10 ms·
I like what you're trying to accomplish, but you are missing a very helpful piece of information in your analysis. I'm sure you noticed how poor of a predictor
by kolbe 10y ago
I like what you're trying to accomplish, but you are missing a very helpful piece of information in your analysis. I'm sure you noticed how poor of a predictor rain fall is in your assessment of how much water will be added to Lake Oroville. This is largely because Oroville is filled from Sierra Nevada runoff. If a particular storm system is warm (as was the case with the latest one), it will mostly rain in the Sierras. This has a twofold effect: one, the precipitation doesn't stay put at higher elevations (as snow does), and two, it melts the existing snow, causing it to also be added to the downstream water accumulation. So a key part of forecasting is not only to look at expected precipitation, but also the expected snow levels.
- lightedman 10y agoAnd the expected temperature of the falling precipitation, and a whole lot of other meteorological stuff which is involved, so in reality this dataset, while admirable for effort, is really useless as there are way, way, way too many unaccounted-for variables.
- sverige 10y agoIf I'm reading the data correctly, there is no snowpack above Lake Oroville right now, so it's all about rain at this point. https://www.wcc.nrcs.usda.gov/snow/ https://www.wcc.nrcs.usda.gov/snow/
- kolbe 10y agoI'm having trouble pulling that map up, but I believe there's snowpack at 5500' and above right now, and there's a huge amount of land upstream of Lake Oroville that is above 5500'. My data is this: here's an Instagram tagged at Emigrant Gap (5200') taken four days ago. https://www.instagram.com/p/BQYzN3sA76u/ https://www.instagram.com/p/BQYzN3sA76u/
- mturmon 10y agoOroville itself is at 900 feet altitude, but the Oroville watershed extends into the Sierra Nevadas, including alpine valleys at 5000 feet. The Sierras have record snowpack this year (150 inches in places, so I hear). Approximate watershed is seen in the map at: https://en.wikipedia.org/wiki/Feather_River https://en.wikipedia.org/wiki/Feather_River
- stuckagain 10y agoI'm not sure where the snow is but it's not at 5000' in Plumas County this year. The ski and snowmobile club in La Porte is closed for lack of snow.
- deleted 10y ago[deleted]
- andys627 10y agoThere isn't any snow left below 5,000 feet. Source: I'm in Reno at 4,415 feet.
- rconti 10y agoOroville is both north and west of where you are. Significant rain shadowing occurs east of the Sierra. and I think the "5000ft high" watershed number for Oroville may be low.
- andys627 10y agoYep all true. There's probably not any snow below even _6,000 or 7,000ft_ in the Sierras right now because the last storm, which was warm/rainy, melted it. This is another reason why the next storm won't put as much water into the reservoir.
- shoyer 10y agoLooking at the map from the page you link to, I see significant amounts of snowpack at the stations above Lake Oroville: https://www.wcc.nrcs.usda.gov/webmap_beta/index.html#version=76&elements=&networks=!&states=!&counties=!&hucs=&minElevation=&maxElevation=&elementSelectType=all&activeOnly=true&activeForecastPointsOnly=false&hucLabels=false&hucParameterLabels=false&stationLabels=&overlays=&hucOverlays=&mode=data&openSections=dataElement,parameter,date,basin,elements,location,networks&controlsOpen=true&popup=FOR:CA:MSNT&base=esriNgwm&displayType=station&basinType=6&dataElement=WTEQ¶meter=PCTMED&frequency=DAILY&duration=I&customDuration=&dayPart=E&year=2017&month=2&day=14&monthPart=E&forecastPubMonth=2&forecastPubDay=1&forecastExceedance=50&seqColor=1&divColor=3&scaleType=D&scaleMin=&scaleMax=&referencePeriodType=POR&referenceBegin=1981&referenceEnd=2010&minimumYears=20&hucAssociations=true&lat=39.6279&lon=-120.8098&zoom=9 https://www.wcc.nrcs.usda.gov/webmap_beta/index.html#version... We see the same thing in NOAA's regional snow analysis maps: https://www.nohrsc.noaa.gov/nsa/?region=Sierras https://www.nohrsc.noaa.gov/nsa/?region=Sierras
- mturmon 10y agoThanks. This data seems to settle it - I'm seeing 20, 30, 40 inches at various sites within the watershed, at elevations from 5150 feet to 6800 feet.
- rodionos 10y agoThanks for the suggestion. We had a discussion internally as to why inflows are higher this seasons compared to previous periods with comparable precipitation levels. We thought it might be due a multiple storms this season or because of discharges from the upstream reservoirs. The timespan we used in the SQL query calculates the inflow/precipitation ratio based on the last few weeks and we use that as an input into the estimate.
- Obi_Juan_Kenobi 10y agoThe 1997 flooding in CA was mostly due to this issue of warm rain + snowmelt, so searching around for information about that might be good. This guy seems to have testified about this flooding damage and claims 30 inches of rain around Oroville, with 18 inches of coincident melting, thus exceeding their worst-case scenario. https://www.youtube.com/watch?v=z_fOdaNTppI&feature=youtu.be&t=7991 https://www.youtube.com/watch?v=z_fOdaNTppI&feature=youtu.be...
- eternalban 10y agoI could find one instance of a word beginning with "ero". An article elsewhere was highlighting the possibility of catastrophic erosion. Outflow rates should have an associated catastrophic failure probability estimate and then we can get a realistic cap on sustained outflows.
- manarth 10y agoOutflow rates should have an associated catastrophic failure probability estimate The emergency spillway was originally rated for 350,000 cfs (cubic feet per second), but when it came into use, the erosion started causing a risk of catastrophic failure at just 6,000 - 12,000 cfs (this is what prompted the evacuation order, and the re-opening of the primary spillway to its capacity). The catastrophic failure probability estimates simply haven't stood up to real-world testing.
- BurningFrog 10y agoThat's how the 1997 flood of Reno happened. https://www.youtube.com/watch?v=0bisSuBAvaQ https://www.youtube.com/watch?v=0bisSuBAvaQ
- vhost- 10y agoI was young, but I was there and remember it well. That flood was crazy. I remember being boxed in with my uncle and he had to do some crazy stuff to his truck's air intake on the fly just so we could get through a deep puddle and out of the box. In retrospect, we probably shouldn't have driven through deep water.
- takk309 10y agoThe analyses do not appear to take the size of the watershed into account either. A large watershed drains into this reservoir. As such, distant storms can still have a large impact on the water levels. Time to concentration (the amount of time it takes for water to flow through the watershed) will play a large roll in the inflow rate.
- barney54 10y agoAs I understand it, the size of the watershed is known. Here's an estimate from a couple days ago: https://twitter.com/RyanMaue/status/831182017685495813 https://twitter.com/RyanMaue/status/831182017685495813
- Dav3xor 10y agoIt is. The story of modern GIS systems is mostly about figuring out who dumped what <choose your own chlorinated organic compound> into a river.
- izend 10y agoThis is exactly what happen in the 2013 Alberta Floods, lots of rain on deep snowpack upstream of Calgary. https://en.wikipedia.org/wiki/2013_Alberta_floods#Meteorology https://en.wikipedia.org/wiki/2013_Alberta_floods#Meteorolog...
- ransom1538 10y ago"I'm sure you noticed how poor of a predictor rain fall is in your assessment of how much water will be added to Lake Oroville." Having worked in hydrology (in forecasting) for a year out of college -- yeah -- you might as well use tea leaves and Tarot cards. People can't even predict weather. Let alone: Snowpack + weather.
- saosebastiao 10y agoI'm not trying to diminish how difficult it is to get precise estimates...but how precise do you need? A 1ft rise in water levels is almost 5 billion gallons of water. That's a pretty big margin for error.
- Symbiote 10y agoThe watershed for Lake Oroville is 9350 km² [1]. 5 billion gallons / 9350 km² is just 2mm. If that fell in one hour, the flow into the lake would be 5200 m³/s, except it would be lower since it takes time for the water to reach the lake. The normal flow of the spillway is 4200 m³/s. Have I done something wrong here, or missed something obvious? 2mm/hr is a pretty moderate rain. [1] https://en.wikipedia.org/wiki/Lake_Oroville https://en.wikipedia.org/wiki/Lake_Oroville
- tbabb 10y agoWell, not all of it would go directly to the lake, for one. It would seep in to the ground, re-evaporate, etc.
- Filligree 10y agoNot all the water (normally!) makes it to the lake, and the average rain over time is probably less than that. Otherwise, no, the math looks fine, but this is why the reservoir is useful as a flood-control system. It can take the fairly large flow caused by even moderate rain, and spread it out over time. Things get iffy once you have heavy rain for long enough that the soil saturates.
- ransom1538 10y ago
- kordless 10y agoI would note, as one example, the ground saturation is insane. I have a sloped backyard in Moraga, CA that goes to a creek which has been running non-stop since the first rains. It's been 3 days of sun and the ground is squishy and it's totally damp under the house. Pre-existing ground saturation will play a part in how fast the rain gets to the lake.