1. How do humans affect watersheds and the hydrologic cycle ?

2. Human caused disturbances Agriculture Timber harvest Mining Urbanization Introduction of exotic species Harvesting of fish and wildlife

3. Land Use and Vegetation The landscape control factor on which humans have the most influence –Mining: extent of vegetation alteration depends on type of mining –Forestry: tree removal and replacement over time –Urbanization: tree removal and replacement with grass and impervious surfaces –Agriculture: tree removal and replacement with pasture or crops

4. Effects of vegetation removal on hydrology and streams Precipitation ?

5. Effects of vegetation removal on hydrology and streams Precipitation ? Evapotranspiration ?

6. Effects of vegetation removal on hydrology and streams Precipitation ? Evapotranspiration Infiltration ?

7. Effects of vegetation removal on hydrology and streams Precipitation ? Evapotranspiration Infiltration Surface runoff ? Subsurface runoff ?

8. Effects of vegetation removal on hydrology and streams Evapotranspiration Infiltration Surface runoff Subsurface runoff Frequency and magnitude of peak flows ?

9. Effects of vegetation removal on hydrology and streams Evapotranspiration Infiltration Surface runoff Subsurface runoff Frequency, magnitude and timing of peak flows Materials transported to stream ?

10. Effects of vegetation removal on hydrology and streams Evapotranspiration Infiltration Surface runoff Subsurface runoff Frequency and magnitude of peak flows Materials transported to stream

11. Aggregate Mining In-channel mining In-channel and floodplain mining Photos by M. Kondolf

12. Effects of instream aggregate mining Continuity of sediment transport interrupted Produces local sediment deficit Incision can lower the water table

13. Effects of instream aggregate mining This can lead to loss of groundwater storage Can affect hyporheic zone Reduce summer base flow

14. FORESTRY

15. Photos by R.S. Lindsay Photo by Carrie Inman Agriculture

16. URBANIZATION

17. Forestry, agriculture and urbanization All of these human activities alter the watershed What alterations do they have in common?

18. Forestry, agriculture and urbanization Remove trees and other vegetation Reduce organic matter delivery Build roads

19. Large storage in soil, channel and valley floor Recharge Natural cleaning Pollutant wash off No recharge Rapid flow limited storage Slow flow NaturalDeveloped Reduced soil storage Limited infiltration Precipitation

20. Floods and Urbanization surface runoff vs. infiltration natural land cover vs. urban area

21. How do we manage watershed? Dept of Natural Resources Regulations U.S. Forest Service Regulations Clean Water Act Endangered Species Act Total Maximum Daily Loads (TMDLs)