Surface Water

1. Surface Water Chapter 9

2. Surface water movement: Water Cycle • Earths water supply is constantly recycled

3. Surface Water Movement • 1) Runoff • Water flowing down slope along Earth’s surface or seep into the ground • Run off speed determined by slope of the hill • Ends up in a stream or lake, evaporate, or accumulate into puddles

4. Movement • Seep into ground • Ground must have large enough pores – loose soil • Evaporate

5. Fate of water: Run off or Seep • Certain characteristics will determine whether not water will either seep into or become runoff • 1) Vegetation • Vegetation allows for loose soil • Loose soil allows water to enter ground • Gardeners do not pack their soil

6. Fate of water • 2) Rate of precipitation • Heavy: • soil clumps together closing pores • Fills up ground to quickly and water becomes runoff • Light: • allows water to gently slide through • Less erosion

7. Fate of Water • 3) Soil Composition • Effects the waters holding capacity • Decayed organic matter (humus) • Creates the pores in soil – Increases retain ability • Minerals • Clay – fine mineral which clump together • Few Spaces • Sand – large pores

8. Fate of Water • 4) Slopes • Steep: allows for high runoff & little absorption • Little: low runoff and high absorption

9. Formation of Stream systems • Runoff • Surface water flows in thin sheets and eventually collects in small channels • Runoff increases, channels widen and become deeper and longer • Channels fill up again each time with rain • Channel can become a stream

10. Water sheds: • drainage basin • Land where all water drains into • Divide • High land area that separates watersheds

11. Mississippi Watershed

12. Stream Load • All the materials that the stream carries • Solution • Material that has been dissolved • Depends on area where the steam runs through • Erosion of rocks and dirt

13. Stream Load • Suspension • Small particles held up by the turbulence of stream • Clay, silt, sand • Depends on volume and velocity of water • Bed Load • Turbulence of water pushes heavy things • Pebbles and cobbles • Larger velocity – large objects • B/c of abrasion, rocks are smooth

14. Stream Velocity & Carrying Capacity • Discharge = width x depth x velocity (m) (m) (m/s) • As discharge increases so does carrying capacity

15. Floods • Water fills over the sides of a stream banks • Floodplain: broad flat area of land that extends out from streams for excess flooding