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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754. HadesGodWyvern (Mod)
1:06 AM GMT on June 21, 2008
I believe this will make Fengshen at least 100 knots using the 1 min sustained winds and a Category 3 on the Safir-Simpson scale.
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753. Weather456
9:05 PM AST on June 20, 2008
gator...yea...but for fun.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
752. HadesGodWyvern (Mod)
1:05 AM GMT on June 21, 2008
Japan Meteorological Agency
Tropical Cyclone Advisory
09:00 AM JST June 21 2008

Subject: Category Four Typhoon over the Philippines

At 0:00 AM UTC Typhoon Fengshen T0806 (945 hPa) located near 11.9N 122.7E has 10 minutes sustained winds of 90 knots with gusts up to 130 knots. The typhoon was reported moving west at 7 knots.

Storm-Force Winds
===============
55 NM from the center

Gale-Force Winds
================
160 NM west from the center
140 NM east from the center

Forecast Position and Intensity
=============================
24 HRS: 14.5N 120.3E - 80 knots (CAT 3)
45 HRS: 17.6N 118.5E - 85 knots (CAT 4)
69 HRS: 20.4N 117.2E - 90 knots (CAT 4)

----
intensifying again between the islands of Philippines... SCARY!!
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751. sflgatorgirl
1:03 AM GMT on June 21, 2008
456...when you called Drak boots, did you mean from Dora the Explorer?
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750. Weather456
8:27 PM AST on June 20, 2008
LOL LOL

This is a must see video!

How To Behave On An Internet Forum
Member Since: July 24, 2005 Posts: 407 Comments: 19076
749. HadesGodWyvern (Mod)
12:33 AM GMT on June 21, 2008
TPPN10 PGTW 210015 COR

A. TYPHOON 07W (FENGSHEN)

B. 20/2330Z

C. 11.8N

D. 122.6E

E. THREE/MTSAT

F. T5.5/5.5/D1.5/24HRS STT: D0.5/06HRS (20/2330Z)

G. IR/EIR/VIS/MSI

11A/PBO RAGGED EYE/ANMTN. SURROUNDING GRAY SHADE OF B
WITH DG EYE TEMP YIELDS A DT OF 5.5. MET AND PT AGREE.
DBO DT. CORD FOR FT.

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748. HadesGodWyvern (Mod)
12:32 AM GMT on June 21, 2008
National Hurricane Center - Miami, Florida
Tropical Cyclone Outlook
0:00 AM UTC June 21 2008
=============================

An area of low pressure is located about 750 miles south-southwest of the southern tip of Baja California. The associated showers and thunderstorm activity remains disorganized and development, if any is expected to be slow to occur.

Tropical Cyclone Development Potential
====================================
LOW (<25%)
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747. Skyepony (Mod)
12:30 AM GMT on June 21, 2008
mimic of Fengshen
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746. HadesGodWyvern (Mod)
12:18 AM GMT on June 21, 2008
Important Note From Typhoon 2000 Website

This Typhoon is similar in track & strength of Typhoon UTOR (SENIANG) of December 10, 2006 which affected Northern Panay and Boracay Island Resort.

Please take precautionary measures!
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745. Weather456
8:11 PM AST on June 20, 2008
738. sporteguy03 7:58 PM AST on June 20, 2008

My favorite season of them all...:D
Member Since: July 24, 2005 Posts: 407 Comments: 19076
744. HadesGodWyvern (Mod)
12:03 AM GMT on June 21, 2008


JMA hasn't adjusted the track.. so its wrong but looks where it's centered.

Another landfall near Masbate or Oriental Mindoro with its movement west
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743. rainraingoaway
6:10 PM CST on June 20, 2008
I have clouds!!! ;)

I am somebody!! I am somebody!!
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742. thelmores
11:59 PM GMT on June 20, 2008
735


Thanks Taz.... the price of gas just went up another 25 cents since your post! LOL
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741. Patrap
7:08 PM CDT on June 20, 2008
May take a lil while.Good luck with the effort.
Member Since: July 3, 2005 Posts: 419 Comments: 127355
740. rainraingoaway
6:07 PM CST on June 20, 2008
TYVM patrap. I tried...will see if it works.
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739. Patrap
6:58 PM CDT on June 20, 2008
See post #474 on the avatar issue
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738. sporteguy03
11:57 PM GMT on June 20, 2008
Three Words:
Welcome to Summer!
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737. rainraingoaway
5:51 PM CST on June 20, 2008
Evening all. Fengshen is certainly awesome. Would NOT want to be in his way.

