Abstract: This paper describes the process and result for the calibration of radioactive ~(46)Sc detector in details. The calibration was carried out under the hydrological conditions similar to the field test. The relation between the intensity of the scattered γ-rays and the various water depths was studied by using a ~(46)Sc plane source. The purpose of calibration of the detector with the plane source is to determine both the detector sensitivity factor and the γ-ray absorption coefficient for sand/water mixture in order to calculate the thickness of the mobile water layer by means of the countrate balance method. The rela tion curve between the various thicknesses of the mobile layers and countrates was studied in details by using a slab source and the uniformly mixed layers with ~(46)Sc glass. The curve is used as the calibration curve for determing the recovery of tracking radioactive tracer in situ. The recovery of tracer shows whether the field tracer data can be used to calculate the transport sediment rate or the infill rate of sed iment.