PORT WORKS DESIGN MANUAL PART 5 Guide to Design of ...

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6. POST-CONSTRUCTON MONITORING
6.1 General
The dynamic nature of beaches makes post-construction monitoring of artificially nourished
beaches essential. A monitoring programme should normally be set up to identify change
and trend in beach alignment, profile and fill volume, to determine when and where fill
recharging is necessary, and to assess the effectiveness of any action taken. The
requirements of the monitoring programme should be determined during the design stage of
the beach project.
6.2 Frequency and Extent of Monitoring
No strict guidelines can be presented regarding the measurements to be carried out in such a
monitoring programme. In particular, the fineness of the measuring grid and the frequency
of measurements are largely dependent on local conditions. At the start of the programme,
these measurements should be carried out quite frequently, say every three months, as the
largest changes usually occur in such period. The frequency of the measurements may be
changed to roughly twice or once a year, say in the second and third year, and may be further
reduced subsequently, depending on the stability of the observed beach conditions. It is
advisable that measurements should also be carried out immediately after storm events during
the initial service life of the beach to assess the beach responses under extreme conditions.
The extent of measurements should cover the area where significant changes due to the beach
fill may take place. This means that measurements should extend seawards to where no
changes in the bathymetry are expected. The measurements should include adjacent shores
that may be affected by the new beach, such as deposition of sand transported from the beach
or possible shoreline erosion. The distance between the measurement positions should
reflect sufficient accuracy on any change in beach plan form, profile and fill volume.
6.3 Monitoring Items
Sounding surveys and topographic surveys should be carried out to determine the evolution
of the beach. Critical profile may be set up as shown in Figure 18 as an indicator to
determine if actions such as re-nourishment should be taken against beach erosion.
Important parameters of the profile, such as crest elevation or width of dry beach area, should