IMHO (regarding the flooding which is sad for all involved) I think that it's just proof that you can't harness Mother Nature or the "mighty mississip"

By the way.. can anyone help me get rid of the stick figure icon and put a picture in there? I'm sure its simple....but I'm evidently braindead. Thanks.
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736. Patrap
6:50 PM CDT on June 20, 2008
Lighten up taz..nola been here Long time.

LOL

..your liable to cause a Oil Speculators dream.

Plus those flow lines change daily.
Member Since: July 3, 2005 Posts: 419 Comments: 127355
735. Tazmanian
4:46 PM PDT on June 20, 2008
oh crap look at this map whats hop we dont get any thing in the Caribbean or it would take it right in to New Orleans what hop this map dos not stay the same or we will be in for vary high gas and with low wind shear in the gulf

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734. guygee
11:31 PM GMT on June 20, 2008
722. ShenValleyFlyFish 11:19 PM GMT on June 20, 2008

Shen - All I noted when reading the regulations is that the so-called "zero-rise" regs did not apply to agricultural land.

I see Dr. Masters cites the WaPo above as his source for blaming "part of the flooding ... due to the draining of wetlands for farming purposes". I will admit that is pretty shaky ground as a source, and I should not have taken this as authoritative and used it a springboard. Thanks for helping to put the brakes on. I will say that more research is needed to understand the problem than the word of the WaPo or even a non-Ag/non-geologist Ph.D. It is some food for further thought.
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733. HadesGodWyvern (Mod)
11:41 PM GMT on June 20, 2008
Taz Adrian is showing a loop of it intensifying near and overland Philippines
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732. Tazmanian
4:35 PM PDT on June 20, 2008
thats old 23

this is the new update with winds of 90kt and a mb of 956mb


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731. HadesGodWyvern (Mod)
11:34 PM GMT on June 20, 2008
intensifying after landfall in Eastern Samar and in between the archipelago Philippines islands is amazing
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730. HIEXPRESS
7:34 PM EDT on June 20, 2008
Third day in a row (three differcnt locations E Ctrl FL)I'm hit by a WW cell. Must just be living right. :)
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729. HadesGodWyvern (Mod)
11:31 PM GMT on June 20, 2008

UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 20 JUN 2008 Time : 213000 UTC
Lat : 11:43:11 N Lon : 123:02:59 E


CI# /Pressure/ Vmax
3.9 / 981.4mb/ 63.0kt


Final T# Adj T# Raw T#
3.9 4.2 6.9

Latitude bias adjustment to MSLP : +3.8mb

Estimated radius of max. wind based on IR :N/A km

Center Temp : -44.4C Cloud Region Temp : -83.2C

Scene Type : EYE

Positioning Method : FORECAST INTERPOLATION

Ocean Basin : WEST PACIFIC
Dvorak CI > MSLP Conversion Used : PACIFIC

Tno/CI Rules : Constraint Limits : 0.5T/hour
Weakening Flag : OFF
Rapid Dissipation Flag : OFF

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728. hurricane23
7:22 PM EDT on June 20, 2008
Impressive....

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727. Tazmanian
4:27 PM PDT on June 20, 2008
wow the cimss has a raw T # for Typhoon FENGSHEN at 6.9 or this about 7.0 this is now a strong cat 4 or low end cat 5


but will wait for the SDD site to see what they say but i think they say like 6.5 or some in

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726. stormdude77
7:19 PM AST on June 20, 2008
We here in Barbados today (at the Airport), recorded a 95 kph wind gust
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725. DocBen
11:19 PM GMT on June 20, 2008
shen, guygee

The key with 'engineering' is that we use geomorphological engineering rather than traditional civil (army corps) engineering. That is, woth WITH instead of AGAINST nature.

I agree with both of you - and with Doc M.

guygee - addendum - the pipes idea is one we used in a lawsuit settlement after my side won. Interesting thing is that it benefitted the 'loser' of the lawsuit as much or more than it did my side. It worked - that was the key.
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724. guygee
11:13 PM GMT on June 20, 2008
711. DocBen 10:45 PM GMT on June 20, 2008

This can be done by installing a dam with pipes through it at the downslope side of playing fields, golf courses etc. Then the area can fill during a surge and drain at a rate that can be handles downstream.

I misread your comment at first. Those are interesting ideas too. It might require that the slope be created, and that other areas drain into the man-made temporary storage site.

That is a creative solution to a problem, thanks for bringing it up, Doc!

