The Water Cycle
http://observe.arc.nasa.gov/nasa/earth/hydrocycle/hydro3.html
What is Water Budget?• balance in the water cycle means the
average annual precipitation over Earth equals the amount of water that evaporates
• the worlds water budget is in balance because precipitation = evaporation
• 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 575 liters of water each day on average–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
What are the 2 ways to ensure water is there
tomorrow?•conserve, conserve, conserve!
•desalination (removing salt from the ocean water)
Desalination Plant in Key West, FL
What are the parts of a 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
What is 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.
What are the types of channel erosion?
stream load:
material carried
by a stream
dissolved load: mineral matter transported in liquid solution
suspended load: particles of fine grains and silt suspended in the water
bed load: large, coarser sand, gravel, and pebbles that move along the bottom
Bed
discharge• volume of water moved by a stream
within a given time
gradient•steepness of a stream’s slope
• distance the water travels in a period of time
velocity
What factors affect stream erosion?
River Systems
What are the features of a Youthful river?
•straight •erodes rapidly•V-shaped•few tributaries•has waterfalls and rapids
What are the features of a Mature river?
•meandering (winding)•slow erosion•U-shaped •lots of tributaries •holds lots of water
What are the features of an Old river?
•gradient and velocity decreases
•no more erosion•more meandering
What is a water gap?
•notch formed where the stream has eroded its channel
What is Stream Deposition?
as the velocity of a stream decreases, it drops the sediment it was carrying
What are deposition features created by
rivers?
1. delta•underwater deposit of sediment at the mouth of a stream into a lake or ocean
2. alluvial fan
•fan-shaped deposit at the base of a slope on land
3. floodplain
•part of the valley floor that may be covered with water during a flood
4. natural levee
•raised riverbank that results when a river deposits its load at the river’s edge
Flood Control
artificial levee
dams
Ohio River Flooding
What is Groundwater? underground water that
fills almost all the pores in rock and sediment
• -makes up 90% of the Earth’s liquid freshwater
What is Porosity? refers to the
percentage of open spaces in rock or
sediment
What affects Porosity? 1. sorting: amount of uniformity in size of particle in a rock or sediment-same size particles=large porosity
-different size particles= small porosity
• 2. way particles are packed together – packed loosely= high porosity- packed tightly= low porosity
What is Permeability?
how freely water passes through open spaces in
rock or sediment
• -open spaces must be connected to be permeable !
Impermeable: rock or sediment that
water cannot flow through
Groundwater Vocabulary Terms
• zone of saturation: layer of groundwater where all pores are full
• aquifer: underground body of water (underground lake); can have sediments and rock in it
•water table: upper surface of the zone of saturation
capillary fringe: where water is drawn up by capillary action from zone of saturation
•zone of aeration: zone that lies between water table and surface (remains dry except during rainfall)
•soil-water region: space around soil accumulates water
Ground water flow depends on permeability of aquifer and gradient of
its water table.• Gradient increase = velocity of
ground water increaseGradient decrease = velocity of ground water decrease
What affects groundwater flow?
• well: a hole that is dug below the water table and fills with groundwater
• cone of depression: cone-shaped depression in water table around a well
• artesian well: well in which water flows freely with no pumping necessary
• cap rock: top layer of impermeable rock
Cone of Depression
•spring: flow of groundwater that emerges naturally at the ground surface
•artesian spring: natural flow of water to the surface from an artesian formation
•hot spring: hot groundwater that rises tosurface before cooling
•geysers: hot springs that erupt periodically
•Conserving Groundwater:Sources of pollution – water dumps, underground storage tanks, agriculture and lawn fertilizers, pesticides, leaking sewage
Groundwater Contamination
•Conservation – monitor levels of water tables, discourage uses of excess water, recycle, purifying used water
Results of Weathering by Groundwater
•hard water: water that contains large amounts of dissolved minerals–has metallic taste, soap won’t make suds, damages appliances that use water
•caverns: large cave with connecting chambers
Observe an animation of cave formation.
•sinkhole: depression formed when the roof of a cavern collapses
stalactite: cone-shaped calcite deposit suspended from the ceiling of a cavern
stalagmite: cone-shaped calcite deposit built up from the floor of a cavern