Hurricane Harvey

[Brat]

And to the people that do not know.... Houston has it designed this way.... flood the streets to protect the houses....

You can put a lot of water in streets... our house has to be 3 feet above street level... so there had to be much more flooding before I worry.... also, we do not have water in our streets as we are probably 15 or so feet higher than surrounding neighborhoods.... it pays to buy in the correct location....

Absolutely, but how many home buyers consider that?

 

[LOL!]

[Houston is experiencing 3rd 500-year (0.2% probability) flood in recent years, how possible?

It is possible because Houston is a huge city. When one little part of the city experiences a 0.2% probability flood many of the other parts may not get a drop of rain or have a 2% probability flood. So 3 floods spread around to different places is very possible.

With Harvey, many (but not all) places are experiencing the 0.2% probability flood.

I see that many bayous have receded by 10 feet or more today. And note that "receded by 10 feet" does not mean they are now within their banks.

 

[KB]

Just thought I'd provide an "on the ground" report from New Orleans. Some people have expressed concern since apparently a few models have Harvey heading towards us so I thought some might be interested.

Thanks for the update, I've been wondering how this storm was effecting you.

 

[txtig]

Our neighborhood is one of the few along the Brazos River in Fort Bend County that is not included in the mandatory evacuation order you are referring to. We are under a voluntary evacuation order, although we are being encouraged to leave. They are expecting the river to crest at a level that is less than one foot below the top of our levee. Too close for comfort. We are staying, because, as pointed out above, there is really no where for us to go.

If all goes well, the levees will hold and we will not flood. But, for the next 4 or 5 days, we would be locked in the neighborhood, as as roads outside of the levee will flood. We have a two story home, so we have an escape route by going upstairs if the levees don't hold or if they are overtopped. We have been preparing all day today by moving key possessions upstairs and prepping a five day supply of food and water for upstairs. Keeping my fingers crossed!!

The National Weather Service has lowered its projection for the crest of the Brazos River in Fort Bend County from 59' to 57.5'. It has also decreased the duration that the river will stay at this level from five days to just over one day. This should make a huge difference in lowering the possibility of a levee failure. I am beginning to feel a lot better about my decision to ignore the voluntary evacuation order.

 

[Ronstar]

You have to wonder what the meaning of 100 or 500 year floods are if they're occurring every decade or two. Clearly, these terms have to be re-evaluated.

A 100 year flood is an event that has a 1% chance of happening within a given year. A 500 year flood is one that has a 0.2% chance of happening in a given year. They probably should have named them something less confusing. Most people think a 100 year flood happens once every 100 years since the name somewhat implies it.

 

[RobbieB]

Google is matching donations now to a million.

 

[lemming]

just fyi Washington Post has suspended its paywall/number of free articles during the hurricane crisis

 

[W2R]

update to the update

Thanks for the update, I've been wondering how this storm was effecting you.

Update to the update: The outlook is greatly improved here in New Orleans. It has only rained lightly, and sometimes not at all, this afternoon. The rain is moderate right now and the total rainfall so far today is about 3". There is a wind advisory for winds gusting up to 35 mph. That bright red line of storms on the radar never arrived here and seems to be gone. We even went out to lunch, and the roads were dryer than they were yesterday. Schools will resume tomorrow, all public buildings will re-open, and the predicted rainfall has gone down to 6-8 inches here between now and Friday.

 

[aja8888]

3" of rain in NO doesn't even get the dust off the streets. Great to hear!

 

[W2R]

3" of rain in NO doesn't even get the dust off the streets. Great to hear!

Exactly!! I am so relieved. Worried about Texas, though. I sure hope for the best for you and everyone going through this catastrophe in Texas right now.

 

[Fermion]

A 100 year flood is an event that has a 1% chance of happening within a given year. A 500 year flood is one that has a 0.2% chance of happening in a given year. They probably should have named them something less confusing. Most people think a 100 year flood happens once every 100 years since the name somewhat implies it.

I guess they thought that if they named the event the 1% flood, people would think it was a rich person's problem.

 

[meierlde]

For those who want to know how flood recurrence intervals are determined here is a link to a class exercise on them: Index2Flood Recurrence.pdf

Basically you plot on a semi log plot with the log scale for years and discharge of a stream as linear scale the set of all discharges you have and the time between the flood (discharge noted) and the next one. Then you draw a line thru the scattered points and you can read the line at the number of years (or percent chance of occurrence you want)

 

[Ronstar]

I guess they thought that if they named the event the 1% flood, people would think it was a rich person's problem.

Exactly! And then they gave the flood zones letter grades (zone A, zone C, etc) and called them Special Flood Hazard Areas

 

[W2R]

One of our TV weather guys, David Bernard, just said something along the lines of: "oh look! The rain has stopped in Houston. They are about done with Harvey" My guess is that he is probably overly optimistic, but still, thank goodness!

