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
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
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
channel • the path that a stream follows
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
bed load: large, coarser sand, gravel, and pebbles that move along the bottom
What factors affect stream erosion? discharge velocity • volume of water moved by a stream within a given time • distance the water travels in a period of time gradient • steepness of a stream’s slope
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