Transcript Watersheds PPT

Watershed Reading
Video
Video 2
Watershed=
area of land that
drains
precipitation to a
body of water
1.
2. Depends on
topography
- Divided by ridges
(hills)  drainage
divides
3. Drainage Divide
One watershed
on one side of
hill
Other
watershed on
other side of hill
Ridges determine where water will flow
4. Drainage Patterns
Dendritic
Looks like a
tree
Most
common
pattern in PA
Drainage Patterns
Radial
 Flows from a
high point
(volcano,
mountain)
 Circular
Drainage Patterns
Rectangular
Forms
right angles
Drainage Patterns
Trellis
 ** What we have
 Valleys in areas of
soft rocks; ridges
(hills) in areas of
hard rock
Drainage Pattern Questions
5. Near volcanos &
mountains  radial
6. Most common 
dendritic
7. Alternating hard & soft
rock  trellis
8. Continental Divide
Many continents have a
continental divide (imaginary
lines that follow ridges). The
continental divide in North
America separates into 2 major
watersheds
 West side drains into the Pacific
Ocean
 East side drains into the Atlantic
Ocean
10-12. PA Watersheds
Methacton HS
is in the
Delaware
watershed
Susquehanna
is the largest
PA watershed.
Into what river
will all smaller
rivers in this
area flow?
If we follow
the Delaware
River out,
what body of
water will we
come to?
Do our
actions
around
the
Schuylkill
River
affect the
Delaware
Bay?
13. Importance of Watersheds
Habitats to many organisms
Collect and store rainfall
Water for agriculture, industry and
households
Recharges groundwater
Wetlands within the watersheds help to filter
out pollutants and absorb water to prevent
flooding
Watershed Impacts Downstream
•We are connected to others downstream
•Our waterway flows into other
waterways.
•Our watershed drains into other
watersheds.
•Our mess / our pollution travels
downstream.
Watershed Pollution
Nonpoint
Source
Pollution
 Cannot
be traced
to one
specific
sourcegenerally
comes from
all of us.
Stormwater Runoff
When rain or melting snow
washes over the ground,
pollutants such as leaked oil
from cars, dog waste and
litter gets carried into our
waterways.
It is often nonpoint source
pollution, so it’s a little bit
here and a little bit there,
which adds up!
Agricultur
e
Pesticides/fertilizers – pollute groundwater & causes
eutrophication
Animal Waste- causes disease/pollutes drinking water
Overgrazing- causes erosion  more sediment in water  clogs
fish gills
Urbanization
Storm water runoff washes all of the following into bodies of
water: Pet waste cleaning chemicals Oil Gas Detergents
Paints
Mines
Heavy metals in runoff  acidify the bodies of water
Industry
Smog causes acid rain (chemicals released into air)
Industrial waste dumped into waterways.
Waste
Disposal
Sewage- untreated human waste causes disease & death in
drinking water
Landfills- chemicals/pollutants from garbage sink into
soil/groundwater when it rains
Solutions