QUICK SUMMARY TABLE EXPLAINED

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Recently we introduced a new way to report the sand level results from beach monitoring.

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In order to be more effective than a whole series of profile charts, some type of graphical display was proposed.

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Objective #1 for the Quick Summary Table (QST) was to provide a summary of the sand levels at a glance for each section along the beach. Dividing the table into rows of beach locations and columns of data for the most recent measurement, the ‘traffic light method’ using Red, Green and Amber gives an instant display of the approximate sand height at each location. For the casual recreational user, this is all they want to know. From personal experience of people asking me “How is the beach”? I suspect they are only looking for a one word answer.

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For those who need a little more detail, other columns provide similar information about the previous measurement and a third column also applies the colour coding to the data from about one year ago.

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Objective #2 for the QST was to have readily available supporting data for the most recent, previous and historic measurements. Each of the coloured blocks also shows the percentage height previously calculated from the profile chart for each of the three time periods. Adjacent to the ‘Recent’ column are the average percentage heights of all the records from April 2013 which can be compared to the individual readings at that location. The QST also contains some information that is useful for engineers:

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* A column listing the PFCG ID for each measuring location and the distance selected at that location to calculate the percentage height.

* The exact date most recent measurements were taken.

* The date when the next measurements are due (Currently 42 days later).

After this date expires, colours in the ‘Recent” column turn Grey.

 

The QST has twelve rows, one for each location of the twelve measuring posts. It also has its own Control Panel where individual monitoring points can be selected. As no measurements at posts 11 and 12 have been made since March 2023, two special monitoring's known as 8.1 and 9B that highlighted erosion after the September storm event were substituted in place of old data for posts 11 and 12. Individual control of the table display allows all of the monitoring points to be displayed in geographical order to assist with situational awareness.

 

Getting the most from the QST

• Look at the colours

  • ​Find locations that are Red or Green

• Compare Recent column with Previous

  • See the change from last measurement

• Compare Recent column with Average

  • See the difference from historical average

 

  

Look at the colours: Red indicates low sand levels, Green is for high sand levels and Amber covers the levels in between. The break points between these colours are adjustable in the QST tab of the PF spreadsheet and are nominated in the Legend at the bottom of the Quick Summary Table.

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Compare the Recent height with the Previous height to see how the sand level is changing. Also compare with this time last year; if it’s different, further proof that seasonal changes are less predictable. Scientists have noted that cyclic changes in sand movement have become less cyclic and more random.

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Compare the percentage height with the average percentage height to provide more detail about the current status of the beach.

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A positive number in a Red square is usually not a concern but if the number is negative, it indicates that a new low sand level has been detected and further consideration of all the data at that point should be investigated, usually by referring back to the profile chart.

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If any of the Recent colours have turned Grey, it indicates that a new measurement is due, however you can still see the percentage height and determine what the condition was at the date of measurement but be aware this condition may not be typical of the current beach status.

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Rules used to select distance

• Sand loss has precedence over sand gain

  • Sand flow from Backshore to Foreshore may need to be discounted

    • Select the backshore value if it lost sand

• Profiles with large range more variable​

  • More likely to need distance adjustment

• Dry posts in secondary dunes are not always representative​

  • After a storm surge, this may change

• The measurement must be from a repeatable area

  • Profiles through the WEDs are variable and cannot be used

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The QST is regularly updated on the PFCG web site after each VCMP drone mapping is processed or any laser measurements are carried out so make www.pfcg.org.au your link for information about Port Fairy beach status.

 

The purpose of the distance setting is to select that part of the beach to calculate the percentage height that shows a typical response to sand movement.

Sand loss (Bad news) has precedence over sand gain.

Profiles that have a large range in elevation (The range envelope) over most of the profile will be more likely to require a change of the percentage height distance.

There must be a Recent and a Previous measurement available, otherwise there cannot be a comparison.

Where there is loss in one part of the profile and accretion in another part, set the distance to record the Loss unless there is a special cause identified for the loss.

Dry posts that are located high on a secondary dune should not normally be included For these locations, a percentage height distance of >10m - 15m is more typical. An exception is when only a few readings are available and a large change at the post has been identified.

Profiles through the Wave Energy Dissipation structure (WEDs) are variable and this area between the rocks cannot give reliable sand heights.