Impacts of Discharged Low-Temperature Water on Water Table and Temperature in the Riparian Zone

Abstract

We observed the water level and temperature in the lower stretch of the Hsin-an river in China for different times to show the characteristics of the water table and temperature in the riparian zone under the influence of discharged low-temperature water. The water table in the riparian zone showed a typical daily cycle change with a fluctuation range of 239.42-275.99 cm, according to the findings. With increasing distance from the river, the amplitudes of the water table fluctuation were reduced, and the phases were lagged. In the high-temperature period, riparian temperatures range from 20.4°C to 26.0°C, whereas in the low-temperature phase, temperatures range from 12.9°C to 19.2°C. The temperature distribution in the riparian zone was described in the vertical direction as “warmer on the surface and cooler at the bottom” during high-temperature periods and “cooler on the surface and warmer at the bottom” during low-temperature periods, with the temperature gradient gradually decreasing with depth. There was clear temperature zonation in the horizontal direction during the high-temperature phase but none during the low-temperature period. The study will serve as a benchmark for future hyporheic zone ecological impact assessments.