A distributed measurement method for in-situ soil moisture content by using carbon-fiber heated cable

Moisture content is a fundamental physical index that quantifies soil property and is closely associated with the hydrological, ecological and engineering behaviors of soil. To measure in-situ soil moisture contents, a distributed measurement system for in-situ soil moisture content (SM-DTS) is introduced. The system is based on carbon-fiber heated cable (CFHC) technology that has been developed to enhance the measuring accuracy of in-situ soil moisture content. Using CFHC technique, a temperature characteristic value (Tt) can be defined from temperature–time curves. A relationship among Tt, soil thermal impedance coefficient and soil moisture content is then established in laboratory. The feasibility of the SM-DTS technology to provide distributed measurements of in-situ soil moisture content is verified through field tests. The research reported herein indicates that the proposed SM-DTS is capable of measuring in-situ soil moisture content over long distances and large areas.