Tangent-line methods and adaptive waveform interpretation with Gaussian filtering (AWIGF) have been proposed for determining reflection positions of time domain reflectometry (TDR) waveforms. However, the accuracy of those methods is limited for short-probe TDR sensors. Second-order bounded mean oscillation (BMO) may be an alternative method to determine reflection positions of short-probe TDR waveforms. For this study, an algorithm of second-order BMO is developed. Example waveforms are analyzed with tangent-line methods, AWIGF method, and second-order BMO to illustrate the difference among the three methods. For some waveforms, second-order BMO appears be able to give more plausible results. Automatic implementation was challenging for the second-order BMO. With second-order BMO, it is difficult to set a default threshold suitably for all TDR waveforms. Thus, manual adjustment may be required to select a suitable threshold for second-order BMO analysis