HOW MUCH WATER ENTERS THE SOIL Infiltration Precipitation

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HOW MUCH WATER ENTERS THE SOIL? Infiltration

HOW MUCH WATER ENTERS THE SOIL? Infiltration

Precipitation Evapotranspiration Infiltration Runoff

Precipitation Evapotranspiration Infiltration Runoff

What Factors Control Infiltration?

What Factors Control Infiltration?

What Factors Control Infiltration? A) Soil Characteristics

What Factors Control Infiltration? A) Soil Characteristics

What Factors Control Infiltration? A) Soil Characteristics 1) Grain Size (size of pores in

What Factors Control Infiltration? A) Soil Characteristics 1) Grain Size (size of pores in soil)

Large Grains

Large Grains

Large Grains Medium Grains

Large Grains Medium Grains

Large Grains Medium Grains Fine Grains

Large Grains Medium Grains Fine Grains

Gravel Large Grains Sand Silt Medium Grains Clay 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

What Factors Control Infiltration? A) Soil Characteristics 1) Grain Size (size of pores in soil) 2) Antecedent moisture

HYGROSCOPIC WATER

HYGROSCOPIC WATER

CAPILLARY WATER

CAPILLARY WATER

FREE or GRAVITATIONAL WATER

FREE or GRAVITATIONAL WATER

FREE or GRAVITATIONAL WATER

FREE or GRAVITATIONAL WATER

MAXIMUM RATES OF INFILTRATION

MAXIMUM RATES OF INFILTRATION

Initial Infiltration Rate is high MAXIMUM RATES OF INFILTRATION Dry Soil. Hygroscopic Water only.

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

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”

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

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

Precipitation Evapotranspiration Infiltration Overland Flow Runoff

CONSTANT HEAVY RAIN FOR FOUR HOURS

CONSTANT HEAVY RAIN FOR FOUR HOURS

DECREASING INFILTRATION RATE FOR FOUR HOURS Rainfall to Overland Flow Rainfall that could be

DECREASING INFILTRATION RATE FOR FOUR HOURS Rainfall to Overland Flow Rainfall that could be Infiltrated

INCREASING OVERLAND FLOW FOR FOUR HOURS No Overland Flow

INCREASING OVERLAND FLOW FOR FOUR HOURS No Overland Flow