Evaluation of River Management by Sediment Bypassing and Management- Optimization and Cost Benefit Analysis ofComprehensive Sediment Management Kunihiro Tomita
ME, MBA, Civil Engineering and Eco-Technology Consultants Co., Ltd., Japan

tomita@kensetsukankyo.co.jp

Tetsuya Sumi
D.Eng., Professor, Water Resources Research Center, Disaster Prevention Research Institute, of Kyoto University, Japan

Mamoru Watanabe
Former manager of Yahagi Dam Management Office, Ministry of Land, Infrastructure, Transport and Tourism(MLIT), Japan

ABSTRACT:
Sedimentation is an essential issue on long-term management of dam reservoirs. Cost and benefit of the comprehensive sedimentmanage project is now a challenging issue by taking account not only keeping the reservoir capacity but also other important issues
such as the improvement of downstream environment by necessary sediment supply, the effect of recycling of sediment, additionalcosts for downstream facilities, CO2 emission by excavating and transporting of sediment. In this study, we studied how to integratethese costs and benefits for the economic evaluation of comprehensive sediment management projects. The benefits of improving riverand coastal environment were estimated by the results of CVM (Contingent Valuation Method) and Conjoint Analysis on Yahagi River.
We have also proposed that preparing a stock yard in the middle river reach is a key factor to manage various objectives.
Keywords: Reservoir sedimentation, Comprehensive sediment management, Cost benefit analysis, CVM, Conjoint Analysis

1. INTRODUCTION

effectiveness and validity in terms of cost and benefit.

In the Yahagi Dam, as part of the comprehensive
sediment management for sediment transport, a sedimentremoval project using sediment bypass (BP) is
proceeding. In a project to remove sediment from a dam
reservoir, it should be evaluate both the advantages anddisadvantages for the maintenance of reservoir capacity
and the effect on environmental performance indownstream river channel. Advantages expected fromsediment replenishment include both environmental
improvement in downstream and promotion of sedimentresource recycling, while issues estimated as
disadvantages include an impact of sediment discharge
on both flood control functions and water utilization onesin downstream river, and increase maintenance costs fordams or weirs resulting the accumulation of sediment.
In this study, we adopted the Contingent Valuation
Method (CVM) and Conjoint Analysis (CA) covering theareas immediately downstream of the Dam, and seashorearea, and evaluated the effect of sediment bypassing on
the environmental improvement. Finally, we conducted
cost- benefit analysis on the comprehensive sedimentmanagement of the Yahagi River sediment transportsystem. Based on the results of such revaluation, we
studied the effect of the sediment BP project and its

Moreover, since it is also considered important for the
Yahagi River to promote sediment recycling, we
conducted a social experiment on the utilization of
sediment resource, which studied the status of utilizationof sediment bypassed from Yahagi Dam by providing a
stockyard in the Koshido Dam area along thedownstream of Yahagi Dam and obtaining theparticipation of a private-sector business in theexperiment. Based on the results of the questionnaire
survey on the sediment users, we analyzed the feasibility
and validity of sediment recycling and examinedpractical issues. Furthermore, based on the results ofsuch analysis and examination, we considered thedevelopment of a system that economically optimizes theutilization of sediment resources with sedimentmanagement using stockyard.

2. OUTLINE AND EFFECT OF THE YAHAGIDAM SEDIMENT BP PROJECT
During The 2000 Keinan Heavy Rainfall , about
2.8million m3 of sediment had accumulated in the Yahagi
dam reservoir.

Yahagi Dam
Sasado Dam (completed in 1935)

Yahagi Dam (completed in 1971)

Yahagi Dam
Ratio of actual sedimentation to
the planned sedimentation: 100%

Dozuki Dam (completed in 1926)
Koshido Dam

Sedimentation ratio: 70%

Sediment
extraction (with BP
sediment
堆積土砂採取（土砂あり）
BP)
Transportby truck (withoutBPsediment
トラック運搬（土砂
なし）
BP)
有効利用
Effectiveuse

Coarse Sediment Supply
for Spawning Redd of
アユ：細粒分は除く×
Sweet fish:

Yahagi Second Dam (completed in 1971)

Asuri Dam (completed in 1934)

Azuri Dam
阿摺ダム

Sedimentation ratio: 10%

Environmental
環境改善
improvement:
3
1.5 万
15,000
m m3
河川環境
River
environment3(ii): 15,000m
②：1.5
万 m3

Sedimentation ratio: 30%
Koshido Dam (completed in 1929)

Sedimentation ratio: 30%

Mikawa Bay

Circled numbers represent
the order of construction.

