ESTIMATION OF FLOOD STORAGE VOLUMES IN THREE RETARDING
BASINS ALONG THE TONE RIVER
TAKASHI MATSUMOTO (1), SHOJI FUKUOKA (2), TETSUTARO SUMI (3)(1): Graduate School of Science and Engineering, Chuo University, Japan
Email: m85t48@civil.chuo-u.ac.jp(2): Research and Development Initiative, Chuo University, Japan(3): Upper Tone River Office, Kanto Regional Development Bureau, Ministry of Land, Infrastructure,
Transport and Tourism, JapanABSTRACT
The Tanaka, Sugo, Inadoi retarding basins were constructed along the Tone River for reducing the flooddischarge for the downstream river. In this paper, we apply the unsteady two-dimensional flood flow analysis
based on the time series data of the observed water surface profiles to the Tone river including the threeretarding basins and confluence of the Kinu river and estimate inflow discharge hydrographs and flood storage
volumes at the retarding basins. From the calculation results, we discussed and evaluated storage effects of thethree retarding basins against 2001 and 2007 floods.
INTRODUCTION
The Tone river having the largest drainage area (16,840km2) in Japan flows through the Kanto plain. TheTanaka, Sugo and Inadoi retarding basins are located around the confluence of the Tone and Kinu river (seeFigure 1) to control the flood discharge in the lower Tone river. Due to the increase of the design flood
discharge in the Tone river, expansion of the flood-control capacities of the three retarding basins has beenimplemented. Therefore, the storage functions of the three retarding basins for the past flood events should beinvestigated.
Nakai et al. [1] showed that inflow discharge hydrograph and storage volume of flood flow entering in aretarding basin can be calculated from high accurate estimation of the time series of the water surface profiles inthe river reach including a retarding basin by the unsteady two-dimensional flood flow analysis. The objectiveof this paper is to estimate inflow discharge hydrographs and flood storage volumes in the Tanaka, Sugo andInadoi retarding basins for the large floods in September 2001 and 2007 by using the above numerical analysis
method.
STUDY AREA AND FLOOD
The Tanaka and Sugo retarding basins were almost completed in 1960 and flood waters in the Tone river are
stored in the retarding basins through the overflow levees constructed on a part of the river bank (see Figure 1).
The height and shape of the overflow levee at the Tanaka retarding basin changed from a broken line to a solidline in Figure 2 as a result of the repair works between the 2001 and 2007 floods. The overflow levee in theInadoi retarding basin was not completed and flood water entered into the Inadoi retarding basin by overflowing
the lower part of the surrounding levee indicated by the gray (2001 flood) and white (2007 flood) squares inFigure 1, respectively.
In the 2001 and 2007 floods, water level hydrographs and discharge hydrographs in the river channels and three
retarding basins were obtained at the observation points of Figure 1. Figure 3 shows the observed dischargehydrographs at the Mefukibashi (104.1 km), Toride (85.3km), Kinugawamitsukaido (11.0km) andTakishitabashi (3.0km) in 2001 and 2007 floods. The flood duration of the 2001 flood is long and the peakdischarge is over 7,500m3/s at the Toride as shown in Figure 3(a). Peak discharge was observed at almost thesame time at the Toride and Kinugawamitsukaido. On the other hand, the peak discharge of the 2007 flood wasabout 7,000m3/s at the Toride and the shapes of the discharge hydrographs are sharp compared with that of the2001 flood (see Figure 3(b)). Additionally, peak discharge was observed at almost the same time at theKinugawamitsukaido and Mefukibashi.
CALCULATION METHOD AND CONDITIONSUnsteady two-dimensional flood flow analysis was made for estimating accurate flood discharge hydrographs
and flood storage volume in the river channels and three retarding basins. The upstream and downstream
boundary conditions are given by observed water level hydrographs at the Mefukibashi, Toride andKinugawamitsukaido observation stations shown in Figure 1.
Proceedings of the 7th International Symposium on Environmental Hydraulics
Copyright © 2014 ISEH VII Organisers. All rights reserved.
ISBN: 978-981-07-8047-0359

