flash flood!
DESCRIPTION
Stream tables experiemnts with flash floods and slopeTRANSCRIPT
Experiments in Erosion and Experiments in Erosion and DepositionDeposition
Flash FloodsFlash Floods and Slippery Slopes!
What is a flash flood?What is a flash flood?
Both slides were taken at 30 seconds. Which one shows a Both slides were taken at 30 seconds. Which one shows a flash flood? flash flood?
That’s right. The one on the right.
A flash flood is a very heavy flow of water which is greater than the normal flow and goes over the banks of the stream or river’s normal channel.
The Jamestown Pennsylvania The Jamestown Pennsylvania Flood 1889Flood 1889
This famous flash flood was cause by days of extremely heavy rains and the failure of a dam upstream. Over 2200 people lost their lives.
How do flash floods affect erosion How do flash floods affect erosion and deposition?and deposition?
Faster! Deeper! Bigger!Erosion happens faster. Channels are straighter.Canyons are deeper and wider.Deltas are wider and longer.
Control Flash flood
Time Elapse LogTime Elapse Log
10 seconds Flood plain forms. Cliff edge beginning
to slump.30 seconds No change.1 minute Delta begins to form.
10 seconds Hole under water source. Cliff edge crumbling.
20 seconds Steep canyons form.30 seconds Large delta forms.1 minutes Water has drained from the hole.
Control Table Flash Flood Table
Which is the flash flood? Which is the control?Which is the flash flood? Which is the control?
control Flash flood!
Two Flash floods, one controlTwo Flash floods, one control
Flash Flood!
Flash Flood!
control
The Effect of Slope on Erosion and The Effect of Slope on Erosion and DepositionDeposition
This slide shows how the stream table looked after about 30 seconds.
This slide also shows a stream table after 30 seconds. What differences do you notice? What could account for these differences?
control slope
What happens when water falls down a incline or What happens when water falls down a incline or runs over a tilted surface?runs over a tilted surface?
It goes It goes faster faster and has more and has more
force force to to
increase the increase the
speedspeed andand
degreedegree of of
erosionerosion..
Faster, deeper, biggerFaster, deeper, bigger
These two slides were both taken at about 3 minutes elapsed time. Which stream table do you think was level? Which one was placed on a slope?
slope
One slope, one controlOne slope, one control
Slope Control
Conducting ExperimentsConducting Experiments
• What do you think would happen if we increased the slope and had flash flood conditions?
• What else might you want to learn about erosion and deposition?
• How can we find out?