This document discusses the importance of understanding past floods to properly assess modern flood risks. It provides examples of paleoflood research along rivers like the Red River of the North, which uncovered major floods in 1826 and around 700 years ago that exceeded any floods measured by modern instrumentation. Understanding a river's full history through both recorded data and geological evidence of past floods is essential for floodplain management, development planning, and infrastructure design to mitigate future flood risks.

1. THE RELEVANCE
OF OLD FLOODS
TO MODERN
HYDROLOGY
Geographisches Institut | Johannes Gutenberg-Universität Mainz | May 18, 2017

2. HOW MUCH TIME
IS NEEDED
TO TRULY KNOW
A RIVER?

3. THE RHINE IN MAINZ

4. Source: Fredrik Von Erichsen/AFP/Ge y Images

6. THE MISSISSIPPI IN MINNEAPOLIS

8. THE MISSISSIPPI DURING THE 1988 DROUGHT

10. WINNIPEG, CANADA

12. THE RED RIVER OF THE NORTH

13. THE RED RIVER OF THE NORTH

14. Source: Morningstarphoto

15. 0.5 METRES
PER KILOMETER
THE RHINE THE RED
0.08 METRES
PER KILOMETER
STREAM GRADIENT

16. LAKE AGASSIZ

17. 1950

18. DURING EXTREME CASES, THE FLOOD ZONE OF THE RED RIVER
CAN EXTEND 40 KM WIDE.

19. “ ”BACK IN 1997,
THE WATER SPILLED ONTO THE FLAT PRAIRIE
LIKE AN OPEN BOTTLE
OF CHOCOLATE MILK
THAT HAD TIPPED OVER
ON THE KITCHEN TABLE.
Roy MacGregor
The Globe and Mail, August 7, 2015

20. Source: Greg Brooks
1997

21. River diversion
Main channel
Source: Dr. Greg Brooks, Geological Survey of Canada
IN THE 1960s, WINNIPEG BUILT A 47-KM LONG DIVERSION CHANNEL
THAT DIVERTS RED RIVER AROUND THE CITY.

22. GRAND FORKS, NORTH DAKOTA

23. THE 1997 RED RIVER FLOOD (AND FIRE) CAUSED
MORE THAN $3.5 BILLION IN DAMAGES.

24. WINNIPEG GRAND FORKS

25. RIVER MEMORY

26. FLOODS — BY
THEIR NATURE
— ARE RARE
EVENTS.

27. EVALUATE
VULNERABILITY
JUDGE
INFRASTRUCTURE
BE MORE AWARE
OF NATURE’S POTENTIAL
A DEEP ‘RIVER MEMORY’
IS ESSENTIAL TO:

28. 2UNCOVERING ANCIENT FLOODS

29. 1GAUGING FLOOD RISKS

30. Source: Roland Schlager/EPA

31. Source: AON Benfield, 2016 Annual Global Climate and Catastrophe Report
FLOODS HAVE BEEN THE COSTLIEST PERIL
FOR THE PAST 4 CONSECUTIVE YEARS,
AND CAUSED
$62B IN LOSSES
GLOBALLY IN 2016.

32. Source: Guha-Sapir et al, 2015, Annual Disaster Statistical Review 2015.
OVER THE PAST DECADE
FLOODS KILL
NEARLY 7000 PEOPLE
WORLDWIDE EACH YEAR.

33. “ ”NO ONE IS GOING TO
MOVE ST. LOUIS
JUST BECAUSE IT HAPPENS
TO BE IN THE RIVER.
David Johnston
The Ohio State University

34. The Quad Cities River Bandits and the Peoria Chiefs play a baseball game April 20, 2011
inside Modern Woodmen Park in Davenport, Iowa.

