The approach of Hurricane Odile. This is an image of the Western Conus (Continental US) water vapor loop, taken at about 11:30 PM PDT on Monday, September 15, 2014. Courtesy of the National Weather Service, Las Vegas, Nevada.
Hurricane Odile formed in the Eastern Pacific Ocean south of the Baja Peninsula in early September 2014. It reached status as a Category 4 major hurricane before hitting landfall at the tip of Baja near Cabo San Lucas, where it dropped huge amounts of rain before weakening and continuing northwards up the rocky spine of the Baja Peninsula. In the image above you can see the eye is in the middle of the peninsula’s Vizcaino Region, with large amounts of clouds and moisture being pushed northwards into Arizona.
Western Conus water vapor loop image taken at 2:30 PM PDT on Tuesday, September 16, 2014, about 14 hours after the first image above.
The satellite image above depicts the progress of Odile northwards. The former eye, now a region of strong circulation that has dropped below tropical storm strength, has crossed the central Sea of Cortez and is entering the mainland of Sonora, Mexico. Of particular interest to this story is the patch of bright white clouds at the top edge of the cloud shield in northwestern Arizona, which has developed into the thunderstorm complex that will bring me the heaviest rain I’ve yet seen in nearly 20 years of me living here.
Western Conus scene of Odile, 90 minutes later, at 4:00 PM PDT on Tuesday September 16, 2014. The heaviest rain occurred between 3:15 PM and 3:45 PM, pretty much as the storm propagated westwards directly overhead at my ranch.
Note how the storms in northwestern Arizona have increased in less than two hours in areal extent and propagated westwards. Additional storm complexes have erupted in southern California, and just southwest of the Las Vegas metropolitan area, along the CA/NV border.
Western Conus image at 5:30 PDT, about 90 minutes after the prior one. Almost all of Arizona is now covered by dense clouds and has received at least some rain. Coverage was more sporadic farther west and north, but some of those areas got nabbed pretty hard as well.
Radar-estimated precipitation storm rainfall totals taken at 5:30 PM PDT on Tuesday September 16, 2018.
My ranch lies in the yellow band indicating 1.5 inches or so of rainfall, just above the second “a” in Havasu. Red zones just to my north and west appear to have received nearly double that quantity! It’s not just the quantity of rain, it was also the speed at which it fell. I received all of this precipitation within 30 minutes, making for a rate of about three inches per hour. This is true tropical downpour territory, and is a rare event for any single given location, especially in the desert, probably occurring only once every 10 to 20 years on average.
The pool that formed on the back patio area during the heavy rains of Hurricane Odile.
This area up against the back side of my house always floods in heavy rains. It drains off of the hillside in two main places (one visible in the background) and accumulates in the flat space that I will someday turn into a patio. The maximum depth of the water is about 4 inches before it runs around the edge of the foundation and drains away. My cement slab is elevated about 10 inches, so there is no danger of it coming inside the house. Still, it’s an issue I’ve been meaning to fix with better hydrological engineering and extra drain pipes, which I will eventually get to. After all, who wants a patio that gets covered in mud every time it rains?
Runoff from Odile coursing away downhill to the northeast.
This view out of my east window shows the water overflowing from the back side of the house in the photo above running away downhill through the garden and nursery pot area. I’d actually never seen that happen before – usually there isn’t enough rain fast enough to really cause this. It did cause annoying erosion that I would have to fix up later on by hauling new dirt in, but overall no real harm was done. I am glad that when I was building the house I foresaw this issue coming and made the cement foundation high enough to avoid it coming inside. Still, the drainage situation needs to be engineered a bit better regardless.
Once the rain had abated to a mere drizzle, it was time to go outside and check the rain gauge and inspect for damage. Here’s the gauge showing the 1.55 inches (40 mm) of rain that fell in just over a half hour.
Runoff from Odile flushing organic debris out of my disposal pit.
If I want to see actual running water in the desert, I have to get outdoors during the storm, or immediately after the rain ends. Streams here are strictly temporary and even the largest drainages with watersheds 50 miles long usually flow for no more than a few hours; smaller local drainages are less than that, only 5 to 20 minutes or so. But it’s such a unique sight that it’s worth getting a bit damp for.
The photo above shows a fair amount of water flowing through a borrow pit that I originally created to get sand from during the leveling of my home’s building pad, which required a bit of filling in before construction could commence. I then used the borrow pit to dump organic matter in – garden waste, dead cacti and agaves, kitchen compost, stones, all sorts of debris as long as it’s not human-manufactured trash. The intention was always to fill the pit with organic stuff, and then allow water to flood into it and deposit sand and mud to cover the debris up so that it could compost in place over time. I had built a small levee to divert the wash channel around the debris pit, but of course all the rain of Hurricane Norbert two weeks ago and now Odile proved far more than that little hand-shoveled levee could handle. It eroded away and the floodwater ran unopposed through the debris pit, rinsing some of the organic waste out and burying much of the rest in mud. Okay, I guess the accelerated time frame was unexpected, but I’ll just roll with it….
Water from Odile coursing down Alamo Road just past my driveway exit.
