Contents■ Message from the Director-General■ Debris Flow Disaster in Houkawachi-Atsumari District of Minamata City in Kumamoto Prefecture on 20th July, 2003
■ Examination of Design and Management Techniques for Disaster Mitigation of Structures across river■ Coastal Hazards 2003: International Workshop on Natural Hazards in Coastal Areas■ The 12th Conference on Public Works Research and Development in Asia
■ RESEARCH REPORT of National Institute for Land and Infrastructure Management (June, 2003)■ TECHNICAL NOTE of National Institute for Land and Infrastructure Management (June, 2003)■ The English Version of "2003 Annual Report of NILIM" is now on our websiteNo.7NI LDecember 2003

I M

N e w sISSN 0389-4150

L e t t e r■ Message from the Director-General
Japan has sufferedefforts to prevent and overcome these disasters. Thanks tofrom a lot of natural

these efforts, the degree of security against natural

disasters in 2003 as

disasters has greatly improved.

before. Large Earthquakes

disaster once occurs, the damage may become remarkablyof a magnitude of 7 to 8

big by the increase in population and properties, and more

occurred in May and July

their concentration in urban areas.

Nevertheless, when ain Miyagi Prefecture and

It is, therefore, essential that we devote ourselves to ourin September in Hokkaido

duties and continue our efforts to reduce the damage

area. Owing to thesecaused by natural disasters. These include further

earthquakes, two persons

technological research relating to disaster prediction,

were missing, a number

information gathering, communication and exactof people were injured

evacuation and guidance in addition to technologies

and serious damage wasimproving earthquake resistance and enhancing security

causedagainst flooding and debris flows.

tohouses,

It is the mission forbuildings, embankments, roads, port facilities and other

those involved in research in the fields of housing andstructures.

infrastructure to deepen the research securing the safety

Meanwhile, the long early summer rainy season andwhich is the basis of human activities.

several typhoons which directly hit Japan caused

Research on properly coping with various disasters is one

downpours and strong winds, resulting in the loss ofof the most important themes of the NILIM and researchers

precious lives and properties.

of many different disciplines are concentrating their energy

As Japan is situated near the boundaries of severalon it.

In order to make such research even more effective,

tectonic plates, it has long suffered from earthquakes. It is

it is necessary to collaborate with researchers in manysaid that the earthquake potential is now large enough todifferent countries.

cause some plate type earthquakes and/or an earthquake

outputs available by means of its Newsletter, Website anddirectly underneath in the Kanto and Tokai districts as well

Annual Report, etc. We will be honoured if you, researchers

as the southeast sea area in which there is a concentration

around the world who are interested in our researchof population and properties. If such an earthquake occurs,

activities, access such information sources and cooperate

there is a possibility of suffering serious damage.

with us to establish an international research network.

The NILIM is making its research

Not only Japan but also many other countries haverepeatedly suffered severe damage caused by earthquakes,
flooding and/or drought. Our predecessors made strenuous

OKUNO Haruhiko, Director-General, NILIMNILIM

News Letter

N I L I M

■ Debris Flow Disaster in Houkawachi-Atsumari District of Minamata City in Kumamoto
Prefecture on 20th July, 2003

The debris flow which ran down through the HoukawachiAtsumari District of Minamata City in Kumamoto Prefecture
on 20th July, 2003 killed 15 people and destroyed 15 houses
completely. Photo1 shows the complete view of thedisastersite in Houkawachi-Atsumari District.
The Erosion and Sediment Control Division conducted afield survey with the Sediment Control Research Group of
the Public Works Research Institute immediately after theoccurrence of the disaster. The survey results suggest that(i) there were two flows: one mainly consisting of mud andanother mainly consisting of boulders and gravel, (ii) theflow mainly consisting of mud preceded the flow mainly
consisting of boulders and gravel, (iii) the flow mainly
consisting of mud covered a distance of some 600 m fromthe landslide site to the outlet of valley in one or two
minutes at a speed of 4.8 – 15.2 m/sec while the flow
mainly consisting of boulders and gravel covered the same
distance in two to four minutes at a speed of 2.9 – 9.1
m/sec and (iv) the volume of the sediment transported by
the debris flow to the Houkawachi-Atsumari District wasapproximately 97,000 – 107,000 m 3 , including voids.

Further investigation will be conducted in the coming years
by means of a channel experiment to analyse themechanism of debris flow causing damage to buildings andto clarify the behaviour of debris flow at a S-bend section ofa torrent to improve the accuracy of flow speed estimation.

Photo 1 Debris flow which occurred in the Houkawachi-Atsumari District of Minamata
City in Kumamoto Prefecture (Full View)■ Examination of Design and Management Techniques for Disaster Mitigation of Structures
across river

Weir for irrigation and groundsill to make the fluctuationof riverbed stabilize are built as structures across river. Thestructures are mainly composed of falling works, aprons
and bed protection works. The bed protection works areconstructed for protection of local scour and as energy
absorber in downstream of the falling works. If hydraulicgradient among bed materials were over criteria, seepage
control seat would be designed for piping under the fallingworks. Piping is runoff from downstream end of the apron
containing bed materials on bottom of falling works due tolarge seepage velocity and large hydraulic gradient ofpressure and position head. These physical quantities are
influenced by water surface. The hydraulic gradient among
bed materials is estimated by use of difference of waterlevels in upstream and downstream of the structures andlength of seepage path.
But the hydraulic gradient may increase by bed
deformation in downstream of the structures. If flood run
among concrete blocks of bed protection works, pressure
would come down from assumption by separate flow in

Hiroshi Kawaguchi, River Division, River Department
downstream end of the apron. If piping under the falling
works occurred and progressed, the structures would notfunction and be washed out with the piping.
Then, it was examined that causes of the piping andcountermeasures of gravels among the bed protection
works in downstream of the apron by large-scale (1/8)
hydraulic experiments on movable bed (Photo 2). Conditionof the experiments followed the Guidance for Structural
Design of the Groundsill (1998). Hydraulic jump occurredon the bed protection works under this condition.
From the experiments, it is concluded for disastermitigation of structures across river that (1)countermeasures of gravels among bed protection works indownstream of apron are useful to control piping progressunder falling works after occurrence of piping and (2)countermeasures of gravels needs some layers to makesmall vertical seepage velocity among gravels and diameterto prevent gravels themselves and bed materials from goingout of the concrete blocks.

Photo 2 Experiment of countermeasures of gravels among bed protection works in downstream of apron for piping under falling works■ Coastal Hazards 2003: International Workshop on Natural Hazards in Coastal Areas
The NILIM and the Port and Airport Research Institute(PARI) jointly held the Coastal Hazards 2003, theInternational Workshop on Natural Hazards in Coastal
Areas(WS), for three days from 20 th to 22 nd August,participating researchers from government research

institutions and universities in not only Japan but also theNetherlands, Australia, Korea, Bangladesh and the US.
Prevention and/or mitigation of the damage caused bysuch coastal hazards as tsunami and storm surge requires
a combination of hard measures that rely on the ,development and improvement of facilities such as dikes
and sea walls, and soft (non-structual)measures, including
provision of adequate precaution information, preparationof hazard map and development of effective evacuation
guidance system. As coastal conservation in Japan has
primarily focused on the construction of structures toimprove the level of protection, the improvement of soft
measures has been relatively slow. The severe storm surge
damage caused by a typhoon in September, 1999 in thewestern part of Japan, however, has led to the serious
reconsideration of the need for the application of soft
measures to combat coastal hazards. At present, theGovernment of Japan is earnestly conducting technicaldevelopment to prepare a storm surge and tsunami hazard
map and to create a database which provides the basis forsuch a hazard map. In order to promote research toestablish comprehensive measures which integrate hardand soft measures, the WS was held to learn about thelatest research achievements in the countries of theparticipants, to exchange opinions and information and tocompare the situation of the relevant research in Japan
with that in other countries.
At the WS, researchers reported on recent examples ofdisaster damage, the latest research findings, efforts tointegrate hard and soft measures and proposals during fivesessions entitled “Damage and Restoration”, “HazardMitigation”, “Countermeasure Systems”, “Facilities andStorm Surge” and “Hazard Map”.
The general proposals made during the plenary session of
the WS featured (i) the need for comprehensive measures
integrating hard and soft measures, i.e. the integration ofmeasures based on risk assessment, the development of
new technologies for protection facilities and the safety
evaluation as well as maintenance of facilities, (ii) theimportance of determining the preconditions for thepreparation of a hazard map and (iii) consideration ofpeople with disabilities.
In mid-September in the aftermath of the WS, Japan and
Korea were directly hit by Typhoon Maemi. Areas along thesouthern coast of Korea in particular sustained severe
damage due to the storm surge. Meanwhile, coastal areas of
Hokkaido and other regions in Japan suffered due to theTokachi-oki earthquake at the end of September.
Cooperation through the international network
strengthened as a result of the WS is expected to positively
contribute to mitigating natural hazards in coastal areas
not only in Japan but also in the rest of the world.

Photo 3 Opening ceremony of the WS

Photo 4 Keynote lecture by Dr. Jorissen of the Netherlands■ The 12th Conference on Public Works Research and Development in Asia
The 12th Conference on Public Works Research andDevelopment in Asia was held from the 20th of October(Monday) to the 31st of October (Friday), 2003 in Tsukuba,
Tokyo and Okinawa.
The conference participants are executive engineers
responsible for infrastructure management ofadministrative and research departments in some 10 Asian
countries with the aim of exchanging views and opinions onsuch common subjects in Asia, including Japan, as theenvironment, natural disasters and infrastructuredevelopment and furthermore establishing research

Photo 5 The 12th International Symposium in Okinawa

exchange networks among participating countries byconfirming the common understanding of the subjects.
The theme of the 12th conference was “Traffic and Road Measures for Urban Traffic Problem in Asian Big Cities”
and participants from Cambodia, China, Korea, Laos,Malaysia, Nepal, Pakistan, Sri Lanka and Japan (Mr.
Okuno, Director General of the NILIM) presented theirreports on case studies in their own countries, followed bydiscussions.
The “12th International Symposium on Land Development
and Civil Engineering in Asia” held in Ginowan City inOkinawa during the latter period of the conference andsupported by the Okinawa General Bureau of the Cabinet
Office and the Okinawa Prefectural Government attracted
some 100 participants, the majority of whom were involvedin public works in Okinawa Prefecture. The overseas
participants were introduced to the advanced technologies
employed in public works in Japan and also to some
application examples in Okinawa, including theconstruction of an urban monorail line (Yui Rail), and wereable to obtain a deeper understanding of Japan’s public
works closely linked to the locality.
The conference concluded with a common understanding
as follows.

(i) The participants recognized the role and need for further
improvement in “Traffic and Road” as well as theimportance to conduct research to facilitate them.
(ii) The participants recognized that each country should
learn from insights and experiences of countries inAsia, to enhance and support the infrastructuredevelopment.
(iii) The participants recognized the needs to cooperatewith each other and continue the conference in thefuture.
The recognizing again the need for this conference, theNILIM will proceed with the preparations for the 13thconference.

Photo 6 The Symposium Participants■ RESEARCH REPORT of National Institute for Land and Infrastructure Management(June, 2003)

Title of Paper
Names of Divisions
Short-Term Spatial and Temporal Variations in Abundance and Sizu-frequency Distribution of Marine Environment Division
8 Planktonic Larvae of Clam Ruditapes Philippinarum in Tokyo Bay
Methodology for the Valuation of Environmental Impacts and Feedback Analysis of the Effects of Coastal Zone Systems Division
9Environment Policy on Coastal Development
A Model for Estimation Scales of Container Terminal Areas at the Stage of Port and Harbor Port Planning Division10
Planning -A Standard for Designing Principal Size in Container Terminals:A Proposal-No.

■ TECHNICAL NOTE of National Institute for Land and Infrastructure Management(June, 2003)

Title of Paper
72 Strong Motion Acceleration Records(No.25)
73 Strong Motion Array Observation Records(No.4)

Names of Divisions
Earthquake Disaster Prevention DivisionNo.

Earthquake Disaster Prevention Division

Variation of Spatial Characteristics in Phytoplankton Bloom and Phosphorus Load from Rivers as Marine Environment Division
87
Mixing Type Change in the Arakawa River Estuary,Tokyo
Distributions of the Wave,Storm Surge and Tsunami Design Conditions On Japanese Nationwide Coastal Disaster Prevention Division88
Coastal Structures
Coastal Disaster Prevention Division
89 Motorization,Remote Sensing and Remote Operating of Water Gates in Harbor
Coastal Zone Systems Division
90 Verification of Wave Forecasting Model,SWAN,by Experimental Results with Wind Wave FlumePort Calling League of World Container Ships (2002)
Analysis of the Statistics Concerning with Port Calling and Influence on New York Port of Terrorism
93 Effects of Surface Roughness of Rubble Mound On Section Force of Bottom Slab of Caisson (Part 2)
Design Method for Bottom Slab of Caisson
94
Considering Surface Roughness of Rubble Mound
95 A Level-1 Reliability-Based Design Method for Caisson Type Breakwaters in view of Sliding Distance
92

96
97
98
99

Analysis of Nationwide Economic Impacts by Airport Development - Computable General
Equilibrium Model Approach A Study on Systematization of Norms and Evaluation Axis of Spatial Developments at Waterfront For Establishing the Principle and Methodology of Making SatohamaA Study on Landscape Potential of Air Terminal and Airport Access Road -For The Establishment ofThe Development Method of Gateway Spaces Considering Value of The RegionA Study on Systematizing the Indexes of Landscape Concerning Exterior Space at Waterfront

Port Planning Division
Port Facilities Division
Port Facilities Division
Port Facilities Division
Airport Planning Division
Airport Terminal Division
Airport Terminal Division
Airport Terminal Division■ The English Version of "2003 Annual Report of NILIM" is now on our website
We publish the English version of "2003 Annual Report of NILIM" to show our research activities and accomplishments, andyou can see all of its contents on our website, www.nilim.go.jp.

National Institute for Land and Infrastructure Management
Ministry of Land, Infrastructure and Transport
Asahi 1, Tsukuba, Ibaraki, 305-0804, Japan(Tachihara) Tachihara 1, Tsukuba Ibaraki, 305-0802, Japan(Yokosuka) Nagase 3-1-1, Yokosuka, Kanagawa, 239-0826, Japan
TEL:+81-29-864-2675 FAX:+81-29-864-4322

N I L I M

N e w sL e t t e rNo.7

December 2003

w w w. ni l i m . go. j p