Watersheds
ESI
A map of streams in an area
N
streams
Can you determine the
watershed for this stream?
Major stream in watershed
Drainage divide N
high spot or ridge
N
What is general
streamflow direction?
Any water flowing north?
A
B
Cross-section
Drainage Divide
Runoff to the west
Runoff to the east
Looking north up ridge
A
Cross-section
B
headwaters
Major streams in watershed
N
Watershed boundary
headwaters
Tributary
to major
stream
mouth
main channel
mouth
Stream Gradient
headwaters
Water flows downhill !
-Idiot’s Guide to Stream Hydrology
Drop in
elevation
mouth
Distance traveled
Stream Gradient =
(average)
Drop in elevation, feet
Distance traveled, miles
Typical stream gradient in Prince George’s County – xxx ft/mi
N
Area of collection
of precipitation
Steps in the hydrologic cycle
•
•
•
•
•
•
precipitation
runoff and stream – surface flow
evaporation
evapotranpiration
transpiration
infiltration
groundwater (subsurface) flow
precipitation
transpiration
runoff
evaporation
infiltration
groundwater
Watershed
subwatershed
Even smaller
subwatershed
N
Nested
watersheds
airshed
Watershed is like a
funnel
watershed
Container such as
Chesapeake Bay
Watershed and Airshed of
Chesapeake Bay
http://www.dnr.state.md.us/streams/acid/page4.html
Maryland’s Watersheds
To the Mississippi River Watershed
To the Delaware
Bay watershed
East coast
continent divide
95% of Maryland
drains water into
the Chesapeake Bay
To the Atlantic Ocean directly
http://mddnr.chesapeakebay.net/wsprofiles/surf/prof/prof.html
Potomac River
Watershed
Drainage Divide in
Prince George’s County
Patuxent River
Watershed