View from Above

Protected WaveClocks, Ocean Winds for Energy, and Seafloor Observations Show the Way!

Ocean Winds for Energy! We were inspired by the first U.S. offshore wind energy farm off of Rhode Island (see below) and released the completely new designs of the WaveClock! Check them out on ETSY and enter BIGWAVES now for your 20% summer discount! In other big news, NOAA is compiling measurements from the Gulf of Mexico and seeing the largest dead zone ever in the Gulf.  The condition arises due to lack of oxygen in the water. In more positive news, the University of Washington is maintaining their live seafloor observatory that measures seafloor volcanic activity. Some great ocean science! Don't forget to check out the latest WaveClocks. You're sure to love the great art from Wetfeet Photography and Ventana Surfboards and Supplies. Check them out on ETSY. Stay tuned and follow us on Instagram, Facebook, and Twitter for the latest info. We'll let you know here first! Happy and Safe Summer to Everyone! The WaveClock Team Find Your WaveClock Here! Share Tweet Forward Pin

Offshore Wind Energy Grows The Offshore Wind Summit recently held in Houston, TX brough together experienced engineers from oil and gas and offshore wind developers to help bring decades of ocean experience to a new budding industry in renewable energy. Learn More! Truly a Dead Zone The hypoxic, or low oxygen, condition in the Gulf of Mexico can cause massive fish kills.  The dead zone for this summer is the largest ever measured in 32 years!  More at NOAA.   Internet of Things on the Seafloor Researchers at the University of Washington are heading out to maintain a deep sea cabled observitory. One of the key missions is to observe life around an undersea volcanoe, the Axial Seamount. Check out more!

What is the WaveClock?

Video post demonstrating the WaveClock in action.  For more information head on over to our Website and our ETSY store to find your own WaveClock!

How to Survive the Summer! You're finally getting some time off, relaxing long weekends to enjoy the sun and water, and all is well! It might feel as if everyone within a thousand miles has also come to join you. There's nothing like summer beach time and surfing to experience the best in crowds. Corky Carroll, one of the wisest surfers out there, has some words of advice on how to look past the crowds and relax and enjoy no matter what. Also, there's a big effort underway in New Zealand to save a surf spot from development. And speaking of surf, this winter was full of spectacular big wave surfing. We couldn't resist sharing a clip of the ten most harrowing wipeouts that make you wonder how anyone comes up again! As you know, the WaveClock is your gateway to the ocean. The WaveClock queries real-time oceanographic databases to find the wave and tide at your spot. You can always check out the app by downloading from our website, but you need your hardware version to keep you updated at a glance.  To get you setup, we are offering FREE SHIPPING this week using the code catchawaveat our Etsy store. Drop into that as soon as possible! Happy and safe July to everyone! The WaveClock Team Free Shipping HERE with the code catchawave!!

While your WaveClock can help you spot the swells not predicted by the forecasters, crowds can still happen. Corky Carroll offers some wisdom from his decades of surfing. Instead of getting frustrated, aggravated, and having a bad session, you can learn how to mentally prepare. Check it out here. The El Nino this winter brought some unprecedented surf for big wave spots around the world. But with those incredible waves come some mighty payments. In this amazingcompilation, Kiwi filmmaker and editor Guy Mac puts together quite possibly the most intense one minute of surfing you’ve ever seen. Dredging Waves Away? Surfers near Wellington Harbor in New Zealand are facing changes at their local spot by a dredging project to allow larger vessels into the Harbor. Overall, it looks like the dredging will decrease the wave energy entering the area thereby decreasing the number of surfable days.  Read about it HERE!

The Holidays are here No matter how we choose to celebrate, the biggest wish from us at the WaveClock to you, is for an amazing time of giving and happiness with friends and family. We hope you're getting a chance to relax and enjoy. On top of that we'd like to bring you fun news from around the world. There is Kelly Slater's new wave park to the continued El Niño, the last few weeks have been exciting.  Central California is expecting waves of 10 ft or greater for the entire next week. It promises waves through the Christmas holiday and hopefully fun waves through the long weekend for everyone. On top of that, continuing rain brings us into drought breaking territory.... enough to wet your whistle, or board as it may be. The CDIP models (right) show steady northwest swell for the Monterey area. Unfortunately, some of these weather systems promise steady strong winds, enough to blow your hair back! Hopefully, you can find a protected spot and enjoy the coast in it's winter glory.

