1. Running Water 6.1

2. Water Water Everywhere  About 97.2% of water is in oceans  Ice sheets and glaciers = 2.15% .65% = divided among lakes, streams, groundwater, and the atmosphere  About 97.2% of water is in oceans  Ice sheets and glaciers = 2.15% .65% = divided among lakes, streams, groundwater, and the atmosphere

3. The Water Cycle  Unending circulation of Earth’s water supply  Water changes states  Powered by the sun  Unending circulation of Earth’s water supply  Water changes states  Powered by the sun

4. The Water Cycle 1. Evaporation = liquid to gas  Water evaporates from oceans and continents into atmosphere 2. Condensation = gas to liquid  Moisture condenses into clouds 3. Precipitation = rain and snow  Falls into oceans = 1 full cycle  Falls onto land = must make its way back to oceans 1. Evaporation = liquid to gas  Water evaporates from oceans and continents into atmosphere 2. Condensation = gas to liquid  Moisture condenses into clouds 3. Precipitation = rain and snow  Falls into oceans = 1 full cycle  Falls onto land = must make its way back to oceans

5. The Water Cycle 4. Runoff = when rate of rainfall exceeds Earth’s ability to absorb it, excess water flows over the surface into lakes and streams 5. Infiltration = water soaks into land and seeps into lakes, streams, oceans 6. Transpiration = evaporation of water from plants 4. Runoff = when rate of rainfall exceeds Earth’s ability to absorb it, excess water flows over the surface into lakes and streams 5. Infiltration = water soaks into land and seeps into lakes, streams, oceans 6. Transpiration = evaporation of water from plants

6. How the Water Cycle Works

8. Earth’s Water Balance  Water cycle is balanced  Average annual precipitation on Earth = amount of water that evaporates  Can have local imbalances  Wind belts  Precipitation exceeds evaporation over continents  Water cycle is balanced  Average annual precipitation on Earth = amount of water that evaporates  Can have local imbalances  Wind belts  Precipitation exceeds evaporation over continents

9. Streamflow  Water moves downslope due to gravity  Ability of stream to erode and transport materials is due to its velocity  Velocity = distance/time  Velocity influenced by: 1. Stream’s gradient 2. Shape, size, and roughness of channel 3. Stream’s discharge  Water moves downslope due to gravity  Ability of stream to erode and transport materials is due to its velocity  Velocity = distance/time  Velocity influenced by: 1. Stream’s gradient 2. Shape, size, and roughness of channel 3. Stream’s discharge

10. Gradient  Gradient = slope or steepness of a stream channel  Steeper the gradient = more energy the stream has  Gradient = slope or steepness of a stream channel  Steeper the gradient = more energy the stream has

11. Gradient

12. Channel Characteristics  Stream channel = main path of the river or stream  Water flows --> friction from sides and bottoms of channel  Channel filled with boulders decreases velocity  Channel with sand and clay (smooth) increases velocity  Larger channels = more efficient water flow  Stream channel = main path of the river or stream  Water flows --> friction from sides and bottoms of channel  Channel filled with boulders decreases velocity  Channel with sand and clay (smooth) increases velocity  Larger channels = more efficient water flow

13. Discharge  Discharge = volume of water/time  Meters 3 per second  Impacts channel size and velocity  Additional water = channel widens and deepens  Additional water = less friction --> water moves faster  Discharge = volume of water/time  Meters 3 per second  Impacts channel size and velocity  Additional water = channel widens and deepens  Additional water = less friction --> water moves faster

14. Discharge  Urbanization around a stream channel  More pavement (streets, parking lots, buildings) = increases surface runoff  Less water soaks into ground  Urbanization around a stream channel  More pavement (streets, parking lots, buildings) = increases surface runoff  Less water soaks into ground

15. The Effects of Urbanization