Estimation of river stage effect on groundwater level, discharge, and bank storage and its field application

Abstract

This paper presents the hydraulic interaction between aquifer and river related with bank storage. A convolution equation was used to analyze the aquifer response, discharge, and bank storage due to river stage fluctuation. River stages were generated to describe flood peak, asymmetry, and duration. The simulation results suggest that the geometry of flood hydrograph can play an important role in affecting the discharge and bank storage. The presented model was applied to a field data, and the site is a floodplain aquifer of the Mangyeong River. Aquifer responses for the various flood duration and flood peak were observed at the site, which is well matched with the simulated results. A model parameter, the riverbed leakance was determined from calibration with the simulated and observed groundwater levels. After the determination of each parameter, the discharge and bank storage can be calculated. The presented method is a good tool to assess the hydraulic interaction between the aquifer and the river, as arbitrary river stage fluctuations are used. The limitation of the method is that the actual discharge and bank storage can be different from the calculated ones, when significant regional groundwater gradient exists. It also can be a useful tool before applying more complex numerical models. Key words: bank storage, aquifer diffusivity, river-aquifer interaction, riverbed leakance, Mangyeong River