Truly amazing artificial wave. Kelly's collaborators have developed a technology with a moving wedge to generate waves over 100 m long with a perfect shape. Another company with some similar technology is here.  Wooden WaveClocks The wooden WaveClocks are ready to roll.  Showing you real-time updates from your favorite wave buoy and tidal station! Our best designs are here for you. Explore WaveClocks It's not just brewing up to be strong Many scientists are starting to feel that the present conditions could start an even larger and longer scale ocean oscillation leading to more large events. Summary in this article.

Do you know why waves move the way they do?

Waves, what are they? A wave transfers energy from one place to another. Whether you're thinking of an ocean wave, a sound wave, or a light wave, they all essentially do the same thing. Waves get some kind of energy from point A to point B through whatever substance, or medium, they are in, be it water, air, or space. Waves oscillate the substance they are in to transfer that energy. What we're interested in for this article are how surface waves in water behave. We are going to demystify two wave things about waves:

• How and where they break
• How they can turn as the move towards the coast

Before we launch into it, let's check out a nice photo of waves. The photo is extra special because it shows some really neat effects of water waves bending light waves and causing bright light ripples in the water.

Nice picture of water waves and light waves interacting from http://oceanleadership.org/

You've probably already developed an intuition for how waves move just by watching. In fact, you might be much more of an expert than you think if you spend your time surfing, sailing, or just hanging out at the water! Experience counts for a lot here, so we'll try to weave a picture between good experience and science.

Let's start with wave breaking. Why do waves break? First, a good rule of thumb to remember is that waves slow down in shallow water. Taking it a step further, when the water is shallow enough, that slow down happens more at the bottom of the wave. The faster moving top of the wave tips over the bottom like a tipping glass of water. Lo and behold ... We have a breaking wave. While the physics is more complicated when you dig into the problem, that's the essential idea!

There is generally a depth of water where waves of a certain height will break.  This depth is cleverly called the "Depth of Breaking". A water depth of approximately one and a quarter (1.25) times the wave height causes a wave to break. So, a 10 ft wave will typically start to break in 12.5 ft of water. While there are a lot of things that can modify this ratio, such as a steep rock reef or very steep beach, its a good rule of thumb. The figure below gives us a conceptual picture of what's happening with waves breaking. You can see the wave marching towards the shore. As the water depth decreases, the wave slows down due to shoaling in the shallow water. When it hits the depth of breaking, the top keeps moving fast and tips over the bottom and we have a breaking wave.

As waves approach the shoreline they feel the bottom which slows them down and
eventually causes them to break at the "depth of breaking" in a depth of water
about 1.25 times the wave height.

The waves change direction by almost 90 degrees in the space of a quarter of a mile!

Curving waves, or wave refraction, is our next topic. Take a moment and look at the picture below. This is Rincon Point in Santa Barbara, California and produces one of the most famous right handed point breaks in the surfing world. Notice the waves at the top of the picture are parallel with the top of the picture frame and the wave at the bottom are facing the right side of the frame. The waves change direction by almost 90 degrees in the space of a quarter of a mile!

Nice aerial showing wave wrapping around the point at Rincon in Santa Barbara , CA. Image from http://www.travelgrom.com/.

So what's happening here? If we think back to our rule of thumb, waves slow down in shallow water, we can put together a picture of what's happening. When we extend this to long wave front, the wave will experience different water depths along its length as it approaches a coast. A point on the coast sticking out into the ocean, like Rincon, provides big depth differences in a small space. In the image below we see the waves coming in from the left and approaching a point.  The portion of the wave near the point hits a shallow water point earlier than the rest of the wave.

So what happens when these waves hit the shallower water near the point? They slow down and eventually break. The shallower bottom is almost like a hand pushing on waves and slowing them down, while in the deeper water the waves keep moving uninterrupted. I drew the  black arrows on the figure below to help visualize this slow down so we can see what happens. The shallower slower moving waves hang back while the waves at the top of the image in deeper water keep marching forward. The wave curves in response and causes the wave to turn, or wave refraction! 

The focusing and curving of energy at coastal points is why point breaks are often such amazing surf spots.  

