February 29, 2016 § 1 Comment
Something came up in a recent discussion I was having about current spate of U.S. Army Corps of Engineers make-work projects to degrade the L.A. River in the name of El Niño. If you haven’t seen it, the cutting vegetation and installing dirt-fill barriers along the edges of parts of the river, resulting in nutty bike path detours.
What makes me sad is that the L.A. River generally hasn’t flooded during El Niño years, but instead mostly during La Niña years.
I know this from an excellent interview that FoLAR bird expert Dan Cooper did with climatology professor Richard Minnich back in 1998. I ran excerpts from this in 2010 – a drier La Niña year with some big storms. Below is the whole article.
Talkin’ El Niño
An interview with Dr. Richard Minnich of University of California Riverside, by Dan Cooper
Richard Minnich is a professor of biogeography and climatology in the Department of Earth Sciences at UC Riverside. He has been studying weather patterns and landscape ecology in Southern California and Baja for the past two decades, and recently spoke with FoLAR’s Technical Advisory Board chair, Dan Cooper, in Riverside on March 6, 1998
Dan: Dr. Minnich, let’s begin with the basics – what causes flooding in L.A.?
Rich: Two components are involved, long-term and short-term causes. In the long-term, the ground has to get completely saturated by rain; water hitting dry ground won’t do a thing. Now, in the short term, it’s the hourly rates throughout the day that are important. These rates are what cause catastrophic flooding like we had in 1938.
Dan: What kind of rain are we talking about?
Rich: Ballpark rates, maybe 20 inches in a day in the Transverse Ranges (incl. the San Gabriel and San Bernardino Mtns.).
Dan: Twenty inches in one day? That’s typically what we get in a year.
Rich: In January ’43, it rained 20″ in the mountains, but it was on dry ground so nothing happened. Now downing the coastal plain where everyone lives, all that concrete has led to the potential for flash flood conditions – the water has nowhere to go but into the channels. But even without concrete, major floods are possible – the floods in ’38 occurred before the whole plain was concrete and the rivers were completely channelized.
Dan: So 1938 must have been a big El Niño year…
Rich: Pretty neutral, actually. Neither El Niño nor La Niña conditions were recorded that year. Another neutral year was the winter of 1966-67 – the Transverse Range got 30 inches in December of ’66. The Transverse Range got 30 inches in December of ’66.
Dan: So El Niños don’t coincide with flooding in the L.A. Basin?
Rich: The three spectacular El Niños we’ve seen this century have been 1940-1, 1982-3, and again in the past season [1997-8]. Not one of them caused extensive flooding in the basin.
February 18, 2015 § 1 Comment
Apologies for not posting anything here for a long time… then posting this puff-piece. I post daily over at Streetsblog L.A. these days, and just haven’t made the time to write a lot about the L.A. River, lately. Just to let folks know that my family and I are still around, and still enjoying the L.A. River, I am posting today with a couple of family photos taken on a family photoshoot yesterday. The photographer is Matt Grashaw who we highly recommend.
I think that the river looks pretty photogenic. The site is Bette Davis Picnic Area – the north end of Griffith Park, next to the recently-opened Glendale Narrows River Walk. See you down by the river.
November 1, 2014 § 4 Comments
Recently we have been having fun with creek freak real estate leads sent to us by Louisa Van Leer. From now on I will post the leads as they come, hoping other creek freaks in the community might be want to jump on creek side property, or pool efforts to make some stream-side amazingness happen.
This 10,000 ft2 lot on the North Branch of the Arroyo Seco is part of a steep hillside dotted with native walnuts. The slope leads down to the former stream bed right behind Aldama Elementary. The route of the North Branch can be viewed on this Google map.
The property and the adjacent undeveloped lot happen to make a lush backdrop for the concrete yard of Aldama Elementary. While millions are being spent on schoolyard greening projects elsewhere, one could imagine Aldama students might one day simply walk out an open gate into an extension of its schoolyard to access hands-on science and ecology fun in a native walnut grove. This greenery is already there.