Proceedings of the 7th International Symposium on Environmental Hydraulics

KKinu
River
10km
Kinugaawamitsukaido
Sugoo retarding baasin
5k

Tone Riiver
1005kmTakisshitabashi
0kmm
Mefukibbashi
100kkmSugoOookisuimon

Inaadoi retarding basinToridee

990km

85kmm
995km

Tanaka reetarding basinn

Tannaka Aoyamasuimon
Road emmbankmentg (m( 3/s))
Discharge

Elevation (Y.P.m)

Figgure 1 - Plan form
fand obseervation pointss of the Tone anda Kinu riveers

Longgitudinal distancee (m)Figgure 2 - Overfflow levee elevation
at thee Tanaka retarrding basin

Manningg's roughness cooefficients-1/3

in maain channels (s䞉 m )Manningg's roughness cooefficients-1/3

in flood
flplains (s䞉mm )Veg
getation permeaability
ccoefficients(m/ss)

9/1112:00

9/1212:00

9/1312:00

9/1412:000

9/1512:00

2007
Tonne Kinu

0.0018 0.019 0.0018

0.02

g (m( 3/s))
Discharge(a) 20011 flood

Taable 1 - Manniing’s roughnesss and vegetattion
permeeability coefficcients
2001
Toone Kinu

9000
8000
7000
6000
5000
4000
3000
2000
1000
0
9/1012:00

9000
8000
7000
6000
5000
4000
3000
2000
1000
0
9/70:00: Mefuk
kibashi: Toride: Kinugaawamitsukaido: Takishhitabashi
Plots : float
LLines: H-Q
9/80:00

9/90:00

9/100:00(b) 20077 flood
0.0030䡚0.032 0.030䡚0.040

Figure 3 – Observed disccharge hydroggraphs

䡚6540䡚7050䡚
䡚6525䡚6550䡚

Bed elevvations of the computationaal grids for thhe river channnels and three retarding bassins are givenn based on
the topoggraphical dataa obtained fromm the cross-s ectional bed shapes
measurements and laaser profiler. Spreadingof the floooding water ini the retarding basins is larrgely affected by the road embankments aand irrigationn networks.
To evaluuate such proppagation mechhanism of the flooding wateer, we consideered properly topographic featuresfin
the retardding basins suuch as the roadd embankmentts and irrigatioon networks.
The Mannning’s roughhness coefficieents and vegeetation permeability coefficcients in the channels and retarding
basins weere determineed as Table 1 sos that the callculated waterr level hydrog
graphs agree w
with the obserrved waterlevel hyddrographs.
CALCULATION RE
ESULTS AND
D CONSIDERRATIONS
Comparrison betweenn the observedd and calculaated results
The calcuulation results are almost similar in thee 2001 and 20
007 floods. We
W investigatee calculation results byfocusing on the 2001 flood.
fFigure 4 shows compaarisons betweeen the calculaated and obserrved water surrface profiles in the 2001 flood.
fThecalculated water surfacce profiles sho
ow a good agrreement with the observed data. Figure 5 shows the coomparison
between the calculatedd and observed water leveel hydrographhs around the overflow levvees at the Taanaka and360

1312
11
10
987

Kinu RiverR

ow levee
Sugo overfloTannaka overflow levee
885

87

8991

93

95

97

99 101 103 105

Loongitudinal distannce (km)
9/11 8:008
9/11 16
6:00
9/12 0:00
9/12 122:00
9/13 0:000
Left baank flood marks
flmarks
Right bank flood
Plots : Observed
Owater lev
vel Lines : Calcuulated water surfaace profiles

Fiigure 4 - Commparison betweeen calculatedd andobserrved water surrface profiles
40

