Project Evaluation of Flood Management Projects in Japan

Project Evaluation
of Flood Management Projects
in Japan
Masato OKABE
Japan Institute of Country-ology and Engineering
2019.9

2
Purpose of Project Evaluation
Q. What is the purpose of project evaluation?
[Japan]
1. Ensuring accountability for public works to the public
2. Promoting efficient and quality public services that is for the
benefit of the public
3. Shifting to outcome-oriented government from the viewpoint of
citizens
Public works projects are evaluated for:
- planning stage, adoption of new project, and justification of continuation or
suspension of project
- completed projects to implement appropriate improvement measures if
necessary
Purpose
Government Policy Evaluations Act (Act. No. 86 of 2001)

3
Process of Planning, Evaluation and Budget Allocation
Q. What is the process of planning, evaluation and budget allocation for flood management
projects?
[Japan]
[Long‐term Plan]
River Improvement
Basic Policy
-Basic policy of river
improvement from a
long-term viewpoint
[Mid‐term Plan]
River Improvement Plan
(every 20～30 years)
-Defining river
improvement targets
for 20-30 years later
-Defining concrete
measures/projects for
river improvement
Statutory Consultees
Implementing Agency
（MLIT）
Local Authorities Experts Residents
Opinion
Adoption of Basic Policy Disclosure of River Improvement Basic Policy
<Minister of MLIT>
Approval
<Panel on Infrastructure Development>
Express opinions on Basic Policy
<Regional Bureaus of MLIT>
Formulation of Draft Basic Policy
Adoption of the Plan Disclosure of River Improvement Plan
<Minister of MLIT>
Approval
<Experts/Residense>
Express opinions on draft Plan
Opinion
<Governors of prefectures>
<Water users>
Express opinions on final draft
Formulation of draft Plan
Conducting project evaluation
（Self-evaluation）
<Ministry of Internal Affairs
and Communications>
Inspection
Submission of evaluation report
Advice/Opinion
<Project Evaluation Monitoring Committee>
Decision on the results of project evaluation
Disclosure of the project evaluation results
<National Diet>
Confirmation
Selection of projects for which
budget will be allocated
Formulation of annual plan
Budget request
<Cabinet,Ministry of Finance>
Policymaking
Formulation of draft budget
<National Diet>
Budget decision
Implementation of project
Allocation of project budget for
the fiscal year
Selection of project
implementation sites
[Project Evaluation]
Conducting project
evaluation
(every 3～5 Years)
-Justifying continuation
or suspension of
project
-Conducting appropriate
improvement measures
as needed
[Budget preparation]
Justify implementation
of project
(every fiscal year)
-Deciding projects to be
implemented in a given
fiscal year
<MLIT HQ>
Decision on response policy
Suspension
Yes
No
Yes
Yes No
No
Government
Review
Review
Consultation
Opinion
Projects may be funded for implementation even in cases where the above
policy/plan is not yet adopted.
Disclosure of draft Plan
Disclosure
Disclosure
<Experts>
Express opinions on draft report
Opinion
Decision on draft response policy
Disclosure
The flow is approximately the same for
-Planning stage evaluation
-New project adoption stage evaluation
-Re-evaluation
-Ex-post evaluation after completion
Submission
<Governors of prefectures>
Express opinions on draft report
Opinion
Submission to MLIT HQ

4
Timing of Project Evaluation
[Process of Project Evaluation]
(before evaluation for
new project adoption ) (continued for 5 years)
(work not started for
3 years)
(3 years after previous
re-evaluation）
（within 5 years
after completion）
conduct prior to adoption
of a new project
(starting 2014)
Planning stage
evaluation
conduct at time of adoption
of a new project
(since 1998)
New project adoption
stage evaluation
conduct re-evaluation every 5
years if construction has started
and is continuing, and every 3
years if construction has not yet
begun.
(since 1998)
Re-evaluation
conduct ex-post evaluation
within 5 years of completion
(since 2003)
Ex-post evaluation after
completion
（New project adoption）（Start work）（Completion）
Q. When is project evaluation for flood management projects conducted?
[Japan]

5
Regulations and Manuals for Project Evaluation
Government Policy Evaluation Act (Act No. 86 of 2001)
Technical Guidance for Cost Benefit Analysis of Public Works (applied to all sectors)
Execution Procedure for Project Evaluation of MLIT Works for Planning Stage
Execution Procedure for Project Evaluation of MLIT Works for Adoption of New Project
Execution Procedure for Project Evaluation of MLIT Works for Re-evaluation
Execution Procedure for Project Evaluation of MLIT Works for Completed Project
Manual for Economic Evaluation of Flood Control Investments (2005.4)
(Property Assessment Unit Values and Deflators” (2013.2 ) - includes the
most recent property unit values, etc)
Manual for Flood Damage Indices Analysis” (2013.6)
Q. What regulations, standards, guidance or manuals are available for project evaluation of
flood management projects?
[Japan]
Execution Procedure for Project Evaluation of Public Works
Economic/quantitative evaluation of flood management project