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723. Weather456
7:02 PM AST on June 20, 2008
Dvorak technique applied to Typhoon FENGSHEN

Pattern : Infrared Eye Pattern

Eye Temperature - LG - -54C

Surrounding Gray Shade CDG - -80C

Embedded Distance I degree
E No 6.5

Eye Adjustment factor -0.5

DT 6.0

Model Expected T-no - DT 5.0

Final T-no based on MET 5.0/90 knots/941 mb.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
722. ShenValleyFlyFish
6:30 PM EDT on June 20, 2008
Sorry I popped off so but you have no idea the regs that are applied to crop land and agricultural usage. Part of the joke of the engineering you are referring to surrounding housing and urban envelopment is that it assumes a number of factors that are not so. It assumes that the amount of water which will enter a stream from a given plot of land remains constant wether it is in dirt or 1/2 covered with asphalt singles and automobile amenities. It assumes that changing streams to drainage ditches has no effect in rise and fall of stream flows. It assumes that communities will actively enforce and envelopers will follow the plans and cut no corners. Additionally at least in this area the standard for a containment lagoon is that it will contain the first 15 min flush and any ensuing run off would be equivalent regardless of the rate duration etc. of any event.

I once saw a presentation from the Chesapeake Bay foundation which asserted that if one assigned a factor of 1 to the negative impact of the watershed's forested areas which have been heavily altered since the European invasion of the continent, Agriculture would receive a factor of 10, Suburbia 100 and urban areas 1000. I have been searching for the source but have not found it but it makes sense to me. It is politically much easier to focus on agricultural land and practice because you can actually make changes and other than the lobbying power of agribusiness you are talking about a minority of voters.

If there was ever a nation that bit the hand that fed it this is it.
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721. ShenValleyFlyFish
6:30 PM EDT on June 20, 2008
Sorry I popped off so but you have no idea the regs that are applied to crop land and agricultural usage. Part of the joke of the engineering you are referring to surrounding housing and urban envelopment is that it assumes a number of factors that are not so. It assumes that the amount of water which will enter a stream from a given plot of land remains constant wether it is in dirt or 1/2 covered with asphalt singles and automobile amenities. It assumes that changing streams to drainage ditches has no effect in rise and fall of stream flows. It assumes that communities will actively enforce and envelopers will follow the plans and cut no corners. Additionally at least in this area the standard for a containment lagoon is that it will contain the first 15 min flush and any ensuing run off would be equivalent regardless of the rate duration etc. of any event.

I once saw a presentation from the Chesapeake Bay foundation which asserted that if one assigned a factor of 1 to the negative impact of the watershed's forested areas which have been heavily altered since the European invasion of the continent, Agriculture would receive a factor of 10, Suburbia 100 and urban areas 1000. I have been searching for the source but have not found it but it makes sense to me. It is politically much easier to focus on agricultural land and practice because you can actually make changes and other than the lobbying power of agribusiness you are talking about a minority of voters.

If there was ever a nation that bit the hand that fed it this is it.
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720. Tazmanian
4:09 PM PDT on June 20, 2008
715. Drakoen 3:59 PM PDT on June 20, 2008
For whats it worth the GFS 18z run is showing some development in the Caribbean 2 weeks from now


and where dos it take it when it gets out of the Caribbean and how strong???
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719. mermaidlaw
11:03 PM GMT on June 20, 2008
Hello everyone, just wanted to say that my local met said that tropical moisture from the GOM would move into Florida over the weekend. Any thoughts? Thanks.

Member Since: July 23, 2006 Posts: 20 Comments: 8758
718. Drakoen
11:07 PM GMT on June 20, 2008
It's also showing a possible system in the EATL. We'll see if it can stay consistent. As the long term upper level winds look to favorable for development in the EATL and marginally favorable for development in the Caribbean.
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717. hurricane23
7:02 PM EDT on June 20, 2008
MJO pulse should create a more favorable environment for development in 2 weeks time frame.
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716. Weather456
6:03 PM AST on June 20, 2008
Rainy Day In the Islands; Tropical Update

Thanks!
Member Since: July 24, 2005 Posts: 407 Comments: 19076
715. Drakoen
10:58 PM GMT on June 20, 2008
For whats it worth the GFS 18z run is showing some development in the Caribbean 2 weeks from now.
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714. guygee
10:46 PM GMT on June 20, 2008
Re: 711
DocBen - Correct, the stormwater retention ponds need to be "engineered" properly. Sorry if that word turns some people off.

This student from Malaysia wrote a decent thesis on stormwater retention pond engineering that can be downloaded here: Flood and Water Quality Management Using Stormwater Dentention Ponds

If you google the phrase "Knox County Tennessee Stormwater Management Manual" you can download their entire detailed stormwater engineering manual, Volumes 1 & 2, one chapter at a time. A very detailed manual.

