28 Jun 10
Monitoring raises concerns over Bar and Tidal Jet performance.
Last week Whangamata Camping Association and Surfbreak Protection Society members met in Whangamata, mainly to study all the Bar surveys that have been conducted as part of a monitoring programme to help determine whether the Marina channel dredging has changed the profile of the bar and degraded the quality of this iconic wave.
The group spent some time pouring over the results and
correlated them with surf data collected by a local surfer. This
was also compared with anecdotal evidence received from what many
locals had observed on the Bar.
It was decided that Surfbreak Protection Society should propose a
motion at the Whangamata Harbour Committee meeting (held 14 June
2010) that Waikato Regional Council (Environment Waikato) coastal
planners come to the next WHC meeting and explain the survey
methodology and findings to that committee. The motion was passed
unanimously. The Regional Councillor Simon Friar said he would
organise for them to come over. He advised that this should be with
in the next 3 months.
Surfbreak Protection Society and the Whangamata surfing community
have asked for the maps to be standardized as a number of different
scales and use of slightly different colour tones has meant that
the group was not able to speak with authority on wave quality -
ie; the reason/s it has changed?
The group felt it was important to get the community involved in
this project so we went through the Harbour Committee. The Marina
Society had one piece of the data published in the local paper. As
a result the radio took it as being the whole truth and broadcast
it as well. There was a lot of debate and feedback from listeners
suggesting that they were broadcasting false information. A
programme on the issue was due to be broadcast on Saturday morning
radio.
Local Surfbreak Protection Society members and other concerned
locals have gone over the monitoring maps again and are coming to
terms with how to read them. It is clear that the Bar has moved
further to the east and south by approximately 5 metres each way.
We believe at this stage that it is caused by the tidal jet* being
blocked or choked.
This choking has occurred through the recent drought. Whangamata
has had 3 heavy rain events in the last month and the last map
shows possible clearing of the tidal jet. However, it is a higher
sand bank and thus the sediment is being pushed to the take-off
point and entrance channel thus impacting both negatively. The
issue of the tidal jet is major for the Harbour Committee on this
issue - the Tidal jet is a channel that crosses the Bar on a
diagonal across a NW - SE direction so the out going tide drops
sediment on the ocean side of the Bar at what we would call the 2nd
& 3rd sections of the wave, that are currently missing.
The clearing of the mangroves now takes on a greater significance
as they are going to release up to 37 hectres of mud based (not
sand) sediment - out to sea? or on to the bar. The result of this
will be a further choking of the tidal jet..
While the monitoring surveys continue Surfbreak Protection Society
are consulting their experts for an appraisal of their 'surfing
based' assessment of the situation.
* Tidal jet refers to process and speed by which the tide carries
sediment to and from an estuary or harbour via a channel to the
ocean.