TDR (Time Domain Reflectometry) and GPR (Ground Penetrating Radar) are two of the electromagneticmethods in applied geophysics,which using themfor various applications are developing. The TimeDomain Reflectometry is a remote sensing method that has been used for years to determine the nature of the materials and spatial location. The use of TDR systemhas led to innovative applications of it and comparing itwith previous measuring techniques, since it has developed. In this study, not only a summary of the basics of TDR application for monitoring of ground deformation is offered, but also a comparison of this technology with other measurement techniques (inclinometer casing) is provided. Actually, this paper presents a case study inwhich the opportunity arose to compare these two technologies in detecting subsurface deformation in slopes. A TDR systemincludes a radar wave receiver & generator, a transmission line and a waveguide. The generated electro-magnetic pulse moves toward the waveguide within the conductor cable and enters the test environment. For this study, slopes overlooking the Darian dam bottom outlet, power house and spillway were instrumented with RG59/U coaxial cables for TDR monitoring and slope inclinometer. Coaxial cables - as a TDR sensor - and inclinometer casings were installed in a same bore holewhere coaxial cablewas attached to the inclinometer casing. Shear and tensile deformations of the cable, which is caused by ground movements, significantly impacts on cable reflection coefficient. In Darian damboreholes, the cable points subject to the shear and stretchwere correlated with deformation points of the inclinometer casings in incremental displacement graphs. This study shows that TDR technique is more sensitive than inclinometer casing for smallmovement in the slide planes. Becausemanual processing of TDR data is hard and need experienced personnel, the authors have designed an algorithm to compare the shape of the new TDR waveforms with th
