Abstract:Soil water flux (Jw) is an important hydrological parameter which determines soil infiltration, runoff and solute transport, yet no corresponding practical techniques are available for its real-time measurement in situ. In this study, heat-pulse measurements were performed of deferent water fluxes in packed soil columns different in texture. Based on temperature changes between upstream and downstream locations from the heat-pulse probe, water flux was then calculated with the MDTD method (maximum dimensionless temperature increase difference), and the Td /Tu method (ratio of temperature changes between downstream and upstream positions), and a modified Td /Tu method along other known parameters. Results indicated that strong linear relationships ( R 2>0.99) existed between the estimated and the measured water fluxes (up to 6×10-5 m s-1). Though, the three methods all down-estimated, however, the Td /Tu method was highest precise and simplest in calculation, and needed the least number of additional parameters. In coarse sand, the Td /Tu method was relatively more accurate in estimation of Jw, yet in fine sandy clay loam, especially when Jw was greater, obvious discrepancies were observed between the estimated and the measured, reaching 20%. Besides, the reason of underestimation of Jw with the heat-pulse technique is explored and presented as a basis for further development of the heat-pulse technique.