HOW MUCH WATER ENTERS THE SOIL Infiltration Precipitation
- Slides: 23
HOW MUCH WATER ENTERS THE SOIL? Infiltration
Precipitation Evapotranspiration Infiltration Runoff
What Factors Control Infiltration?
What Factors Control Infiltration? A) Soil Characteristics
What Factors Control Infiltration? A) Soil Characteristics 1) Grain Size (size of pores in soil)
Large Grains
Large Grains Medium Grains
Large Grains Medium Grains Fine Grains
Gravel Large Grains Sand Silt Medium Grains Clay Fine Grains
What Factors Control Infiltration? A) Soil Characteristics 1) Grain Size (size of pores in soil) 2) Antecedent moisture
HYGROSCOPIC WATER
CAPILLARY WATER
FREE or GRAVITATIONAL WATER
FREE or GRAVITATIONAL WATER
MAXIMUM RATES OF INFILTRATION
Initial Infiltration Rate is high MAXIMUM RATES OF INFILTRATION Dry Soil. Hygroscopic Water only. Lots of soil air to fill with water.
Initial Infiltration Rate is high Exponential decline in rate MAXIMUM RATES OF INFILTRATION Moist soil. Capillary Water. Progressively fewer voids to fill with water.
Initial Infiltration Rate is high Exponential decline in rate Minimum rate, or “field capacity” set by drainage MAXIMUM RATES OF INFILTRATION Saturated soil. Free or Gravitational Water. Voids to fill with water determined by rate of loss.
What Factors Control Infiltration? A) Soil Characteristics 1) Grain Size (size of pores in soil) 2) Antecedent moisture B) Rainfall intensity (how fast rain is arriving!)
Precipitation Evapotranspiration Infiltration Overland Flow Runoff
CONSTANT HEAVY RAIN FOR FOUR HOURS
DECREASING INFILTRATION RATE FOR FOUR HOURS Rainfall to Overland Flow Rainfall that could be Infiltrated
INCREASING OVERLAND FLOW FOR FOUR HOURS No Overland Flow