2016-07-18 General Committee Meeting - Item 3 - Attachment 1 - Flood Management Plan

         7
    Flood records
     and survey




The collection and archiving of flood records is a task        7.1 Historical Flood records
undertaken to assist future generations by continuing to
improve the understanding of the flood characteristics         Noosa Council has a relatively short history of flood
of an area. Records of historical floods are an important      records for the region. The majority of the region’s highest
reference to support planning and decision making. The         recorded flood levels were obtained following the February
validity of a flood model is often determined by a model’s     1992 flood event. Prior to this a sparse selection of records
ability to reproduce the recordings of an historical event.    exists for the major flood event of 1968 and other significant
                                                               events throughout the 1970’s.
The capture and storage of flood levels is predominantly
a spatial mapping exercise. However, it is important that      It is often difficult to confirm the accuracy and reliability of
these records be maintained in conjunction with design         historical flood levels. Flood levels are often recorded from
flood levels derived from flood studies to ensure anomalies    the remnants of vegetation debris, water stains, damage to
in either data set are recognised (and explored), and to       infrastructure and occasionally from anecdotal references.
maintain a context of reference between actual recorded        These records offer a limited insight into the nature of each
event levels and those proposed as design levels. In doing     flood event and may be influenced by local conditions,
so it is also important to maintain access to all available    survey datums and other physical changes which may have
historical flood records (not just the highest). This will     occurred in the floodway. For these reasons some caution
enable further consideration of the frequency of flooding      is required when interpreting historical records.
at a location.

Determining the frequency of flooding from a series of
historic flood records requires some consistency in the
collection of records to ensure the events recorded reflect
the full nature of flooding experienced over periods of time
at a location.




                                                                                     Noosa Council | Flood Management Plan | Page 25