One benefit of Odile however was the second complete filling of my water basins in under two weeks. I covered the hydrodynamics of that in a post on Hurricane Norbert in the post linked below. The water flooding through the debris pit above enters the smaller basin, and the runoff from Alamo Road’s hard-packed surface supplies the larger basin. All of this water sheeting down the roadway is heading straight for my basins to help me recharge my aquifer. That’s exciting! (It was also the point of making the basins back in 2008.)
Uh oh.
Of course the benefit of the flooding with respect to groundwater recharge also came with an additional cost in this instance: Another dam breach. Technically, the dam was already breached from Hurricane Norbert’s rains 10 days before, but the damage was modest and not too worrisome. Now with the excessively strong deluge from Odile coming right on the heels of Norbert, the erosion problem was about ten times worse.
Major erosion exposing formerly buried water pipes, electrical cable, and valve infrastructure. The well shaft casing is threatened also.
The dam’s unintentional new spillway was now missing 7 to 8 cubic yards of soil, leaving a chasm two feet deep and 8 feet wide. Damn! This is going to be much harder to fix than the original damage from Norbert!
The new temporary river, flowing muddily past my solar panels.
To be honest, I was not really surprised at the dam blowout being much worse than what happened with Norbert. Norbert’s rains didn’t arrive as quickly – the two inches of precip I got there fell over the course of about 5 hours, not 30 minutes. Plus that was the first set of rains so the desert soil had been better able to absorb it since it was drier. But with the saturation level elevated from Norbert and with Odile’s rains arriving so much faster, it stood to reason that the dam would overflow much more vigorously and the trouble it caused would be worse.
Well. This is going to be a lot of trouble to fix.
The smaller basin filled again, for the second time in 10 days.
One casualty of the flooding and erosion.
This red barrel cactus (Ferocactus acanthodes) measured about 30 inches (75 cm) tall. It had been growing at the base of the dam where I planted it as a salvage rescue before the dam was ever even built circa 2000 or 2001. In 2008 when I excavated the flood basins and made the earthen dam, I was careful to not disturb the barrel. All that was fine until this flood. The torrent of water eroded the soil away from underneath the plant and the force of the water was strong enough to push the 75 lb cactus about 10 yards downstream, where it came to rest in the position shown here.
Based upon past experience with relocating older and larger cacti such as this barrel, I didn’t think it would be able to survive this kid of uprooting even if I were to try to replant it somewhere. They do tolerate some moving for sure, but the older and larger they are, the less resilient to transplanting they become. This is particularly true if it is a second or third move. I’d estimate that somewhere between 25% and 35% of ones this age die within 2 years of their initial move, and the rate goes up further with a second move.
Since this was an old and declining plant that had been transplanted once before, I figured that expending the effort on trying to rescue it was unlikely to pay off. So I wrote it off, took this memorial photo, and waited for its final curtain call. I ended up being correct – the trauma of the move and all the wetness and flooding of the storms made it decay and collapse in a rotten mess within a few months. By spring it was dead. I eventually covered up the dead spine network with more dirt when I finally fixed the dam breach in the summer of 2015. I tossed the barrel carcass into the gap and buried it for good. C’est la vie.
A photo of the red barrel discussed above during the flooding from Hurricane Norbert less then two weeks before. Note how close the new flood channel is to the base of the cactus. It’s only because the flooding and erosion from Norbert was less severe that the barrel didn’t die. But the much worse flooding from Odile took it out. I am sorry to see you go, red barrel. But nothing lives forever….
The barrel cactus wasn’t the only thing swept away by Odile’s flooding.
Additionally, there were more casualties from this particular event. Upstream of the smaller basin I had stored hundreds of nursery pots, stacked in the shade of a juniper tree on the banks of the wash channel. As with the red barrel, the force of the water and subsequent erosion were enough to sweep away several stacks of pots and disperse them downstream.
The majority of the pots were retained within the two flood basins, but a number of them had managed to be rinsed through the dam blowout and made a run for the Colorado River 35 miles away. Not all made it, and were instead stranded in the sand.
A couple of pots, one in the distance, dreaming of voyaging down the Colorado River all the way to the Sea Of Cortez 300 miles away.
Like I said, most of the pots remained trapped in the tangled thickets of catclaw acacia (Acacia greggii) and other vegetation growing on the banks of the flood basins. It’s a huge pain in the ass to extract pots out from under muddy catclaw shrubs. They’re accurately named catclaw for a reason. Slippery mud doesn’t help the clawing nature of these meanly spiny shrubs either.
About an hour later, the water in the debris pit had sunk away into the ground, leaving dead cactus parts scattered around. It took some time to gather all the debris back up and toss it back into the pit. Future floods would bury that too in 2015 and 2016. As was intended.
An alluvial fan of sand and mud sits in the lower basin coming off of Alamo Road.
The floods from Norbert and Odile deposited many tons of new mud and sand in the retention basins, which reduces water storage capacity and percolation speed. In July 2015 I would hire a bulldozer to ream out the sediments and use them to fix up the dam breach, fill in the eroded stream channel below the dam, and restore the water capacity of the system. I’ll probably need to do a cleanout every few years, depending upon how often the basins fill and how heavy the floods bringing in silt and sand are. But water harvesting remains one of my best ideas in living sustainably out here in the remote desert. 🙂