THE HYDROLOGIC CYCLE

1. THE HYDROLOGIC CYCLE

2. The Hydrologic Cycle

3. The Hydrologic Cycle - Fresh Water Storage Reservoir % of Total Fresh Water Glaciers (Frozen) 76% Groundwater 22% Rivers & Lakes < 2% Although it only makes up < 2% of total fresh water on earth, surface water is the most utilized and perhaps precious natural resource!

4. The Hydrologic Cycle How Does Water Move Within The Cycle?

5. The Hydrologic Cycle 1)RIVER SYSTEMS • Important source of fresh water. • Most important agent of erosion. • Most abundant continental landform. • Essential to agriculture & industry

6. Three Main Parts To A River System Collection system; Transportation system; Dispersing system

7. DIFFERENCES IN RIVER SUB-SYSTEM CHARACTERISTICS

8. The Collection System – A Drainage Basin

10. Types of Drainage Basins – Controlled by Geology

11. The Transportation System • The Dynamics of Stream Flow • Velocity • Discharge • Channel Parameters • Roughness • Dimensions • Sediment Load • Gradient and Base Level

12. 1) VELOCITY – Straight Channel

13. 1) VELOCITY – Curving Channel

14. 2) GRADIENT High V: Erosion LowV: Deposition

15. MEASURING DISCHARGE (Q): Q m3/sec = V (AVG. ) XWidth meters XDepth meters

16. 4) SEDIMENT LOAD AND TRANSPORTATION

17. TRANSPORTING SEDIMENT

18. Ideal Stream Profile Increasing discharge, velocity & sediment load Decreasing gradient, turbulence & competence Base level – level of deepest possible erosion.

19. Dynamic Equilibrium – “You can never change just one thing about a stream.” • The sensitive, ever-evolving balance between erosion and deposition. • Graded Stream: erosion = deposition. • If deposition > erosion, stream builds up its bed, thus increasing gradient and average velocity to restore balance. • If erosion > deposition, stream erodes bed, decreasing gradient and velocity.

20. Departures from Equilibrium Waterfalls – signs of a shifting balance: increased discharge or gradient

21. Dam That Stream! A System Out of Balance • Dam Effects • Upstream deposition • Discharge of clear, turbulent water & potential erosion. • Elimination of floods (reduced competence); • Choke off down-stream sediment flow. • Disturbed ecosystems

22. Meandering Streams

23. Floodplains have a purpose!