Effect of bank curvatures on hyporheic water exchange at meter scale

Abstract

The micro-topography feature of a riverine system is a controlling attribute to induce the change of patterns and magnitudes of hyporheic water exchange. The study aims to determine how hyporheic water exchange is affected by the bank curvatures of test points at meter scale. A one-dimensional heat steady-state transport model was applied to determine patterns and magnitudes of vertical hyporheic water exchange in January and July 2015. The bank curvatures were calculated based on the curvature formula. The results demonstrate that vertical water exchange patterns of all test points were upwards during the two test periods, and the higher vertical fluxes mostly occurred in January 2015. Large curvatures for either sides of convex banks in the two periods resulted in higher vertical water exchange fluxes, and the significantly higher vertical fluxes occurred near the apex of bends. Additionally, a flow pattern from river bank discharging into stream was derived during the campaign in July 2015, and significantly higher fluxes were obtained along the straight bank where more riparian vegetation was adjacent to the bank/water interface. It can be suggested that the bank curvatures and riparian vegetation are considered the crucial attributes influencing hyporheic water exchange.