TOPICS

Maintenance and operation of the flood
control facilities that support the water disasterprevention system

TORII Kenichi, Research Coordinator for Integrated Water Disaster Management (Ph. D., Engineering)
River Department
FUKUSHIMA Masaki, Senior researcher (Ph. D., Engineering)
River Division（Key words） Function, Maintenance, Check, Repair
1. Actual state and problem on deterioration of river
structures due to aging
A river has, addition to the dike and bank protection,
miscellaneous facilities such as water gates, sluice gates ,and sluice ducts that are constructed to secure thefunction of the dike in a junction such as side streams andwater channels, weir, groundsill that are constructedrunning across the river channel as well as the water
evacuation yard that is constructed to evacuate the water
inside. These river structures are important to support thewater disaster prevention system that protects the human
lives and properties in the watershed as flood control
facilities. If we take examples of the water gates, sluicegates, sluice ducts, weir, groundsill and drainage pumpstations, there exist some ten thousands of such facilities
under direct control of the government, of whichapproximately 40% have presently passed forty years ofage since construction and that percentage would reach
60% in ten years and 80% in twenty years1).
We are concerned that cracks, opening in joints, caving
and land subsidence, resulted from deterioration of thematerial itself such as cement and steel, local scour by
flood flow and uneven settlement of ground will occur inthe structure. By that reason, we are confronting themthrough repair based on the survey and check results
made by mainly visual check. The same procedure isapplied to aged machinery facilities, gates and pumping
facilities.
2. Establishment of river structure management researchtask force
Study on the maintenance and operation of the river
structure needs to have the knowledge and experience of
researchers in a number of fields as their objective
facilities are diversified and constructed on the groundthat is a part of the natural levee and likely to suffer fromlandform change caused by flood flow. Based on thatreason, it is required to have continuous organizational
collaboration among administrative staff, practicing
engineers and researchers. However, to the present,
systematic operation has been never implemented on theresearch task related to the maintenance and operation of
the river structures. In particular, satisfactory study is not
implemented so far on the technical study concerning thelong term prediction on the aging of the river structuresand middle and long term management based on thatstudy although it is a significant task of the actualoperation.
MLIT Water and Disaster Management Bureau River

Environment Division, NILIM River Department andPWRI Construction Technology Research Department
have, under common task recognition and understandingof the situation of overall social capital maintenance,
established the river structure management research task
force on April 2012 in order to organize researcher group
to pursue the structural subject management technology
appropriate to the river.
3. Operation to ensure the function of the Water disasterprevention system
A number of flood control facilities suffering fromaging are something we have to implement maintenanceand operation in a good effect securing the efficiency
with a restricted budget. For that purpose, it is imperative
to give the priority on the executing check andcountermeasure on considering the significance of thewater disaster prevention system as well as that ofdeterioration degree of individual facility. What isanticipated further for the maintenance and operation of
the flood control facility is to implement check without
error through developed check method for invisible
portion such as underground, high places and narrowplaces.
To meet such tasks, the river structure management
research task force is considering studying a method toevaluate the effect given by deteriorated materials on thefunction of the flood control facility and link it to evaluate
the function of the water disaster prevention system
supported by the flood control facilities. Further we are toimplement survey on the actual state of the visual checkand repair works executed in the last five years, and docomparison between disturbances checked visually andactual disturbance verified on the repair works in order tosubmit proposition of the method to use suchinvestigation and check results more effectively. We are
to make the example report on the disturbance and repair
so as to make clear the characteristics of remarkabledisturbances and portion pursuant to the type and location
environment of the flood control facilities. Furthermore,
we would promote the technology development toimplement check and diagnosis of invisible portion undercollaboration of industry, academy and administration.
【Reference】
1) YAMAMOTO Hiroshi and OMATA Atsushi: On the“Master plan for long-life and update of river structure”,
Pump, No.47, pp.8-13.