35. SACRAMENTO RIVER, CALIFORNIA

36. WHAT ARE THE RISKS POSED
BY FUTURE FLOODS?

38. FFA(Flood Frequency Analysis)

40. FFACITY PLANNING INSURANCE PRICING MANAGEMENT PLANS

41. NEAR TUCSON, ARIZONA

42. THE RILLITO RIVER, TUCSON

43. “ ”THE 100-YEAR FLOOD HAS
COME AND GONE
SO, BY ALL RIGHTS,
TUSCONANS SHOULD ENJOY
ANOTHER CENTURY
OF GREAT SOUTHWEST WEATHER.
Metropolitan Tucson Convention and Visitor’s Bureau
Sent immediately a er a severe flood

44. FREQUENCY
MAGNITUDEsmall large
common
rare

45. EMIL GUMBEL (MATHS)

46. “ ”FOR THE TWO OR THREE EXTREME FLOODS,
THE RETURN PERIODS ARE BASED
ON A FEW OBSERVATIONS,
AND CONSEQUENTLY, THE AGREEMENT
IS NOT VERY GOOD.
Gumbel, 1941
The Annals of Mathematical Statistics

47. An aerial image of downtown shows flood-affected areas June 13, 2008
in Cedar Rapids, Iowa

48. EVEN WITH KNOWLEDGE OF A HISTORICAL FLOOD IN 1851,
THE 2008 FLOOD IS STILL NEARLY TWICE AS LARGE
AS ANY OTHER FLOOD ON RECORD.
0
1000
2000
3000
4000
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Discharge (m3/s)

50. PASSAU, GERMANY

51. Source: Christian Gries

53. “ ”FOR GREATER FLOODS,
THE MAXIMUM KNOWN FLOOD ELEVATION
IS MORE IMPORTANT
THAN ITS RECURRENCE INTERVAL.
IF THE FUTURE IS LIKE THE PAST,
THE OLDEST AND SIMPLEST IDEA IS THE BEST -
A FUTURE FLOOD COULD RISE
AT LEAST AS HIGH
AS THE PREVIOUS MAXIMUM.
James Eychaner
Lessons from a 500-year Record of Flood Elevations

55. 2UNCOVERING ANCIENT FLOODS

56. WHAT ARE THE RISKS POSED
BY FUTURE FLOODS?

58. THE FIRST STREAM GAGE IN THE UNITED STATES
WAS ESTABLISHED AT EMBUDO, NM IN 1889.

59. PALEOFLOOD
HYDROLOGY

60. VIC BAKER, UNIVERSITY OF ARIZONA

61. “ ”PALEOFLOODS ARE
PAST OR ANCIENT FLOODS
THAT OCCURRED WITHOUT BEING RECORDED BY EITHER
(1) DIRECT HYDROLOGICAL MEASUREMENT
DURING THE COURSE OF OPERATION (KNOWN AS INSTRUMENTAL
OR “SYSTEMATIC” RECORDING) OR
(2) OBSERVATION AND/OR DOCUMENTATION
BY NON-HYDROLOGISTS.
Victor Baker (2008)
Paleoflood hydrology: Origin, progress, prospects

62. COLORADO RIVER
RED RIVER OF THE NORTH

64. Source: Katie Rampala

65. Source: Robert Jarre , US Geological Survey
SLACKWATER DEPOSITS

67. Source: Greenbaum et al., (2014), Water Resources Research.

68. 44“100-YEAR FLOODS”
IN THE PAST 2100 YRS.

69. “ ”OUR RESULTS INDICATE
THAT VERY LARGE FLOODS
(A) ARE MUCH MORE FREQUENT
THAN INDICATED BY PREVIOUS ESTIMATIONS
WHICH WERE BASED EXCLUSIVELY ON ANALYSIS
OF THE MEASURED, SYSTEMATIC GAGE RECORD, AND
(B) THEIR FREQUENCY HAS INCREASED
DURING THE LAST 500 YEARS.
Greenbaum et al, 2014
Water Resources Research

70. PMF(Probable Maximum Flood)

71. THE ESTIMATED DISCHARGES FOR THE TWO LARGEST PALEOFLOODS
ARE BIGGER THAN THE PROBABLE MAXIMUM FLOOD FOR THE MOAB VALLEY.

