What is the Difference Between Infiltration Rate and Percolation Rate

The key difference between infiltration rate and percolation rate is that infiltration rate refers to the rate at which water enters the soil from the surface, whereas percolation rate refers to the movement of water within the soil.

Infiltration rate is the volume of water that flows into a unit area of soil. Percolation rate is the rate at which water moves into the soil as determined by the percolation test.

1. Overview and Key Difference
2. What is Infiltration Rate
3. What is Percolation Rate
4. Infiltration Rate vs Percolation Rate in Tabular Form
5. Summary – Infiltration Rate vs Percolation Rate

What is Infiltration Rate?

Infiltration rate is the volume of water that flows into a unit area of soil. In other words, it is the velocity or speed at which water enters per unit surface area of soil. Usually, when we supply water to the soil, the infiltration rate tends to decrease from its initial high rate. This is because of the formation of a thin layer of water at the surface of the soil. We call it a “seal”. Infiltration rate can be abbreviated as IR.

The term infiltration (which refers to the process through which the water on the ground enters the soil) is useful in both hydrology and in soil science. Another related term is infiltration capacity. It is the maximum rate of infiltration. Typically, infiltration is measured in the unit “meters per day”. The infiltration rate is usually measured in the “depth of the water layer entering the soil per one hour”.

Several factors can influence the infiltration rate of the soil, including the humus content, soil moisture content, depth of the soil, soil surface roughness, capillary forces, gravity, adsorption, and osmosis. There are some devices we can use for the measurement of infiltration rate, e.g. infiltrometers, permeameters and rainfall simulators.

Moreover, there are some infiltration calculation methods, including general hydrologic budget method, Richard’s equation, finite water-content vadose zone flow method, green and Ampt method, Horton’s equation, and Kostiakov equation.

What is Percolation Rate?

Percolation rate is the rate at which water moves into the soil as determined by the percolation test. Percolation test or perc test is an analytical technique in which we can determine the absorption rate of the soil. This test is very important in preparing buildings of a septic drain field or in an infiltration basin. Generally, sandy soil tends to absorb more water compared to clay soil or at places where the water table is situated close to the soil surface.

Percolation Rate = Amount of water in mL / time in minutes

When considering the methodology of percolation rate, this test includes digging one or more holes at the considered area of soil, presoaking the holes to maintain a high water level in the holes and then we can run the test by filling these holes to a certain level to time the drop of water level due to percolation.

What is the Difference Between Infiltration Rate and Percolation Rate?

Infiltration rate is the volume of water that flows into a unit area of soil while percolation rate is the rate at which water moves into the soil as determined by the percolation test. The key difference between infiltration rate and percolation rate is that infiltration rate refers to the rate at which water enters the soil from the surface, whereas percolation rate refers to the movement of water within the soil.

The following infographic lists the differences between infiltration rate and percolation rate in tabular form for side by side comparison.

Summary – Infiltration Rate vs Percolation Rate

Infiltration rate is the volume of water that flows into a unit area of soil. Percolation rate is the rate at which water moves into the soil as determined by the percolation test. The key difference between infiltration rate and percolation rate is that infiltration rate refers to the rate at which water enters the soil from the surface, whereas percolation rate refers to the movement of water within the soil.

Reference:

1.“Infiltration Rate.” GeoLearning, 15 Dec. 2014.

Image Courtesy:

1. “Single ring” By Soil Physics at English Wikipedia – Transferred from en.wikipedia to Commons by Quedel using CommonsHelper. (Public Domain) via Commons Wikimedia