LLongitudinal
distaance (m)
80
8120
1660
200

240
0(a) 2001 flood

280
Discharge (m3/s)

13
12
11
10
9
8
7
6
10:00 9/1112:00
0 9/120:00 9/12
212:00 9/130:00
0 9/1312:00
9/11OoSugo (in river)okisuimon(in retaarding basin)
P
Plots: Observed waterw
level
Overflow levee’’s shapeL
Lines: Calculated waterw
level(a) Sugo
Sretarding
g basinElevation (Y.P.m)

9/80:00

9/90:00

2400
2200
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Ͳ200
9/100:00(b) 20077 flood

Longitudinal distaance (m)L
100 150 200 250
0 300 350 400
4450

050
1098
7
6
9/12 6:00 9/12 18:00
54
3
9/11
10:00 9/1112:00
0 9/120:00 9/12
212:00 9/130:00
0 9/1312:00
masuimon(in retaarding basin)
AoyamTTanaka(in river)w
level
Plots : Observed waterO
Overflowlevee’s shapes

9000
8000
7000
6000
5000
4000
3000
2000
1000
0
Ͳ1000
Ͳ2000
Ͳ3000
Ͳ4000
9/70:000

Inflow discharge (m3/s)

Elevation (Y.P.m)

0

9000
2600
2400
8000
2200
7000
2000
6000
1800
5000
1600
4000
1400
3000
1200
2000
1000
1000
800
0
600
Ͳ1000
400
Ͳ2000
200
Ͳ3000
0
Ͳ4000
Ͳ200
9/1018::00 9/1118:00 9/1218:00
99/13118:00

Inflow discharge (m3/s)

Discharge (m3/s)

Elevation (Y.P.m)

Proceedings of the 7th International Symposium on Environmental Hydraulics: Mefukkibashi: Toridee: Kinuggawamitsukaido: Takishhitabashi: Inadoi retaarding basin: Sugo retardding basin: Tanaka retarding basin
w discharge: Total inflow
Plots : Observ
ved data

Lines : Caalculated dischaarge and inflow discharge

Figure 6 – River dischargee and inflow dischargedhyydrographs too retarding bassins

LLines: Calculated water level(b) Tanaka retard
ding basin
Figurre 5 - Comparrison between calculated annd observed
water leevel hydrograp
phs in the Tonne river and reetarding basin
nsSugo retarding basinss. The calculaated water levvel hydrograp
ph in the Sug
go retarding bbasin (see Figgure 5(a))
becomes higher than thet observed waterwlevel hyydrograph in flood
ffalling period.
pThe mmain reason is discussed
below. Inn reality, floooding water storedsin the retarding basin returns too the Tone riiver channel throughtadrainage gate in the fallling period, however,
hit waas not consideered in this anaalysis.㻌
The wateer level of Aoyyamasuimon in
i the Tanakaa retarding bassin is almost unchanged
uafteer 6:00 Septemmber 12th
as shownn in Figure 5((b), however, the water levvel at the Tanaaka observatio
on point is higgher than the height ofthe overfflow levee unttil 18:00 Septeember 12th. F
First, flooding waters in the Tanaka retardding basin aree stored in
the downnstream area of the road embankmente((see Figure 1)). When the waterw
level inn the retarding
g basin is
above abbout 8m, floodding waters sprread to the uppstream area across the roadd embankmentt.
Figure 6 shows the comparisoncbetween the ccalculated andd observed river dischargee hydrographs and thecalculated inflow discharge hydrographs enteringg into three reetarding basin
ns in the 20011 and 2007 flooods. Thecalculatioon results in thet rising periiod can almosst reproduce th
he observed dischargedhydrdrographs at thhe Toride,Mefukibaashi and Kinuugawamitsukaido (see Figurre 6(a)). But, thet calculated discharges teend to be largeer than theobservedd discharges ata the Toride and Mefukibbashi in the fallingfperiod.. In this calcuulation, the Manning’sM
roughnesss coefficient wasw determineed so that the calculated waater surface prrofiles agree w
with the obserrved water
surface pprofiles around peak-water levels. So it is highly possible that the Manning’s rooughness coeffficient offlood fallling period iss higher than that of rising and peak perriod. It seems to be relatedd with the forrmation ofdunes in the falling perriod.
361

