Two 500-year floods in 15 years

By: Dr. Jeff Masters , 2:48 PM GMT on June 19, 2008

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The U.S. Geological Survey has preliminary data showing that this month's floods on four of Iowa's rivers--the Cedar, Iowa, Shell Rock, and Wapsipinicon--were 500-year floods. Back in 1993, many rivers in the Midwest also experienced 500-year floods, so the region has endured two 500-year floods in the past 15 years. How can this be? First of all a definition--a 500-year flood is an event that has only a 0.2% chance of occurring in a given year, based on available river flow data. Of course, reliable data only goes back a century at most, so designation of a 500-year flood event is somewhat subjective. Still, it seems rather improbable that two such huge floods should occur within such a short time span, raising the question of whether the floods were, in part, human-caused.

In a provocative story in the Washington Post today, it was pointed out that part of the flooding is due to the draining of wetlands for farming purposes. As nature's natural buffers against flooding are drained and filled to provide room for more farmland, run-off and flooding are bound to increase. Furthermore, as more levees are built to protect more valuable farmland and new developments, flood waters are pushed out of the former areas they were allowed to spread out in and forced into river channels behind the new levees. Even higher levees must then be constructed to hold back the increased volume of water they are asked to contain.

Climate change contributing to flooding?
The heaviest types of rains--those likely to cause flooding--have increased in recent years (see my February blog, "The future of flooding", for more detail). According to the United Nations' Intergovernmental Panel on Climate Change (IPCC) 2007 report, "The frequency of heavy precipitation events has increased over most land areas". Indeed, global warming theory has long predicted an increase in heavy precipitation events. As the climate warms, evaporation of moisture from the oceans increases, resulting in more water vapor in the air. According to the 2007 IPCC report, water vapor in the global atmosphere has increased by about 5% over the 20th century, and 4% since 1970.

Over the U.S., where we have very good precipitation records, annual average precipitation has increased 7% over the past century (Groisman et al., 2004). The same study also found a 14% increase in heavy (top 5%) and 20% increase in very heavy (top 1%) precipitation events over the U.S. in the past century. Kunkel et al. (2003) also found an increase in heavy precipitation events over the U.S. in recent decades, but noted that heavy precipitation events were nearly as frequent at the end of the 19th century and beginning of the 20th century, though the data is not as reliable back then. Thus, climate change is likely partly to blame for increased flooding in the U.S., although we cannot rule out long-term natural variations in precipitation.


Figure 1. Forecast change in precipitation and runoff for the period 2080 to 2099 compared to 1980 to 1999. The forecasts come from the A1B scenario from multiple climate models used for the Intergovernmental Panel on Climate Change (IPCC) 2007 report.

The forecast
According to a multi-model consensus of the climate models run for the Intergovernmental Panel on Climate Change (IPCC) 2007 report, precipitation and river runoff for the Mississippi River drainage basin are expected to increase only slightly by the end of this century (Figure 1). However, more of this rain is expected to fall in heavy precipitation events, the ones most likely to cause flooding. As a result, the U.S. needs to prepare for an increase in the number and severity of 100-year and 500-year flooding events in the coming century.

References
Kunkel, K. E., D. R. Easterling, K. Redmond, and K. Hubbard, 2003, "Temporal variations of extreme precipitation events in the United States: 1895.2000", Geophys. Res. Lett., 30(17), 1900, doi:10.1029/2003GL018052.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64.85.

Tropics
It's quiet in the tropics. There are no threat areas to discuss, and none of the models are forecasting tropical storm formation in the next seven days.

Jeff Masters

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1304. melwerle
1:38 PM GMT on June 22, 2008
ok - enough stupid questions from me today...Panera bound for an everything bagel and a cup of coffee.

Bring on some more rain too! My lawn is finally turning green again. Gotta love those tstorms...
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1303. surfmom
1:35 PM GMT on June 22, 2008
It means my mango tree may be a good predictor (last bumper crop was '04) and we better buckle our seatbelts 'cause were all going for a ride.....and if in the big woo-woo world of patterns and cycles - things do repeat - I wonder if Sarasota/Tampa gets nailed like it did in 1921 when the real estate market went bust. Stay tuned
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1302. melwerle
1:34 PM GMT on June 22, 2008
Morning Flood!
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1301. melwerle
1:33 PM GMT on June 22, 2008
Thanks HM...appreciate the answer. Does that mean more east coast landfalls or gulf?
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1300. XoendHoroeken
9:32 AM EDT on June 22, 2008
Morning all -

checking in to see what is going on before I go out and get some bagels with the family for breakfast. I'm with Destin on the question (post 1282) - what does that mean for hurricane landfall? Still learning...


