MG
4|FG
2|VFG|Gravel
1|VCS
0.5|CS
0.25|MS
0.125|FS
0.0625|VFS|Sand
0.031|CM
0.016|MM
0.008|FM
0.004|VFM|Silt
0.002|CC
0.001|MC
0.0005|FC
0.00024|VFC|Clay
Tra
p ef
ficie
ncy,
TE, %
Fin
er (
%)
Grain size, ds (mm)
< LEGEND >Bed material dist.Suspended load dist.Trap efficiency curves
(Q=30 ,300 ,300m 3/s [L R])
64|SC|Cobble
32|VCG
16|CG
8|MG
4|FG
2|VFG|Gravel
1|VCS
0.5|CS
0.25|MS
0.125|FS
0.0625|VFS|Sand
0.031|CM
0.016|MM
0.008|FM
0.004|VFM|Silt
0.002|CC
0.001|MC
0.0005|FC
0.00024|VFC|Clay
< LEGEND >Bed material dist.Suspended load dist.Trap efficiency curves
(Q=30 ,300 ,300m 3/s [L R])
64|SC|Cobble
32|VCG
16|CG
8|MG
4|FG
2|VFG|Gravel
1|VCS
0.5|CS
0.25|MS
0.125|FS
0.0625|VFS|Sand
0.031|CM
0.016|MM
0.008|FM
0.004|VFM|Silt
0.002|CC
0.001|MC
0.0005|FC
0.00024|VFC|Clay
< LEGEND >Bed material dist.Suspended load dist.Trap efficiency curves
(Q=30 ,300 ,300m 3/s [L R])
10-3
10-2
10-1
100
101
0
0.2
0.4
0.6
0.8
164
|SC|Cobble
32|VCG
16|CG
8|MG
4|FG
2|VFG|Gravel
1|VCS
0.5|CS
0.25|MS
0.125|FS
0.0625|VFS|Sand
0.031|CM
0.016|MM
0.008|FM
0.004|VFM|Silt
0.002|CC
0.001|MC
0.0005|FC
0.00024|VFC|Clay
Tra
p ef
ficie
ncy,
TE, %
Fin
er (
%)
Grain size, ds (mm)
< LEGEND >Bed material dist.Suspended load dist.Trap efficiency curves
(Q=30 ,300 ,300m 3/s [L R])
64|SC|Cobble
32|VCG
16|CG
8|MG
4|FG
2|VFG|Gravel
1|VCS
0.5|CS
0.25|MS
0.125|FS
0.0625|VFS|Sand
0.031|CM
0.016|MM
0.008|FM
0.004|VFM|Silt
0.002|CC
0.001|MC
0.0005|FC
0.00024|VFC|Clay
< LEGEND >Bed material dist.Suspended load dist.Trap efficiency curves
(Q=30 ,300 ,300m 3/s [L R])
64|SC|Cobble
32|VCG
16|CG
8|MG
4|FG
2|VFG|Gravel
1|VCS
0.5|CS
0.25|MS
0.125|FS
0.0625|VFS|Sand
0.031|CM
0.016|MM
0.008|FM
0.004|VFM|Silt
0.002|CC
0.001|MC
0.0005|FC
0.00024|VFC|Clay
< LEGEND >Bed material dist.Suspended load dist.Trap efficiency curves
(Q=30 ,300 ,300m 3/s [L R])
Trap efficiency ( )
37
Q=30 m3/s
Q=300 m3/s Q=3,000 m3/s
Q=30 m3/s
Q=300 m3/s Q=3,000 m3/s
Low StageEl. 37.2m
High StageEl. 47.0m
avgTE = 77.9%
avgTE = 49.3%
/37
Sediment Yield & Reservoir Sedimentation
38
Time intervals (%)Mid-point
(%)delP Q (cms) C (mg/l) Q × delP
Measured load, qp (tons/yr)
qp/qt ratio(%)
Total load, qt (tons/year)
Avg. TE (%)
Res. Sed. (tons/year)
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)=(9)*(10)
0 ~ 0.02 0.01 0.02 1,670 355 0.3 3,743 2% 91% 4,113 2% 37.8 1,555 1%
0.02 ~ 0.1 0.06 0.08 1,615 350 1.3 14,257 7% 91% 15,667 7% 38.2 5,991 5%
0.1 ~ 0.5 0.3 0.4 1,268 312 5.1 49,886 23% 91% 54,820 23% 41.3 22,654 17%0.5 ~ 1.5 1 1 678 232 6.8 49,576 23% 91% 54,480 23% 49.5 26,992 21%
1.5 ~ 5 3.25 3.5 263 148 9.2 42,840 20% 91% 47,077 20% 62.2 29,260 22%
