Laboratory development of TDR automatic distributed settlement sensing for land subsidence monitoring

Chih Chung Chung, Wei Feng Chien, Van Nhiem Tran, Hong Ting Tang, Zih Yi Li, Muhammad Saqlain

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Recognizing land subsidence to reduce the risk is critical in complex alluvial-basin aquifers and the subsidence profiling requires multi-leveling techniques. However, the manual magnetic ring sampling is limited with low temporal resolution. This study adopted Time Domain Reflectometry (TDR) for automatic and high-accuracy instrumentation with designs of subsidence sensor and data reductions. A physical model was included to examine measurement accuracy and standard deviation due to the groundwater variation. The water fluctuates in the unconfined aquifer scenario affected the measurement accuracy to −1.52 cm/m by the Maximum point method. Additionally, the Maximum point accuracy is 0.84 mm/m with a stable water level as the confined aquifer case, proofing the measurement feasibility but limited measurement range due to signal attenuation. Thus, a novel TDR multi-sections schema was provided to solve the signal attenuation, resulting in the measurement range extending to 150 m with a standard deviation ≤ 1 mm.

Original languageEnglish
Article number112938
JournalMeasurement: Journal of the International Measurement Confederation
StatePublished - Jul 2023


  • Automatic monitoring
  • Distributed sensors
  • Land subsidence
  • Time Domain Reflectometry (TDR)


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