Like Weather456 said earlier, the Highs are in a position to give us a year similar to 2004.
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1299. Floodman
8:33 AM CDT on June 22, 2008
Hiya, mel!
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1298. Floodman
8:28 AM CDT on June 22, 2008
1290. XoendHoroeken

What he said was that the Bermuda High is an extension of the Azores High...
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1297. HurricaneMyles
1:32 PM GMT on June 22, 2008
DestinJeff - If such a strong high continued any storm forming in the Atlantic would be pushed west and not have a chance to recurve until the Caribbean. The details of the weather setup at the time would determine whether it comes north into the US, stays south, or if everyone gets lcuky and a strong trough turns it northeast before it gets into the heart of the Caribbean.

In general though, a strong high such as we have now will tend to make US landfall chances higher.
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1296. melwerle
1:31 PM GMT on June 22, 2008
Morning all -

checking in to see what is going on before I go out and get some bagels with the family for breakfast. I'm with Destin on the question (post 1282) - what does that mean for hurricane landfall? Still learning...

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1295. Patrap
8:32 AM CDT on June 22, 2008
Being overdue is a misnomer.

Climatology and History show us that every year brings the same chance of a strike....

Being Prepared to react and having a Plan if a threat arises is the way to be ready.

Calamity may come, but communities are resilient.
A Catastrophic event is rare.

Tossing around catastrophic scenarios is easy.
..rebuilding and restoring whole communities is hard,but rewarding work.

And the American People are seeing a lot of that.It dosent take a Hurricane to destroy Homes and Businesse's..as the recent events upriver has shown us, so sadly again.
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1294. Patrap
8:31 AM CDT on June 22, 2008
See,Senor.


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1293. Weather456
9:27 AM AST on June 22, 2008
1290. XoendHoroeken 9:25 AM AST on June 22, 2008

It is actually one subtropical ridge. But sometimes, the Azores High extends towards the Western Atlantic, where it dubbed the Bermuda High but its not actually a single seperate anticyclone.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1292. Floodman
8:24 AM CDT on June 22, 2008
1280. Patrap

You got that right, Pat! Dos cervezas, por favor!
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1291. severstorm
9:24 AM EDT on June 22, 2008
1289,i must say i totally agree with your comment. i too think in the near future one will do just that IMHO
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1290. XoendHoroeken
9:23 AM EDT on June 22, 2008
Ok 456. I actually didn't know there was an Azores high AND a Bermuda high. But now I gotcha'
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1289. XoendHoroeken
9:08 AM EDT on June 22, 2008
Re: 1279

I wasn't making a correction surfmom. I was just saying that Tampa is more overdue than Sarasota... I have no idea if there was a '44 Storm there. And yes, I believe a Hurricane coming up the West Coast of Florida would be one of the worst scenarios. Charley was a mere hint at what may happen. It is not out of the realm of possibilities at all that a major Hurricane could cross Cuba and ride right up our coast affecting Florida City, Naples, Sarasota, St, Pete, Clearwater, New Port Richey... etc etc.. This would be the end of the economy in our area.
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1288. Weather456
9:13 AM AST on June 22, 2008
1267. XoendHoroeken 8:59 AM AST on June 22, 2008
Wow. In the last few frames of the CMC and GFS the Atlantic high takes a huge move East and sits right above the Azores. I thought the consensus was that we would have the high fairly close to bermuda this year...


huh?

The consensus is for a NAO similar to 2004, which favored a high in the Central Atlantic. Bermuda is in the Western Atlantic.

For the Subtropical Ridge to be centered near Bermuda is rather unusual becuz after all its call the Azores high. The Bermuda High is only a westward extension of the Azores High.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1287. surfmom
1:15 PM GMT on June 22, 2008
1286 - I figure he's OK too - sometimes it not good to look at the pictures...get the imagination going. Well, got some domestics to do --BBL

The rain here in Sarasota yesterday was delightful, everything is green and very steamy this AM. Hope we get more.
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1286. txalwaysprepared
1:13 PM GMT on June 22, 2008
surfmom - yeah I was asking my dad why the heck those people were on a ferry. And he said they didn't think the storm was coming. He said those that knew of a storm didn't think it was headed there and the others didn't even know a storm existed.