72. “ ”WHAT SHOULD BE DONE
IF A STIPULATED PMF VALUE
(WHAT IS THEORIZED TO BE THE FLOOD THAT WILL RESULT
FROM THE “MOST SEVERE COMBINATION OF CRITICAL
METEOROLOGICAL AND HYDROLOGIC CONDITIONS THAT ARE
REASONABLY POSSIBLE”)
IS DISCOVERED TO BE CONTRARY TO
WHAT ACTUALLY EXISTS IN NATURE?
Greenbaum et al, 2014
Water Resources Research

73. Source: FlickrLiren Chen
THE RED RIVER OF THE NORTH

74. WINNIPEG GRAND FORKS

75. GRAND FORKS
1872

76. WINNIPEG
1812

77. FORT GARRY, HUDSON’S BAY COMPANY

78. MAY 31826

79. THE RIVER ROSE SIX FEET
LAST NIGHT PERPENDICULARLY ,
SEVERAL TENTS ARE NOW PITCHED UPON
THE MOST ELEVATED SPOTS:
TERROR IS STRONGLY DEPICTED
ON EVERY COUNTENANCE.
“ ”
David Jones Journal
May 1826

80. MAY 51826

81. THE RIVER
OVERFLOWED ITS BANKS
EVERY WHERE,
AND CARRIED THE ICE WITH GREAT VELOCITY
TO A GREATER DISTANCE FROM ITS COURSE,
THAN HAD EVER BEEN SEEN BEFORE
BY THE OLDEST INHABITANTS.
“ ”
Red River Journal
May 1826

82. MAY 161826

83. THE WHOLE FACE OF THE COUNTRY,
BOTH BELOW AND ABOVE OUR ENCAMPMENT
IS COVERED WITH WATER,
AND IN THIS WINDY WEATHER, LOOKS LIKE
AN IMMENSE LAKE IN A STORM.
“ ”
Red River Journal
May 1826

84. SIR SANFORD FLEMING

85. THE LARGEST FLOODS ARE KNOWN FROM HISTORICAL ACCOUNTS
AND POST HOC SURVEYS OF LOCAL ELDERS.
Source: Manitoba Conservation and Water Stewardship
0
60,000
120,000
180,000
240,000
2006 1996 1979 1950 2011 1861 2009 1997 1852 1826
discharge (cfs)
historical reports
river gauges

86. 1950

87. Source: Greg Brooks
1997

89. QUERCUS

90. √
24
OAK TREE RINGS
(NORMAL ANATOMY)

91. 91
Source: St. George and Nielsen, The Holocene, 2003
1826
19

92. 700-YRFLOOD

94. … ALTHOUGH THE 1826 FLOOD
DEVASTATED THE FLEDGLING
RED RIVER SETTLEMENT,
IT ALSO LED TO THE DEVELOPMENT OF
A SUPERIOR LEVEL
OF FLOOD PROTECTION
FOR MODERN WINNIPEG…
“ ”
St. George and Rannie
Canadian Water Resources Journal, 2003

95. HOW MUCH TIME
IS NEEDED
TO TRULY KNOW
A RIVER?

96. Source: Fredrik Von Erichsen/AFP/Ge y Images

97. “ ”(RHENUS) FLUVIUS GALLIAE
QUI GERMANOS A GALLIA DIVIDIT.
(THE RHINE IS A) RIVER OF GAUL, WHICH DIVIDES
THE GERMANIC PEOPLE FROM GAUL.
Maurus Servius Honoratus
Commentary on the Aeneid of Vergil
4th Century CE

98. EVALUATE
VULNERABILITY
JUDGE
INFRASTRUCTURE
BE MORE AWARE
OF NATURE’S POTENTIAL
A DEEP ‘RIVER MEMORY’
IS ESSENTIAL TO:

99. VIC BAKER, UNIVERSITY OF ARIZONA

100. THE HISTORY OF PAST FLOODS,
NOT THE HISTORICAL IDEALIZATION
OF THEIR FUTURE POSSIBILITIES,
IS THE UNDERSTANDABLE BASIS
UPON WHICH PEOPLE
MAY BE GUIDED TO EFFECTIVE ACTION.
“ ”
Baker et al., 2002
The Scientific and Societal Value of Paleoflood Research

102. MANITOBA MUSEUM

103. 103
Source: St. George and Nielsen, The Holocene, 2003
1826
19

104. MANITOBA MUSEUM

105. “ ”Believe me, you will find more lessons in the woods than
in books. Trees and stones will teach you what you cannot
learn from masters.
ST. BERNARD OF CLAIRVAUX
1090 - 1153 CE

106. @sco stgeorge