PrecipitationPrecipitation

The process of depositing moisture in the form of rain,

snow…

We know it starts with condensation, We know it starts with condensation, but what does it take for but what does it take for condensation to occur?condensation to occur?

Condensation requiresCondensation requires

HumidityHumidity The right air pressureThe right air pressure Particles in the atmosphereParticles in the atmosphere

Types of precipitation: RainTypes of precipitation: Rain

….See they really do look like buns….

Types of precipitation: SnowTypes of precipitation: Snow

Types of precipitation: HailTypes of precipitation: Hail

Of course there are also dew, fog, sleet…Of course there are also dew, fog, sleet…

http://www.ocs.orst.edu/pub/maps/Precipitation/Total/States/NC/nc.gif

What controls the fate of What controls the fate of precipitation once it falls?precipitation once it falls?

Climate Climate Geomorphology Geomorphology Infiltration Infiltration VegetationVegetation

Infiltration: Where does the water go?

www.uwsp.edu/geo/faculty/ritter/geog101/modules/hydrosphere/subsurface_water_1.html

Why does water infiltrate some land more than other land ?

Topography Steep verses gentle slopes

Soil/Land Surface TypeVegetation

Geomorphology and Run-offTopography

The general configuration of a land surface or any part of the Earth's surface, including its relief and the position of its natural and man-made features

Slope Also known as “gradient” when referring to streams

Drainage PatternsChannel Shape

http://water.usgs.gov/pubs/

For surface-water systems, the greater the likelihood that water will run off the land surface, (that is, the higher the slope), the higher the rating applied on a scale of 1 to 10

What is soil?Soil-

a natural body of solids, liquid, and gases with either horizons, or layers and/or the ability to support rooted plants.

http://soils.usda.gov/education/resources/

O – Organic Horizon

A- Zone of leaching

B – Zone of Accumulation

C – Broken-up bedrock

R – Regolith – hard bedrock

(not soil)See Fig. 11.4 Text

What soil zones do you see here?

How does the type of soil or the lack of soil affect infiltration?

Porosity PermeabilityPervious verses Impervious Surfaces

Soil cover verses bare rockSoil verses concrete and asphalt

The type of material in the unsaturated zone influences whether precipitation runs off or infiltrates into the subsurface. The greater the likelihood that water infiltrates into the subsurface, the higher the rating applied on a scale of 1 to 10.

The hydraulic conductance is related to permeability and represents the ability of the unsaturated zone to transmit water. The higher the conductance of the unsaturated zone, the higher the rating applied on a scale of 1 to 10

How does vegetation affect runoff?Provides a physical barrier and decreases the rate at which water enters a stream

Roots loosen soil and provide conduits for water

Plants absorb water

What happens when vegetation is removed for building?

For surface-water systems, the greater the likelihood that water runs off the land surface, the higher the rating applied on a scale of 1 to 10

Confused about water terminology?Check out the on-line water dictionary at http://water.nv.gov/Water%20planning/dict-1/ww-index.htm

Stream Restoration at NCSUhttp://www.ncsu.edu/environmental_sustainability/extension_engagement.html

Achieving a balance between run-off and infiltration