| Full text | |
| Author(s): |
Bertotto, Luis Eduardo
;
Reis, Alan
;
Cobalchini, Erick Rubens Oliveira
;
Schwamback, Dimaghi
;
Uchoa, Jose Gescilam Sousa Mota
;
Wendland, Edson Cezar
Total Authors: 6
|
| Document type: | Journal article |
| Source: | European Journal of Soil Science; v. 75, n. 4, p. 17-pg., 2024-07-01. |
| Abstract | |
In recent decades, distributed temperature sensing (DTS) has emerged as a robust technology for environmental applications, enabling high-resolution temperature measurements along fibre optic cables (FOCs). The actively heated fibre optic (AHFO) method is employed to monitor soil moisture (theta, m(3) m(-3)), wherein the soil temperature subsequent to the application of a heat pulse is measured by a DTS (AHFO-DTS approach). Despite significant improvements in the application of AHFO-DTS under controlled and natural conditions, the thermal behaviour of soil during multiple saturation-natural drying cycles has been insufficiently evaluated. This study aimed to address this gap by constructing an experimental horizontal soil profile in the laboratory for the application of the AHFO-DTS method during two successive saturation-drainage-evaporation (SDE) cycles. Three heating strategies were applied to a metallic alloy in contact with a FOC, and calibration models were used to correlate theta with the thermal conductivity (lambda ), cumulative temperature increase (T-cum), and maximum temperature increase (T-max). The results indicated that during the second SDE cycle, the highest errors in theta estimates were observed with the low power-short heat pulse, whereas the application of the low power-long duration and high power-short duration pulses improved the accuracy of calculations. Additionally, errors in theta estimates escalated under wetter conditions, attributed to a shift in soil heat transfer capacity from the first to the second SDE cycle for theta > 0.10 m(3) m(-3). This behaviour was ascribed to thermal hysteresis, arising from the contact resistance of the FOC and the alloy with the surrounding soil. Furthermore, the T-max method exhibited the least sensitivity to this effect and yielded reliable theta estimates, thus its adoption is recommended. Moreover, the use of the low power-long duration heating strategy is suggested as it promotes a trade-off between energy saving and accurate estimates. We concluded that assessing soil thermal response under multiple SDE cycles enhances the comprehension of the AHFO-DTS method. Overall, our findings provide insights into enhancing the applicability of this approach under field conditions, particularly following irrigation schedules and natural rainfall events. (AU) | |
| FAPESP's process: | 15/03806-1 - Water availability and quality threats in a Guarani Aquifer System outcrop zone |
| Grantee: | Edson Cezar Wendland |
| Support Opportunities: | Program for Research on Bioenergy (BIOEN) - Thematic Grants |
| FAPESP's process: | 19/24292-7 - Infiltration and runoff dynamics under different land uses and climate change in the Brazilian Cerrado area |
| Grantee: | Dimaghi Schwamback |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 23/08756-9 - Spatio-temporal characterization of water dynamics in a vertical profile of unsaturated soil, utilizing the temperature measurement in heated fiber optics |
| Grantee: | Luis Eduardo Bertotto |
| Support Opportunities: | Scholarships in Brazil - Doctorate |
| FAPESP's process: | 21/14016-2 - Hydrus model for the theoretical representation of vertical flow under different land uses commonly found in the Brazilian Cerrado biome |
| Grantee: | Dimaghi Schwamback |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate |