٨Research Trends and Results

Systematic initiatives to linkdisaster case studies to theimprovement of rivertechnologiesHATTORI Atsushi, Head NOBUTSUNE Kouji, Researcher
FUKUHARA Naoki, Researcher
River Division, River Department

Research Trends and Results(Key words) Disaster case study, technological improvement, database1.Maintaining technologies Needless to say, river improvement and river course
management play a role in maintaining and improving
safety from flooding, but recent large-scale disasters
have been sharp reminders of the importance ofmaintaining the technologies which support theseactivities 1). A Levee Research Committee and RiverStructure Technology Council established by the River
Bureau last year have presented a framework for
performing field surveys of disaster cases toaccumulate technical knowledge and revise technicalstandards etc. Under this framework, the NILIM isconducting the following three research projects
related to the above technological maintenance. 

2. Analysis information concerning disaster cases
are the touchstone of river technologies
A disaster case survey diverges from theconventional perspective by, based on a variety ofactually measured values, connecting the processes
resulting in damage one at a time to mechanicallyverify the appropriateness of its findings. Based on
knowledge obtained from such meticulous analyses,reviews and improvements of design methods are
made continually. In order to put the above ideas into
practice, the NILIM conducts disaster case studies
jointly with regional development bureaus, and taking
the disaster study of the weir and its adjoining leveeson the Angagawa River System 2) as an example, theimpact of the previous year’s fluctuation of the rivercourse downstream from the weir on the water leveland on riverbed scouring near the disaster location wasanalyzed.
3. Discovering technological information ininspection and patrol records
 Records of inspections and patrols of levees andpast disasters and repairs are checked to abstract thetypes of deformation, members deformed, and degreeof their deformation which are linked to decline offunctions at the same time as all conditions forinspections and patrols done to accurately grasp suchdeformations (walking, driving or other travelingmethod, implementation frequency, state of vegetation,etc.) are clarified. To establish such an analysis
method, records of inspections and patrols, etc.
performed during the previous five years are used toanalyze data. Even initial organization by
superimposing locations where deformation isconfirmed and locations repaired on a plane map of
the river course provide clues drawing out informationof use for inspections by, for example, permitting
sections where deformation was concentrated andconfirmed to be distinguished. 
4. Need for mechanisms to continue disaster casestudies
For the NILIM and regional development bureaus
to continue to jointly survey disaster cases etc. in suchdetail, considerable labor is required and the numberof surveys performed each year is probably naturallylimited. Consequently, it is important to also provide amechanism to strengthen motivation to continue
studies. The NILIM is constructing a database as ameans for river managers to share cases in which they
have been involved with river managers throughout
Japan, and to obtain hints for solutions to challenges
they face. The River Bureau has established animplementation system to contact the NILIM after adisaster, to perform joint studies to obtain moredetailed results, and to record the results in thedatabase. The NILIM intends to take initiatives inorder to apply information which has been
accumulated in the database to improve technologies.
[Sources]
1) Report by Hurricane Katrina External Review Panelof the American Society of Civil Engineers (Japanesetranslation):
http://www.nilim.go.jp/lab/bbg/saigai-gaikoku/asce.pdf
2) Survey of Causes of Levee Disaster on theAgagawa River and Future Policies: Journal, River,February, 2013