5 ~ 15 10 10 104 95 10.4 31,218 15% 91% 34,306 15% 72.1 24,723 19%15 ~ 25 20 10 55 70 5.5 12,058 6% 91% 13,250 6% 76.2 10,103 8%
25 ~ 35 30 10 33 55 3.3 5,743 3% 91% 6,311 3% 78.3 4,942 4%
35 ~ 45 40 10 21 44 2.1 2,943 1% 91% 3,234 1% 79.4 2,569 2%45 ~ 55 50 10 13 35 1.3 1,435 1% 91% 1,576 1% 80.0 1,261 1%
55 ~ 65 60 10 7 27 0.7 640 0% 91% 703 0% 80.4 565 0%
65 ~ 75 70 10 3 18 0.3 167 0% 91% 183 0% 81.1 148 0%
75 ~ 85 80 10 1 10 0.1 29 0% 91% 32 0% 83.3 27 0%85 ~ 95 90 10 0 3 0 0 0% 91% 0 0% 94.5 0 0%
95 ~ 100 97.5 5 0 0 0 0 0% 91% 0 0% 100.0 0 0%
Total Naesung 214,534 100% 91% 235,752 100% 55.5% 130,790 100%
Yeong 44,331 82% 54,063 48.4% 26,193
Nakdong 128,310 94% 136,501 38.9% 53,042
Total 387,175 426,316 49.3% 210,025
FD SRC SEMEPP TE
Conventional FD/SRC method New approach
@Low stage
Sediment Yield: 426,000 tons/yr
Integrated Reservoir Sedimentation Estimation Procedure (IRSEP)
/37
Excavation Costs
39
Photos of excavationNakdong River Estuary Barrage
• Nakdong River Estuary Barrage (1990 – 2010)
• V = 13,678,000 m3 ( 43.2 million dollars)
• Unit cost = 6.31 USD/m3
Credit: K‐water
14
/37
Benefit and Cost AnalysisHydropower Revenues
• Capacity: 1,500 kW * 2 units
• 9.81
• Unit cost of sales = 0.13 USD/kWh
40
WeirProduction and benefit Unit cost of sales
MWh Benefit(106 KRW) benefit(103USD) KRW/kWh USD/kWhSangju 8,004 1,179 1,072 147.32 0.13
(Data: K‐water, 2014, 1 USD = 1,100 KRW)
/37
Hydraulic Thresholds
Open the gates above Q threshold = 620 m3/s
Operate the dam above H threshold = EL. 43.6 m
41
41 42 43 44 45 46 470
0.5
1
1.5
2
2.5
WS (El.m)
B/C
rat
io
WS threshold
/37
MCDA Optimization
[MCDA Characteristics]
• Decision making method to choose the best alternative
• Systematic process based on the familiar concept of an overall score
• Provides a way to document and audit decisions
42
• Main-Criteria and Sub-Criteria IdentificationSTEP 1
• Relative Importance Factors (RIF) Definition
STEP 2
• Constraints AnalysisSTEP 3
• Alternatives DevelopmentSTEP 4
• Rating method Determination and Modeling STEP 5
[MCDA procedure]
15
/37
Water Supply
Max. Reservoir Storage (V)
43
36 38 40 42 44 460
0.5
1
1.5
2
2.5
3x 10
7
Water stage (El.m)
Res
evoi
r st
orag
e (m
3 )
Maximum storage for water supply
Minimum storage for water supply (Pungyang intake facility)
Available storage
Intake pipe
/37
36 38 40 42 44 46 48 50 52 540
1
2
3
4
5
6
7
8x 10
7
Water stage (El.m)
Res
evoi
r st
orag
e (m
3 )
Maximum flood space
Top of banks
Current management storage (24.7 MCM)
Flood Control
44
Flood prevention space
Min. Reservoir storage (V)
/37