I'm sure he is fine. I'm sure power is down everywhere. He probably can't get info out yet.
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1285. Patrap
8:13 AM CDT on June 22, 2008
The Philippines are very Typhoon Savvy folks,They get at Least 2-3 Avg Landfalls a year.

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1284. ShenValleyFlyFish
9:10 AM EDT on June 22, 2008
1280. Patrap

Might not work in a Mennonite Restaurant LOL
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1283. surfmom
1:08 PM GMT on June 22, 2008
Thanks Ike.

#1276 What you saying is what he told me, not to worry, he teased me for being a worrygirl, told him to log on here, plus I kept sending him the information that Hades was posting (WHO BY THE WAY CALLED THIS!!) I just don't know how much he checked, as he was getting ready to get married, had company in from the states - so I just hope my words got through to him - now it's wait and see
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1281. txalwaysprepared
1:09 PM GMT on June 22, 2008
awww TS are you saying that just for me about the BOC ;)
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1280. Patrap
8:08 AM CDT on June 22, 2008
As a traveler,...language is universal.

2 fingers means 2 beer's, Anywhere
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1279. surfmom
1:02 PM GMT on June 22, 2008
#1270 - thanks for that correction. I didn't think I had ever heard of a 1944 in sarasota - my mate was born during a 'cane in St. Augustine, FL in 1944

In 1921 Sarasota went into a severe real estate bust. The hurricane pushed the economics over the cliff. I wonder, since we are experiencing the same economic slide here again - if "cycles" being what they may - we will get slapped around this year with a hurricane.
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1278. IKE
8:06 AM CDT on June 22, 2008
People can post in whatever language they want. It's no big deal to me.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1277. TampaSpin
9:02 AM EDT on June 22, 2008
Gotta go soon but, the BOC needs monitiored today. Vorticity indicates possible low there and alot of convection is flaring up....Just did a quikscat and nothing appears. Could be just the divergence of the trough still there......
Member Since: September 2, 2007 Posts: 179 Comments: 20448
1276. txalwaysprepared
1:04 PM GMT on June 22, 2008
surfmom - sadly I don't think any of them were prepared. I talked to my dad (who lives in KL and in Singapore). He said the general public was told it was to recurve north and miss them. They did not think it would hit land. Very sad situation.

TS - that is an amazing High. wow
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1275. IKE
8:05 AM CDT on June 22, 2008
1272. jphurricane2006 8:04 AM CDT on June 22, 2008
IKE I meant in general, there will be nights this year that some will want to stay up to cover a storm, but these nights in June arent those nights

I just meant that the nights in which there is nothing to track, we should take advantage and get some sleep


Yo bud.

Hang in there surfmom...hope you get an email from him.

Also hope your mom and other half get along!
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1274. ShenValleyFlyFish
8:58 AM EDT on June 22, 2008

1265. TampaSpin 8:51 AM EDT on June 22, 2008
It would be wrong for someone to post something in a language that could not be interpeted by others and be wrong and cost lives.


I take it then that posting in English about a German storm is Verboten.

Oh wait, that rules out posting in any language about any storm. LMAO

Love you man but this should take some absurdity award.
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1273. Patrap
8:03 AM CDT on June 22, 2008
Any language is available for any wunderground user.
On every wu-page....in the Left column menu is a Language tab.

"Forecast Flyer"
Page Preferences
Language: English
ยป Select Language
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1271. surfmom
12:56 PM GMT on June 22, 2008
morning, so worried about my surf friend in PI He was to be married this past Saturday. Had people from the states that flew over to be at the wedding. He was marrying a girl from a village near Cebu. Thanks to Hades I was able to e-mail him and make him aware that the storm was showing signs of being very nasty (more then what then general population was thinking at the time)

I know not to worry - but I am on pins and needles waiting to get some kind of an e-mail from him. From the looks of the photo's from Floodman's link --it's going to be a while.
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1270. XoendHoroeken
8:59 AM EDT on June 22, 2008
1259. sarasotaman 4:59 AM EDT on June 22, 2008 Hide this comment.
Thank you for that post from the typhoon. We here in sarasota have not had a eye of a hurricane since oct. 1944. so we are overdue.


1921 was the last time for Tampa
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1269. TampaSpin
8:56 AM EDT on June 22, 2008
Dam what a High in the Atlantic. This looks like an August High not June......WOW
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1268. txalwaysprepared
12:58 PM GMT on June 22, 2008
LOL! I was actually thinking of going to the beach today.

