When doesn't a watershed work?
OK, so everyone seems to be good with the concept that water moves downhill. But there's one thing I didn't mention, a key assumption we use when we take the watershed as our study unit, and it can throw a monkey wrench in the whole idea of a watershed boundary.
Today we got a first look underground - in the field digging in the soil - and way underground as Ivan Fernandez told us about bedrock and surficial geology.
That's the hint - can you figure out where we might be missing some water and leaking some of our study chemicals out of the watershed, without us even realizing?
Today we got a first look underground - in the field digging in the soil - and way underground as Ivan Fernandez told us about bedrock and surficial geology.
That's the hint - can you figure out where we might be missing some water and leaking some of our study chemicals out of the watershed, without us even realizing?
5 Comments:
I'm not completely sure of this, but i think what Sarah is trying to gt at is that water moves not only over the layer of organic soil and over the litter, but there is also groundwater -- the water that naturally runs underneath the organic soil layer -- and this could also have a significant amount of mercury which could be affecting our watershed. Was I close to understanding?
By Rhyan Ahearn, At January 11, 2007 9:01 AM
I think that possibly some chemicals from our watershed could be below the top layer of soil or it could be leached out of the top layer. Also some water stays in the soil. Soil we learned was 25% water so if some of that is below where we got our samples we would be missing any chemicals that would be there. Also the groundwater could contain mercury and where it's underneath the ground it could flow differently than any water we get above the ground so we could be missing some there.
By Ashley Chenevert, At January 11, 2007 9:09 AM
I think Rhyan is right about groundwater. If it's not groundwater we're leaving out, it's the fact that the relief of the bedrock may very well be different from that of the topography. "I think it might be a little of both" as Ken would say.
By Natalie Jimenez, At January 11, 2007 7:23 PM
I think that the water that runs in a stream isnt chemically similar on the smallest levels. I mean sure its water but it doesnt have the same amount of things done to it as the water that meanders through the bear poop beaver fever and humans sloshing about in it. So what it comes down to is that it seems that the water underground is protected from a decent amount if not most of the problems that an above ground river has to face.
By Jordan Dolan, At January 11, 2007 7:29 PM
Nice job, Rhyan! You got it - groundwater is sometimes out of sight, out of mind, but there's water down there that doesn't respect our watershed boundaries. Although groundwater usually (roughly) follows the lay of the land (although it's a bit less pronounced as far as high and low points), there is also regional groundwater flow, so groundwater can travel long distances in different types of bedrock and surficial geology. At Acadia, all those fractures and cracks in the granite bedrock can be worrisome - water doesn't penetrate the solid parts of the granite much, but it can travel through those cracks very easily.
Also Jordan points out that the chemical makeup of groundwater may be different than surface water like lakes and streams. Is there a lot of mercury in groundwater? Maybe you can find out on the USGS fact sheet Bill posted the other day? And maybe that ties in to the Poland Spring question...hmmm...
By Sarah Nelson, At January 11, 2007 7:36 PM
Post a Comment
<< Home