Looking around, we found some mysterious notes, a tree which might possibly be making pecans, and numerous balls of all sorts. Poking one’s head into a culvert opening at the end of the lot, one can hear, deep underground in a pipe, the echos of the waters of the North Branch flowing toward Sycamore Grove Park and the Arroyo Seco.
October 24, 2014 § Leave a comment
When I passed this truck on the 210 freeway this afternoon, I wondered what watershed these huge pipe sections were destined for. I thought about all the rain gardens, bioswales, wetlands, stream restorations, urban parks, and urban biodiversity that could be created if we had spent the $$$ used for the digging of trenches and laying of such massive pipes on something that actually benefited the everyday quality of life of urban residents, that replenished local groundwater supplies so we can reduce our dependence on imported water, while nurturing native riparian and wetland biota, while improving the quality of water in our bays, while providing non-electronic entertainment for all the kids that live in parts of the city that otherwise have no easy access to parks, while still providing flood control benefits.
I wondered why we still invest in stormwater infrastructure that perpetuates a cycle of dependence on more infrastructure. Just like it has been shown that building more and wider freeways and roads results in stronger dependence on cars; adding more impermeable surfaces in a watershed (buildings, asphalt parking lots, roads) results in the need for increasingly extremist drainage infrastructure, like super gargantuan pipes…
Tell me these pipes are meant for something other than to convey one of our urban underground streams toward the ocean in a way that prevents their use by native biota, and which prevents us nature-starved city people from experiencing the physiological and public health and microclimate benefits that urban greenery provides. Tell me that these pipes are being transported because urban streams all over are being daylighted, and that using bigger and bigger pipes to convey a precious resource like water toward the ocean is recognized as a quaint part of our historical past. Tell me underground pipes are being replaced by wetlands, infiltration zones, and streams, and that the reuse of pipe sections that used to convey urban streams is now choice material for architecture for the homeless, where the thick concrete walls of pipes are perfect as thermal mass that creates passive climate control… or that these pipes are being reused as wildlife crossings under freeways…. or that sci-arc students are making them into the new modular architecture? pod hotels? something…..
August 25, 2014 § 2 Comments
Sorry to keep doing this – but I am writing full time over at Streetsblog L.A., and not much time left over for my extracurricular blogging at LACF. Check out this very Creek Freak article I posted today – about the city of Los Angeles getting close to purchasing Taylor Yard Parcel G2. This is , in my opinion, the single most important restoration site along the 51+miles of the L.A. River. I can remember Lewis MacAdams pushing for this site way back in the 1990s; Melanie Winter championing it for many many years. It looks like there’s a willing seller, and the parcel could be in public ownership, maybe by late 2014. Then, over time, it will be part of a 100+ acre park. Woot Wooooooot!!
The city is seeking public comment – see the SBLA article for details.
August 6, 2014 § 2 Comments
The city of Los Angeles is proceeding with demolition of the historic Riverside-Figueroa Bridge over the L.A. River. I’ve been covering this story over at Streetsblog Los Angeles, see today’s article featuring sad photographs showing the bridge being torn up. It makes me sad that this neighborhood-scale bridge is being torn down in favor of a freeway-scale bridge. In this earlier post, I called the project “nothing but zombie engineers fulfilling a now obsolete paean to the automobile.” I don’t think I can outdo that characterization today.
Water is a Living Archive: Examining myths of where various urban streams come from: Pt. 1: Kellogg Creek
July 2, 2014 § 3 Comments
Have you ever heard rumors that water in various urban streams in Los Angeles originates in significant part from irrigation runoff?
It’s true that car wash and irrigation runoff are often seen flowing into storm drains. Dry season (summer) is the time these activities are most likely to take place. In the case of the Los Angeles River, a good deal of the river’s dry season flow comes from point source discharges rather than groundwater: one report says this figure is about 80% (Arup, 2011). Point sources include storm drains which convey irrigation runoff and carwash runoff, but also effluent from wastewater treatment plants. Flow data collected in 2000-2001 by Stein and Ackerman (2007) indicated that on the average, half of dry season flow in the Los Angeles River originated as effluent from wastewater treatment plants and half from storm drains.
As Josh Link puts it, the Los Angeles River, the end of pipe destination for a good deal of imported tap water, is effectively a « Read the rest of this entry »