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INFILTRATION - HYDROLOGY

WHAT IS INFILTRATION?
-              DISTRIBUTION OF SOIL MOISTURE IN THE INFILTRATION PROCESS
-              ANALOGY FOR INFILTRATION
-              INFILTRATION MODEL

 

WHAT IS INFILTRATION?

¡  It is the flow of water into the ground through the soil surface.

¡  Infiltration is governed by two forces: gravity, and capillary action.

¡  Infiltration is the physical process involving movement of water through the boundary area where the atmosphere interfaces with the soil.

 

Water transfer is related to:

¡  the porosity of the soil and

¡  the permeability of the soil profile.

 

The topic of infiltration has received a great deal of attention because of its importance to topics as widely ranging as

IRRIGATION

Distribution of soil moisture in the infiltration process

STEP 1: SATURATION ZONE

•       It is the soil or rock located below the top of the groundwater table.

•       The zone of saturation is saturated with water. Also see water table.

STEP 2: TRANSITION ZONE

•       This zone is characterized by a rapid decrease in water content with depth and will extend approximately a few centimeters.

•       The transmission zone is a lengthening unsaturated zone with uniform water content. The hydraulic gradient in this zone is primarily driven by gravitational forces.

STEP 3: TRANSMISSION ZONE

•       This zone is characterized by a small change in water content with depth.

•       In this zone, the water content sharply decreases with depth from the water content of the transmission zone to near the initial water content of the soil.

STEP 4: WETTING ZONE

•       Wetting Front is the boundary of wetting zone where a sharp discontinuity exists between the newly wet soil and original moisture content of the soil.

•       Depending upon the amount  of infiltration and physical properties of the soil, it can extend from a few centimeters to meters.

 

AN ANALOGY FOR INFILTRATION

This analogy underscores two important aspects:

1. INFILTRATION CAPACITY
2. FIELD CAPACITY

 

INFILTRATION CAPACITY

ü  The maximum rate at which soil can absorb the water

FIELD CAPACITY

ü  The volume of water that the ground/soil can hold