6
Unit and Scale of Project
Q. What projects are subject to project evaluation and what are their unit and scale? Are
there any regulations specifying them? What is typically applied?
[Scope of projects subjected to project evaluation]
All public works under the jurisdiction of MLIT are targeted except for
those related to maintenance or disaster recovery/rehabilitation.
(1) Projects implemented by MLIT (national projects)
(2) Projects by Incorporated Administrative Agencies
(3) Projects under the jurisdiction of MLIT but are implemented by
local government
[Projects subjected to project evaluation]
Following projects are subjected to evaluation
1. Projects for which budget is to be allocated
2. Projects for which budget is to be allocated for preparation and
planning (large scale projects such as dams only)
[Project unit for evaluation]
The project unit for evaluation of flood management projects is
defined as the segment of the river that experiences series of impacts
of the project. (e.g. evaluation is typically conducted for a set of
projects within a “river basin”, or “individual project” such as dam,
retarding basin or a segment of levee)
Dam
Individual projects such as
dam, retarding basin or a
segment of levees
River Basin
Project unit for evaluation
Retarding basin
Levee
[Japan]

7
Q. What information is evaluated in the project evaluation?
Evaluation Criteria for Project Evaluation
[Evaluation Criteria] （River/Dam project）
(1) Necessity of the project
1. Changes in socio-economic situation
1)Impact of potential disasters
2)Historical disasters
3)Risk of disaster occurrence
4)Conditions of regional development
5)Regional cooperation schemes
2. Investment effectiveness
1) Cost-Benefit Analysis
2) Flood Damage Indices
3. Condition of project progress
1)Project adoption year, 2)Land acquisition and construction start year, 3)Condition of project progress
(2)Expected progress of the project
1) Future project schedule, etc
(3)Possibility of cost reduction and alternative options
1) Consideration of possibility of alternative options
2) Plans for cost reduction
6) Urgency of the project
7) Importance within the water system
(river project only)
8) Disaster information dissemination system
9) Consistency with relevant project
10) Possibility of alternative options
Re-
evaluation
New project
evaluation
←economic evaluation by Benefit Cost ratio (B/C)
←quantitative evaluation of flood impact difficult to
translate into monetary values.
・ The information considered for project evaluation includes not only cost-benefit analysis but also
necessity of the project, project schedule and expected progress, and possibility of cost reduction or
alternative options.
[Japan]

8
Benefit Cost Ratio (B/C) > standard value (often 1.0)
Cost Benefit Analysis in Japan
Source: Technical Guidance for Cost Benefit Analysis of Public Works, 2009 MLIT
Q. What are the quantitative evaluation criteria of project evaluation? Are there any decision
criteria or standards?
Quantitative Evaluation Criteria of Project Evaluation
Investment
efficiency of
residual project
Investment efficiency of
the overall project
Treatment of evaluation
result from the perspective of
economic efficiency
Over the standard
value
Over the standard value Continue
Under the standard
value
Continue in principle but
revise the project as
necessary
Under standard
value
Over standard value
Re-examine after revision of
the project
Under standard value Discontinue in principle
[Japan]

910. Increase in land prices as a result of improvement in flood protection
Direct damage
Indirect damage
Intensification benefit
3. Business interruption
・ Business interruption damage (household , businesses, public and public interest services )
・ Emergency response costs (household, businesses, public and public interest service)
4. Impairment of social welfare facilities (hospitals, social welfare facilities, disaster management facilities)
5. Economic impact (disruption of traffic , lifeline, cascading economic impact of damages)
6. Other damage (underground space, cultural facilities, waste generated by flood)
7. Psychological damage
8. Risk premium (insecurities due to possibility of damage)
9. Damages that cause permanent changes to the local economic system (Because the region as a whole is
severely damaged by a large-scale flood the economic system cannot recover to its pre-disaster state.)
Q. What categories of damages are considered for cost-benefit analysis?
What is included in the benefit? Are there any impacts that cannot be monetized but are quantitatively
assessed? What damages are usually considered for real cases?
Categories of Damages considered for Cost-Benefit Analysis
( : Damages not considered in Cost-Benefit Analysis (difficult to monetize) but
are quantitatively assessed
( : Considered in Cost-Benefit Analysis)[Japan]
1. Damage to asset
・General property damage (houses, residential properties depreciable assets and inventory assets of
businesses, depreciable assets of fishing and farming properties, etc.)
・ Agricultural product damage
・ Infrastructure damage
2. Human damage (human loss, people isolated etc.)
( : Damages not considered in Cost-Benefit Analysis (difficult to monetize) but
are quantitatively assessed
( : Considered in Cost-Benefit Analysis)

