Infiltrometer

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Infiltrometer is a device used to measure the rate of water infiltration into soil or other porous media. Commonly used infiltrometer are single ring or double ring infiltrometer, and also disc permeameter.

The single ring involves driving a ring into the soil and supplying water in the ring either at constant head or falling head condition. Constant head refers to condition where the amount of water in the ring that is always held constant, this is done by supplying water with a Mariotte's bottle. Falling head refers to condition where water is supplied in the ring, and the water is allowed to drop with time. The operator records how much water goes into the soil for a given time period. The rate of which water goes into the soil is related to the soil's hydraulic conductivity.

Double ring infiltrometer requires two rings: an inner and outer ring. The purpose is to create a one dimensional flow of water from the inner ring, as the analysis of data is simplified. If water is flowing in one-dimension at steady state condition, the infiltration rate is approximately equals to the saturated hydraulic conductivity. An inner ring is driven into the ground, and a second bigger ring around that to help control the flow of water through the first ring. Water is supplied either with a constant or falling head condition, and the operator records how much water infiltrated from the inner ring into the soil over a given time period.