Discharge of saline groundwater into a freshwater stream —River Murray, Australia

摘要

Salinization of water resources is a major problem on a global scale. In the Loxton-Bookpurnong irrigation area (South Australia) saline groundwater is pushed towards the river by advective Groundwater was sampled from beneath the river. In all cases, fresh river water overlies saline groundwater, a stable stratification with regard to the fluid density. The salinities encountered partly exceed those of seawater. Modelling was done to determine what role variable-density flow behaviour plays in surface water-groundwater interaction in a stably-stratified fresh surface water-saline groundwater interface. Comparison of measured and simulated concentrations vs depth profiles reveals a qualitative resemblance of the profiles for simulations where density was the dominating force. The clear stratification of fresh over saline water, with a sharp increase at a certain depth, leads to the hypothesis that the high density of the fluid may partly suppress discharge in stagnant pockets below the river.