Water
Water Distribution
Water use in the US in 2000
The Water Cycle
Transpiration (plants)
Parts of a River
Collection
Transportation
Dispersal
Dendritic pattern
Yemen
Limestone Bedrock:
Naturally fractures into squares & rectangles
Common in the Appalachians where rivers
have cut through parallel ridgelines.
Drainage Basin
Delta Development
Distributary
Water coming down a river hits the ocean; gradient goes to zero
Sediment is deposited; channel eventually fills
River jump its banks and takes a new course
Process repeats
Very common in deltas
Distributaries
Mississippi River Delta
Mature Deltas
Mississippi Delta
Left to its own devices, the
Mississippi would now be
flowing down the Atchafalaya Basin.
Oil refineries line the Mississippi
Mississippi
Embankment
Atchafalaya River
New Orleans
Hurricane Threat -- very real
River Dynamics
Rivers are complex systems influenced by number of things, which are:
- discharge
- velocity
- gradient
- sediment load
- base level
Stream Discharge
- amount of water passing by a given
point during a specific time interval
- measured in cubic meters/second
Discharge Station
Velocity
Meanders
Cut Bank
Meandering
Oxbow Lakes
NE/SD border
Slope
- fine particles are moved in suspension,
never touching the ground (suspended
load)
- silt & clay giving the water a muddy
look
- coarse particles are moved by traction
along the stream bed, jumping along
(bed load)
- move by saltation: short leaps as a
strong current picks them up and moves
them a short distance.
- 7-10% of the total sediment load, on
average.
- abrasion between particles causing
them to wear, smoothing them and
forming round pebbles and stones.
- also wears away the stream channel
along the sides and bottom of the
channel.
- dissolved materials are carried along in
solution (dissolved load)
- invisible chemical ions
Sediment Load
QuickTime™ and a
Sorenson Video decompressor
are needed to see this picture.
Mississippi Sediment
Base Level
The lowest elevation (depth) to which a river can erode its bed.
Stream Maturity
Youthful
Mature
Old Age
Old Age River
Flooded River
Levees occur when active deposition takes place along the banks of an older river
when it is in a flood. Each time this happens the banks get higher forming a natural
levee -- a barrier to future flooding.
Natural Levee
Levees
River channel
Urban Runoff
More pavement = dramatically increased runoff rates
Levee
If the river doesn’t flood, sediment is deposited on the river bed;
causes water level to rise
Concrete Paving
Smooth bottom = less friction = fast-moving water = less sediment deposition
Levee Breech
Siltation
Wastewater
15,000,000 people. All pavement. 50 inches of precipitation per year. Where does all the water go?
Urban sewer system
Many urban sewer systems are outdated
Wilmington, Delaware
Delaware Streams
Storm Sewer Runoff
Storm Sewer Runoff
Raw untreated
sewage
KMEG News: Storm Lake, IA
“IOWA'S BEACHES WILL STAY OPEN THIS YEAR.EVEN IF THEY
*ARE* POLLUTED WITH FECAL BACTERIA.THE IOWA
DEPARTMENT OF NATURAL RESOURCES SAYS THE BEACHES AT
STATE PARKS ARE TOO POPULAR AND VALUABLE TO IOWANS TO
CLOSE THEM WHEN THERE ISN'T CLEAR EVIDENCE OF A HEALTH
RISK.LAST YEAR, EMERSON BAY IN LAKE OKOBOJI WAS ONE OF
SEVERAL BEACHES CLOSED.THE D-N-R SAYS THIS YEAR THE
STATE WILL POST WARNING SIGNS INSTEAD.WORKERS WILL
BASE THEIR FINDINGS ONLY ON TESTS FOR FECAL COLIFORM
BACTERIA.LAST YEAR, THE STATE CONSIDERED THREE
DIFFERENT BACTERIAS.THE D-N-R SAYS IT CONSULTED HEALTH
OFFICIALS BEFORE DECIDING THAT USING THREE WAS
CONFUSING AND CUMBERSOME.”
Alesund, Norway
Wastewater Treatment
Toxic Runoff
Acid Drainage
Summitville, CO:
All aquatic life absent for
17 miles away from mine.
How bad is it?