@article{hatley_shehata_sayde_castro-bolinaga_2023, title={High-Resolution Monitoring of Scour Using a Novel Fiber-Optic Distributed Temperature Sensing Device: A Proof-of-Concept Laboratory Study}, volume={23}, ISSN={1424-8220}, url={https://doi.org/10.3390/s23073758}, DOI={10.3390/s23073758}, abstractNote={Scour events can severely change the characteristics of streams and impose detrimental hazards on any structures built on them. The development of robust and accurate devices to monitor scour is therefore essential for studying and developing mitigation strategies for these adverse consequences. This technical note introduces a novel scour-monitoring device that utilizes new advances in the fiber-optic distributed temperature sensing (FO-DTS) technology. The novel FO-DTS scour-monitoring device utilizes the differential thermal responses of sediment, water, and air media to a heating event to accurately identify the locations of the interfaces between them. The performance of the device was tested in a laboratory flume under flow conditions with water velocities ranging from 0 m/s to 0.16 m/s. In addition, the effect of the measurement duration on the device’s measurement accuracy was also investigated. The FO-DTS scour-monitoring device managed to detect the sediment–water and water–air interfaces with average absolute errors of 1.60 cm and 0.63 cm, respectively. A measurement duration of fewer than 238 s was sufficient to obtain stable measurements of the locations of the sediment–water and water–air interfaces for all the tested flow conditions.}, number={7}, journal={SENSORS}, author={Hatley, Rebecca and Shehata, Mahmoud and Sayde, Chadi and Castro-Bolinaga, Celso}, year={2023}, month={Apr}, pages={3758} }
 @article{shehata_gentine_nelson_sayde_2023, title={Optimization of the number and locations of the calibration stations needed to monitor soil moisture using distributed temperature sensing systems: A proof-of-concept study}, volume={620}, ISSN={["1879-2707"]}, DOI={10.1016/j.jhydrol.2023.129449}, abstractNote={The single-probe heat-pulse (SPHP) technique combined with the Fiber-optic Distributed Temperature Sensing (DTS) technology can offer novel high-resolution measurements of soil moisture (θ) over spatial scales ranging from several centimeters to several kilometers. However, the key limitation of this method is in obtaining the calibration relationship between θ and soil thermal conductivity (λ) across a specific field. In a previous study, a new methodology using a Gaussian processes model was presented to account for the spatial variability in the λ-θ relationship. The model aggregated θ measurements from soil moisture sensors scattered over the SPHP transect with the corresponding DTS λ measurements at their locations. In this study, a novel methodology is tested to optimize the number and locations of soil moisture sensors required to account for the spatial variability of the λ-θ relationship to achieve higher accuracy from the SPHP technique. The proposed methodology utilizes hierarchical clustering to analyze the information contained in the spatial structure of the SPHP measurements as the soil dries from a nearly-saturated condition. The proposed methodology was tested using data from a field in Oklahoma. Monte-Carlo simulation was performed to validate the performance of the proposed methodology. The predictions obtained from the proposed methodology resulted in θ measurements accuracy comparable to those obtained from the 10% best Monte-Carlo iterations of randomly assigned soil moisture locations. This study demonstrates that the proposed methodology is more efficient than the traditional practice of randomly spreading calibration soil moisture sensors along the SPHP transect.}, journal={JOURNAL OF HYDROLOGY}, author={Shehata, Mahmoud and Gentine, Pierre and Nelson, Natalie and Sayde, Chadi}, year={2023}, month={May} }
 @article{shehata_gentine_nelson_sayde_2022, title={Characterizing soil water content variability across spatial scales from optimized high-resolution distributed temperature sensing technique}, volume={612}, ISSN={["1879-2707"]}, DOI={10.1016/j.jhydrol.2022.128195}, abstractNote={Fiber-optic Distributed Temperature Sensing, when combined with the Single-probe Heat-pulse technique can measure soil moisture (θ) across spatial scales. The key limitation of this system is in obtaining the relationship between soil thermal conductivity (λ) and θ for a specific field. Using the Department of Energy Atmospheric Radiation Measurement (ARM) site, this study tested a new methodology to account for the spatial variability in the λ-θ relationship using a Gaussian processes model. The resulting accurate θ measurements (RMSE = 0.03 m3m−3) were used to characterize the spatial variability of θ across scales and to develop an empirical equation that can correct for the changes in the θ spatial variability observed at different spatial resolutions. In addition, the number of required samples to accurately characterize θ and its variability over scales ranging from 5 m and 350 m were estimated. These findings provide key information to scale soil moisture from centimeters to hundreds of meters for process understanding.}, journal={JOURNAL OF HYDROLOGY}, author={Shehata, Mahmoud and Gentine, Pierre and Nelson, Natalie and Sayde, Chadi}, year={2022}, month={Sep} }
 @article{shehata_heitman_sayde_2022, title={High-Resolution Field Measurement of Soil Heat Capacity and Changes in Soil Moisture Using a Dual-Probe Heat-Pulse Distributed Temperature Sensing Approach}, volume={58}, ISSN={["1944-7973"]}, DOI={10.1029/2021WR031680}, abstractNote={Abstract}, number={6}, journal={WATER RESOURCES RESEARCH}, author={Shehata, Mahmoud and Heitman, Joshua and Sayde, Chadi}, year={2022}, month={Jun} }
 @article{shehata_heitman_ishak_sayde_2020, title={High-Resolution Measurement of Soil Thermal Properties and Moisture Content Using a Novel Heated Fiber Optics Approach}, volume={56}, ISSN={["1944-7973"]}, DOI={10.1029/2019WR025204}, abstractNote={Abstract}, number={7}, journal={WATER RESOURCES RESEARCH}, author={Shehata, Mahmoud and Heitman, Joshua and Ishak, Joseph and Sayde, Chadi}, year={2020}, month={Jul} }