1. Surface Water
Chapter 9 Notes

2. The Water Cycle

3. Runoff Surface water flowing downslope is called runoff.
Factors affecting runoff/infiltration:
Soil composition
Soil saturation
Rate of precipitation
Vegetation
Steepness of slope

4. Stream Systems All streams flow downhill
Rivers that flow into other streams are called tributaries.
A watershed or drainage basin is the land area whose water flows into a stream system.
A divide is an elevated land area that separates two watersheds.

5. Watersheds

6. Stream Load/Carrying Capacity
Moving water carries sediment
The amount of sediment (carrying capacity) depends on the amount of water and its velocity
Sediment can be
Suspended (silt, clay, and sand)
Bed load (sand, pebbles, and cobbles)
Dissolved (salts and minerals)

7. Discharge of a Stream
Discharge is the volume of water that flows past a point in a given amount of time
Discharge = width x depth x velocity
Mississippi: 17,000 m3 per second
Amazon: 170,000 m3 per second

8. Floods Floods occur when water spills over the stream’s banks
The broad, flat area covered by flood waters is known as a floodplain
Floodplains develop very fertile soil due deposits of nutrients

9. Natural Levees
Sediment carried by flood water is deposited along the banks
Natural ridges called levees are formed

10. Stream Development

11. Deposition of Sediment
When streams slow down, sediment they are carrying is deposited
Deltas: triangular deposit where a stream enters a lake or ocean
Alluvial fans: sloping, fan-shaped deposits in dry stream beds

12. Stream Rejuvenation
A change in base level can cause an “old” stream to begin downcutting again.
Meanders can become deep canyons (entrenched meanders)
example: Colorado River

13. Lakes
Most lakes in Europe and North America are in recently glaciated areas
A meandering river can form an oxbow lake through erosion and deposition of sediment

14. Eutrophication

15. Wetlands Wetlands play an important role in improving water quality
Wetlands serve as a filtering system that traps pollutants, sediment and pathogenic bacteria
Wetlands provide important habitat for wildlife