SurfingSurfing

Beaches and Rip Currents Beaches and Rip Currents 1D Outdoor Ed 1D Outdoor Ed

20092009

Introduction

Why are beaches different?

• Australia has the best beaches in the world and there are many different types. The features on beaches such as sand bars, rips, berms and cusps can change shape almost on a daily basis.

• Know your beach, know when it's safe to swim and get out there and have fun!

Beaches are:Beaches are:

• accumulations of sediment deposited by waves.

• The type of sediment is very important in determining what the beach looks like.

Beaches are made up of:Beaches are made up of:

•Fine sand

•Coarse sand,

•or even gravel.

•The general rule is that the smaller the size of the sand, the flatter the beach.

ElementsElements

There are 3 elements that determine There are 3 elements that determine the make up of beaches:the make up of beaches:

• WavesWaves

• TidesTides

• WindWind

Waves

•Waves are very important. Some areas naturally get larger waves and some areas are more protected and get smaller waves.

Waves Waves

•Big waves move sand offshore

•Small waves bring sand back to the beach.

• Beaches with bigger waves tend to be wide and flat and protected beaches tend to be narrow and steep

TidesTides

•Beaches that have a large tide range (e.g. the difference between high and low tide is more than 4 m) are generally wide and flat with no sand bars and channels.

•Eg Broome

Cable Beach, BroomeCable Beach, Broome

TidesTides

•Beaches that have a small tide range (less

than 2 m) are narrower, steeper and have

sand bars and rips.

•Eg Scarborough

ScarbsScarbs

Wind

•Wind is important because wind creates sand dunes.

•Beaches that are wide, have a lot of small sand and consistent wind will always have sand dunes behind them.

WindWind

•Narrow beaches with larger sand and less wind have smaller dunes or no dunes at all.

TYPES OF BEACHES

•Although beaches are different, there are a number of common types of beaches that occur around Australia (and overseas).

•The most common are:

Common Beaches are:Common Beaches are:

•High-Energy (Dissipative) Beaches

•Low-Energy (Reflective) Beaches

• Intermediate (Bar and Rip) Beaches

High-Energy (Dissipative) Beaches

•Have small sand and large waves

•Are very wide and flat with large sand dunes behind them

•Have wide surf zones

High Energy cont…High Energy cont…

•Water returns seaward as gentle, return flow so there are no rips.

•There may be 1-2 sand bars separated by troughs.

High Energy cont…High Energy cont…

• They are called dissipative because wave energy is spread out (or dissipated) over a large area.

• These beaches are very stable and don't change much at all.

• Commonly found in SA where the waves are large and the sand is smaller.

Kangaroo Island Beach, SAKangaroo Island Beach, SA

Low-Energy (Reflective) Beaches

•Have smaller waves usually because they are protected, but they also have bigger sand (or gravel) which makes them steeper.

•Tend to be steep and narrow with no rip currents or sand bars.

Low-Energy cont…

• Waves break by plunging at the shoreline and there are often cuspate features on the beach.

Intermediate (Bar and Rip) Beaches

•Have medium sized waves and sand and are dominated by various shapes of sand bars and rip currents.

•They change all the time!

Intermediate cont…

•Most beaches in NSW are intermediate and depending on wave conditions, they may look like one of the following:

Intermediate cont…

•Rhythmic bar and beach

•Transverse bar and rip

•Longshore bar and trough

•Low tide terrace

Which beaches are most dangerous?•Different beaches have different

types of hazards.

•High-energy dissipative beaches have large waves and very energetic surf zones so you need to be a strong swimmer.

Dangers:Dangers:

•Low-energy reflective beaches have a steep beach and a plunging wave shore dump so be careful getting in the water.

Dangers:Dangers:

• Intermediate beaches have a bit of both, but also have a lot of rip currents.

• The key thing is to know what to look for to identify the type of beach and then assess the conditions on the day.

What are Rip Currents?What are Rip Currents?

• Rips are strong, narrow currents that Rips are strong, narrow currents that flow flow

from the shoreline seaward past the from the shoreline seaward past the

breaking waves. breaking waves.

