Hydrology

1. Hydrology Unit 6 Topic 8 in your Review Book

2. Hydrology is the study of water in, on and around the earth • The water cycle • a model of the movement and changes in phase of water at and near the surface of the earth

3. Evapotranspiration: • A combination of: • the evaporation of surface and ground water and • the release of water vapor through the pores of leaves • It is the source of all atmospheric water vapor

4. Precipitation: • the source of water for the earth • in the form of rain, drizzle, snow, sleet, freezing rain and/or hail

5. 3. Water and Climate • Climate is the overall view of a region’s weather conditions over a long period of time • The two factors tied to climate are: • Temperature • Moisture

6. Potential evapotranspiration is the amount of water vapor that would occur in an area if the water was available. • It is mostly determined by the amount of insolation an area receives (which determines the regions’ average temperature)

7. When • PPT < ET: the climate is arid or dry • PPT > ET: the climate is humid or wet

9. Storage: • ground and surface waters • Surplus: • excess water • Deficit: • not enough water

10. A. Factors influencing climate • Latitude: as latitude increases, temperature decreases • Planetary wind and pressure belt: see ESRT page 14

11. Oceans and other large bodies of water • Mountains • Elevation • Cloud cover • Vegetation

12. Concepts of the Water Cycle A. Infiltration: • the process by which water soaks into the ground under the influence of gravity • The water table is the limit of infiltration

13. If the ground is saturated (holding all of the water it can hold) infiltration cannot occur • If the ground is frozen, infiltration will not occur • If the precipitation is rapid and/or intense, infiltration is less likely to occur

14. If the slope is steep, infiltration is less likely to occur • If the ground is covered with pavement and/or buildings, infiltration is not likely to occur • If the soil is impermeable, infiltration cannot occur

15. Permeable soil or sediment allows water to flow down through it. • Porosity is the ability of a material to hold water in open spaces • Porosity depends upon the interconnectedness of the spaces between the sediment

16. Well-sorted sediments with round grains have a high porosity • Size does not affect porosity • Shape and sorting does! • Porous sediment is very permeable

17. As porosity increases • permeability increases • As degree of sorting increases • porosity increases and • permeability increases • As roundness increases • porosity increases and • permeability increases

18. B. Water Table • The interface between the zone of aeration and the zone of saturation • Its depth fluctuates and is dependent upon the amount of available moisture

19. At times of moisture surplus • the water table is located closer to the surface… • the depth of the water table decreases

20. At times of moisture deficit: • the water table is located farther from the surface… • the depth of the water table increases

22. Normal depth Deficit depth Surplus depth Z of A Zone of aeration Zone of saturation

23. The end!