James River in Richmond, Virginia looking upriver from the Robert E. Lee bridge.

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1. What is happening in this picture? 2. What
makes the water so brown?
James River in Richmond, Virginia looking upriver
from the Robert E. Lee bridge. Belle Isle is on
the right, November 1985.
http//serc.carleton.edu/introgeo/interactive/exam
ples/flood.html
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3. Estimate the height of the river during the
flood shown in the previous image. 4. How could
we obtain or estimate past flooding? 5. How can
we predict the future flood potential?
James River in Richmond, Virginia. The Robert E.
Lee bridge and the bridge in the previous photo
are in the background.
http//serc.carleton.edu/introgeo/interactive/exam
ples/flood.html
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6. Describe the shape of the bedrock river
channel. 7. How were those holes formed?
Potholes along the James River at Belle Isle, the
same location as previous images.
http//serc.carleton.edu/introgeo/interactive/exam
ples/flood.html
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Presidential disaster declarations related to
flooding in the United States, shown by county,
between June 1, 1965, and June 1, 2003
Floods are common and costly natural disasters
Green 1 declaration Yellow 2 declarations
Orange 3 declarations Red 4 declarations
Map not to scale. Sources FEMA, Michael Baker
Jr., Inc., the National Atlas, and the USGS
http//www.usgs.gov/hazards/images/maps/flood_hire
s.jpg
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Floods are common and costly natural disasters
Hurricane Katrina - largely from flood rain and
storm surge damage 105 Billion
http//en.wikipedia.org/wiki/Economic_effects_of_H
urricane_Katrina
http//ks.water.usgs.gov/Kansas/pubs/fact-sheets/f
s.024-00.html
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Drainage Basin
http//www.lpb.org/education/tah/Workshop111905_fi
les/slide0034_image009.jpg
http//wps.prenhall.com/wps/media/tmp/labeling/390
600_dyn.jpg
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Meandering river carve out the flood plain
Flood plains normally are dry
http//www.uwm.edu/Course/geosci697/rivers-deltas/
http//pubs.usgs.gov/fs/OFR93-641/
http//www.uwsp.edu/geo/faculty/ritter/geog101/uws
p_lectures/lecture_fluvial_processes.html
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Map of real-time streamflow compared to
historical streamflow for the day of the year
http//water.usgs.gov/waterwatch/index.php?map_typ
erealstatenj
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Stream Discharge (Q)
Hydrograph
Q A X V
Lag time
http//www.uwsp.edu/geo/faculty/ritter/geog101/uws
p_lectures/lecture_fluvial_processes.html
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Weather patterns can determine when floods occur
http//pubs.usgs.gov/fs/OFR93-641/
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steep topography intense rain short lag time
Upstream (flash flood) flood
August 1, 1976
7.5 inches of rain in 70 minutes ? flood water
velocity of 23 ft/sec The Big Thompson Canyon
flood killed 145 people, destroyed 418 houses
and damaged another 138, destroyed 152 businesses
and caused more than 40 million in damages.
http//www.super70s.com/Super70s/Tech/Nature/Disas
ters/Floods/76July31-Big_Thompson.asp
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Affect of Urbanization on Flooding
Streamflow in Mercer Creek, an urban stream in
western Washington, increases more quickly,
reaches a higher peak discharge, and has a larger
volume during a one-day storm on February 1,
2000, than streamflow in Newaukum Creek, a nearby
rural stream. Streamflow during the following
week, however, was greater in Newaukum Creek.
What is it about urbanization that is problematic?
http//www.geo.hunter.cuny.edu/bight/chap9.html
http//pubs.usgs.gov/fs/fs07603/
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• What parameters influence flooding?
• Weather patterns precipitation, snow melt
• Topography (steep or flat)
• Properties of the soil (porous and permeable)
• Land use (impervious covers, channalization)
• All come down to surface runoff gtgt infiltration
  ? increase flood potential

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Very large floods happen very seldom
The extrapolations of recurrence intervals are
used to forecast the future probability of a
flood of a given discharge. The probability (P)
of an flood with recurrence interval T is P
1/T The 100 year flood A flood discharge that
has a 100-year recurrence interval has a 1
chance of occurring or being exceeded in a given
year.
Flood Frequency Diagram
http//serc.carleton.edu/quantskills/methods/quant
lit/floods.html
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The stage of such a flood can be back-calculated
using the rating curve for the river. Once the
stage is known, a topographic map can be
consulted to examine inundation
http//www.nws.noaa.gov/oh/Dis_Svy/RedR_Apr97/grap
hics/Fig2.gif
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Retention ponds can reduce floods
Wetlands (veg.) can reduce floods
http//www.dnr.wa.gov/htdocs/lm/field_guides/recog
nizing/functions.html
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Zoning restrictions limit flood damage
Dams and levees can reduce the risk of floods
Floodwalls along Willow Creek in Rosemont,
Illinois. Source Kevin D. Richards, U.S.
Geological Survey.
http//pubs.usgs.gov/fs/OFR93-641/
http//pubs.usgs.gov/fs/fs07603/
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http//www.macchuck.com/KATRINA/GALLERIES/info/Ele
vationMap.html
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A map from the U.S. Army Corps of Engineers sets
out areas of flooding in New Orleans following
Katrina, Sept. 2.
http//www.npr.org/templates/story/story.php?story
Id4826934
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Levees (and channalization) can constrict a
river, increasing flow velocities and causing
flooding upstream and downstream
http//www.friendsoftheriver.org/Publications/Beyo
ndFloodControl/no6.html
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http//www.friendsoftheriver.org/Publications/Beyo
ndFloodControl/no8.html
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http//ks.water.usgs.gov/Kansas/pubs/fact-sheets/f
s.024-00.html