Investigation on temperature tracer method calculated flow rate of hyporheic layer in riparian zone

The hyporheic layer is an important part of riparian zones. To reveal the distribution of temperature and flow field of hyporheic layers in riparian zones under the influence of low temperature water, a real-time monitoring test of temperature and water level was used to study the thermal structure of a hyporheic layer in different seasons and spatial locations, which could be used to calculate the groundwater velocity. Our results show that the temperature field of the hyporheic layer is characterized by seasonal reversal of thermal stratification: surface-warm and deep-cold during the summer and surface-cold and deep-warm during the winter. Among the four methods of calculation of the groundwater flow using temperature tracer, the Hatch phase method yielded the highest accuracy. The flow velocities ranged from 1.03×10^-4 to 7.96×10^-4m/s during the period of Dec. 15—31, 2014, which decreased with the increasing depth in section and the groundwater flow velocity curves were close to parallel.