Class Notes (837,548)
Canada (510,312)
EARTHSC 2GG3 (199)

Earth Science - Lecture 31 Notes.docx

3 Pages
Unlock Document

Earth Sciences
Sergei Basik

STREAMS AND FLOODING PROCESSES Groundwater, Precipitation and Stream Flow  Some of precipitation in an area percolates through soil to become groundwater and is collected by rivers and streams  Gaining streams are fed by groundwater  Losing streams lose water into the ground Gaining and Losing Streams  Wet climates: groundwater flows into gaining streams, ensuring year-round flow  Dry climates: water from streams feed groundwater  Losing streams may dry up between rainstorms  Areas of moderate to high annual rainfall: o Groundwater continuously feeds streams o Changes in precipitation result in changes to groundwater levels but stream inflow is generally constant  Semi-arid to arid regions: o Water from losing streams sinks into ground and streams may dry up between storms o Flash floods can occur after any major or prolonged rainfall Precipitation and Surface Runoff  Runoff: liquid water that travels over the surface of the Earth, moving downward due to gravity  Some precipitation flows as surface runoff during torrential rainfall (rapid runoff is overland flow)  Ability of ground to absorb rainwater depends on: o Rate of precipitation o Permeability of soil o Extent of prior saturation o Whether ground is frozen  Some regions are more prone to heavy rainfall: o Weather patterns such as major storm systems o Higher elevations and heavy snowfall Flooding Processes  Bankfull level: level at which water spills over banks  Streams generally reach bankfull every 1.5 to 3 years  Increase in discharge during flood involves increase in water velocity, water depth and stream width Changes in Channel Shape during Flooding  Channel scour: depth of sediment eroded during floods  Flood increases water velocity  increases frictional drag on stream bottom  causes more erosion  Waning flow as flood declines  coarser material in suspension drops out  deposition raises streambed  Slow water velocity at edge of deeper channel forms natural levee of sediments: o Nearly continuous low ridge along edge of channel o May keep small floods within channel Flood Intensity  Intensity of flood depends on: o Discharge of floodwater o Rate of rise of water  Va
More Less

Related notes for EARTHSC 2GG3

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.