Tools of the Trade - Infiltrometer

Double Ring Infiltrometer

This is a simple, inexpensive method for determining permeability of soils. The infiltration rate is controlled by the least permeable zone in the subsurface soils. With the Double Ring Infiltrometer, it is easy to test several areas of a large tract to find the infiltration rate. It also provides comparative information that is useful for determining erosion rates, leaching and drainage efficiencies, irrigation patterns and rainfall runoff.

The instrument consists of two concentric rings. The outer ring is 24" diameter; the inner ring 12" diameter. The two rings are driven into the ground and partially filled with water. The double ring design helps prevent divergent flow in layered soils. The outer ring acts as a barrier to encourage only vertical flow from the inner ring.

The water level is maintained for a specific period of time, depending on the type of soil and permeability level. The volume of water needed to maintain a specified level and the time factors are recorded. This information is converted into a specific infiltration rate.