Abstract:In order to investigate the applicability of the Simultaneous heat and water (SHAW) model in simulating the soil hydrothermal salinity dynamics during freeze-thaw period in long-term drip-irrigated cotton fields in the northern Xinjiang region. The measured soil data of cotton fields with the starting year of 1998 (21 a) for drip irrigation were used to calibrate the SHAW model in this study. The SHAW model was validated with the data from drip irrigation start years of 2006 (13 a), 2008 (11 a), 2012 (7 a), and barren land (0 a). Results showed that the simulation accuracy of soil temperature was better with the increasing soil depth, and the simulation accuracy of soil water salinity was enhanced and then weakened. The Nash coefficient (NSE), root-mean-square error (RMSE) and R2 of simulated soil temperature ranged from 0.713 to 0.993, 0.209 to 2.498 °C and 0.911 to 0.994, respectively. The NSE and RMSE of simulated soil moisture ranged from 0.824-0.967 and 0.009-0.032%, respectively, and NSE and RMSE of simulated soil salinity ranged from 0.609-0.844 and 0.001-0.012 g/kg, respectively. Results of model validation showed that the simulation accuracy was better with the increase in the number of years of drip irrigation, and the NSE of simulated soil temperature was greater than 0.600 and RMSE ranged from 0.143 to 3.213 ℃ in all layers of the drip-irrigated plots of 7 a, 11 a, and 13 a, except that the NSE of soil temperature in the soil layer of 20-60 cm in the barren land was less than 0.600. NSE of soil moisture was greater than 0.670 and RMSE ranged from 0.009 to 0.057 % in all soil layers of simulated drip irrigated plots for 0 a, 7 a, 11 a and 13 a. NSE of soil salinity for 0 a, 7 a, 11 a and 13 a had greater than 0.616 and RMSE ranged from 0.000-0.016 g/kg in all soil layers, except for the 140 cm soil layer, where NSE was less than 0.6. Overall, the SHAW model is an available tool to simulate the soil water, heat, and salt in cotton fields under long-term mulched drip irrigation during the freezing and thawing period in northern Xinjiang.