3
21,0002.1 万mm3

River mouth /河口・海浜
seashore (iii):
3③：2.9
29,000万m m3

308,000
m3
30.8
万 m3

SasadoDam
笹戸ダム

Dozuki
Dam
百月ダム

Dam
越戸ダム
Headworks of Meiji Koshido
明治頭首工
Irrigation
Water

Meiji Irrigation Water

YahagiDam
矢作ダム

261,000
26.1 万 m
m33

133,000
13.3 万 m
m33
15,000
1.5 万mm33
3
3
17,000m
1.7 万 m3
23,0002.3 万mm33
84,0008.4 万mm3
Dumping
78,000
7.8 万mm33
榊野捨土atストックヤード
Stockyard:
3
8.4 万mm3+α+α84,000

Sakakino

Aggregate
骨材利用等
utilization, etc.
①：4
万 m3 m3(i): 40,000

Figure 1. Main Facilities concerning Sediment Replenishment
in Yahagi River Basin

Figure 3. Sediment Movement / Excavation / Transport Model
after Completion of Sediment BP in Yahagi River

It is therefore expected to implement measures against
sediment as soon as possible in order to maintain thesoundness of dam functions and extend the life of thereservoir. As one of such measures, a sediment BP
project is planned in order to remove sediment in case offlood.

Setting the Yahagi River basin as a model, we adopted
CVM and CA to examine the effect of environmental
improvement in the river and coast area resulting fromconstruction of sediment BP in the Yahagi Dam andincluded results of the examination in the cost-benefit
calculation. Then, estimating the costs of various
measures arising from sediment discharge from the dam,
we evaluated the project by computing costs and benefits
concerning construction of sediment BP. Further, for thecomprehensive sediment management of the whole basin,
it should be considered how to take a balance of allocation
for river environment improvement / utilization andsediment recycling while maintaining the flood control /water utilization functions, which are in a relationship oftrade-off, and where from and where to sediment should
be excavated / transported and how sediment should be
utilized in order to achieve the most appropriate economic
effect. For these reasons, we have set a sediment
stockyard near the Koshido Dam to allow business
operators to carry out sediment freely, and conducted afollow-up questionnaire survey to them to study the actual
state of sediment recycling and its conditions.

The Yahagi River was originally a sand-bed river, but
now an average of about 310,000 m3 of sediment flows
into the Yahagi Dam reservoir every year. Out of thisquantity, about 250,000 m3 of bed load and suspended
load accumulate in the reservoir, and about 60,000m3 ofwash load (fine-grained sediment) flows into thedownstream of the dam through flood spillway (See Fig.2).
After sediment BP is completed, it is expected that about
200,000m3 of sediment mainly consisting of sand is newly
supplied to the downstream through BP and that the
sediment transport environment of the Yahagi River
restores to the original state.
Meanwhile, there are also issues of the impacts on thedownstream environment, adjustment with stakeholders,since some utilization facilities are located in thedownstream of the dam, including hydropower dams, andriver-based activities such as fishing and recreation at
water front, are proceeding. Then, it would be necessary
to establish an optimum sediment management approachthat covers the overall basin (see Figs. 1 and 2).
Inflow
308,000m3/year

Sedimentation
247,000m3/year
Yahagi Dam

Yahagi
Secondary Dam

Discharge
61,000m3/year

Present condition(2007)

Sediment BP

Inflow
308,000m3/year

Sedimentation
47,000m3/year

Yahagi
Secondary Dam

3. ECONOMIC EVALUATION OF SEDIMENTMANAGEMENT
3.1 Model Setting

Average amount of
bypassed sediment
201,000m3/year

Yahagi Dam

Comprehensively considering the data obtained, we
studied economically optimal sediment management.