Stream Ecology & Riverside Environment
Max. GVSR(Good View Station Ratio)
45
36 38 40 42 44 46 48 50 520
5
10
15
20
25
30
35
40
45
50
Managing water stage (El.m)
Per
cent
of
pref
eren
ce f
low
wid
th r
atio
(%
)
16
/37
Stage (H) Constraints
46
0 2 4 6 8 10 12 1440
42
44
46
48
50
52
Distance from Sangju Weir (km)
Con
stra
int
wat
er s
tage
(E
l.m)
Pungyang(44.2)
Jukam(45.0) Hoesang(45.0) Maeho(45.0)
Drinking
Irrigation
Water Supply Constraints
Critical stage (El.45.0m)
* Irrigation duration: May‐September
Flood Drainage Constraints
Critical stage (El.46.1m)
0 2 4 6 8 10 12 1440
42
44
46
48
50
52
Distance from Sangju Weir (km)
Con
stra
int
wat
er s
tage
(E
l.m)
Maeho G4(46.1) Yaryong G5(46.1)
Flood drainage
* Flood season: June 21st – Sep. 20th
(Dam management Code, Mar. 1974)
/37
Discharge (Q) Constraints
• Hydropower production
Q > 50 m3/s
• Break‐even discharge
Q < 620 m3/s
• Turbidity limit Discharge
Q < 1,000 m3/s
47
/37
101
102
103
43
43.5
44
44.5
45
45.5
46
46.5
47
47.5
Q (m3/s)
Sta
ge (
El.m
)
h < EL 47.0 m (Flood control, Jun-Sep)
h < EL 46.1 m (Flood drainage, "Waryong", Jun-Sep)
h > EL 44.2 m (Drinking, "Pungyang")
h > EL 45.0 m (Irrigation, "Maeho", May-Sep)
h > EL 43.7 m (Break-even, B/C=1)
Q > 50 m3/s (Hydropower production)
Q < 620 m3/s (Break-even between HP and Sed.)
Q < 1000 m3/s (Turbidity downstream)
H and Q ConstraintsH range: EL. 44.2 ‐ 47.0mQ range: 50 m3/s – 620 m3/s
48
17
/37
Jan.1 Feb.1 Mar.1 Apr.1 May 1 Jun.1 Jul.1 Aug.1 Sep.1 Oct.1 Nov.1 Dec.1t Dec.3136
38
40
42
44
46
48
Month
Wat
er s
tage
(E
l.m)
Dringking water supply duration (Pungyang, El.44.2m)Irrigation duration (Maeho, El.45.0m)Flood drainage duration (Waryong G5, El.46.1m)Case1: High stage (El. 47.0m)Case2: Medium stage (El. 43.6m)Case3: Lowest stage (El. 37.2m)Case4: Seasonal stage control
Alternatives development
49
[Alt. 1]
High stage (El.47.0m)
[Alt. 2]
Medium stage (El.43.6m)
[Alt. 3]
The lowest stage (El.37.2m)
[Alt. 4]
Seasonal stage control
(1) Normal season (El.47.0m)(2) Flood season (EL.46.0m) ❸
❶
❹
❷
/37
07/17/2012 10/01/2012 01/01/2013 04/01/2013 07/01/2013 10/01/2013 01/01/2014 04/01/2014 07/01/2014 10/01/2014 12/31/201410
-2
10-1
100
101
102
103
104
Inflo
w &
dis
cha
rge
(m3 /s
)
Inflow and discharge
inflowtotal dischargedischarge for hydropowerQ threshold
07/17/2012 10/01/2012 01/01/2013 04/01/2013 07/01/2013 10/01/2013 01/01/2014 04/01/2014 07/01/2014 10/01/2014 12/31/201435
40
45
50
55
60
65
70
Wa
ter
sta
ge
at
Sa
ng
ju W
eir
(E
L.m
)
Water stages and movable gate opening at Sangju Weir
upstreamgate1 openinggate2 opening
Historical Operational Data
