Estimating Water Infiltration Rate Using Time-Lapse GPR Technique

Estimating soil infiltration rate is of utmost importance in agricultural applications. The infiltration rate determines the amount of water to enter the soil, which in turn controls the load of dissolved chemicals (nutrients or pollutants) that will interact with the soil. The soil infiltration rate is commonly measured using the cylinder infiltrometer method, which is tedious and time consuming. Geophysical methods on the other hand have proven to be a powerful tool in providing valuable information about water content in the soil, but rarely used to give a quantitative estimation of the infiltration rate. Ground-penetrating radar (GPR) in particular has the potential to offer a suitable, non-invasive, and cost-effective method for studying the wetting front at shallow depths. A time-lapse GPR experiment was conducted in order to study the feasibility of utilizing GPR method in estimating the soil infiltration rate. A GPR survey was conducted along a 20 m traverse before and immediately after pouring water at two specific locations over the traverse. The GPR measurements were repeated over the same traverse with 5 min time interval, to monitor the downward movement of the wetting front. The time-lapse GPR sections were successful in monitoring the changes of the location of the wetting front with time, which can be used to estimate the vertical soil infiltration rate. The preliminary results are quite encouraging and show that GPR can be efficiently used in monitoring the wetting front downwards movement.