QUANTITATIVE ANALYSIS OF TIDE EMBANKMENTCONSTRUCTION AND RESIDENT’S SELECTING ACTION

Ai TASHIRO
Master’s Student, Dept. of International Studies, Graduate School of Frontier Sciences, The University of Tokyo1.

level1, L12)), the heights of seawall are getting

INTRODUCTION

constructed. Regarding that, they concluded that
About three and a half years has passed since thecosts, around 24.6 billion yen would be needed andGreat East Japan earthquake in March, 2011. The

in that case, the net benefit (benefit minus cost)damaged by Tsunami has still left in many disasterwould be negative (-20.75billion yen).

areas. In most of those areas, as one of the restoration,
Plans

of

giant

seawall(tide

According to the review of the previous studies,embankment)

found that construction a seawall with L1 is negative

construction are pushed forward by governments

aspect of cost benefit. However, quantitative

and administrations. Based on the standards decided

evaluation for cost benefit analysis under the

by government's Central Disaster Management

consideration of environmental damages andCouncil, much higher seawalls are planned to beresidents selecting behavior has not yet been

constructed than before collapsed. Movements

conducted enough in this district. Recently, theagainst giant seawall construction, however, arelandscape and environmental issues are even moreslightly but surely gathering force among a part ofstirring up in those areas.

residents in disaster areas. Some people point out

This study focuses on Koizumi district. Over thelandscape would have been destroyed by theseawall construction, it clarifies what residents

construction, and others wonder if residents move torecognize, what they really interested in and what

the high ground, nobody would be suffered fromthey wish to solve the problem. Firstly, by means ofdisasters. Over the issue of the construction, many

cost benefit analysis and multi standard analysis,

conflicts are happened.

suggests the preferable choice of the giant seawall

Kesennuma City, located in Miyagi prefecture, isconstruction and decision making, using outranking

no exception. In Kesennuma City, many districts

method. Secondly, by using covariance structurenear the coast suffered massive damages in theanalysis shows a difference of resident’s recognition

tsunami disaster. Plans of seawall construction are

structure to achieve agreement formation between

promoted regardless of cost benefit effects. Several

Koizumi and total areas in Kesennuma.

studies on cost benefit analysis of the seawall
construction have been conducted. Jun, K. et al1)
studied that in Koizumi district, Kesennuma. In this
district, in order to prevent tsunami, 14.7m (set with

2.

MethodThen, duv is defined as follows:|𝑃𝑗𝑢−𝑃𝑗𝑣|
max)
𝑑𝑗duv =max(j∊D ̅ ̅u v

(1) Study contents
The period of survey is from 15 September to 18

s.t. 𝑑𝑗 =max{ j|pju－pjv }
max

(ⅳ)

1≤u,v≤M

September (in the case of 2014) in Koizumi andconducted household survey by using questionnaire

・Step3 Solution
Based on cuv , duv obtained by Step1 and Step2,

consisting of 4 classifications; a basic attribute, adetermine the preference order as follows:other district in Kesennuma. The survey wastheIf cu>cv, then select plan u,

consciousness to a seawall. To compare more

If du<dv, then select plan v.

universally analysis to that of Koizumi, I also asked
people all areas in Kesennuma.

cu=∑𝑢 𝐶𝑢𝑣 − ∑𝑣 𝐶𝑣𝑢,
du=∑𝑢 𝑑𝑢𝑣 − ∑𝑣 𝑑𝑣𝑢(2)Analysis Method

Secondly, I conduct covariance structure analysis,

livingcondition,

disasterprevention,

As for cost benefit analysis, in this study,
3)

(ⅴ)
(ⅵ)

using SPSS Amos ver. 22.0 IBM SPSS Final object

concordance matrix is applied . It is explained ason this survey is to examine find out the influence offollows. It is a method of outranking analysis. Roy.

what kinds of factor lead to agree or disagree to the4)

B developed it in 1960s, leading position in Europe.

sea wall construction. Finally, identify the resident’s

It has a common characteristic to cost benefit

selection behavior. Based on collected data fromanalysis; it is started from a plan impact matrix toquestionnaire, two categories were made; Koizumi

unify associated standard results of alternative plans.

and Total districts in Kesennuma.

