iowa floods 21st century

8/14/2019 Iowa Floods 21st Century

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Iowa Floods 21st Century

visuals100-yr type floods are now expected to

average one in 17-years.

With Climate change; 100-yr type floodscould average one in 5-years


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Rain days per year have increased substantially


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y = 0.0517x - 69.076

0

10

20

30

40

50

60

1880 1900 1920 1940 1960 1980 2000 2020

Ames, IA Precipitation by year 1893-2007

100+ yr Precipitation, 20%+ increase


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Final, Revised for: Bulletin of the American Meteorological

Society, Vol. 77, No. 2, Feb. 1996, pp 279-292.

http://www.ncdc.noaa.gov/oa/climate/gcps/papers/icc-us.pdf


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1950-1993 Precipitation

Most of the United States experienced significant

precipitation increase. Diminished Tropical

Storms impacted Florida.


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Heavy rain events are more common.


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Increased River Flow (NE Iowa)

y = 6.932x - 12627

0

500

1000

1500

2000

2500

3000

3500

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010 2020

Turkey River at Garber, IA

6-fold increase of Flood Prone Years

2-fold increase in annual river flow


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Kishwaukee @ DeKalb

y = 18.825x - 35716

0

1000

2000

3000

4000

5000

6000

1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

meanann

ualcfs

Year

Nishnabotna @Hamburg, IAhttp://nwis.waterdata.usgs.gov/ia/nwis/annual

(SW Iowa)

2-fold increase in annual river flow

6-fold increase of Flood Prone Years


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y = 14.586x - 26619

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010

meanannualcfs

year

Iowa River@ IowaCity

Flood prone years have reduced amplitude

during years that reservoir is effective


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Cedar River @ Austin, MN

0

100

200

300

400

500

600

700

800

900

1945 1955 1965 1975 1985 1995 2005 2015


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a10

20

30

40

50

1900 1920 1940 1960 1980 2000 2020

South Central MN Precip Oct- Sep


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Wet Interval Wet Interval

Dry Interval

Wet/Dry Intervals are typical of 2/3 of USA


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Cyclic Climate Events, Global Scale

Some contend that since 1950 or so all globalscale climate change is related to the CO2change.

Some contend that a global scale cyclicclimate event will impact the global climate.

Cyclic cooling or precipitation reduction

should not be considered to negategreenhouse potential impact on climate.


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Natural andanthropogeniccontributions to globaltemperature change

(Meehl et al., 2004).Observed values fromJones and Moberg 2001.Grey bands indicate 68%and 95% range derived

from multiple simulations.

Dominance of

greenhouse over some

other factors influencing

global scale climate.Periodic major ocean

currents are not

included and are

considered to have a

major global

temperature impact.


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The PDO Dr. Don J. Easterbrook (PDO + CO2)

Pacific impact on temperature at global scale.

Dr. Easterbrook feels the PDO remains functional.


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Do Not be fooled by 30 years of cooling


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Iowa Not Dry @ +2.5C

Wm Gutowski

Climate change models: like pattern, 17% more rain.

Iowa Oct 15, 2007


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PET @ +2.5C Will crops benefit from a 17% increase in precipitation or

will potential evapotranspiration increase exceed it? Assuming that the diurnal range is 13C (23F) in summer

now and at +2.5 C and that most midsummer morningshave dew.

July average high now: 30C, Mid-day VPD= 15.73

July with change: 32.5C, for a VPD= 17.74

Increase in PET = 13%

Assumes sun and wind are unchanged from now.

So the added rain exceeds the max added water use by 4%.

A 4% increase in water increases the flood events by 3x(that is have 3 times the floods in Iowa we have now.

A 2.5C global scale warming could be expected

to increase Iowa flood events by 3X


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The ice change demonstrates a major shortcoming of the GCMs (none can put the melt toCO2 forcing).

Clearly state of the science GCM (globalclimate models) cannot at this time explainthe global scale reduction of sea ice observedin the 15 years. This indicates that it is not yettime to withdraw GCM modeling research anddevelopment funding.

A ti S I E t t Ob d d P j t d b Gl b l Cli t M d l


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Meehl, G.A.,et al, 2007: Global Climate Projections. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to theFourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt,

M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Chapter 10, p. 771

Arctic Sea-Ice Extent Observed and Projected by Global Climate Models

2005

20072008


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Where has all the Sea Ice gone?

It may be differentialimpacts of particulates

2009 is the year to

learn


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http://www.bluewaterstudios.com/

David Thoreson , Iowa


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iowa floods 21st century

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