This is an excerpt from Safer Beaches by Thomas Griffiths.
Beach Types and Hazards
Vive la difference! Because beaches are so unique with many advantages and disadvantages, beach managers need to know how to best educate beachgoers so their visitors can safely enjoy their beaches. Knowing the demographics of those using the beach along with the idiosyncrasies of the beach will provide for optimal and safe recreational use. This chapter helps you attain this goal so the beach experience will be memorable.
No two beaches are alike. Many beaches do, however, have some similarities. When considering all different beaches, perhaps it is best to establish three major categories for better discussion: surf beaches, flat-water beaches, and river beaches. Regardless of what type of beach is maintained, each has unique hazards that must be known and identified. Reducing conflicts between diverse user groups and warning guests of hidden hazards are of the utmost importance.
Approximately 71 percent of the earth's surface is covered by oceans. This much water produces 375,000 miles (600,000 km) of coastline throughout the world, with 13,000 miles (21,000 km) of coastline found in the United States. The end result is that the world is blessed with hundreds of thousands of beaches for people of all walks of life to enjoy. Many of these beaches have varying amounts of surf and tides. Although often thought to be ocean beaches exclusively, surf beaches also include other large bodies of water with waves and currents and “great waters,” including such water bodies as the Great Lakes and the Gulf of Mexico. Wind-generated waves affect sand, rocks, and corals to produce beach sand along with river sediment deposits. The forces of nature produce dynamic and diverse surf beaches that are not only aesthetically pleasing, meditative in nature, and enjoyable but also sometimes dangerous, containing inherent risks and hazards.
Surf beach dangers can vary from very slight to very severe depending on environmental conditions. These dangers include but are not limited to high surf and rip currents; dangerous marine life varying with locality; geological hazards such as rocks, cliffs, reefs, and drop-offs; and pollution from industrial, agricultural, and urban sources. Well-known geographer Bernard Nietschmann maintains that the severity of beach hazards depends on three interacting factors:
- The prevalence and severity of hazards
- The knowledge and experience of the surf beach user
- The presence or absence of professional lifeguards
A more comprehensive discussion of the intricacies of surf beaches can be found in the manual Open Water Lifesaving, published by the United States Lifesaving Association (Brewster 2003).
As dangerous as they are, rip currents may be the surf beach hazard beachgoers understand the least. However, beachgoers must be aware of and knowledgeable about rip currents more than any other hazard. According to the United States Lifesaving Association, approximately 80 percent of all ocean rescues are the result of rip currents. These are localized inshore currents produced by local conditions and should not be referred to as tides. Perhaps it is best to describe rip currents in simple terms: as fast-flowing streams or rivers running out away from the beach and beyond the breaker line. Rip currents are relatively narrow but extremely strong and forceful, and they can pull swimmers and waders away from the beach at an alarming rate. Even the strongest of competitive swimmers cannot beat a rip current by swimming against it. Fortunately, rip currents are easily dealt with by swimming parallel to the beach to remove oneself from the current's grasp. Unfortunately, when people find themselves in the clutches of a rip current, they do exactly what they should not do—they attempt to swim back to the beach, directly into the stronger current. Panic sets in quickly, and drowning follows. Another good thing about rip currents is that they are typically very short lived. Although some rip currents can be more than a quarter mile (.4 km) long, most are not more than a few hundred yards or meters. Strong swimmers, surfers, lifeguards, and scuba divers actually use rip currents as a shortcut beyond the surf zone.
It is important to understand how a rip current is born. When wind and waves grow in size and intensity, water pushes and piles up on the beach. After running up the beach, the water seeks its own level by rushing quickly back into the ocean. The strong returning rush of water will often follow underwater channels and troughs on the ocean floor, flow between sandbars, or arise where two opposing longshore currents meet. Rip currents may also arise alongside jetties. In general, the greater the wind, wave, and surf activity, the stronger the rip currents (see figure 1.1).
Although rip currents do display some telltale signs, they are difficult for most tourists and day-trippers to detect. Because only the most seasoned beachgoers, lifeguards, and surfers easily recognize rip currents, they should be considered a hidden hazard to guests and therefore should be signed aggressively. Beach warning flags may also help educate guests if they can be changed in a timely fashion. Detecting rip currents calls for an astute observation of the seascape. Rip currents usually display irregularities on the surface of the water. Typically, these surface irregularities show subtle yet significant traces in a perpendicular path away from the shoreline. A line of small, choppy waves; a line of discolored muddy, murky water; or a line of foam and bubbles going out away from the beach and through the surf zone are perhaps the most reliable signs of a rip current. These signs exist in the narrow, strong neck of the rip and quickly dissipate once the neck dissipates in the head of the current.
Again, although these markers are easy to observe by some, they are readily missed by many. Once caught in a rip current, the unsuspecting victim should attempt to remain calm and work on rhythmic breathing. Two good choices are available when caught in a rip current. One is to simply float and tread water and ride out the rip current beyond the breaker line. Once the rip current dissipates, the swimmer can move slowly parallel to the beach and away from the rip.The other option is to simply swim parallel to shore immediately following the grasp of the rip current without waiting for the rip to pull the swimmer too far from shore.If the swim back to the shoreline is lengthy, the swimmer should wave for assistance. Tragically, swimmers learn about rip currents only when it is too late, and some never live to tell about them.
Undoubtedly, it's the surf that attracts so many people to our coastlines. The surf zone refers to the wave action between the shoreline and the waves breaking farthest from it. Surf is composed of wind-generated waves. As the wind increases, so do the height and strength of the waves. Big surf attracts many avid water sports enthusiasts, but it also brings with it a myriad of risks and hazards.
Plunging wavesare produced by a combination of strong waves and a steeply inclined beach. These waves are characterized by their height and force and are distinguishable in that the breaking crest of the wave curls over and forward to the wave's base without touching the face of the wave. The more enticing the waves are for surfers, the more dangerous they are. Warning beach flags can be especially useful as wave height and strength change, but again, flags must be updated in a timely fashion as the surf conditions change. Entering and exiting the surf zone through large plunging waves can be tricky and even dangerous at times.
When plunging waves seem to come from nowhere and break directly on the beach rather than farther out in the surf zone, it is called a shorebreak. This wave action can literally pick people up and rotate them onto their heads, causing severe head and neck injuries. Shorebreak waves can knock people off their feet and then drag them back into the surf with their resulting backwash. Whenever a surf beach is characterized by shorebreak, beachgoers must be warned.
Spilling waves tend to be more user friendly and safer for waders, novice swimmers, and beginning surfers. Spilling waves simply roll up through the surf zone and onto the beach without breaking or crashing and most often occur at beaches with gradual bottom slopes. When waves break on the beach, water moves up the beach, known as a wash, swash, or uprush. Conversely, when this same water returns to the ocean, it is called backwash. Backwash can be strong and problematic, but it is not the mysterious undertow that really does not exist. The taller the waves and the steeper the beach, the more severe backwash becomes.
Surging waves neither curl nor break but simply and quickly rise and fall. The sudden rise and fall of a huge mass of water can cause real problems for unsuspecting visitors. These types of waves are most problematic around rocky coastlines, piers, jetties, and some steep beaches. The powerful rise and fall of surging waves can quickly and abruptly lift people off their feet and deposit them on rocks, and people have been killed by severe head trauma as a result. When it comes to surging waves, the old Hawaiian saying applies: “Never turn your back on the sea!”
Read more about Safer Beaches.