What happens to the snow in the spring?

reply to post by davespanners




Just buy some food, thats not such a tall order.

I'd hate to see it all float away on you

-G

reply to post by Gradius Maximus


nice video

Ok I will make sure I have plenty of tinned food and perhaps and inflatable boat for the end of winter! Plus booze lots and lots of booze

it doesn't just go from - 15 to +85 overnight, it gradually melts over weeks and gets soaked up by the ground or runs off into rivers.

the grass and trees use this water as nutrients to help them grow and get strong as the weather improves and there is more sunshine.

reply to post by rogerstigers

As others have said, it's a combination of factors. From my perspective here in Central Europe, there are a few key variables that determine if there'll be flooding during or after the snow melts:

-- average amounts of snow but rapid temp increase in spring: this can cause the snow to melt faster than most of the water can be absorbed by the ground.
-- average amounts of snow but a rainy spring: if we get above-average rainfall during the melt season then flooding is a distinct possibility. The rain itself hastens the melt and seriously increases runoff into catchment areas.
-- above-average snow and normal to above-average temperatures in spring, combined with plenty of rain: a very serious situation and almost guaranteed to cause serious flooding.

When analysis by our hydrology experts shows that the conditions for a spring-melt flood are likely, the flood gates at the dams are opened to lower reservoir levels. This often helps to reduce the flooding effects, but has negative impacts on locations down-river from us (mainly Germany).

This winter, it's way too early to say if we're facing a potential spring melt flood. Yes, we've had a fair amount of snow but we've had more in the past with no serious effects. And other times, we've had less snow but been hit by floods due to an extremely rapid melt combined with a very rainy spring.

Statistically, while January/February give us the most precipitation, our wettest months are in summer. In fact, the Czech's worst flood in the past 500 years occurred in the summer of 2002. The 2001/2002 winter was around normal but as the snow melt had already saturated the ground in spring, when heavy rains hit in August most of the water ran off and the floods were very extensive and devastating.

So, it's not just the snow melt that we have to be concerned about, but its possible influence even months later.

Mike

In 1997, Reno Nevada had to deal with that unusual combination.
HUGE snowfall
Followed by unseasonably warm temperatures.
Accompanied by steady rainfall.

Normally, the snow collects, then melts slowly. We have reservoirs that capture that.
If they get full...Some water is released. The cycle repeats until winter is over. Then we use that water for all the usual purposes. Drinking, flushing, watering lawns. throughout the dry season.
the hope is for Lots of snow..And an easing into spring with a slow melt. good snowpack can carry us into the next year.

Back to 1997.

We had an awesome snow pack. Way above normal. But no one expected the warm weather.
We lost the whole snow pack. Lots of homes and businesses. A few human lives, and many livestock.
And it would not stop raining. 4 or 5 days of medium to heavy rain.
We're a desert!

I lived near the airport at time. the entire airport was flooded, and we were just a few feet higher in elevation.
the floodwaters came all the way to my backyard..but never made it into the yard. We were lucky. Other's weren't so lucky.

10,000 years earlier. At the end of the last glacial period, the floods were different.
Ice dams would form upstream. HUGE natural dams. That would hold billions and billions of gallons of water.
In the spring...The dams would burst. Causing biblical sized deluges. There is evidence all over, in the form of Giant boulders that look completely out of place. They are..They belong 20 or 30 miles upstream.

This year, is good...A little snow, a melt, more snow, more melt. But nothing out of the ordinary.

Here in the UK, the amount of water in the snow we have at the moment is nothing compared to the amount of rainfall we often get. If there is a sudden rise in temperature causing rapid melting, there could be some localised flooding as river levels rise but nothing out of the ordinary.

Originally posted by davespanners
I just realised that I don;t really have too much to worry about as I'm on the "good" side of the Thames Barrier.
I fell pretty sorry for those on the other side though

[atsimg]http://files.abovetopsecret.com/images/member/020b545496fa.jpg[/atsimg]

The Thames Barrier is to protect the Thames Valley from flooding due to storm surges in the North Sea. Not gonna help in the envent of increased river water levels.

Originally posted by randomname
it doesn't just go from - 15 to +85 overnight, it gradually melts over weeks and gets soaked up by the ground or runs off into rivers.

It only needs to go from 30 to 40F which can happen in a few hours, and add some direct sun and a whole lot of snow can melt quickly.

My next door neighbor's lot didn't have drainage as good as my lot and when we had a large rapid snow melt on the big hill above our street, his basement got completely flooded, it can happen. My basement probably would have flooded too but I had extra grading done on the lot to improve drainage before I moved in.

Originally posted by Whereweheaded
It melts?

LOL that is funny.

We can get flooding here in the spring even if we don't have a lot of snow. Snow north and melting into the Mississippi river can cause flooding a couple of states away. I was raised in east Tennessee and the mountain creeks and streams were always so clear in early spring with the melting snow. Really, really pretty area of the country