A modified soil water content measurement technique using actively heated fiber optic sensor

Abstract

Soil water content measurement is critical in practical engineering. The actively heated fiber Bragg grating optic sensor (FBGS) has great potential of multi-point measurement for soil water content measurement in field. In this study, the effect of heating time on the measurement accuracy is discussed, and modifications are made for actively heated fiber optic (AHFO) sensors. The results demonstrate that if an integration data analysis method is used, the accuracy and reliability of soil water content measurement with AHFO sensors will be improved. Both a short fiber length and a short-term heating pattern are effective and can help to reduce soil disturbance. With the proposed integration method, a short heating time is guaranteed for measuring the soil water content. Such improvements will reduce the thermal disturbance to soil sample and improve the reliability of measurement.

Keywords

• Fiber bragg grating
• Carbon fiber heated sensor
• Unsaturated soil
• Field monitoring
• Soil water content measurement