Shortly after I arrived in San Diego on April 27, 1993, one of the weekly tabloids ran an exposé on rivers in San Diego and Los Angeles counties. It noted that San Diego was in the process of “Los Angelesizing” its rivers. “Los Angelesizing” means that the river bed was being cleaned of soil and vegetation, and being replaced with concrete. At one point every river in the city of Los Angeles, and many in Los Angeles County, had been Los Angelesized. Here is a picture of one concrete river that I took in Los Angeles County on April 13, 2014.
The theory was that soil and vegetation caused the water to slow down and build up, thus being more likely to cause flooding. We thought we knew more than Mother & Father Nature did. Turns out that Mother & Father Nature are quite smart.
When the water flows more slowly, it has a better chance of being soaked up by the soil and the vegetation. When there is nothing to slow it down, it speeds right along until it hits an obstruction, like a curve in the river, or bridge abutments, and that’s where the water piles up and floods. With more water continuing to rush in, the flooding gets worse.
Now that we know the purpose of soil and vegetation, concrete is being removed from the channels, returning them to being rivers full of soil and vegetation, returning them to their formerly natural beauty.
A few days ago I was up in Los Angeles County and saw the Santa Ana River being returned to Mother & Father Nature. In the first two pictures you can see the concrete river bed.
You can see that the concrete at the right actually was removed. That’s because there is a bridge downstream about 500 feet, so instead of just letting the concrete deteriorate and silt over, they actually removed it, allowing the vegetation to come back more quickly and the soil to absorb the water, slowing it down. Here’s the downstream bridge:
Notice the silt and vegetation. If you have ever stuck a branch into a flowing stream, you might remember how the water rushed around the branch. Same thing when flowing water hits a bridge abutment, so you want to slow down the water as much as possible. Soil and vegetation do that.
Unfortunately, many decades ago people didn’t seem to understand that concept, so in some places where they needed to slow down the water, they put in mini-abutments, as in this picture:
That might have worked if they had staggered the mini-abutments. Instead, they lined them up perfectly and spaced the rows out evenly so that the water increased in speed each time it rushed around another min-abutment. Mother & Father Nature are not dumb.
I’m not sure when they decided to let this river return to its natural state but I’d sure like to visit it in 50 years to see how Mother & Father Nature have progressed. If I make it another 50 years to age 111, somehow I suspect that I won’t be out & about with my camera…..
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