An approximate point source method for soil infiltration process measurement

•Point source method for soil infiltration process measurement was introduced with high accuracy.•The advancing process is closely related to the soil infiltration process.•The whole soil infiltration process was obtained.•Three soils, each with 2–3 different inflow rates were applied to verify the method.•The results were compared with those measured with the linear source method.

The infiltration of water into soil is an important component of the hydrologic cycle. Quantifying infiltration is useful for estimating overland flow, irrigation management, water distribution after rainfall, and soil erosion. A new approximate point source method for estimating the complete infiltration process is introduced in this paper. The experimental apparatus was designed to include a Mariotte bottle and a source outlet unit for water supply, as well as a scaled soil box. A mathematical model was derived to estimate the soil infiltration rate from the wetted soil surface. Soil infiltrations for three soil types, each with two or three different inflow rates, were investigated in laboratory experiments. To verify this new method, the results were compared with values measured using the linear source method. The balance between the supplied and recovered water showed that the relative errors of the experiments were all less than 2.5%, indicating the high accuracy of this method. The proposed point source method requires very little water and time, and is a useful tool for related lab studies and trickle irrigation designs.