When we pull this all together at a coastal point we get an interesting phenomenon called wave focusing. Let's marry up the figure above with the other half of a point and plot it out in the figure below. Now we have the waves curving in towards the point from both sides focusing the wave energy at the point. You can see the energy coming from both sides to make the waves bigger. The blue arrows showing wave direction help visualize this "focusing" of energy at the point. The focusing and curving of energy at coastal points is why point breaks are often such amazing surf spots.  

An important parting note is what we started talking about in the post about how sand moves around at the coast. The change in wave energy from the point to the adjacent beaches causes two interesting things to happen.  First, the focusing of energy will pick up sand and even erode cliffs where the energy is high. Second, the material moved at the point is carried down the coast to lower energy areas due to longshore transport. The sand creates our beaches, sand bars, and even fills our harbors as we discussed in the previous articles! Now you're starting to see a picture of how all of this works together.

Please help support our efforts by signing up for our newsletter on the right side of this page or on our website to get regular updates on the world of ocean science, ocean energy, surfing, and other fun topics. Or course you can get the BEST idea as to what the ocean is doing with your very own WaveClock. Great resources like Dean and Dalrymple (2002) provide the detailed wave mechanics behind these processes I have greatly simplified here. Check it out to dive in more.

Enjoy the the beach!
Craig

R.J. Dean and R.A. Dalrymple (2002). Coastal processes with engineering applications. Cambridge University Press. ISBN 0-521-60275-0. p. 96–97.

How does the sand get to the beach?!

Now we get to the fun stuff ... the beach! In the last post we explored how the sand gets to the coast from the mountains. We all know it's rivers, but it's a great process to explore. Then the sand hits that crazy area where currents, waves, and tides all interact. These competing forces move the sand around and get it to the place we are most often thinking about ... the beach.

I am going to take a step back a little, because we haven't really talked about what sand is. The particles that make up sand have an important characteristic that makes them sand and that's the size of the particles. The most common definition of sand is any particle that is larger than 63 microns (0.063 mm) in diameter according to whats called the Wentworth size scale. Now that's pretty small!  More commonly what we think of as nice "beach sand" is larger than about 200 micron (0.2 mm) in diameter. So, beach sand is essentially quartz sediment larger that about 200 microns in particle size.

Great, that's the size, but what is sand made of? Most commonly, sand coming from the land is made up of the mineral quartz. Straight from the dictionary, quartz is:

 A hard white or colorless mineral consisting of silicon dioxide, found widely in igneous, metamorphic, and sedimentary rocks. It is often colored by impurities (as in amethyst, citrine, and cairngorm). (Google, 2015)

However, that definition gives us some good insight into the sources of most sand. Much of our land on this planet is made up of some type of igneous, metamorphic, or sedimentary rock. When rain erodes these rocks over time, a lot of the sand ground out is made up of quartz. The ground up rock washes down gullies, hillsides, and other streams to the rivers and so on, to the coast.

One other big source of sand, in areas such as the pacific islands, is coral reefs. The reefs are made up primarily of a material called carbonate (another mineral like quartz). Interestingly, fish are a common way some reefs get broken up into sand. Parrot fish cruise along munching on the reef and grind it up into sand.  One parrot fish can produce up to 200 lb of sand a year (Thurman and Webber, 1984). That's a lot of sand!

One parrot fish can produce up to 200 lb of sand a year!

Suffice to say there are a few different sources of the sand grains. Now let's get down to it and talk about how it get's where it is going! We have a pile of sand on the coast where a river has dumped it out, parrot fish has pooped it all over, a cliff has eroded, or some other source has dumped it there. Once on the coast, the waves can start pushing this stuff around. We'll save a full wave mechanics discussion for future articles, but we are going talk about some of the important things the waves do at shorelines to move the sand.

There are two ways our sand can be moved by the waves:

• along the shore, called longshore transport, and
• on or off the shore, called cross-shore transport.

Longshore transport moves the sand in pretty exciting and phenomenal ways. I'm sure you've sat on the shore watching the waves come in and have probably noticed that they hardly ever come straight into the shoreline. If you can imagine, this is because of that angle the waves are often peeling along the beach. Think of that peeling like a push along the beach from the waves. That push is a real force expressed by the waves and is felt by the sand out there under the waves. The force moves our sand down the shoreline in ... you guessed it ... longshore transport.