(Of course, maintenance in another matter... A lot of localities are neglectful and just let the ponds fill with vegetation, silt and sludge, and that probably even makes things worse).
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713. IPlayTS3
6:54 AM CST on June 21, 2008
Oh my God, Fengshen is on its way to our place!
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712. hurricane23
6:53 PM EDT on June 20, 2008
Hello!

Had some pc problems over the last day or so but things are up and running.Significant rainfall down here across southeast florida this afternoon with flooding in many areas across dade/broward counties.Things should dry out this weekend otherwise nothing to worry about tropics wise. Adrian
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711. DocBen
10:41 PM GMT on June 20, 2008
705. guygee 10:21 PM GMT on June 20, 2008

I would note that simply creating deep ponds won't work if the ponds are then kept full. That is what has been done around here and has resulted in more flooding. Whet is needed is "freeboard" - storage space that is empty until the rain event.

This can be done by installing a dam with pipes through it at the downslope side of playing fields, golf courses etc. Then the area can fill during a surge and drain at a rate that can be handles downstream.

In effect; this mimics the wetlands that pre-existed the "improvement" (sic)
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710. stormdude77
6:39 PM AST on June 20, 2008
Wow, what a day here today in Barbados...I recorded 37 mm of rain today, and a little more looks to be on the way tonight. Tomorrow the Twave should move out of the area, though.

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709. Skyepony (Mod)
10:36 PM GMT on June 20, 2008
Manila livecam
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708. pottery
6:30 PM AST on June 20, 2008
LOL.
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707. HadesGodWyvern (Mod)
10:31 PM GMT on June 20, 2008
Philippines Atmospheric Geophysical Astronomical Services Administration

Typhoon "FRANK" has moved westward for the past six hour and is now threatening Panay and Mindoro area.

Tropical Cyclone Bulletin #10
============================
At 5:00 A.M. PST, Typhoon Frank located near 11.9ºN, 123.2ºE or 70 kms South of Masbate and 60 kms Northeast of Roxas City has sustained winds of 75 knots with gusts up to 90 knots.

Storm Signals Raised
====================

Warning Signal #3 (100-185 km/h)

Luzon Region
1.Lubang Island
2.Oriental Mindoro
3.Occidental Mindoro
4.Romblon
5.Marinduque
6.Masbate
7.Burias Island
8.Calamian Group of Islands

Visayas Region
1.Aklan
2.Northern Antique
3.Capiz
4.Northern Iloilo

Mindanao Region
1.No Signal Raised

Warning Signal #2 (60-100 km/h)

Luzon Region
1.Laguna
2.Cavite
3.Batangas
4.Southern Quezon
5.Camarines Sur
6.Albay
7.Sorsogon
8.Northern Palawan
9.Cuyo Island

Visayas Region
1.Samar Provinces
2.Biliran Island
3.Leyte
4.Rest of Antique
5.Rest of Iloilo
6.Northern Negros Occidental
7.Northern Cebu

Mindanao Region
1. No Signals Raised

Warning Signal #1 (30-50 km/h)

Luzon Region
1.Rest of Palawan
2.Bataan
3.Zambales
4.Pampanga
5.Bulacan
6.Rizal
7.Rest of Quezon
8.Polillo Island
9.Camarines Norte
10.Catanduanes
11.Metro Manila

Visayas Region
1.Rest of Negros Occidental
2.Negros Oriental
3.Rest of Cebu
4.Bohol
5.Southern Leyte

Mindanao Region
1.Dinagat Island

Public Storm Signals elsewhere is now lowered.

Residents in low lying areas and near mountain slopes are advised to take all the necessary precautions against possible flashfloods and landslides. Likewise, those living in coastal areas under signal 2 and 3 are alerted against big waves or storm surges generated by this typhoon.

The public and the disaster coordinating councils concerned are advised to take appropriate action and watch for the next bulletin to be issued at 11 a.m. today.
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706. Skyepony (Mod)
10:29 PM GMT on June 20, 2008
How's that?
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705. guygee
10:12 PM GMT on June 20, 2008
Re: 702. ShenValleyFlyFish

This is true ShenValley, I used to wander around a lot in the New Hampshire hills and it was almost all very old abandoned farmland.

The heart of my point is that if you drain a swamp for farmland, you should be required to do something like dig some deep ponds to compensate for the water storage in case of flooding. According to Dr. Masters, this was not done, and according to his blog above, poor land management practices get part of the blame for the magnitude of the floods.

I am not trying to blame the small farmer, but I am thinking that big agriculture has influenced the land use regulations through the usual lobbying channels. That is what I would like to see investigated.
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704. pottery
6:13 PM AST on June 20, 2008
...But where is my new image then ?? Huh ?!!
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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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