10
Categories0 Methods of evaluation
Manual Manual for Economic Evaluation of Flood Control Investment (April 2005,
MLIT)
General
conditions
Evaluation period The project implementation period plus 50 years after completion of the
project.
Lifetimes of assets levee 50 years, dam 80 years
Evaluated
damages
Direct damage property damage, agricultural damage, infrastructure damage
Indirect damage business interruption loss, emergency response cost at household levels
Calculating method of total benefit Damage reduction, difference between the damages calculated for with and
without project cases, is multiplied by the annual exceedance probability,
and are summed up to calculate the expected average annual damage,
which becomes the annual benefit. Annual benefit is accumulated over the
evaluation period and the residual value of the asset constructed by the
project is added to determine the total benefit.
Calculating method of total cost Project construction cost (including construction cost, land acquisition cost
and compensation cost) and maintenance/operation cost
Social discount rate 4%（based on the real rate of interest of national bond）
Quantitative evaluation criteria Benefit Cost Ratio (B/C)
Methodology of Cost-Benefit Analysis in Japan
Methodology of Cost-Benefit Analysis
Q. What is the methodology of Cost-Benefit Analysis employed?
What are the criteria, conditions of damage rate, unit value of property, residual value, etc used for
cost benefit analysis, and how are they defined?
[Japan]

11
Items Methods of evaluation
Manual “Manual for Flood Damage Indices Analysis” (2013.6, MLIT)
General
conditions
Flood magnitudes In principle damage reduction is not converted into expected annual damage
reduction, but instead the magnitude of damage reduction is assessed under a
specific size of flood, such as a design flood (single or multiple floods).
Evaluated
damages
Direct damage Human damage (inundated population, expected loss of life, maximum
number of persons isolated, etc.)
Indirect damage Damage caused by impaired social functions (medical/welfare facilities,
disaster management facilities)
Cascading impact (traffic disruption, lifeline, economic damage)
Others (underground space, cultural facilities, debris waste generated by
flood)
Computation of overall non-
monetized impact
For each of the damage categories damages are evaluated quantitatively
whenever possible, e.g., affected population, etc
Quantitative Evaluation of Damages difficult to be included in the Cost-Benefit Analysis
Quantitative Evaluation of Damages Difficult to be
Included in the Cost-Benefit Analysis
Q. What is the methodology used to evaluate damages that are difficult to be monetized to
be included in the Cost-Benefit Analysis?
What categories of damages are quantitatively evaluated but are not monetized to be included in
the benefit? (What types of damages? Are there standards or manuals?)
[Japan]

Methodology for evaluating
economic effectiveness of flood
management project in Japan
(Example of A River)
12
1. Outline of Project Evaluation
2. Cost-Benefit Analysis
3. Flood Damage Indices Analysis

13
医療施設の機能低下による影響に関する試算結果Overview of the River Basin
River Basin Area：667km2
Basin Area Population：
273,000 people
Overview of A-River
Section of
Project
A-River
Sea
Length of River
（35.4km）

14
Outline of A-River Improvement Plan Project Evaluation
医療施設の機能低下による影響に関する試算結果1. Outline of Project Evaluation
Outline Remarks
Implementing body
of the project
River Office of the Regional Development Bureau, Ministry
of Land, Infrastructure, Transport and Tourism (MLIT)
Purpose of the
project evaluation
[Re-evaluation] (for justification of continuation or
suspension of the project for which construction has not
begun after adoption of the project (3 years for nationally
implemented projects))
Evaluation procedure Re-evaluation is conducted by the Regional Development
Bureau. The opinions of the relevant prefectures and the
Project Evaluation Monitoring Committee consisted of third
party specialists are accounted for in decision making.
Project to be
evaluated
River channel improvement measures (river channel
excavation, construction of embankment, confluence
improvement, etc)
Evaluation period 80 years (Improvement period (30 years) and evaluation
period after completion (50 years))
In principle 50 years after
the project implementation
and completion of flood
control facilities.
Scale of the project Project cost : approx. 5,343 million yen
Indices used for
evaluation
Cost-Benefit Ratio (B/C), Flood Damage Indices, etc See p6

