Does Venus Bay get King Tides?

With a lot of current focus on flooding and King Tides it is a good time to answer the question.

"Does Venus Bay get King Tides?"

It certainly does!

In fact the next ones are due now and over the weekend. We get higher tides twice each month corresponding roughly with the new moon and full moon (look outside tonight and you will see a full moon). These are also known as spring tides (despite the fact that they occut all year round) and also represent the times when the difference between high and low tides are at there maximum. So from tonight till monday will will have higher than average tides overnight and lower than average low tides in the late afternoon and evenings.

I found this graph on a great site called willy weather, which as well as putting weather details on the net for a lot of Australian locations, including focasts for Venus Bay (they are pretty much taken from the Bureau of Meterology's Pound Creek station), They also sell lots of things to do with weather and tide prediction, worth a look if you are interested in such things.

Wikipedia has a fairly comprehensive page on tides, if you are looking for more detail.

Remember atmospheric pressure helps raise and lower the sea level. So a high pressure system, as we are in right now (1012 hPa and rising) will lower the sea level and stop the higher tide reaching so high but helping the low tide go lower, compared with the predicted level in the chart above or any preprinted tide chart.

The new beach profile

Taken at 4:25pm (approx 2 hours before "official" low tide) on 11/1/2009 atmospheric pressure was 1012 hPa

The low tides at the moment seem exceptionally low for three reasons

1. The 18.6 year maximum tide cycle (its related to the full moon)

2. High atmospheric pressure ( lowers the sea level)

3. the beach profile has change. (little of no summer berm developed and lowering of the beach generally)


The above photo shows how different the beach profile is this year. The erosion scars at the back of the beach are "healing", the front faces have mainly collapsing and are forming a more even rill, The dry sand is being carried by the wind, eroding a smooth slope in some places and depositing and riling down in others. In front of this in only a few places a narrow summer berm is developing. This is the area mainly above high tide where the beach can dry out and wind erosion take over as the main erosion agent. The wind flattens out this zone to almost horizontal (which is why it is called a berm) When it develops a distinct bump can be seen, where the gradient of the beach changes. In previous years this summer berm may have reach 10-30m wide by mid January. Now it is only present in a few places and seldom wider than 3m. The beach in front of that still have the steep gradient more characteristic of winter and the old beach profile has been clearly lowered (much sand eroded away). In front of that there are extensive flatter areas of sandbank being developed. This sand is frequently soft (unconsolidated) because it is being moved back and forth a lot with each tide). Extensive rutting, guttering and ripple pools are being developed and then wash away in the next tide or their position and form changing daily. The beach is reaching width of 100m to 150m from dune to water edge at low tide.