Proceedings of the 7th International Symposium on Environmental Hydraulics

Storage volume (×106 m3)

60

Table 2 – Maximum inflow discharge

50

340

retarding basin name30

Inadoi
Sugo
Tanakatotal20100
9/1018:00 9/1118:00 9/1218:00 9/1318:00

Table 3 – Maximum storage volume andusage percentage of flood-control capacity(a) 2001 flood
60(a) 2001 flood

50

retarding basin flood-control capacity maximum storage volume usage percentage of flood6 3
6 3
namecontrol capacity (%)(㽢10 m )(㽢10 m )Inadoi
19.08
8.99
47.1
Sugo
26.90
19.71
73.3
Tanaka
60.68
28.33
46.7
total
106.66
54.02
50.6

63

Storage volume (×10 m )㻌maximum inflow discharge(m /s)
2001
2007
273
311333
164
474
0829
462

403020100
9/70:00(b) 2007 flood
9/80:00

9/90:00

9/100:00(b) 2007 flood: Inadoi retarding basin: Sugo retarding basin: Tanaka retarding basin: Total storage volumeretarding basin flood-control capacity maximum storage volume usage percentage of flood6 3
6 3
namecontrol capacity (%)(㽢10 m )(㽢10 m )Inadoi
19.08
8.62
45.2
Sugo
26.90
3.95
14.7
Tanaka
60.68
0.00
0.0
total
106.6612.55
11.8

Figure 7 – Calculated storage volume hydrographs
Calculated inflow discharge and flood storage volume in the 2001 and 2007 floods
In the 2001 flood, the calculated inflow discharge of the Tanaka and Sugo retarding basins take a maximum
when the flood discharge at the Toride was almost in peak (see Figure 6(a)). On the other hand, the inflow
discharge of the Inadoi retarding basin reaches its maximum before the flood discharges is in peak at theMefukibashi, Toride and Kinugawamitsukaido. Table 2 shows the calculated maximum inflow discharges at thethree retarding basins in each flood. The maximum total inflow discharge of the three retarding basins becomes
829m3/s in the 2001 flood. Figure 7 shows the calculated storage volume hydrographs of the three retarding
basins. The storage volume in the Sugo and Inadoi retarding basin decreases in the flood falling period in the2001 flood (see Figure 7(a)) since the flooding waters returned from the retarding basins to the Tone riverthrough the overflow levee at the Sugo retarding basin or lower part of the surrounding levee at the Inadoi
retarding basin. Table 3 shows the maximum storage volume and usage percentage of the flood-control capacityin the three retarding basins in each flood. The maximum total storage volumes comprise 50.6% of the total
flood-control capacity in the 2001 flood.
As shown in Figure 6(b), flood water doesn’t enter the Tanaka retarding basin in the 2007 flood because theheight of the overflow levee becomes higher than that in the 2001 flood (see Figure 2). The maximum inflow
discharge of the Inadoi retarding basin becomes larger than that of the Sugo retarding basin, contrary to the 2001
flood. The maximum storage volumes at the Inadoi retarding basin is almost same in the 2001 and 2007 floods,
but the total storage volume of the three retarding basins in the 2007 flood is about one-fifth of that in the 2001
flood (see Table 3).㻌㻌

㻌CONCLUSIONS
By the unsteady two-dimensional flood flow analysis using the time series data of the observed water surface
profiles, we estimated flood discharge hydrographs in the river channels and flood storage volume of three
retarding basins for the 2001 and 2007 floods and compared the analysis results with measured results. Themaximum inflow discharges of the three retarding basins were 829m3/s in the 2001 flood and 462m3/s in the2007 flood, respectively. Additionally, the calculated maximum total storage volumes comprise 50.6% of thetotal flood-control capacity even in the long duration flood of 2001.
REFERENCES[1] Nakai T., Sutoh J. and Fukuoka S., “Study on flood control of Watarase retarding basin in 2007 flood”,
Proceedings of 66th Annual Conference of JSCE, (2011), pp 243-244.
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