Rips cont…Rips cont…

• They exist as a way of getting water They exist as a way of getting water carried to the beach by breaking carried to the beach by breaking waves back out to sea waves back out to sea

• Are usually confined to deeper Are usually confined to deeper channels between shallow sand bars. channels between shallow sand bars.

Rips Cont…Rips Cont…

• The bigger the waves, the stronger The bigger the waves, the stronger the rip. the rip.

• Think of them as "rivers of the sea".Think of them as "rivers of the sea".

Go To…Go To…

• www.ripcurrents.com.auwww.ripcurrents.com.au

• http://www.ripcurrents.com.au/Rip-Chttp://www.ripcurrents.com.au/Rip-Currents-Safety/How-to-spot-a-Rip-Cururrents-Safety/How-to-spot-a-Rip-Current.aspxrent.aspx

• http://beachsafe.org.auhttp://beachsafe.org.au

Types of RipsTypes of Rips

Low energy rips:Low energy rips:

• Are the most common and occur Are the most common and occur when waves are smaller or haven't when waves are smaller or haven't changed in a while. changed in a while.

• They are usually They are usually fixed in placefixed in place• Sit in channels Sit in channels between sand bars between sand bars • Don't move muchDon't move much

High Energy or flash rips:High Energy or flash rips:

• Are bigger and occur when waves have Are bigger and occur when waves have increased suddenly, or during a storm.increased suddenly, or during a storm.

• They tend to They tend to

move around a move around a

bit and flow bit and flow

faster.faster.

Headland or Fixed RipsHeadland or Fixed Rips

• Are often permanentAre often permanent

• Occur next to headlands and Occur next to headlands and structures such as groynes and structures such as groynes and jetties.jetties.

Are Rips Dangerous?Are Rips Dangerous?

• Rips are only dangerous if you don't Rips are only dangerous if you don't understand what they are and you understand what they are and you are not a good swimmer. are not a good swimmer.

• They can carry you more than 100 m They can carry you more than 100 m offshore in less than a minute and offshore in less than a minute and are the major cause of surf are the major cause of surf drownings and rescues in Australia. drownings and rescues in Australia.

Rips cont…Rips cont…

• However, surfers use rips to their However, surfers use rips to their advantage to help them swim out advantage to help them swim out through the surf quickly.through the surf quickly.

Spotting a RipSpotting a Rip

Spotting a RipSpotting a Rip

• Always spend 5-10 minutes looking Always spend 5-10 minutes looking at the surf zone for consistent darker at the surf zone for consistent darker and "calmer" areas of water that and "calmer" areas of water that extend offshore between the extend offshore between the breaking waves. breaking waves.

Spotting a rip cont…Spotting a rip cont…

• Rips flow against the direction of the Rips flow against the direction of the incoming waves so there's often a incoming waves so there's often a weird, disturbed surface compared to weird, disturbed surface compared to the rest of the surf. the rest of the surf.

• Rips also move things so look for Rips also move things so look for moving sand, seaweed, foam and moving sand, seaweed, foam and people!people!

How do you get out of a How do you get out of a rip?rip?

• DON'T PANIC! The rip won't pull you DON'T PANIC! The rip won't pull you under the water and drown you, it under the water and drown you, it will just carry you seaward.will just carry you seaward.

How do you get out of a How do you get out of a rip?rip?

• Do not swim against the rip or else Do not swim against the rip or else you will tire quickly. you will tire quickly.

• Either swim to the side, or let it take Either swim to the side, or let it take you out to the back of the surf you out to the back of the surf

• Signal for helpSignal for help

How do you get out of a How do you get out of a rip?rip?• Stay with your board, it will help you Stay with your board, it will help you

stay afloat.stay afloat.

• Don't get caught in one in the first Don't get caught in one in the first place! place!

• Make sure you understand what rips are Make sure you understand what rips are and ALWAYS swim between the flags on and ALWAYS swim between the flags on patrolled beaches.patrolled beaches.

Using the picture show how a Using the picture show how a week swimmer and a strong week swimmer and a strong swimmer would escape the rip. swimmer would escape the rip.