50
Water Stage is kept high according to the current rule
• Sangju Weir, July 2012 – December 2014 (2yrs)
/37
MCDA Rating (WAM)
51
Main Criteria (5)
Sub‐criteria (4)
Sub‐criteria (3)
Sub‐criteria (2)
Sub‐criteria (3)
Sub‐criteria (2)
Overall score and Ranking
Rating
18
52
Part II – Sediment Management
1. Sedimentation problems near dams
2. Density currents in reservoirs
3. Dambreak impact
4. Multi-objective dam operations
5. Socio-economic considerations
Example: Peligre Dam in Haiti
Demographic Expansion
22
Could this be avoided?
Summary and Conclusions
1. Sedimentation Problems near Dams
Flushing and dredging are possible in low-head dams
2. Density Currents in Reservoirs
Turbidity currents can be modeled and predicted
3. Dambreak Impact
Dam breaks impact rivers over long distances
4. Multi-objective Operations
Hydraulic thresholds and MCDA are useful for dam operations
5. Socio-Economic Considerations
Sedimentation can have a large socio-economic impact
Sediment Management References
1. Sedimentation Problems near DamsJi, U., P.Y. Julien and S.K. Park, “Case-Study: Sediment Flushing and Dredging near the Nakdong River Estuary Barrage”, J. Hydraulic Eng., ASCE, 137(11), 2011, pp. 1522-1535.
2. Density Currents in ReservoirsAn, S.D., and P.Y. Julien, “Case-study: Three-Dimensional Modeling of Turbid Density Currents in Imha Reservoir, South Korea”, ASCE J. Hydraulic Eng., 140(5), 2014,
3. Dambreak ImpactShin, Y.H. and P.Y. Julien, "Case-Study: Effect of Flow Pulses on Degradation Downstream of Hapcheon Dam, South Korea”, J. Hydraulic Eng., ASCE, 137(1), 2011, pp. 100-111.
23
Sediment Management References
4. Multi-objective OperationsKim, H.Y., and P.Y. Julien, “Case Study: Hydraulic Thresholds to Mitigate Sedimentation Problems at SangjuWeir”, ASCE J. Hydraulic Eng., 144(6), 2018, ISSN 0733-9429, 13p.
Kim, H.Y., D. G. Fontane, P.Y. Julien, and J.H. Lee, “Multi-objective Analysis of the Sedimentation behind Sangju Weir, South Korea”, ASCE J. Water Resources Planning and Management, 144(2), 2018, 12p.
5. Socio-Economic ConsiderationsLuis, J., Sidek, M.L., Desa, M.N.B.M. and P.Y. Julien, “Hydropower Reservoir for Flood Control: A Case Study on Ringlet Reservoir, Cameron Highlands, Malaysia”, J. Flood Engineering, 4(1), January-June 2013, pp. 87-102.
NEW 2018
69
Thank You!
Terima Kasih!
ACKNOWLEDGMENTSSangdo An, KICT, South Korea Marcos Palu, BrazilHwayoung Kim, K-Water, South KoreaMarcel Frenette, Québec, CanadaChris Thornton, CSU, USAPhil Combs, USACE, USANeil Andika, Indonesiaand apologies to those forgotten …
Terima kasih atasperhatian Anda!