The Water Cycle

http://observe.arc.nasa.gov/nasa/earth/hydrocycle/hydro3.html

Water Budget• a continuous cycle of evaporation,

condensation, and precipitation• the worlds water budget is in balance

because precipitation = evaporation• precipitation= income evaporation and runoff= expenses• local water budgets (that of a particular

area) are NOT balanced due to temperature, presence of vegetation, wind, and amount and duration of rainfall

Water Conservation

•each person in the U.S. uses ~95 cm3 of water each year–bathing, washing clothes, dishes, brushing teeth, watering lawn, carrying waste away, drinking

Agriculture and industry use the greatest amount of water

90% of this used water is returned to rivers, lakes,

oceans, etc.

http://wwwga.usgs.gov/edu/wwvisit.html

two ways to insure that there is water for

tomorrow:•conserve, conserve, conserve!

•desalination (removing salt from the ocean water)

Desalination Plant in Key West, FL

River Questions(Write answers on your paper-to turn in-it’s ok if you

don’t know all the answers- Do Your BEST!)

River Questions(Write answers on your paper-to turn in-it’s ok if you

don’t know all the answers- Do Your BEST!)

• What river most affects us here in Wilmington?

• What are some ways that our town benefits from that river?

• What are some of the ways humans can impact the health of the river?

• What can you do to improve the quality of water in the river?

River Systems

watershed•land from which water runs off into streams (drainage basin)

Surf your watershed

http://www.epa.gov/surf/

Know your watershed

http://ctic.purdue.edu/kyw/kyw.html

tributaries•feeder streams that flow into a main river

divide•ridges or elevated regions of high ground that separate watersheds

headwaters•beginning of a stream

Stream Erosion

channel•the path that a stream follows

bank

bed

headward erosion

•process of lengthening and branching of a stream

stream piracy•the capture of a stream in one watershed by a stream with a higher rate of erosion in another watershed

Stage 1 - Beaverdam Creek, Gap Run, and Goose Creek flow eastward through the Blue Ridge and enter the Potomac.

Stage 2 - As the land is eroded downward, the three east flowing creeks do not have the power to erode as far through the Blue Ridge as the Shenandoah, Potomac system. The Shenandoah extends itself southward by headward erosion through the relatively high land west of the Blue Ridge. It eventually captures Beaverdam Creek.

Stage 3 - The capture of Beaverdam Creek added more discharge to the Shenandoah which was able to therefore erode more. Headward erosion leads to the capture of Gap Run. The water gaps where Beaverdam Creek and Gap Run used to flow through the Blue Ridge are left as wind gaps.

Stage 4 - Eventually Goose Creek is captured as well. Snicker's Gap, Ashby Gap, and Manassas Gap are left as wind gaps. As the land on either side of the ridge is eroded down together with the ridge summit, the relative elevation of the wind gaps becomes higher and higher.

channel erosion5 things that affect the rate

• stream load: material carried by a stream1. suspended load: particles of fine

grains and silt2. bed load: made of larger, coarser

sand, gravel, and pebbles3. dissolved load: mineral matter

transported in liquid solution

Bed

4. discharge•volume of water moved by a stream within a given time5. gradient

•steepness of a stream slope

water gap

•notch formed where the stream has eroded its channel

River Systems

Youthful river•straight •erodes rapidly•V-shaped•few tributaries•has waterfalls and rapids

Mature river•meandering (winding)•slow erosion•U-shaped •lots of tributaries •holds lots of water

Old river•gradient and velocity decreases

•no more erosion•more meandering

rejuvenated river•a river whose gradient increases due to movement in the Earth’s crust (form a step-like terrace) or velocity increases due to more water movement

Stream Deposition

as the velocity of a stream decreases, it drops the sediment it was carrying

delta•underwater deposit of sediment at the mouth of a river or stream

alluvial fan•fan-shaped deposit at the base of a slope on land

floodplain•part of the valley floor that may be covered with water during a flood

natural levee•raised riverbank that results when a river deposits its load at the river’s edge

Flood Control

artificial levee

dams