-Inundation simulation is conducted for multiple flood sizes
-Inundation areas under pre- and post-project status are assessed
1. Inundation Simulation
River Improvement Plan
-Compute expected damage for each flood size based on simulation results
[Amount of damage reduction for a given flood size]
＝[Expected damage under without-project state]
－[Expected damage under with-project state]
[Reduction in expected annual damage]
＝Σ([Amount of damage reduction for a given flood size]
x [probability of occurrence])
2. Computing reduction in annual
average flood damages
-Total benefit＝Sum of [reduction in expected annual damage] of each year
Evaluation period: improvement period + 50 years
Base year for discounting: the year the evaluation is conducted
Discount rate: 4%
Add residual value of the constructed asset at the end of the evaluation period
3. Computing total benefit
5. Computing B/C
[cost]＝[annual project cost]
+ [maintenance and management cost]
[total cost]＝ sum of
[annual project cost] of each year
Evaluation period：
improvement period + 50 years
Base year for discounting:
evaluation year
Discount rate:4%
4. Computing total cost
２－２．２．便益の算出
2. Flowchart of Cost-Benefit analysis
15
2. Cost-Benefit analysis
Source: “Manual for
Economic Evaluation
of Flood Control
Investments”
(MLIT, 2005.6)

16
Inundation Simulation Conditions
医療施設の機能低下による影響に関する試算結果2.1 Inundation Simulation (Example of A-River)
specification
Model
Computation method Two-dimensional floodplain & one-dimensional river channel flow model
Grid size 50m grid
Inundation blocks 6 blocks defined (independent inundation blocks that are separated by embankments
of tributaries, etc)
Ground elevation Average ground elevation is assigned to each grid size based on aerial survey data
Continuous structures
in floodplain
Location of continuous structures in floodplain are set by field survey
Roughness coefficient Defined based on land use
Buildings Average building occupancy ratio is defined as the average ratio of randomly sampled
areas
Conditions
Flood magnitude Design flood (simulations conducted for six magnitudes of floods between 5yr flood
(above no-damage flow) to 100yr flood (design level))
Locations of levee
failure
6 locations (1 location for each inundation block)
* Location that results in largest damage is selected
Condition of levee
failure
Completed levee: High Water Level (HWL) (design water level)
Temporary levee: Hypothetical levee height is set to satisfy the cross-sectional stability
with the current levee width. Failure water level is assumed to be the hypothetical
levee height minus freeboard.
References: “Manual for Economic Evaluation of Flood Control Investments” (MLIT, 2005.6)
“Inundation Simulation Manual” (1996.2)

17
医療施設の機能低下による影響に関する試算結果2.1 Inundation Simulation (Example of A-River)
Division of inundation blocks
Divide into areas considered as independent inundation areas due to embankments of
tributaries Divide into 6 inundation blocks
Locations of levee breach
Defined for each block at the location where breached would result in maximum damage
6 locations defined
(Total damage is the sum of damages of all blocks)
Inundation blocks and
location of levee breach

L1 Block
R1 Block
L2 Block
R2 Block
Flood area
extend
according
to increase
probability
scale
・Simulation conducted for floods with
different return-periods to determine
inundation extent in each block
ダム
ダム
ダム
Simulated inundation
area for before project
Simulated inundation area
for after project＊
probability
scale
１／５
１／５０
１／８０
１／１００
１／１０
１／３０
●
●
●
●
●
●
●
●
●
●
Expected annual average
damage before project
Expected annual average
damage after project
■ Inundation simulation
■ Computation of expected annual
damage for each return-period
Without With
・Estimate the inundation areas expected
without project and with project
2.2 Computing Reduction in Annual Average Flood Damage
Computing expected annual damage for floods with different return-periods
Expected annual damage is calculated for with and without project, based on simulation results
18
・Expected annual damage for each
return-period is computed based on
the property value in each grid cell
(quantity of property x unit value of
property), inundation depth and
damage rate defined by inundation
depth.
References: “Manual for Economic Evaluation of Flood
Control Investments” (MLIT, 2005.6)

Computing reduction in expected flood damage
9 ×0.3 billion=2.7 billion
0 ×2.0 billion=0 billion
整備整備
Without With
7.4 billion
Reduction in expected damage
15.7－7.4=8.3 billion15.7 billion
Riverimprovement
浸水深
0～0.5m 未満
～1.0m 未満
～3.0m 未満
～5.0m 未満
浸水深
0～0.5m 未満
～1.0m 未満
～3.0m 未満
～5.0m 未満
・Grid data (elevation, properties, gradient) and simulation results are used to determine expected damage for each grid
・Expected damage reduction (benefit) is computed as a difference between damages of with and without project
19
Image Image
Expected Damage 15.7 billion Expected Damage 7.4 billion() ()
Inundation depth
Project
Site
Project
Site