He says Harvey is beating up west Louisiana right now.

He also says there is a broad line of intense storms south of us, moving north, that should be dropping rain at 4"/hour on New Orleans tonight and has at least one tornado embedded in it. What happened to our improved forecasts? I am skeptical; maybe this line of storms will vanish. We now officially have a "street flood advisory".

 

[aja8888]

One of our TV weather guys, David Bernard, just said something along the lines of: "oh look! The rain has stopped in Houston. They are about done with Harvey" My guess is that he is probably overly optimistic, but still, thank goodness!

We may be "about" done with the rain, but NOT with the flooding as the wet land areas are still draining large amounts of water into the drainage system, which is over capacity right now.

 

[Chuckanut]

Way back in the 70's I worked for a company that had a refinery in Pasadena Texas, right next to Huston. I remember one of the locals I worked with telling me how land with homes on it suffered from subsidence when they dredged the canal. Homes that had been water free when they were built a decade or more earlier now flooded during heavy rains. The local owners would wait for the dry season, do cosmetic fixes and then sell the homes to the "Yankees' moving to Houston.

 

[MichaelB]

Is all this overrun causing problems with the potable water supply? That seems to be one of the bigger problems with flooding in South Fl.

 

[LOL!]

Sunshine appears!

Good luck to folks eastward especially Beaumont, Lake Charles, and New Orleans!

 

[Texas Proud]

Way back in the 70's I worked for a company that had a refinery in Pasadena Texas, right next to Huston. I remember one of the locals I worked with telling me how land with homes on it suffered from subsidence when they dredged the canal. Homes that had been water free when they were built a decade or more earlier now flooded during heavy rains. The local owners would wait for the dry season, do cosmetic fixes and then sell the homes to the "Yankees' moving to Houston.

I do not know how long it has been, but the disclosure form you have to fill out in order to sell your house has a question about the house flooding... if you answer it incorrectly you can be held liable...


I will admit that the people who were getting flooded today next to the levees had never been flooded before... this morning their streets were dry, by noon boats were going back in the neighborhood to rescue them....

 

[Texas Proud]

Well, just checked.... the rain gauge that is near me (a couple of miles away) JUST hit the 30 inch mark for this storm....


Some places have almost 52 inches...


The bayou is only 9 feet out of bank... it was over 11, so the water is going down...


AND, the sun is out!!!

 

[Breedlove]

Prayer does help ! , decided to not leave our house . There were only about 7 families on our street that stayed . We are in Riata Ranch about a mile from Hwy 290 near the country club and golf course .

It was frightening as we watched the water rise , one of the neighbors that stayed was across the street from us so we would yell across the street all night long .

The National Guard came through in huge trucks , then later at night the VFD came through on a flat bottom boat . All night long you could hear and see the Coast Guard Helos coming and going . I don't know where they were working but we had lots of support.

The water was rising fast and was about 5" from my door when we noticed it looked like it was no longer rising. I placed a piece of PVC in my driveway to mark the high water mark . Every hour I ran out and checked and it dropped from 8" to a foot every hour . Right now all is dried out still only one way out of the neighborhood . Went to Kroger's waited in line to get in . But overall we dodged a real bullet !

 

[LOL!]

FM 2978 closed due to possible damage to Spring Creek Bridge - The Courier
This is a big deal for locals. 2978 bridge over Spring Creek may have been damaged.

 

[Breedlove]

I got to make a run to my retirement home in Grimes county tomorrow . Where I live I can't get onto 290 ( today )

 

[NW-Bound]

They have collected rainfall data for 100 years or so. In order to get an estimate of the 0.2% probable rainfall (once in 500 years, on the average), they have to extrapolate the statistics, and that requires a presumption of a statistical model.

Perhaps the real occurrence in life has a fat-tail distribution compared to the presumed model, similar to what we have learned about large stock market declines occurring more often that the presumed simple model.

Or could it be that the climate is changing and falling outside a static model? See chart below showing "extreme events" occurring more and more frequently.

 

[meierlde]

Way back in the 70's I worked for a company that had a refinery in Pasadena Texas, right next to Huston. I remember one of the locals I worked with telling me how land with homes on it suffered from subsidence when they dredged the canal. Homes that had been water free when they were built a decade or more earlier now flooded during heavy rains. The local owners would wait for the dry season, do cosmetic fixes and then sell the homes to the "Yankees' moving to Houston.

Part of the subsidence was due to ground water pumping to run the area. Eventually the built Lake Livingston and a canal to carry water down to the east part of houston to allow them to stop pumping ground water.