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Old 05-05-2013, 11:16 PM
 
741 posts, read 1,483,639 times
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Quote:
Originally Posted by DaninEGF View Post
Hi I enjoy and look forward to your posts....

This issue has been debated a lot of course. One of many issues includes the data ingested into the River Forecast Center's river models need to be entered with a specific format....so that it can be read by the program. The river modeling is all done on computers using current conditions....modeled into their system.

What is needed is a much denser network of observers who will do snow core water measurements. There are very very very few out there....and not nearly enough to get a good spatial representation to current conditions. Thus what is ingested into the river models is modeled snow water as read by remote sensing (satellites). Sometimes they are too high/low. Also when frost probes say the frost is xx deep....the models read that to mean nothing will infiltrate down. It appears that dry ground freezing can accept much more liquid than a wet frozen ground. But in the modeling world it is yes/no and not maybe.

Thus when you have unusual circumstances such as 2013 with the very late melt the usual modeled data ingested can be in error as it turned out this year.

The entire NWS observation system is being cut very severely right now....there are cooperative observers who form the backbone of the climate network who for years have done daily temps/precip records and they are paid monthly for their services and dedication as they must do it daily or if they are gone have someone else come and do it. But with budget cutbacks at NWS....paid observers may be on the way out. Also snow paid observers may be cut too. Like in Fargo....the ASOS at Fargo Hector Airport is the where the climate data for fargo is kept. ASOS doesnt measure snow and has a very hard time measuring liquid equivalent in the snow as wind often blows the snow and thus misses the catch. Thus for Fargo we depend on a snow paid observer who happens to be the cooperative observer in North Moorhead. He is close enough to the airport to count so we can use his snow/water for the Fargo climate. He is paid additionally for every 6 hour snow report he makes. If he is not paid. he will likely quit. Thus the real possibility in the future of losing snowfall data for Fargo for climate purposes. For official climate purposes you must have a 12 UTC report. The FAA forbids tower personnel from going outside and doing any measurements.

Thus without paid observers we are left at trying to recruit volunteer dedicated observers who would do snow core water readings each Monday Jan-Mar period. Some water shed districts have them in Minnesota....but not in North Dakota.

So what I am saying the farmers may feel like there will be no flood from what they see....but there is no way to turn what they feel into a specific numerical number for input into the river models.

Dan
Some of my extended family might actually be interested in being a volunteer observer for those months: maybe you could forward a contact.

Guess what I'm saying is that model isn't comprehensive enough. For example, in the Red River Valley, there is a lot of gumbo soil. During a dry summer like last year, there get to be cracks that go down like 10 feet. Without fall rain, there essentially is no runoff in those areas, as gumbo soil almost self-corrects for drought: the cracks don't allow run off until the cracks in the frozen gumbo are bull. Another example is dry/silty soil: when it is dry is just doesn't freeze up solid like rock in the winter as there isn't enough moisture to keep the sand particles frozen together. Therefore, little runoff occurs because it can infiltrate that type soil. In areas where there is a huge slope to land, the soil type isn't that important, but in flat lands where water has more potential to seep, soil type (including dryness and if it is frozen) is hugely important.

I've actually done environmental modeling for pollutants and contaminants (both long term degradation and short term plumes), so am aware of the shortcomings of almost all models. What matters in one topography/environment is inconsequential elsewhere and vice versa. A model has to be extremely rigorous for it in most cases for the model to predict within 10% at any area within the model. Within 50% is actually pretty good and for a flood that doesn't reflect flood height but cubic feet of flow for the river.
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Old 05-06-2013, 12:29 AM
 
Location: E ND & NW MN
4,731 posts, read 9,087,263 times
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Quote:
Originally Posted by fourwinds View Post
Some of my extended family might actually be interested in being a volunteer observer for those months: maybe you could forward a contact.

Guess what I'm saying is that model isn't comprehensive enough. For example, in the Red River Valley, there is a lot of gumbo soil. During a dry summer like last year, there get to be cracks that go down like 10 feet. Without fall rain, there essentially is no runoff in those areas, as gumbo soil almost self-corrects for drought: the cracks don't allow run off until the cracks in the frozen gumbo are bull. Another example is dry/silty soil: when it is dry is just doesn't freeze up solid like rock in the winter as there isn't enough moisture to keep the sand particles frozen together. Therefore, little runoff occurs because it can infiltrate that type soil. In areas where there is a huge slope to land, the soil type isn't that important, but in flat lands where water has more potential to seep, soil type (including dryness and if it is frozen) is hugely important.

I've actually done environmental modeling for pollutants and contaminants (both long term degradation and short term plumes), so am aware of the shortcomings of almost all models. What matters in one topography/environment is inconsequential elsewhere and vice versa. A model has to be extremely rigorous for it in most cases for the model to predict within 10% at any area within the model. Within 50% is actually pretty good and for a flood that doesn't reflect flood height but cubic feet of flow for the river.
Great info....I sent you a PM...

Dan
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