Ok, I gotta bounce this one off of you guys. What is your take on the dark filled area on this FIS Profile? Is it the flood thats contained within the culvert?
Here's the FIS profile:
and here's the FIRM:
thanks
my wild-arse guess is that it is supposed to represent the floodway. i just looked at some of our FIS's and saw very few with that and none had any explaination.
call your local FEMA office and ask them.
It appears to be what is termed the "hydraulic grade line" of the water contained/flowing in the culvert.
> It appears to be what is termed the "hydraulic grade line" of the water contained/flowing in the culvert.
That was my first (well only) guess; although I haven't dealt with or computed an HGL since taking the Maryland state specific exam in October of 2004.
The dark area is the 'ground cover' over the culverts. Look how the 1% chance flood 'ponds'.
DDSM;-)
It appears to be someone's graphed hydraulic calculations.:-S
A change in Direction
Hey there I played in Cobbs Creek when I was growing up. You are talking a very urban environment there. As I recall the Marshall Road area is frequently flooded.
You can see the 10% annual chance flood parallel to the channel bottom and the 0.2%, 1% and 2% chance floods more or less level after Hampton Road with a big drop at the culvert outlet. From the maps this appears to be a lengthy underground conduit which largely follows South 69th Street. The conduit throttles the stream flow which is why the HGLs drop significantly at the outlet.
I couldn't tell you what the black means. Maybe head pressure inside the conduit? I'm not sure.