Alright, the only funny/amusing thing I have thought about so far is that, when I was the city Drainage Engineer, the men on the crews called me the “Ditch Witch”. heh.
Most anectodes come from the old gray heads, the folks who have been there a lot longer than I have and have probably forgotten more than I’ll ever know about the science.
Once upon a time, my colleague James worked for the USGS (James is almost 80 now). One of the things they did was to go out and measure flood flows. A common method was to walk along the flooded bridge and take flow measurements every so-often-feet. This one day, one of those South Mississippi rivers was flooding; and James went with a colleague to measure flood flows across the bridge deck. Their method was to have a man walking in front of the pickup truck, taking measurements while the vehicle followed.
This river was flooding pretty good, and the water was a bit high in the roadway. James was the one walking out front with the flow-meter, he remembers the truck driver being very nervous. At any rate, they get about 2/3rds of the way across the road, and the driver convinced James to get in the truck and head for dry land.
As the truck got out of the water and began up the approach, James turned back to look at the bridge. Two spans were gone.
Turns out, the floodwaters had scoured a hole beneath the bridge which ultimately undermined the pilings, which caused two sections to fall. There were 2 MDOT employees standing there at the time.
Their bodies were never found.
The scour hole was measured later by divers, as about 60 ft deep and 60 ft across. This was after silt/sand had filled it in. The USGS estimates that the hole at the time of bridge failure was 2 to 3 times that size.
Did you have to change carriers, to an insurer called the Connecticut FAIR Plan? If your previous carrier had decided to get out of insuring coastal and near-coastal property, and no other insurance company in the voluntary market* was willing to pick you up, then your agent would have to put you in that plan to get coverage for you.
A lot of Northeast insurance companies have cut back on insuring coastal properties, or exited the market altogether, after seeing what Katrina did. We don’t often get hurricanes up here, but it does happen, and they can wreak tremendous havoc when they do make landfall, not least because our coast is so densely built up.
The voluntary insurance market is the pool of insureds that the carriers are willing to write coverage for on whatever underwriting terms they decide to offer (as governed by state regulations). The mandatory market (FAIR Plan or whatever a particular state calls it) is for those folks who can’t get insurance otherwise; the rates and terms are set by the state’s insurance regulatory department.
For you it would be the Dane County Board of Supervisors. Whomever your county/zone/parrish muckety mucks are. It’s my own gut feeling that Lake Delton allowed their participation in the NFIP to lapse because it saved a certain mega resort a bucketload of cash not to have to purchase commerical flood insurance. This is nothing more than crazy tinfoil hattedness on my part though.
Interesting, my building and the one next to it are Zone X but the entire surrounding area is AE. My alley is listed as a Flood encroachment something or other, it’s got blue polka sots on it, I think I’ll park the motorcycle in the front of the house next time it rains
Sounds like the buildings are up on pads of fill, which makes them out of the 100-year.
There are two Zone X designations: one is the 500-year floodplain and the other is either ‘not studied’ or ‘not a flood risk area’. Clear as mud, I know.
Those darn polka sots! Always with their beer and polkas!
I heard that the current flood is a “500 year flood.” As you explained above, a 100 year flood is a flood that has a 1% chance of occuring each year, what is the yearly percentage chance of a 500 year flood?
Also, what do you think of the theory that agriculture is responsible for altering the landscape thus making the areas in Iowa more prone to flooding than they would be otherwise?
Mods, if I’m resurrecting a dead thread I apologize. I wanted to ask the other day but didn’t have time.
0.2%. Divide 1 by 500. That works for all frequencies - Example: what’s the probability of the 25-year flood occuring in any given year? A: 1/25, which is 4%. The 10-year? 1/10, which is 10%.
I’ve heard it just recently, but haven’t delved into the information. Before the '93 floods, were there other large floods? How much has gone from woodlands to plowed field, and when? For example, if Iowa land has been put into agricultural use since the 1950’s, and we have a large event in '93 and another in '08, then agriculture is not likely to be the culprit. I am very curious about it.
I think this falls under the category of ‘new information’ but I’m not sure. We can start a new one if need be - but it would be handy to have all the posts in one thread.
mmouse, after thinking on this a bit I want to clarify something. The change in land use can cause changes in the peak flow; but the rainfall is unaffected by that. So, whatever changes occured in land use in Iowa wouldn’t have anything to do with the extreme amount of rain which fell in WI and IA in this flood.
Adding a couple of links to other pertinent threads:
