Although can’t find any dictionary that backs me up on this, I have always considered a barranca to be a man-made, concrete-lined channel that street gutters drain into. At least that’s what we called them when I was a kid. We had one running behind the house I lived in when I was 9. They were great for skateboarding.
FWIW, concrete lined channels in L.A. are usually refered to as “flood control channels”.
The L.A. River actually is a river. A long time ago the U.S. Army Corp of Engineers got the bright idea to straighten it and line it with concrete so as to improve it’s flood control capabilities. Of course, all of that water that used to percolate into the aquifers now runs right into the Pacific Ocean.
Huell Howser did an episode of his program (I think it’s now called Visiting) on KCET (PBS) about the L.A. River several years ago. He and a guide went from the northern-most part and followed it to the bay; sometimes in a canoe. Parts of it are still “natural” and very pretty. There have been periodic movements to make it more park-like to give people a new place to go, but I think the county is concerned about liability. It’s plenty dangerous, as can be seen annually when helicopters have to chase people who have fallen in and rescue them.
They freakin’ took a natural river and lined it with concrete?? And they thought that was a good idea?? What the hell were they thinking? :: :pounding head against keyboard:::
Ow. That hurt.
“Flood control channels.” That sounds good (and accurate enough) to me. I knew not all of them could be this horribly disfigured LA River. How long ago was that bright idea carried out?
(Disclaimer: posting under the influence of flu and a fever. I’m finding all kinds of malaprops and misspellings and overall bad writing in my posts from today. Right now, I don’t care. Later, I will. Hope you don’t. 
)
Teaching: The ultimate birth control method.
Dammit, I did not want that tongue smiley thing. Moderator! Moderator!
I don’t remember when the flood control channels were created. I want to say the 20s or 30s, but I’m just not sure.
Johnny, I was referring to the concretization of the LA River. When was that done?
The short answer: 1936.
The medium answer:
The long answer: See http://www.folar.org/history.html, from which the above quote was excerpted.
Here is another L.A. River site: http://www.lalc.k12.ca.us/target/units/river/riverweb.html
And finally, one from the Museum of Natural History: http://www.nhm.org/education/publicscienceday/lariver.html
Oops. Got a comma in the FoLAR URL. Here it is again: http://www.folar.org/history.html
Some definitional help:
Contrast the word river, which is not really the bed so much as it is the flowing water (don’t talk to me about it, just read the definitions 
).
In Southern California, there are few ‘rivers’ that actually flow year-round. Thanks to the fact the area is not only a natural desert but also gets almost all its rain over only three or four months in the winter, there simply isn’t any ready source of constantly running water. Because the area was originally colonized by the Spanish, Californios tend to use old spanish words to describe the channels left by the streams of the area, such as arroyo and barranca. In most of its length through the San Fernando Valley and the Los Angeles Basin, the Los Angeles River is neither an arroyo or a barranca, just a dry stream that is now encased, along with the San Gabriel, Santa Ana, and San Juan rivers among others, in concrete. Perversely, in LA, they often route freeways alongside the concrete rivers, a different river of concrete that is rarely without flow.