Computing reduction in annual average flood damage
Without
project ①
With project
②
Damage
reduction
③＝①－②
Ｄ０＋Ｄ１
2
Ｄ１＋Ｄ２
2
Ｄｍ－１＋Ｄｍ
2
Discharge
Level
Exceedance
probability
Damage Reduction
Ｑ０Ｎ０
Average damage
per interval④
Average
probability per
interval⑤
Annual
average
damage
④×⑤
Sum of annual average damage
= Expected reduction in annual
average damage
Ｑ１Ｎ１
ｄ１
Ｄ１
Ｎ１－Ｎ２ｄ２ｄ１＋ｄ２
Ｎ０－Ｎ１ｄ１
Ｄ０（＝０）
Ｎｍ－Ｎｍ＋１ｄｍ
Ｄｍ
Ｑ２
ＱｍＮｍ
Ｎ２Ｄ２
ｄ１＋ｄ２＋・・・＋ｄｍ
Design discharge of River Improvement Plan (design level)
e.g., 100yr flood discharge
Sock impact of flood management projects
Reduction in annual average flood
damage
・Damage reduction is the difference between damages caused under with and without project.
・Damage reduction for a given return period flood is
multiplied by the occurrence probability and is added up to
the design return period to obtain “reduction in annual
average flood damage”
Damage reduction for a given return period flood ＝expected damage without project – expected damage with project
Annual average damage reduction ＝
Σ(damage reduction for a given return period)
x (occurrence probability)
20
2.Cost-Benefit Analysis
Flood return period
Amountof
damage
1/50 1/100
Before project
1/30
After project
Discharge capacity at time of evaluation (no
damage flow) e.g., 10yr flood discharge

Computing expected flood damage
21
Directdamage
generalassetdamage
Categories Indices Unit price of asset
Damage rate
(depend on depth)
Remarks
Residential Houses
Total floor
area
135.8～226.3
(thousand yen/m2)
0.032～0.888
Damage rate depends on land gradient and
sedimentation
Residential properties (content)
Number of
households
14,683
(thousand yen/house)
0.21～0.991
Damage rate changes by occurrence of
sedimentation
Offices
depreciable assets
Number of
employees
1,115～49,950
(thousand yen/person)
0.099～0.995
Asset values for industrial categories.
Damage rate changes with sedimentation
inventory assets
57～63,414
(thousand yen/person)
0.056～0.982
Asset values for industrial categories.
Damage rate changes with sedimentation
Damage to
fishing and
farming
properties
depreciable assets
Number of
properties
1,900 (thousand
yen/house)
0.0～0.725
sedimentation
inventory assets 536 (thousand yen/house) 0.0～0.845
sedimentation
Agricultural product damage
(rice paddy/field)
Amount of
yield
11～2,145 (thousand
yen/ton)
0.11～1.00
Set for each crop. Damage rate depends on
depth and days of inundation
Infrastructure 1.694 multiplied by general asset (total value)
Indirectdamage
Categories Indices
Damage per unit
(depends on inundation depth ranks)
Remarks
Business interruption
Number of
employees
20,734～102,880 (yen/person)
Emergency
response cost
at households
Clean-up works
Number of
houses
10,749 (yen/day)
Cost increase due to
alternative activities
Number of
houses
82.5～343.3
(thousand yen/household)
Emergency response costs of
businesses
Number of
offices
470～6,619 (thousand yen/office)
[expected damage] = [direct damage]＋[indirect damage]
[direct damage] = Σ([asset values in grid cell] x [damage rate])
[indirect damage] = Σ([number of asset units in grid cell]×[damage per unit])
References:
“Manual for Economic Evaluation of Flood Control
Investments” (MLIT, 2005.6)
“Property Assessment Unit Values and Deflators”
(2013.2 )

22
・Unit value of properties are revised every year based on the fluctuation in prices
Property value of businesses Values of agricultural products
（1000 yen/ton）
Unit price Unit price
Rice 200 Podded peas 1051
Wheat 53 Green beans 754
Soybeans 103 White raddich 65
Azuki beans 350 Carrots 108
Peanuts 460 Burdocks 194
Sweat potatoes 188 Taros 248
White potatoes 109 Apples 223
Cucumbers 237 Oranges 190
Eggplants 295 Chinese citrons 136
Tomatoes 278 Pears 282
Pumpkins 158 Persimmons 215
Watermelons 156 Grapes 774
Strawberries 815 Peaches 349
Green peppers 335 Tea leaves 654
Melons 619 Sugar beet 11
Chinese cabbages 53 Konjac 227
Cabbages 56 Tobacco leaves 2,145
Lettuces 131 Rushes 908
Spinach 372 Chrysanthemum 53
Long green onions 246 roses 63
Onions 97 Carnations 38
Cocoons
Fruites
Industrial
crops
Petals
Leaf and
stem
vegetables
Name Name
Fruites
and
Vegitables
Potatoes
Beans
Vegetable
legumes
Root
vegetables
Reference: “Property Assessment Unit Values and Deflators” (2013.2 )
（thousand yen/person）
Depreciable assets Inventory assets
Amount of added
value
(Suspension of
business)
Ｄ Mining 12,839 3,784 103
Ｅ Construction 1,472 3,649 20
Ｆ Manufacturing 5,107 4,527 28
Ｇ Electric/Gas/Heat supply/Water supply 109,953 5,455 54
Ｈ Information and communication 5,641 1,426 37
Ｉ Transport 5,178 1,254 22
Ｊ Wholesale/Retail 1,815 2,162 27
Ｋ Finance/Insurance 4,622 290 21
Ｌ Real estate 24,251 9,296 49
Ｍ Food/Hotel 1,943 154 22
Ｎ Medical/Welfare 1,712 57 14
Ｏ Education/Learning support 864 271 23
Ｐ Multiservice 4,622 290 22
Ｑ Service 4,622 290 22
Ｒ Public service 4,622 290 22
(Note）For industrial classification, refer to Japan Standard Industrial Classification（revised in March 2002）
Industrial classification

