Raúl Sánchez Calvo

Calibration of soil moisture sensing with subsurface heated fiber optics using numerical simulation

The heat pulse probe method can be implemented with actively heated fiber optics (AHFO) to obtain distributed measurements of soil water content (θ) by using reported soil thermal responses measured by Distributed Temperature Sensing (DTS) and with a soil-specific calibration relationship. However, most reported applications have been calibrated to homogeneous soils in a laboratory, while inexpensive efficient in situ calibration procedures useful in heterogeneous soils are lacking. Here we employed the Hydrus 2-D/3-D code to define a soil-specific calibration curve. We define a 2-D geometry of the fiber optic cable and the surrounding soil media, and simulate heat pulses to capture the soil thermal response at different soil water contents. The model was validated in an irrigated field using DTS data from two locations along the FO deployment in which reference moisture sensors were installed. Results indicate that θ was measured with the model-based calibration with accuracy better than 0.022 m3 m−3.

Encouraging the learning of hydraulic engineering subjects in agricultural engineering schools

Several methodological approaches to improve the understanding and motivation of students in Hydraulic Engineering courses have been adopted in the Agricultural Engineering School at Technical University of Madrid. During three years students progress and satisfaction have been assessed by continuous monitoring and the use of ‘online’ and web tools in two undergraduate courses. Results from their application to encourage learning and communication skills in Hydraulic Engineering subjects are analysed and compared to the initial situation. Students academic performance has improved since their application, but surveys made among students showed that not all the methodological proposals were perceived as beneficial. Their participation in the ‘online’, classroom and reading activities was low although they were well assessed.