Discharge
60,000m3/year

Permanent measure(with sediment BP)

Figure 2. Sediment Balance and Effect of Sediment BP in
Yahagi Dam

We have set a model of sediment management to the
Yahagi Dam after sediment BP is completed.
As shown in Fig. 3, as new destinations of sediment thatpasses through the dam after sediment BP completion, we
considered a combination of supply (sediment
replenishment) to river channel and seashore andsediment recycling. If no sediment BP is provided, toachieve the above with excavation from the dam reservoir
and truck transport, it will be necessary for trucks to drivea long distance along the dotted lines on Fig. 3, emitting alarge amount of CO2. When sediment BP is provided foruse, an average of about 200,000 m3 of sediment will
newly flow every year through the river channel and asediment flow environment is expected to restore
favorably. Further, from a viewpoint of sediment
recycling, the distance of transport to the point of demand
will be shortened, which is favorable in terms of cost andtransport environment. Meanwhile, the flow of sedimentis anticipated to cause local accumulation on the channel
and raise the bed height. This study assumed that a bedheight is maintained to a certain level determined on the
discharge capacity of the channel and that sediment inexcess of the set height is excavated with age. In addition,
as sediment volume required for the improvement ofchannel environment, it was estimated based on bed
height, predicted changes to grain size, etc. to replenish
15,000 m3 of sediment to the downstream of Koshido
Dam, 15,000 m3 to the downstream of the Intake weir of
Meiji Irrigation Water, 29,000 m3 to the river mouth /seashore, and to use 40,000 m3 as sediment resources for
aggregate utilization. In this setting, a stockyard of 84,000
m3 or more is required near the Koshido Dam for
temporary storage and adjustment of sediment to bereused.
Including these conditions, we built a "Sediment
Movement / Transport Model" (See Fig. 3).
3.2 Economic Evaluation Method of Comprehensive
Sediment Management
The items for economic evaluation of comprehensive
sediment management are organized and comparedaccording to two cases where (i) sediment BP is providedand (ii) sediment is transported by truck. It is common in
the economic evaluation of infrastructure improvement tocalculate costs (C) and benefits (B) and to makeevaluation based on cost-benefit ratio (B/C) or difference(B-C). For an existing project that has been operating formany years, like Yahagi Dam, since it would be practicalto make economic evaluation for a case of starting a(sediment BP) project as a new option at the present time,
without considering the project costs so far spent andeffects, evaluation at the present time (real option) was
adopted in this study.
Evaluation items etc. are as follows.
3.2.1 Evaluation items
・Cost calculation
In addition to the construction and maintenance costs of
sediment BP, we calculated the costs of measures for
reduced generation from the hydropower dam due toincreased supply of sediment to the downstream channel,
excavation of sediment from Yahagi Dam, hydropower
dam, etc., truck transport, and environmental measures toreduce CO2 resulting from truck transport. Stockyard
maintenance and other costs are taken into consideration
after details of the project are determined, including
business entity and management method.

Flow (m3/s)

流量(m3/s)
2,500

Planned inflow
計画流入量Planneddischarge
Current計画放流量
discharge
現況の放流量Discharge
after 10 years
10年後放流量
Discharge
after 30 years
30年後放流量
Discharge
after 60 years
60年後放流量

2,000

1,500

1,000

500
1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

経過時間(hr)Elapsedtime (hrs)

Figure 4. Expected Benefits from Dam Life Extension
Benefit(hundred million yen)
便益(億円)
1,000
Benefit from no
measures

無対策の便益800

Plannedcontrol rate
計画調節率
Controlrate if no
無対策の調節率
measures

Control調節率(%)
rate (%)

100%

Plannedbenefit
計画の便益

80%

600

60%

400
200

Benefitfrom sediment
堆砂対策を実施することの便益
measures(現在価値)taken
3,027億円
Benefit from no
無対策の便益(現在価値)
measures(Present
value)

40%
20%

0
0%
30-year 40-year
60-year50-year20-year 30年後
80-yea 90-year
100-year
0年後 10-year
10年後 20年後50年後60年後 70-year
70年後
90年後 100年後
after 80年後after 40年後
after after
after
after
r after after
after
after 管理年
Management years

Figure 5. Benefits from Life Extension (sediment removal)

・Benefit calculation
As a benefit of dam life extension, we calculated thebenefit of flood control resulting from the effects that
sediment BP enables the dam reservoir capacity to be kept
at the planned level and that reduction of flood cut can be
avoided (see Figs. 4 and 5).
In addition, the effect of river environmental improvement
was calculated with CVM and CA covering the wholebasin of Yahagi River from the Yahagi River downstream
to Mikawa Bay seashore.
For the benefit of sediment recycling, we calculated morepractical benefit by analyzing transaction prices,
applications, transport destinations, etc. with the data of
the survey conducted near the Koshido Dam to examine
the utilization of sediment discharged from the Yahagi
Dam.
3.2.2 Goal of sediment management
We aimed at a situation that achieves the largest (optimal)
cost effectiveness by realizing "dam life extension" by
bypassing sediment from the dam reservoir, while
maximizing the benefits of the whole basin throughimprovement of the environment of the downstream riverand seashore, promotion of sediment recycling, etc. andminimizing the project cost. Accordingly, the goal of
sediment management is total optimization of the wholebasin.