Damage rates are mainly derived from the interviews and surveys conducted in disaster areas
23
Damage rates for residential houses
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5
Damagerate[-]
Inundation depth [m]
A-Group
B-Group
C-Group
Floor height
Reference: “Manual for Economic Evaluation of Flood Control Investments” (MLIT, 2005.6)
*Damage rate computed from ”Flood damage survey” 1993-1996
(Damage situations in flood affected areas were surveyed by
conducting questionnaires and interviews)
(Damage rates in case of sedimentation are the conventionally
used rates and are not based on the above surveys)
* The values reflect complete or partial destruction of the house
Inundation
depth
Gradient
Below
floor level
Above floor level
Sedimentation
(Above floor level)
less than
50cm
50 – 99
cm
100 - 199
cm
200- 299
cm
over
300cm
less than
50cm
less than
50cm
A-Group
（I<1/1000）
0.032 0.092 0.119 0.266 0.580 0.834
0.43 0.785
B-Group
（1/1000≦I＜1/500）
0.044 0.126 0.176 0.343 0.647 0.870
C-Group
（I<1/500）
0.050 0.144 0.205 0.382 0.681 0.888

Example of A-River
24
Directdamage
generalassetdamage Categories Subjects
Amount of asset
evaluation
(million yen）
Amount of damage
(million yen）
Remarks
Residential houses Buildings 228,587 3,915 No sedimentation
Residential properties (content) Household goods/cars 7,294 2,705 No sedimentation
Offices
depreciable assets Fixed asset 30,493 2,238 No sedimentation
inventory assets Inventory asset 18,189 1,223 No sedimentation
Damage to fishing
and farming
properties
depreciable assets Fixed asset 240 8 No sedimentation
inventory assets Inventory asset 63 3 No sedimentation
Agricultural product damage
(rice paddy/field)
agricultural product 786 50
Infrastructure Road/ bridge etc. 592,250 17,094
Indirectdamage
Asset items Subjects
Amount of damage
(million yen）
Remarks
Business interruption Suspension of production 539
Emergency
response cost at
households
Clean-up works value Ex-post activity of clean-up etc. 110
Cost increase due to
alternative activities
Substitute purchase of drinking water etc. 170
Emergency response costs of businesses Ex-post activity of clean-up etc. 192
Computation of total damage (without project, 1/100 flood)
Without project , 1/100 flood
Expected Damage = 28,247 million yen

Example of A-River
Simulated inundation
area for before project
Simulated inundation area
for after project
＊
probability
scale
１／５
１／５０
１／８０
１／１００
１／１０
１／３０
■Inundation simulation
■ Computation of expected annual
damage for each return-period
Without With
Expected annual damage for each
return-period flood is computed based
on the property value in each grid cell
(quantity of property x unit value of
property), inundation depth and
damage rate defined by inundation
depth.
●
●
●
●
●
●
●
Damage: 28,247 million yen
Damage: 20,184 million yen
Damage: 790million yen
No inundation: 1/5 -1/30
Damage: 115 million yen
Damage 264 million yen
●
●
●
1/5 flood
1/50 flood
1/100 flood 1/100 flood
1/50 flood
Damage reduction
20,069 million yen
Damage reduction
27,983 million yen
Damage reduction
790 million yen
25
■Expected reduction in annual
average flood damage
・Compute expected damage reduction
for each return-period flood by taking
the difference in damages of without
project and with project
・Simulation conducted for floods with
different return-periods to determine
inundation extent in each block
・Estimate the inundation areas expected
without project and with project