Conceder Concordance index Cij and Cji,. Difference

In order to specify the difference in affected

between Cij and Cji indicates superiority weighted

factors each district, I use Mean Structure model5).

plan i to weighted plan j

By using this model, it is possible to estimate theaverage of latent variable. In this sense, we can・Step1: Concordance Index

regard the average as the difference between groups.

There assume two alternative plan u,v. First, a set,𝐶̅ uv is defined as follows:𝐶̅ uv={ j|pju≥pjv }(ⅰ)̅
s.t. 𝐶 : set, j: evaluation item, pju, pjv : effect of

3.

plan u, plan v(1) Responder’s Basic Data
The following fig.1 andfig.2 shows the collected

Then, cuv is defined as follows:
cuv =∑𝑗∊𝐶̅ 𝑢𝑣 𝑤j

Results and Discussion

data of responder’s basic information. It can be seen(ⅱ)

obtained 106 responders. Regarding Fig.1 showss.t. w j : (𝑗 ∊ 𝐶̅ 𝑢𝑣)

most responders are over 40s and ratio of 60s is thehighest in this survey.

・Step2: Discordance Index
duv is the index that the degree of plan u inferior
to planv. There assume two alternative plan u,v.
̅ uv is defined as follows:First, a set, 𝐷̅ uv={ j|pju ≤ pjv }
𝐷

(ⅲ)

80～

10

who live in Own house, they answered, most of their

4

70

19

60

22

50

their own paddy field and allocate funds for housing.

3
23

30

9

20

6
0

they wish to buy a house or replace. Some people sold

12

17

40

house are partially destroyed, or even take out a loan,

11

6

n=237

Total

6

Koizumi

2
10

20

30

No.1

40

Fig. 1 Responder’s Age distribution
No.2
33
Others19
4
Self employment
Subsidiary…21
public worker 7 0
Fisheries 20
Farmer 4 2
24
6
Office worker
15
13Housewife

0

20

18

No.3

Total

Koizumi40

60

Fig.2 Distribution of Occupation(master of house income)

0

10

20

19

Unachieved Agreeement
Lack of Manegement

master. Most people belong to Office worker and others.

Lack of fund

Other represent ratio of older responders is much highEnvironmental activities

and most of them retired and live on pension.

Opponents

Surprisingly in Koizumi, people who are gaged in

Delay of Administration

New House
0%

50%

100%

Fig.3 shows the responders current house status.
From this figure, we can find most of people live in
own house. I conducted interviews to some responders

70

8

27

No.1

44 8

No.2

13 8 6

No.3

25

20

10

11 9 3

44

24
0

10

20

30

40

50

60

Fig.5 Top3 Ranking of Delayed Reconstruction
Kesennuma

Defer toelders

50
40
30
20
10
0

OthersRentalHouse

Fig.3 Current House situation60

2 11 8Delay of the construction

TemporaryHouse
Own House50

7 13 4

Delay of Raising
NationalRoad

Fig. 3 House Status information is as follows:

n=101

40

Fig.4 Top 3 Ranking of Key person
n=252(Multiple answered)Fig.2 shows occupation status of house income

Agriculture is only 2 in this survey.

30

IgnoreCBA

KoizumiHard toelicitviews

Lack ofeffort toachieveagreement

Fig.6 Not Favorable Custom in Community

Kesennuma
KoizumiLife
Environme
nt

60

About Alternative Plan B is designed to

FamilySafetyenvironmental-friendly. It was assumed to reduce

40
20
Protect
Environme
nt

ProvidingHouse0Industrial
Recovery/Reconstruction

maintenance costs in the next 50 years. Each year, ittakes 0.05%8) of total construction cost for each plan.