3.3 Economic Evaluation
3.3.1 Implementation of CVM and CA
According to existing studies, sediment discharge fromthe dam is expected to bring environmental improvement
effects such as "improvement of landscape and living /growing environment of living things" from river
downstream to seashore. For environmental goods,
which are not traded in the market, it is effective formeasurement to use CVM, an approach to evaluate theeffect of environmental improvement on a monetary basis,or CA.
Therefore, we calculated the effect of environmental
improvement of downstream area. with CVM andcalculated willingness to pay (WTP) with the method
designated by the Ministry of Land, Infrastructure,
Transport and Tourism (MLIT). We also conducted CA
in order to grasp what factors of environmental
improvement are highly evaluated by local residents andutilize them for sediment management.
The research areas covered were Toyota City, an area
immediately downstream of the dam, in fiscal 2009, andOkazaki City and seashore (Okazaki City etc.),
downstream areas, in 2010.
For the number of necessary samples, we secured thenumbers of samples needed in the case where reliability is
95% and absolute accuracy is 5% as specified in CVM
Guideline. For the questionnaire of CVM, the multi-stage(5 stages) YES / NO question type was used, and for CA,
card-selection type with 4 questions was used. In
reference to the past questionnaires, we assumed thequestionnaire collection rate to be 30% and valid response
rate to be 60%, and distributed 1,000 copies of thequestionnaire by mail to each area and collected them (SeeTable 1).
Table 1. Questionnaire Covered Areas and the Number ofHouseholds
Areas
River
area
(upstream)
River
area
(downstream)
Seashore area

Municipalities covered
Toyota City etc.
Okazaki City etc.
Okazaki City etc.

Total
number ofhouseholds
153,539
households
368,421
households
390,198
households

Table 2. Collection Rate and Valid Response Rate
Item

Number of
Number of
Number ofcopiescopiesvalid responses
distributed collected (rate)(rate)

River environment
Seashore environment

1,000
1,000

469 (46.9%)
463 (46.3%)

228 (49%)314 (68%)

Reference: 2009 Upstream
river environment

1,000

472 (47.2%)

336 (71%)

The questionnaire consisted of questions about project
effect scenario and expected effects, question about theamount of WTP for CVM, reasons for approval, reasonsfor opposition, explanatory factors of CA and explanationof how to answer questions, image of explanatory factors,
questions about CA, and attributes of the respondent.
The collection rate of the questionnaire was very higharound 50% -- 46.9% for river environment and 46.3% for
the seashore environment--, which shows that local
residents are highly concerned about sediment supply.
Eliminating invalid and biased responses from the above,
we made analysis based on the valid response forms(River environment: 228 forms, Seashore environment:
314 forms) (see Table. 2).
3.3.2 Estimation of the effect of environmental
improvement effect (WTP) in river area
Based on the valid responses from 200 residents, weestimated a curve line showing acceptance to the amountprovided by CVM using the parametric method with anestimation model. As a result, the average amount of
WTP for sediment discharge from the dam to thedownstream of Yahagi River was 378.2 yen/month per
household (see Fig. 6). This is about 60 yen higher thanthe WTP of the area immediately downstream of the dam(covering Toyota City) of 317.4 yen, which shows aslightly higher expectation for sediment replenishment in
the downstream area.
Meanwhile, the amount of marginal willingness to pay(MWTP: WTP per unit) according to CA for each item inthe downstream area is shown in Table 3, which indicatesthat WTP for "sandy river bed" was low in the upstream(area immediately downstream of the dam), while it washigh in the downstream area. This would suggest thatthe awareness of returning to "sandy river bed" as"original landscape" of Yahagi River might be stronger inthe downstream area. MWTP for "paddling pool" is alsohigh at 234 yen, which would suggest strong aspiration for"formative experience" that they played in sandy river bed
in their childhood.
WTP
acceptance rate
WTP賛成率WTP
acceptancerate
WTP
acceptancerate
WTP賛成率

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Actual
実測値
measurement
Estimation
推定曲線
curve

Average WTP: \378.2/month per
household

0

500

1,000
1,500
2,000
WTPWTP（円／月・世帯）(yen/month per household)

2,500

Figure 6. Estimated WTP for River Environment Improvementin Yahagi River Downstream Area