Construction of river levees
Before
improvement
After
improvement
Damage:10 billion yen Damage: 0 yen
For those projects that generate benefit during the construction phase (such as levees),
annually expected benefit (damage reduction) is determined for the project
implementation phase as well as after completion.
2.3 Total Benefits
Computing expected annual damage reduction (river improvement)
・Project impact
Damage reduction
of 10 billion yen
・Generation of benefit
Implementation
period
Evaluation period after
completion of facilities
Completion of levee
Evaluation periodProject start
(time of evaluation)
Benefit is realized during
construction phase
Annual average damage
reduction discounted to
present value
Annual average
damage reduction
年
・・・・
During project
implementation
26

2.3 Total Benefit
Computing expected annual damage reduction (dams)
Evaluation period
after completion
Benefit of the project will be only realized after completion of structures. Generates
benefit not only through damage reduction but also by maintaining the normal functions
of river (augmenting river flows to satisfy normal uses, etc)
・Project impact
Before project
50 billion yen
After project
0 yen
Damage reduction
of 50 billion yen
Completion of dam
evaluation period
Project start
(time of evaluation)
Annual average damage
reduction discounted to
present value
Annual average
damage reduction
Benefit is generated only
after completion
年
27
Construction of dams
・Generation of benefit
Implementation
period

(1) River improvements
●Levees and low flow channels, etc.
If the facilities are adequately maintained,
their flood control functions will not deteriorate.
Accordingly the asset values of the facilities will not
decrease until the end of an evaluation period.
●Structures including revetments, etc.
It is assumed that the residual values of the
structure at the end of the evaluation period
shall be 10% of total costs.
(2) Dam
Dams should depreciate with time
by a straight line method based
on the legal durable period.
(3) Land
49
1
0
1
1
50
)1( 






S
S
t
t
S
r
c
C
49
1
0
2
2
50
)1(
1.0








S
S
t
t
S
r
c
C
49
1
0
49
1
0
50
)1(
1.0
)1(
)
80
50
1(9.0 











S
S
t
t
S
S
t
t
S
r
d
r
d
D
49
1
0
50
)1( 






S
S
t
t
S
r
k
KC,D,K ： residual values discounted to the
present as of the point in time when
evaluation of river channels, dams, costs of land is conducted
ct ,dt ： miscellaneous costs incurred every year for construction except for costs
of land, compensation costs, indirect costs, construction costs
kt ： the costs of land that incurs every year
r ： discount rate(i.e., 4%)
S ： project period(year)
2.3 Total Benefit Computation of total benefit
Total benefits is calculated by summing the annual benefits during the evaluation period and by
adding the residual value of the constructed asset at the end of the evaluation period.
28
Residual valueSum of annual benefits


 

49
0
0
)1(
S
t
t
t
r
b
B
Total sum of annual benefits during
the evaluation period discounted to
the present value at the time of
evaluation
B ： total sum of annual benefit
bt ： annual benefit
r ： discount rate (i.e., 4%)
S ： project period (year)
Total benefit(B) = Sum of annual benefits (B0) + Residual value(C+D+K)
References: “Manual for Economic
Evaluation of Flood Control Investments”
(MLIT, 2005.6)

29
医療施設の機能低下による影響に関する試算結果2.3. Total Benefit Example of A-River
0
200
400
600
800
1000
1200
1400
0 10 20 30 40 50 60 70 80
金額（百万円）
経過年数（年）
年平均被害軽減期待額
Evaluation period after completion (50yrs)Project period
(30 years)
Project completion
Evaluation period: 80years
Annual average damage reduction
discounted to present value
Annual average damage reduction
Computation of annual average damage reduction (annual benefit)
Annual damage
reduction increases as
the project progresses
Annual average benefit is computed from damage reduction and occurrence probability
Total benefit(B)
15,914 million yen


 

49
0
0
)1(
S
t
t
t
r
b
B
B ： total sum of benefits during the
evaluation period
bt ： benefits generated in t year
①Current
(2013)
②After
completion
③Damage
reduction (①－
②)
229
53
152
546 698
27,983
25,071
1,10822,570 0.008
W=1/100 0.010
181
26,527 0.003
20,069
17,593 0.013
28,247 264
Annual
average
damage
reduction
Sum of annual
average damag
reduction
W=1/ 80 0.013 25,302 231
927
80 1,188
W=1/ 5 0.200 790 0
Return
period
Exceedance
probability
Damage Reduction
Average
reduction
Probability
53
790
990 0.100 99
1,190
8,153
0
395
0.067
15,116
0.020
W=1/ 30 0.033 15,116
0.133
W=1/ 3 0.333 0 0
0
20,184 115
W=1/ 10 0.100 1,190 0
W=1/ 50
Annual benefit is discounted to present value (discount rate r=0.04)