And no closet needed today, thankfully ;)
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1267. XoendHoroeken
8:52 AM EDT on June 22, 2008
Wow. In the last few frames of the CMC and GFS the Atlantic high takes a huge move East and sits right above the Azores. I thought the consensus was that we would have the high fairly close to bermuda this year...
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1266. TampaSpin
8:52 AM EDT on June 22, 2008
1264. txalwaysprepared 8:50 AM EDT on June 22, 2008

Nothing to worry about for several days. Go to the beach with the kids...just take your closet with ya tho......lol
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1265. TampaSpin
8:44 AM EDT on June 22, 2008
1262. ShenValleyFlyFish 8:04 AM EDT on June 22, 2008

Everyone has their own blog that they can post in any language they wish. That is their option. It would be wrong for someone to post something in a language that could not be interpeted by others and be wrong and cost lives. Let those that need Babel Fish to tranlate english to spanish do so...why inconvince the largest majority of the bloggers.....thats liberal thinking at its best!
Member Since: September 2, 2007 Posts: 179 Comments: 20448
1264. txalwaysprepared
12:48 PM GMT on June 22, 2008
Good Morning.. anyone out there yet? Going to check on the wave.
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1263. Weather456
6:07 AM AST on June 22, 2008
Good Morning,

The tropics and Tracking Tropical Cyclones Part 1: Center Fix
Member Since: July 24, 2005 Posts: 407 Comments: 19076
1262. ShenValleyFlyFish
7:27 AM EDT on June 22, 2008
Who cares what language people choose to post in. If you are paranoid about what is being said go to Babel Fish and get a rough translation. Better yet politely ask the poster for one.

My personal assumption has always been that the poster has a piece of information they feel is important to folks for whom the post is a first or only language that they do not want garbled by double translation. Them->English->Reciever

Come on folks this is a tinny blue marble and weather affects us all. If someone comes on and posts in a tribal amazonian language odds are that they have a friend with a satellite link who frequents the Doc's blog who needs some foolproof clarification of a weather point.

If is an insiders conversation about nonessential non-weather stuff it's perhaps annoying but not that unusual. Face it not everyone gets everything said on this blog. (I'm hot sure I want to get Kansas jokes, NOL talk is strange and don't get me started on the "Carolinas". LOL)
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1260. IKE
5:55 AM CDT on June 22, 2008
1253. jphurricane2006 12:41 AM CDT on June 22, 2008
I say get to bed early at times of quiet, there will be times this season when we will have to stay up late


It's almost 2 in the morning your time....is that early?
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1259. sarasotaman
8:55 AM GMT on June 22, 2008
Thank you for that post from the typhoon. We here in sarasota have not had a eye of a hurricane since oct. 1944. so we are overdue.
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1258. IPlayTS3
8:41 AM GMT on June 22, 2008
Hi. I'm from the Philippines and in our place is where Fengshen directly hit before going directly to Manila. Electricity was just restored here. The winds were very strong. The rains were pouring down monstrously while I heard the scary howling of the wind. It was an eerie. I was scared that my roof will be blown away. The rain stopped and the winds calmed down. I looked ouside and I saw lightning strikes around like a circle. Then the very strong wind and rain came back in the opposite direction. I fell asleep and woke up later in the morning and it was all over.

I doubt that there will be more survivors in the ferry ship that sank near Romblon. 3 were only found survived. Fengshen directly hit Romblon while the ferry ship was stranded in the middle of the sea because of engine failure. If the engine failure didn't happen and the ferry didn't sail, they all may be alive today.
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1257. Floodman
1:49 AM CDT on June 22, 2008
Why in the name of all things holy do you run a ferry in the middle of a Typhoon...incredible to me, the foolishness and lack of intelligence we humans display on such a regular basis:

Phillipine ferry sinks; 700 plus passengers missing
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1256. HurakanPR
1:53 AM AST on June 22, 2008
Is kind of strange that when people write in SPANISH ON THIS BIOG SOME PEOPLE 0VER REACT, actually wE DON'T HAVE any problem writing in english but remember out of the 30 million people that live on these island 28 millions are latinAmericans. When we speak Spanish among us is to clear points of views that are strictly related to our culture.....Not to disrespect Those that aren't multi linguistics like us.
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1255. 0741
5:45 AM GMT on June 22, 2008
ok it look everyone want to bed so i going too like jp2006 say keep eye wave see what happen
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1254. 0741
5:43 AM GMT on June 22, 2008
i saw radar that you hammer in afternoon
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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