Table 3. Results of Conjoint Analysis in Yahagi River
Downstream Area
MWTP(yen/month per household)

Item

Per unit
Muddy water per-5 days
per +10%

Water quality

111

Reed field3

Sandy river bed

110

per +10%

Paddling pool234

per +5 locations

Ecosystem

187

per -5 types

WTP
acceptance rate
WTP賛成率WTP
acceptance rate
WTP賛成率

100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

Actual
実測値
measurement
Estimation
推定曲線
curve
WTP 平均値円／月・世perAverage
WTP:350.4\350.4/monthhousehold
帯

0

500

1,000
1,500
2,000
WTPWTP（円／月・世帯）(yen/month per household)

2,500

Figure 7. Estimated WTP for Seashore Environment
Improvement
Table 4. Results of Conjoint Analysis in Seashore Are
Item
Shallow bottom /tidal flat
Water quality
Clam-digging
area
Beach
Aquatic life

WTP (yen/month per
household)Per unit139

per +50 ha

105

Red tide per -10 days

33

per +100%37

per +100%140

per +5 types

operators who carried out sediment from the stockyard forbusiness purpose.
According to the questionnaire results, as the cost of using
sediment, the sum of "waste removal cost" and "transportcost" amounted to about 770 yen /t on average. Since themarket research conducted in 2009 showed that theestimated sales price of sediment discharged from the dam
was 300 yen/t, sales price based on this survey would beapproximately 1,070 yen/t as a result of adding 770 yen(sum of disposal and transport costs) provided in thisquestionnaire survey to the 300 yen. Since the circulation
price of sediment at the time of the 2009 research was
1,860 yen/t, the sediment discharged from the dam could
be sold about 800 yen/t lower than the circulation price.
The use of such difference as the cost of stockyard
maintenance in the future would be worthy of
consideration.
In addition, according to the request stated in many
responses, there is a seasonality in the distribution of
aggregates, i.e., 60-70% of the annual consumption
concentrates on a season from October to next March, sothat an issue is whether a sufficient amount of sedimentcan be distributed during this season.
In the future, it should be considered how to ensure
operational cost reduction and stable supply (balance of
supply and demand) and it would be important to promoteutilization for the development of shallow bottom / tidal
flat in the seashore (coast of Mikawa Bay), which was
highly evaluated in the CVM questionnaire survey.
Therefore, it would be necessary for sedimentmanagement to study a system that promotes the use ofdam sediment for seashore area and a flow of sedimentfrom the dam to seashore.
3.3.5 Cost benefit evaluation

3.3.3 Estimation of the effect of environmental
improvement effect (WTP) in seashore area
As a result of estimating an acceptance rate curve from314 valid responses of the questionnaire, average WTP for
environmental improvement of seashore was 350.4
yen/month per household (see Fig. 7), which was lower
than 378.2 yen of WTP for river environment.
Meanwhile, the amount of MWTP calculated according toevaluation items with CA was higher in "Shallow bottom /tidal flat (landscape)" and "Aquatic life" (see Table 4),
which would suggest that residents have a strong
aspiration for them, while WTP for recreation activities
including "clam digging" and "sea bathing" was lower.
3.3.4 Survey on the effective use of sediment resources
In order to study the feasibility of effective use of
sediment in the Yahagi Dam, we conducted a social
experiment using a temporary sediment stockyard in the
dam downstream, and analyzed the results of thequestionnaire survey we conducted for private-sector

Annual benefit from the improvement of river andseashore environment was calculated based on the resultsof CVM survey with the formula, "Annual benefit = WTP
under CVM x Number of households in target areas x 12
months. For the benefit of improvement in the riverenvironment, since there is a difference in the section of
sediment replenishment, the sum of values for the
upstream and downstream of Yahagi River was adopted
for sediment BP, while only the value of Yahagi Riverdownstream was adopted due to the absence of sediment
replenishment between Yahagi Dam and Koshido Dam(see Fig. 3).
Based on these data, we evaluated the costs and benefits of
sediment management in the Yahagi Dam for the cases of"with BP" and "Truck transport (without BP)." Thecalculation period is 100 years to come and the future
costs and benefits calculated were converted into thepresent values at the discount rate of 4% and cost-benefit
ratios (B/C) were calculated in real option (see Table 5).

