Date: Sunday, 3 November 2013
 

Monitoring Team: Max, Nick and Paul, assisted by Jenny & Sylvia
 

Analysis & Report: David Bills-Thompson, PFCG Technical Officer and Data Co-ordinator

Comments: Rather than discuss what has changed since last month, I feel it is now valid to look at the trends that we see from the accumulated data in the charts. I have extracted a number of significant charts and attached them as PDF's for easier reference.

One of the important charts is titled Post Sand Height - Post Series 1113. This uses the same data as the earlier chart Post Sand Height - Date Series 1113 but displays it in a more meaningful way.

If sand movement at Post 8 was to continue at the present rate, a Trend Line on the above chart will show that by September 2014, the sand height will be below 1 metre at the base of the post and consequently under water at high tide.

The chart titled Sand Height Range 1113 shows that the greatest variation in post sand height occurs at posts 10, 8 and 7 respectively, while the minimum variation occurs at posts 3, and 9 respectively.

The chart titled Toe Distance Range1113 shows that post 8 has by far the greatest change in toe distance, indicating intense erosion activity. Posts 9 and 4 respectively have the lease active toe erosion.

The beach profile charts reflect the erosion activity around their respective posts. The height of the beach along the profile tends to follow the sand height at the post. Compare the profiles at stable post 4 with the profiles at active post 8.

For most of the year, the beach around post 8 has been the lowest point and consequently suffers more from wave erosion, however it is likely that this area of beach has the highest wave energy due to its position facing the Southern Ocean which may have caused the low point.

Sand movement in this area of East Beach is apparently very complex. Compare post 9 activity with posts 8 and 10 either side of it. Perhaps we need to look again at sand characteristics to better understand where the sand is going to and where was its source.