30
医療施設の機能低下による影響に関する試算結果2.3 Total Benefit Example of A-River
Categories
Benefit
(million yen)
Total sum of annual benefit (B0) 15,914
Residual value
River
channels(C)
Non-structures 129
Structures 9
Dam (D) -
Land (K) 11
Total benefit (B) 16,063
Computation of total benefit
Total benefit(B) = Total sum of annual benefit (B0) + Residual value (C+D+K)

2.4 Total Cost computation of total cost
Flood control investment cost consists of the total construction costs and the maintenance
costs incurred during the evaluation period
Total cost (C) = Construction cost (C1) + Maintenance costs (C2)
[C1] Total cost include all construction costs up to completion of facility. (e.g. cost related
to construction, land acquisition and compensation, etc.)
[C2] Maintenance cost is computed as the total sum of the maintenance costs incurred
during the evaluation period. (50 years after completion of facility)
(Ex. Case of river improvement (construction of levee)) (Ex. Dam construction)
Improvement
period
Evaluation period after completion of facility
Completion of levee
Evaluation periodTime of
evaluation
year
Improvement
period
Evaluation period after completion of facility
Completion of dam
Evaluation periodTime of evaluation
Construction costs Construction costsMaintenance costs Maintenance costs
Project cost discounted
to the present value
Project cost discounted
to the present value
31

32
医療施設の機能低下による影響に関する試算結果2.4 Total Cost Computation of total cost
0
50
100
150
200
250
300
350
400
450
500
0 10 20 30 40 50 60 70 80
金額（百万円）
経過年数（年）
費用
Evaluation period after completion of
facility (50 years)
Maintenance costs(C2)
Improvement period
(30 years)
Construction costs(C1)
Project completion
Evaluation period: 80 years
Total costs(C) = Construction costs + Maintenance costs(C2)
Cost (million yen)
Construction cost (C1) 5,343
Maintenance cost (C2) 440
Total cost (C) 5,783
Annual project cost
discounted to present
value
Annual project cost


 

49
0 )1(
S
t
t
t
r
c
C
C ： total sum of the costs during
evaluation period
Ｃt ： cost generated in t year
years
Cost

2.5 Computation of Cost-Benefit Ratio (B/C) Example of A-River
33
Total (million yen)
Total benefit (B) 16,063
Total cost (C) 5,783
Cost-Benefit ratio (B/C) 2.78
Computation of Cost-Benefit Ratio
Cost-Benefit ratio(B/C) = total benefit (B) / total cost (C)
Compute Cost-Benefit ratio (B/C)

34
医療施設の機能低下による影響に関する試算結果3. Analysis of Flood Damage Indices
items Consideration contents Items Consideration contents
1:
Human
damage
1-1 population in inundation area
5:
Lifeline
5-1 population affected by disruption of electric power supply
1-2 number of vulnerable people in inundation area
requiring assistance under disaster conditions
5-2 population affected by disruption of gas supply
1-3 expected loss of life 5-3 population affected by disruption of water supply
1-4 maximum number of people isolated 5-4 population affected by disruption of sewerage system
1-5 number of people isolated for more than 3 days 5-5 population affected by communication service (fixed)
1-6 total number of people subject to evacuation per 10
years
5-6 population affected by communication service (cellular phone)
2:
Medical/social
welfare facility
2-4 number of impaired social welfare facilities 6:
Economic
impact
within and
outside
the region
6-1 economic losses using economic models such as input-output
inter-industrial relations, etc
2-5 number of users of impaired social welfare facilities 6-2 impact on supply chain caused by damage to high market share
companies
3:
Base facility
for disaster
management
3-1 number of impaired major disaster management
facilities (police station, firehouse, public office etc.) 6-3 number of listed companies suffered by flood
3-2 population of jurisdictional area with impaired major
disaster management facilities
6-4 number of employees suffered by flood
7:
Under-
ground
space
7-1 routes and stations, etc. of subway suffered by flood
4: Losses
caused by
disruption of
traffic
4-1 disruption of major road
7-2 number of users affected by flooding of subway services
4-2 amount of traffic affected by disruption of road
7-3 flooded underground shopping complex/facility
4-3 increase in travel time due to disruption of road
7-4 number of users affected by inundation of underground
shopping complex/facility4-4 disruption of main railway
8:
Cultural
facility
8-1 flooded cultural facilities, etc.
4-5 number of users affected by disruption of railway
9:
Waste
9-1 amount of flood disaster waste generated
9-2 management cost of flood disaster waste
3. Analysis of Damage Indices
Reference: “Manual for Flood Damage Indices Analysis” (2013.6, MLIT)
Categories of damages considered for non-monetary evaluation (quantitative impacts are analyzed)

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