Table 5. Calculation Table for Cost Benefit Evaluation

Cost

Sediment bypass Transport by truck(hundred mil. (hundred mil. yen
yen /100 years)/100 years)

Benefit*

Maintenance cost
Cost of measures forseashore
Total
Dam life extension
River environment
Seashore environment
Sediment recycling
Total

Cost-benefit ratio (B/C)

34.9
111.1
129.0

-

2.4

-

Case
ケース1
1

Case 2
ケース2

Case
3
ケース3

12.0

55.3
296.8

10.0
B/C

Excavation cost
Transport cost
Cost of constructing bypass
tunnel and suction facilities
Cost of measures forhydropower dam
Environmental spending

14.0

8.0
6.0
4.0

1.1

2.8
mainly road
41.4
maintenance cost
15.0

15.0

334.8
3027.0
552.8
402.1
25.3
4007.2
120369.93027.0
409.7
402.1
25.3
3864.1
10.4*) Calculated by authors on a trial basis, not officially announced.

In Fig., Case 1 shows B/C calculated by limiting thebenefit to only dam life extension (benefit of flood
control); Case 2 limited the benefit to the effect ofenvironmental improvement in the seashore and sediment
recycling; and Case 3 indicates B/C in combination ofCases 1 and 2, i.e., dam life extension and the effect ofenvironmental improvement etc. As the result, it wasverified that the development of sediment BP greatly
exceeds 1.0 in B/C evaluation and therefore has asufficient effect as a project and high cost performance.
Particularly, it was confirmed that even the effect ofenvironmental improvement alone has an effect exceeding
2.0.
AS described, sediment BP has been verified to be an
economically efficient and effective means from not only
the effect of dam life extension (flood control) but also theproject evaluation based on the comprehensive sedimentmanagement conducted including indirect effects such asenvironment improvement and sediment recycling.

4. CONCLUSION
In this study, economic evaluation was conducted for
sediment discharge from the dam through sediment BP
and river management based on sediment management,using the Yahagi River basin as a model.
The conclusions from this study are as follows.
(i) As the result of evaluating the effect (benefit) of
sediment discharge from the dam and cost of measures,
including the benefits of the effect of environmental
improvement, which was examined with CVM, CA, etc.,
covering the whole basin of Yahagi River from thedownstream to river mouth and Mikawa Bay seashore, thestructure of cost-benefit on sediment supply and its factors
have been clarified.

2.0
0.0
土砂バイパス
Sediment
bypassTransportby truck
トラック運搬Figure 8. Comparison of B/C on Sediment BP and Truck
Transport(ii) Sediment BP project has been verified to have great
economic advantages and social benefits as the result of
evaluating indirect effects over the whole area of sedimenttransport system, including environmental improvement,in addition to the effect of flood control, i.e., the life
extension of the reservoir resulting from measures against
sedimentation in the dam.
(iii) We proposed an appropriate matching of supply anddemand that optimizes cost effectiveness by setting a
stockyard in the midstream of the river and conducting
sediment management involving private-sector operators
etc.
(iv) As an issue to address in the future, it is desirable toestablish a project approach that enables economically
viable operation by studying operation method including
specific location and size, PFI, etc. for stockyard, which is
expected to promote the functions of flood control, water
utilization, and environment.
Note that this study has examined modeling of sedimentmanagement and economic evaluation model using the
Yahagi Dam Sediment BP Project as a case study, and notevaluated this Project itself.
REFERENCES
Tomita, K., Sumi, T. and Watanabe, M. (2010): Economic
Evaluation of Comprehensive Sediment Management inRiver, Advances in River Engineering, JSCE, Vol.16, pp.
529-534. (in Japanese)
Yahagi Dam and Reservoir Management Office, Chubu
Regional Bureau, MLIT (2010): Documents concerning the
Yahagi Dam Sediment Bypass. (in Japanese)
Yahagi Dam and Reservoir Management Office, Chubu
Regional Bureau, MLIT (2009): Documents concerning theeffective use of sediment. (in Japanese)
MLIT(2009): Technical Guideline on Cost-Benefit Analysis in
Public Project Evaluation (Common Part).
MLIT(2009): “Contingent Valuation Method (CVM)
Implementation Guideline”. (in Japanese)
Sumi, T. and Fujita, M. (2009): Current Status and Future
Challenges of Sediment Replenishment to Downstream River,
Advances in River Engineering, JSCE, Vol.15, pp. 459-464.
Ikebuchi S. (2009) Edited: Science of Dam and Environment I,
Ecosystem in Rivers Downstream of Dam, Kyoto University
Press. (in Japanese)