Estimation of infiltration along unsaturated soil transects with active heated fiber optics

In order to estimate the infiltration rate and its variability in an agricultural field with sandy-loam soil, a fiber optic cable was installed in the field at two depths, 0.30 m and 0.60 m, and in 39.5 m long parallel transects. Two ring infiltrometers of 1 m diameter, spaced 0.5 m, were placed above the fiber transects to measure the infiltration and they were filled with water to a height of 0.10 m. Simultaneously, the fiber optic cable was heated by applying a power of 20 W/m to its metallic protective jacket. Temperature was recorded in the DTS unit every 2 s and its evolution over time was studied to determine the infiltration rate. First, readings were taken in one infiltrometer, then they were taken with the other while the first was moved forward to the next location. This procedure was replicated along the transects at our defined measurement points.