James River in Richmond, Virginia looking upriver from the Robert E. Lee bridge.Belle Isle is on the right, November 1985.

1. What is happening in this picture?

2. What makes the water so brown?

http://serc.carleton.edu/introgeo/interactive/examples/flood.html

James River in Richmond, Virginia. The Robert E. Lee bridge and the bridge in the previous photo are in the background.

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?

http://serc.carleton.edu/introgeo/interactive/examples/flood.html

Potholes along the James River at Belle Isle, the same location as previous images.

6. Describe the shape of the bedrock river channel. 7. How were those holes formed?

http://serc.carleton.edu/introgeo/interactive/examples/flood.html

http://www.usgs.gov/hazards/images/maps/flood_hires.jpg

Presidential disaster declarations related to flooding in the United States, shown by county, between June 1, 1965, and June 1, 2003

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

Floods are common and costly natural disasters

http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.024-00.html

Hurricane Katrina- largely from flood [rain and storm surge] damage$105 Billion

http://en.wikipedia.org/wiki/Economic_effects_of_Hurricane_Katrina

Floods are common and costly natural disasters

Drainage Basin

http://wps.prenhall.com/wps/media/tmp/labeling/390600_dyn.jpg

http://www.lpb.org/education/tah/Workshop111905_files/slide0034_image009.jpg

Flood plains normally are dry

http://pubs.usgs.gov/fs/OFR93-641/ http://www.uwsp.edu/geo/faculty/ritter/geog101/uwsp_lectures/lecture_fluvial_processes.html

Meandering river carve out the flood plain

http://www.uwm.edu/Course/geosci697/rivers-deltas/

Map of real-time streamflow compared to historical streamflow for the day of the year

http://water.usgs.gov/waterwatch/index.php?map_type=real&state=nj

Q = A X V

Stream Discharge (Q)Hydrograph

http://www.uwsp.edu/geo/faculty/ritter/geog101/uwsp_lectures/lecture_fluvial_processes.html

Lag time

Weather patterns can determine when floods occur

http://pubs.usgs.gov/fs/OFR93-641/

steep topography + intense rain = short lag time = “Upstream” (flash flood) flood

7.5 inches of rain in 70 minutes flood water velocity of 23 ft/secThe 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.

August 1, 1976

http://www.super70s.com/Super70s/Tech/Nature/Disasters/Floods/76July31-Big_Thompson.asp

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.

http://pubs.usgs.gov/fs/fs07603/

Affect of Urbanization on Flooding

What is it about urbanization that is problematic?

http://www.geo.hunter.cuny.edu/bight/chap9.html

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 >> infiltration increase flood potential

Flood Fequency Curve for Raging River at Wetsfield

100

1000

10000

0 10 20 30 40 50 60 70 80 90 100

Recurrence Interval (yrs)

Disc

harg

e (c

fs)

http://serc.carleton.edu/quantskills/methods/quantlit/floods.html

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.

Very large floods happen very seldom

Flood Frequency Diagram

http://www.nws.noaa.gov/oh/Dis_Svy/RedR_Apr97/graphics/Fig2.gif

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

Wetlands (veg.) can reduce floods Retention ponds can reduce floods

http://www.dnr.wa.gov/htdocs/lm/field_guides/recognizing/functions.html

Zoning restrictions limit flood damage

Dams and levees can reduce the risk of floods

http://pubs.usgs.gov/fs/OFR93-641/

Floodwalls along Willow Creek in Rosemont, Illinois. Source: Kevin D. Richards, U.S. Geological Survey.

http://pubs.usgs.gov/fs/fs07603/

http://www.macchuck.com/KATRINA/GALLERIES/info/ElevationMap.html

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?storyId=4826934

Levees (and channalization) can constrict a river, increasing flow velocities and causing flooding upstream and downstream

http://www.friendsoftheriver.org/Publications/BeyondFloodControl/no6.html

http://www.friendsoftheriver.org/Publications/BeyondFloodControl/no8.html

http://ks.water.usgs.gov/Kansas/pubs/fact-sheets/fs.024-00.html