I think it's safe to say that most people living in southern California take the beautiful beaches for granted as part of nature's blessing on the state. But for many, if not most beaches in southern California, human modifications to the landscape have resulted in our having to take responsibility for their maintenance.
Beach sand is typically the product of erosion in the highland areas inland from the beach. The sand is carried from higher elevations to the shoreline by creeks, streams and rivers, or by simple movement of diffuse surface runoff from closer sources. As the water flowing toward the coast reaches areas with lower and lower slopes, the water slows down and the material it is carrying begins to settle to the bottom. By means of this process sand is transported from our local mountains to the coast where it forms sandy beaches. Or at least it used to happen that way.
With the advent of extensive agricultural and urban development in the Los Angeles Basin in early part of the 20th century, the unpredictable Los Angeles River, along with all of the other natural drainages in the area, proved to be a flooding hazard during exceptional storm events. Along with the flooding across the flatter areas of the basin, mudslides rushing out of the mountain canyons proved to be dangerous and in need of some sort of control.
The engineering solution was to build debris basins along the front of the San Gabriel Mountains, and to channelize our major water courses in concrete. This combined effort sought to capture the onslaught of mud, rocks and other debris flowing out of the mountains, and to channel the water and runoff down to the ocean as quickly as possible. While this approach arguably controlled the dangers of mudslides and flooding, it brought with it a major unintended consequence.
With our mountain canyons blocked by the apparently empty reservoirs that are debris basins, and water being put on a fast-track to the ocean at single fixed points, the rock and sand that used to move from the mountains to the coast was prevented from making the trip. As a result, the wave action and currents along the coast began to wear away our beaches. With no new sand coming in to maintain them, the ocean relentlessly moved the remaining sand from the beaches into deep ocean canyons that periodically dot our coastline.
The only way that the famous beaches of southern California could be maintained was by human intervention, moving sand from the mountains to the coast by artificial means which could never really keep up with the demand. So the next time you visit a beach in southern California, consider the fact that without continued maintenance by humans, the beach would likely be much narrower, and a much less enjoyable place to visit. Further, consider the impact that sea level rise caused by climate change is likely to have on our feeble efforts to maintain our beaches.
Today's photo was taken at Pomponio State Beach about 12 miles south of Halfmoon Bay on the central California coast. While not part of the situation happening in southern California, the obvious flow of water illustrates the relentless force of moving water that carries sand from the mountains to the sea.
This photo was taken with a Canon EF 17-40 f/4L USM lens zoomed to 40 mm on a Canon EOS 5D Mk. III. The exposure was set to 1/10 sec at f/11 and ISO 800.
To see more of my photos of or read other blogs, visit www.chuckkopczakphotography.com.