... here in Santa Cruz, waves can push enough sand in the harbor mouth to fill in up to 15 ft of channel overnight during a storm!

Figure from the Santa Cruz Harbor showing how sand is
moved from the river down the coast to the Harbor and
beyond due to longshore transport (also called littoral drift).
Source: http://www.santacruzharbor.org/dredgeWhy.html

Longshore transport is typically the biggest way sand is moved out of the river mouth or delta to other areas along the coast. In fact, here in Santa Cruz, waves can push enough sand in the harbor mouth to fill in a 15 ft deep channel overnight during a storm!

When you look at the figure below, imagine a river has dumped sand on the left side of the picture (upcoast direction). The waves coming in from offshore are also coming from the left slightly and moving to the right (blue arrows show the wave direction). The pushing from the waves moves the sand to the right (downcoast direction). The black arrows point in the direction of the steady march of sand due to longshore transport.

Waves coming into the coast from the upper left push to the right along the beach. Sand gets picked up by the waves and moved along that direction. The movement along the shore is called Longshore Transport.

If the sand is just pushed along the shoreline how does any sand get onto the beach? When the waves move to the coast they create another force pushing to the beach. Just like longshore transport, the force of the waves pushing into the beach creates a cross-shore transport of the sand.

In the summertime, when the waves are smaller, the sand piles up on the beach with each wave and slowly builds up. Over time that sand builds to a happy status quo called the equilibrium profile. The equilibrium profile typically has a nice berm with a flat beach behind it.  This is where we set our towels down, throw up some volley ball, and roast ourselves in the sun while enjoying a frosty cold beverage. Those gentle waves push the sand higher and higher up the beach with each tide.  The sand eventually builds us a summer beach profile as shown in the figure below. 

Cross-sections showing summertime and wintertime beach formation and sand movement. Smaller waves in the summer typically bring sand to the beach, while large winter waves move sand offshore into sand bars.

The whole sand dynamic on the beach does somersaults in the wintertime.

You're well aware that things liven up quite a bit in the wintertime. The weather gets cooler, the sky darkens, and the wind starts brewing in the ocean. The winds build up big waves that get bigger ... and bigger .. until we have big storm waves breaking along our nice calm summer beach. Those waves, as you'd expect, pack a much bigger punch when they slam onto the sand. They pick up the sand in all that turbulent mess and pull it off the beach. The assault pulls the sand out to deeper, somewhat calmer, water where it forms a new underwater sand bar. The figure above shows how our nice summer berm was cut away by the waves and moved to the winter sand bar. 

In Santa Cruz County at Manresa Beach, the winter sand bars cause the waves to break offshore and give us some fantastic surfing conditions when the conditions are right. That's what inspired the invention of the WaveClock, to see the waves and tide out there in real time. We've got a number of them up on Etsy ready to go now, or order a custom one on the website. Also, don't forget to sign up for our free newsletter on the left of this page to keep up with what's going on in the ocean world!

This article describes pretty ideal world stuff. Some beaches may have no sand in the summertime and lots of sand in the winter depending on the waves, sources of sand, and the type of coast (such as cliffs or offshore reefs). Also there are rip currents, offshore canyons, rocky points, and other coastal features that can modify the movement of all this sand. In the next articles we will explore sediment budgets (yeah sediment has a budget too!) and wave mechanics to develop a deeper understanding of how all these things play together on the coast.

Happy Exploring!
Craig Jones

Reference
Thurman, H.V; Webber, H.H. (1984). "Chapter 12, Benthos on the Continental Shelf". Marine Biology. Charles E. Merrill Publishing. pp. 303–313.

Where in the hell do our beaches come from? Sand on the brain ...

View of the Homochitto River.
Source: Google Earth, Imagery Date: 4/9/2013

I was flying across Mississippi last week, looked down on a river, and was struck by the white sand bars shining brilliant through the green forests. Going on Google Earth it took a few minutes to find out what river I was looking at, but I found it. The image here shows the tortuous path of the Homochitto Rive. The white sand pops through the green-forested terrain outlining its path as it flows eventually to the Mississippi River.  To me, an engineer/scientist who has been looking at water bodies for most of my career, it truly floored me the amount of sand in this river.  Certainly, this river has no problems there!

Sand is an important, sometimes critical resource, in coastal communities.

