Refining the Calibration Process for Heat Dissipation Sensors.

Heat dissipation sensors (HDS), used to measure soil water matric potential, were used in long-term field studies designed to evaluate net infiltration of water into reclaimed mine tailing and waste rock facilities.� The mine waste facilities were reclaimed by placing a store and release soil cover over the mine waste.� HDS were employed as part of a vadose zone monitoring program to characterize the unsaturated flow through the reclaimed soil profile (soil cover and mine waste).� The primary goal of the vadose zone monitoring program is to calibrate existing soil water balance models (UNSAT-H) for the mine facilities and to predict long-term performance of the soil cover based on data collected during the cover performance period.� Thus, it is imperative that the vadose zone instrumentation be carefully calibrated.� Campbell Scientific 229 sensors (HDS) are the primary instrument used to calibrate the model in this study.� Prior to installation, the HDS were calibrated over a range of matric potentials and fit to the van Genucthen equation.� Using the initial laboratory calibration points and field data, the sensor calibration coefficients were refined over a period of 6 years to correct for variances in field and laboratory conditions.� This presentation discusses the specific methods used to refine the HDS calibration process.