Coastal processes

Transcript of Coastal processes video

[music, bird calls]

I've come down to the northern Illawarra beach of Scarborough Wombarra to teach you about a process called longshore drift.

This particular day the swell was small because the wind was blowing west from the land toward the ocean. Because the waves are then traveling into the wind the surf becomes small, the water becomes smooth and the waves become what they call constructive.

Constructive waves are when the waves are softer carrying the sand onto the front of the beach forming what they call a beach berm. A huge amount of sand gets carried onto the beach this way.

Because the most common swell direction here on the east coast of Australia is from the south then the wave action is carrying the sand slowly to the north. That movement of sand is called longshore drift.

The late winter west winds blows the sand out of the dunes across the beach smoothing the beach out. Only two weeks earlier it looked like this when a southerly storm created destructive waves that washed away the back of the beach. This can damage the dune vegetation and be very difficult to manage. The next day I looked up my weather app and saw when it was high tide and a two-metre swell was running so I went down to Thirroul Beach and saw the waves washing in like this.

Makes you wonder with sea level rise slowly happening how it's going to affect the coastline.

The large seas from two weeks earlier had brought the sand right in over the sea wall which is expensive for Council to have to clean up.

Another thing I wanted to show you is how to read where a rip is. You can see the wave breaking on the shallow sandbank out the back pushing the current in to the darker water at the front where it's carved out a rip channel, and from right to left out to sea the rip current takes everything with it. You can see here in this photo quite a strong rip.

The beach and ocean is such a dynamic place forever changing, constantly constructing and deconstructing. The sandstone rocks eventually becoming the sand on the beach.

We know we need to plan ahead for sea level rise. It's unknown how quickly that's going to happen but that's what geographers are for.

I thought I'd finish off my little seaside jaunt down to Headlands Cove where all the beautiful shells had been washed in from the storm.

So many different colours and forms.

Some cunje had been washed in too and was ah a bit on the nose.

There's only a week or two later sand had covered over all the shells on the beach.

A reminder of that continual process of change.

[End of transcript]