Anyone living near the coast can likely relate to a local beach or coastal region where sand or a lack thereof, is a problem for local communities. Sand is an important, sometimes critical resource, in coastal communities. It can provide a resource in the form of a thriving tourist industry to lay it’s blanket down and support a local economy. It also provides an important protective barrier in regions ravaged by periodic hurricanes. Sand is akin to a band-aid protecting the tender shoreline from the ravages of storm waves.

The high value of sand, and its management throughout the world, had me reflecting on the importance of what I saw abundantly in the Homochitto River from above and what we desire so deeply the coasts. If we take a brief journey from the hillsides, fields, and mountainsides where this sand originates, we can follow it through the river, down to the coast, and eventually to the deep ocean. 

The river itself provides the true punch of the mighty force to deliver this precious gold (figuratively and literally) from the mountains to the coast. Most of us know, or can certainly surmise, that most of the sand and mud we see flowing in a river comes from upstream. What we well understand is that scouring, erosion, and removal of soil and rocks from upstream bring sediment (sand and mud) downstream. Leonardo Da Vinci pondered these problems in the 15^th and 16^th century while watching the complex course of water flowing through local rivers (Graf, 1984).  We'll hear a bit more from him in a bit.

All this “stuff” transports downstream through the river like a conveyor belt. Of course, some of this material rains out in deposits along the river’s course during this journey. Where does it rain out? Rivers twist and turn, and like a freeway zooming with cars, the water speeds up and slows down. Slowing down along the inside of turns and speeding up on the outside of turns. Sediment drops out in the slower flow and is picked up and moved through the faster flow. Where the sediment drops out and builds up on the inside of the turns “point bars” are formed.  Where sediment picks up and the water cuts away at the riverbanks are features called “cut banks”.

Point bars form on the inside of river bends where the
water slows down and drops out sediment.

An interesting little rule of thumb as true today as in Da Vinci’s time is an observation he noted (Simons and Sentruk, 1992):

Where water has the least movement, the bottom will be of the finest mud or sand, where the water has a stronger current the shingle is larger.

What he is saying is that where the water is moving slow the sand and mud drop out of the river flow, and where it is fast the “shingle” (or material the river bottom is made up of), is larger. We see this in rivers that have cobblestones and boulders where it is fastest flowing. Pretty cool physics in action!

What struck me looking at this river from the airplane is no just that there is sand, there is a TON of sand on the point bars visible from 30,000 ft in the air.

Why do we care about this and why are you laboring through my long-winded explanation? If we go back to that picture of the Homochitto River we see sand. What struck me looking at this river from the airplane is no just that there is sand, there is a TON of sand on the point bars visible from 30,000 ft in the air. The blatant display of sand by this river is unique. It’s not easy to go to Google Earth and look for lots of rivers around that appear as brilliant with sand. To me, that means there is TONS and TONS more sand making it downstream that we don't see. Downstream to the coast!

What happens to all of this sandy gold when it hits the coast? It can hit an estuary, think San Francisco or Chesapeake Bay, it can form a delta like the Mississippi River, or it can tumble full bore into the ocean. The interaction of the fresh water and salt water in these zones form many fields of science, but it is sufficient to say that the sand makes it to the coast eventually.

If we think about that sand going from a pretty swift flowing river to the big deep slow moving coastal current, we can imagine all that sand dropping out like it did on the point bars. At this point (no pun intended), the waves start to take over. Similar to the high and low speeds in the river, big waves pick up the sand and move it around, while smaller waves allow that sand to drop out. We all know that these waves vary in size daily, monthly, yearly, and by location and depth of water. The movement and fate of sand along the coast is amazing topic I am going to save for our next article titled “Now I am at the beach, where do I go?” or something equally satisfying!

Sign up for our newsletter and keep up with our comings and goings on this page and at The WaveClock. Order your very own WaveClock there to see the ocean in real-time and really know how that sand is moving. Email us anytime at contact@thewaveclock.com

All the best!
Craig Jones

References

U.S. EPA (2014, February 5^th) WATERS Data. Retrieved from http://water.epa.gov/scitech/datait/tools/waters/tools/waters_kmz.cfm

Graf, W. (1984) Hydraulics of Sediment Transport. Water Resource Publications.

Simons, D. and F. Sentruk (1992) Sediment Transport Technology: Water and Sediment Dynamics. Water Resource Publications.