What happens to the water that is received on Earths surface? 1.) Water storage – stored on land as ice or snow, held on leaves 2.)Infiltration (seep) – water sinks into the ground to become ground water 3.)Runoff – flows over land surfaces into bodies of water 4.) Evapotranspiration – evaporation and transpiration by plants back into the atmosphere

Factors Effecting Infiltration 1. Slope steeper slope (gradient) = less infiltration INFILTRATION GRADIENT

2. Porosity- The amount of open space in between sediments or rock The higher the porosity, more infiltration will occur INFILTRATION POROSITY

Porosity is determined by: a. Shape - Well rounded particles have greater porosity than angular. ROUND ANGULAR POROSITY ROUNDNESS

b. PACKING- The more closely packed the particles the lower the porosity. UNPACKED PACKED

- If all particles are the same size they are sorted. c. SORTING- - If all particles are the same size they are sorted. - If the particles are different sizes/mixed they are unsorted - The more sorted, the higher the porosity POROSITY SORTING

Particle Size alone does NOT effect porosity Particle Size alone does NOT effect porosity!!!!! (Shaping, Packing, Sorting does)

Real world application: Clay vs. Sand Sand has a LOWER porosity than clay even though it has a larger grain size

3. Degree of saturation- if pore spaces are already filled with water, less water will infiltrate INFILTRATION SATURATION

The more permeable the soil/rock, the greater the infiltration 4. Permeability- ability of a material to allow fluids to pass through; is measured by how CONNECTED the pores are Impermeable = means water cannot pass through (Ex: clay layers in ground) The more permeable the soil/rock, the greater the infiltration INFILTRATION PERMEABILITY

Porosity is not the same as permeability!

Retention increases with a decrease in particle size. 5. Retention- When water “sticks” to the materials that it is passing through. Retention increases with a decrease in particle size. *Fine sand has greater retention than coarse sand *Smaller grains= less infiltration RETENTION PARTICLE SIZE

6. Vegetation- Plants retain water and decrease runoff allowing more time for water to infiltrate into the ground Main relationship: little vegetation = high runoff, less infiltration INFILTRATION VEGETATION

7. Anthropogenic Influences – Roads and buildings are impermeable, reducing infiltration. Urbanization

Real world connection: How does the local geology influence a regions likelihood of flash flooding?

An look at Ground Water Movement

FINE SAND Moderate drainage PERMEABILITY GRAVEL  Rapid drainage  FINE SAND Moderate drainage  CLAY Slow drainage

Other Activities Complete Porosity/Permeability/Capillarity worksheet