Monitoring and Maintenance of Stabilization Works
and channel depths of the crossing and bend immediately upstream of the study reach if
stream migration is a concern. If degradation is a concern, cross-section measurements at a
convenient location downstream of the study site (a bridge for example) may be recorded.
11.2.7.5 Level 5 Monitoring
A Level 5 monitoring effort consists of all activities performed during a Level 4
monitoring effort plus additional data on bed material size and gradation, water quality,
roughness, fish habitat, and biomass analysis, etc.
11.2.7.6 Pulsed Monitoring
A "pulsed" monitoring system is where a project or reach of stream is monitored on
a long-term schedule with varying levels of effort. In most cases a pulsed effort will provide
sufficient data and at the same time meet economic and time constraints.
An example of a pulsed monitoring effort would be to comprehensively survey and
intensely monitor (Level 4 or 5 effort) a site annually for two to three years following
construction, followed by a less intensive monitoring effort (Level l or 2) at the same
frequency and after major flood events.
11.3 MAINTENANCE
11.3.1 DETERMINATION OF NEED
Two alternative approaches to determining the need for major maintenance
(sometimes called "repairs" or "reinforcement") seem on the surface to be mutually exclusive:
Take action at the first indication of a threat to the work
Take no action until major maintenance appears inevitable.
When carried to extremes, these approaches are in fact contradictory. However, an
effective compromise can be reached through the concept of "functionality," in which the
engineer considers the consequences of failure, probable trends in stream behavior, type of
protection (i.e., ability to function even if not intact), and availability of funds. Streambank
protection works do not have to be in pristine condition to be effective. What appears to be
damage may actually be minor and non-progressive "adjustment."
This contradiction is typified by toe deepening, which often requires no action, yet at
the same time is a common cause of major failure. Adequacy of the original design to
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