Most of the flooding took place in flood zones that were 100 yr, so that really doesn't help much. 100 yr used to be fairly good. Sooner or later, FEMA will have to update zones
Very little of Detroit falls into a FEMA high or moderate risk flood zone. The June event was a pluvial flood, which is not indicated by FEMA flood maps. A 100-year rain fall does not mean that you will only experience that amount of rain once every 100 years. A lot of misunderstanding of that statistic out there.
I used to work for Floodzones, inc. We were a division of TransUnion. I was tech support in the mapping division. I worked with one of the GIS guys who created the maps that were used by FEMA. We were instrumental in issuing flood certs for use in real estate transactions. Flood zones change over time due to a lot of factors, some of them being amount of paving in a given area, number of houses/buildings being built; if the paving isn't offset by creating retention areas, you will get more flooding over a period of time because there is no place for water, be it rainfall or rising rivers, to run off to. If a community doesn't adhere to the FEMA standards, that community can be refused flood ins until they are in spec
Very little of Detroit falls into a FEMA high or moderate risk flood zone. The June event was a pluvial flood, which is not indicated by FEMA flood maps. A 100-year rain fall does not mean that you will only experience that amount of rain once every 100 years. A lot of misunderstanding of that statistic out there.
Last edited by jcole; August-05-21 at 11:12 AM.
IIRC, most of Detroit is zone X, which is defined by FEMA as:
B and X [[shaded) Area of moderate flood hazard, usually the area between the limits of the 100‐year and 500‐year floods. B Zones are also used to designate base floodplains of lesser hazards, such as areas protected by levees from 100‐year flood, or shallow flooding areas with average depths of less than one foot or drainage areas less than 1 square mile.
Some parts of Detroit, especially near the canals, are AE:
A: Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life ofa 30‐year mortgage. Because detailed analyses are not performed for such areas; no depths or base flood elevations are shown within these zones.
AE: The base floodplain where base flood elevations are provided. AE Zones are now used on new format FIRMs instead of A1‐A30 Zones.
A1‐30: These are known as numbered A Zones [[e.g., A7 or A14). This is the base flood plain where the FIRM shows a BFE [[old format).
Here is an elevation map of Detroit. This should give everyone an idea which parts of the city [and Pointes] are more prone to flooding. The "Hill" area of Grosse Pointe Farms is safe from flooding, but the rest of the Pointes are less so. Ditto for the canal areas of the lower east side of Detroit.
Here it comes again.
Over 500,000 DTE customers in the dark, nearly a quarter of their total customers.
Do these flood zones apply to pluvial flooding?IIRC, most of Detroit is zone X, which is defined by FEMA as:
B and X [[shaded) Area of moderate flood hazard, usually the area between the limits of the 100‐year and 500‐year floods. B Zones are also used to designate base floodplains of lesser hazards, such as areas protected by levees from 100‐year flood, or shallow flooding areas with average depths of less than one foot or drainage areas less than 1 square mile.
Some parts of Detroit, especially near the canals, are AE:
A: Areas with a 1% annual chance of flooding and a 26% chance of flooding over the life ofa 30‐year mortgage. Because detailed analyses are not performed for such areas; no depths or base flood elevations are shown within these zones.
AE: The base floodplain where base flood elevations are provided. AE Zones are now used on new format FIRMs instead of A1‐A30 Zones.
A1‐30: These are known as numbered A Zones [[e.g., A7 or A14). This is the base flood plain where the FIRM shows a BFE [[old format).
Get used to act of God and global climate change. Because they will be more storms on the way.
Video shows roads, freeways flooded in Metro Detroit on Aug. 12, 2021
Thunderstorms with heavy rainfall caused flooding overnight and into the early morning Thursday across Metro Detroit. This video shows some of the flooded areas on roads and freeways.
Dearborn Heights residents among those hard-hit in another bout of extreme weather
Meanwhile, here in Las Vegas, we've had 1.8 inches of rain for the entire year so far.
'There's definitely been a change.' DTE preparing for increasing storm events
Another round of storms, another round of damage. High winds brought down trees and branches across metro Detroit, falling on power lines and even on homes. “We heard some cracking going on and then the tree started falling very slow over the house,” said Kaelynn Euseary, who lives in Oak Park.
Most of SE Michigan was in a flood zone prior to industrialization. Paving over then building on flood plains such as the Ecorse creek, Bear creek, Red Run, Roulo creek, Baby creek, Parents creek, Bloody Run, Campbell creek, Plum Creek, and much of the Rouge river was probably not the best long term urban strategy. In addition to draining off large marshes, peat bogs and swamps, all of this created conditions ripe for massive flooding we see today. No matter how many drainage systems are built, those systems will never replace what nature provided in the first place.
Day 6 without power
Yes, sorry about that Jcole... especially the first 4 days have had brutal heat... finally cooled down starting the weekend.
Here in St. Clair Shores, about 10% of the homeowners now own a generator. People are just so tired of the outages from the past.
It's kind of weird during an outage to hear what sounds like a large group of lawn mowers running, but actually are people using their generators.
Came back up last night; we were able to borrow a generator from my SIL for a few days but Gistok is right, the heat the first few days was brutal. Never looked forward to work so much as last Thurs. The library had air, ice and coffee. Now I have internet but no cable TV. Borrowed an HD antenna and can pick up all the locals tho, so at least we have background noise aside from the generator now. Life could be worse
^Jcole, about 5 years ago we had a 4 day DTE outage in my neighborhood of SCS. The subdivision that borders me across the street did not. So my kind neighbor [whose garage faces my house] let me connect a 150 ft. extension cord across the street to his garage.
Yes cars/trucks drove across the extension cord continuously but it didn't hurt my cord or connection.
It was spring... and I had enough juice to power my refrigerator, my computer/TV [in my bedroom] and one light. It did the trick.
Most of the "flooded" homes weren't really flooded. It was sewer backflow through their basement floor drains.
The sewerage system you guys have is a travesty.
https://www.detroitnews.com/story/ne...ne/5619216001/
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