80
Othersby Jun, K. et al1). All plans are assumed they takeCommunity
Promotion
Rising/selling
landFig. 7 Residents current interest

30% cost of Current plan. So the total cost is 236×
0.7=165.2.
About Benefit: Benefit is assumed to prevent L1’s
tsunami wave and most of residents would be safe.
So, damaged reduction rate is set for each plan in
Fig.8.
Net benefit is calculated as follows:

In the upper page, Fig 4 shows Top 3 ranked key

B/C =Prevent L1 (%)/ Cost

person, who responders think could improve theircurrent environment. From this figure, notice that eachranking occupies high percentages of Government,
Administration, and Residents. However, Residents
have the highest ratio as the total result. On the other
hand, Fig. 5 shows that Top3 ranked causes of delaying
Sea wall construction. As the results, we can notice

About WTP: In this survey, I asked responders toanswer the question how much you are willing topay (WTP) for protecting the seaside environment. I
collected data and obtained average of 1,944yen in
Kesennuma and of 1,903yen in Koizumi. So, I set up
WTP to Current plan is 1,944 per person and its plan

responders think most causes of constructing delay are

B is 1903yen per person. Then 1,5889) is applied tounachieved agreement and delay of administration. As

plan A. In Koizumi, as of 2014.8.3110), there are 557

the results, it seems to believe that Environmental
activities are not so crucial cause of the delay.

households. So total WTP of each plan is WTP*557.
It is represented in Table.1

Fig.6 shows not favorable customs of each
responder’s community. Comparing Koizumi with
Kesennuma, we see that both districts have the same
tangency. Hard to elicit views is the top ranked. Fig.7
shows higher ranked items are Family Safety andIndustrial Recovery/Reconstruction.
(2) Results of Outranking Method

About Weight: Weight was decided by items ofquestionnaire. Responders felt most burden cost andnot so much people are willing to pay. So, in thiscase, weight is regarded as exogenous variable.
Table.1 shows the final using matrix as follows.
Table.1 Effect of seawall construction (0.1billion)

In this method, from the previous surveys and

Cost

WTP

seawall, assumed three plans toward only Koizumi

Current
Plan

236

0.0108

1.61

district. Then, analyzed cost benefit and ordered

Plan A245

0.0088

1.63

Plan B

165.2

0.0106

1.94

weight

0.7

0.1

0.2

land scape designer’s alternative plans6) to the giant

preferable ranking to each plan.
About Cost： Each plans costs are showed in theFig. 7. Total cost of Current plan needs 23.6 billionyen7). Cost of Plan A is referenced the previous study

B/CTable.2 Matrix of Concordance
Current

Plan A

Plan B

0.8

0.1

0.9

0

0.2

Current
Plan
Plan A

0.2

Plan B

0.9

1

Total

1.1

1.8

Total

1.9
0.1

Table.3 Matrix of Dis-concordance
Current

Plan A

Plan B

0.06

1

1.06

1

2

Current
Plan
Plan A

1

Plan B

0.12

0

Total

1.12

0.06

Total

Fig.8 Awareness Model of Koizumi district

0.12
2

Table.4 Results of Concordance matrix
Cu

duCurrent
Plan
Plan A

-0.2

-0.06

-0.14

2

-1.6

1.94

-3.54

3

Plan B

1.8

-1.88

3.68

1

0

0

Total

Total

Rank

In Table.3 and Table.4, each matrix showsconcordance and dis-concordance matrix.

From

Fig.9 Awareness Model of Kesennuma

Table.4, the preference order is Plan B>Current
Plan> Plan A.
It indicates even prevent L1 of Plan A is 80%,they should accept it and prepare for L1, which isassumed to happen once in 50 years.
(3) Results of covariance structure analysis
The following same typed models are assumed. It
is investigated what current factors affect resident’s
behavior and what is different from districts. As aresult, obtained some related factors in Fig.8 andFig.9.
In those models, meanings of each model are as
follows:
ART: Awareness of Risk of Tsunami,
APEnv: Awareness of Protection seaside Environment
ITGSW: Interesting Degree of GSW ,SIM: simulation of evacuation ,APD: Awareness of disaster prevention
OTPD: Opportunity to talk about disaster prevention
HID: Higher interest in Disaster
TaxGSW: knowing Giant Sea Wall construction is usednational tax.
TACGSW: Trust to administrative project of Giant Sea
Wall construction
Hgsafe : knowing if resident’s moving to High ground,
nobody will not be suffered
NDEcon: Need to construct Giant sea wall even if
seaside ecosystem will be damaged
Intisea : Intimate to seaside
ProEco: will to protect ecosystem for the next
generation
Alt Gsw: knowing Alternative Giant seawall
GSWAG: Agree to Giant seawall

As for results in Koizumi, it is illustrated in Fig.8,
we can notice that APEnv→ProEco(0.85), ART→
SIM/OTPD(0.85) show high positive correlation.
On the other hand, the factor, having higher

interested in giant seawall affects negative influence(3) In this study, actual detailed data about cost andthe factor, not to need giant seawall (ITGSF→

reduction rate of damages couldn’t be got. In

NDEcon：-0.77). As for the influence of lateral

Kesennuma, there are some difficulties to use material

variables, having awareness of protection Ecosystemwith actual survey data and predict. As for cost benefit

and Interested in giant seawall affects negative

analysis, as the future challenges, analysis based on

decision to construction of current plan’s seawall

actual data should be conducted.

(APEnv →GSWAG:-0.45, ITGSW→GSWAG:-0.27).

Furthermore, much amount of data couldn’t beCompared with those factors in Kesennuma, it iscollected. So, in order to verify the universality of thisobvious that the influence of APEnv to GSWAG issurvey, collecting much more data should be needed.

stronger than in Kesennuma (-0.44<-0.34). As forawareness of risk prevention, it affects positive
decision to construct GSW. However, the influenceis much weak(Koizumi:0.06, Kesennuma:0.16).

References

Regarding Comparative fit index (CIF), which takes

1) Jun, K., Taisuke, K., Yuichi, S., Tomoki, S. andKazuya, F. :Cost-benefit analysis about seawall
construction plan in Koizumi district, Kesennuma
City:Economic evaluation of the public policy,
Graduate School of Public Policy, The University ofTokyo, March 2014
2) Miyagi Prefectural Government, : Study on
alternative plan of Nakajima beach, Evaluated resultsof tsunami simulation,(http://www.pref.miyagi.jp/uploaded/attachment/2721
69.pdf), last access 22, Sep,2014.
3) Yoshimi, H. : “Adaptive system planning
methodology for Environment Risk Management”,
Kyoto university press, pp.611-618, 2008
4) Roy, B. :Classement et choix en présence de points devue multiple (La méthode ELECTRE), Revue
Française d’ Informatique et de Recherche
Opérationnelle 8 pp. 57-75, 1968
5) Nobuo, O. and Hiromu, T. “Study with Amos, data
analysis ”, Tokyo Library, 20096) Shunsuke, H. : Alternative Proposals for the Tsuya
District and Koizumi District Disaster Recovery
Initiative: revised version(http://shunsukehirose.blogspot.jp/2014/05/alternativ
e-proposals-for-tsuya.html) access 22, Sep, 20147) Miyagi prefecture department of engineering river, :Basic flow and rule of seawall construction, 20128) Aomori prefecture, : Ominato coast (erosion) project :Explanation material, effect of cost benefit analysis,
20099) Kasai, M., et al. : Survey on consciousness of coast
space value, coastal engineering collected paper, vol.
46, pp.1286-1290, 1999
10) Kesennuma official website, : Population andhouseholds in Kesennuma(http://www.city.kesennuma.lg.jp/www/contents/114
6185553349/) access 22, Sep, 2014

from 0-1, indicate consistency between model anddata is 0.953. It shows good fitness of this model. In
this study, CIF is applied to judge the degree offitness.

4.

Conclusions
The following conclusions can be derived fromthis survey.
(1) According to previous surveys and newspapers,in Kesennuma City, most of people accept
administrative decisions even if they don’t wish the
project about seawall construction. However, fromthis survey, it is found that, in fact, people are notwilling to accept it. Actually, they have higher
reliability to Government and Administrative andbelieve they may improve their environment andcommunity from results of collected data. Moreover,they also believe residents can improve theirenvironment. In order to encourage their
expectations, it is necessary to change the situation
hard to tell their own mind more casually.
(2) In Koizumi, there is beautiful beach where filledwith biological diversity. In this survey, I could get
only 44 data sets in this district, However much
more people seems to be interested in Environmental
protection. If current giant seawall will be
constructed, damages of sea ecosystem will not be
inevitable. Administrations should listen to resident’s
opinion with flexibility.