Abstract
Both shallow and deep groundwater flow mediates a variety of geologic
processes. In the discharge zones of the nested groundwater flow
systems, saltwater often emerges due to high evaporation (in endorheic
drainage basin), tide surge, or marine transgression and regression (in
coastal areas) or salt pollution (in streams). However, to our best
knowledge there are limited studies that consider the impact of density
flow in the discharge zone on the nested groundwater flow systems. In
this study, nested groundwater flow systems are analyzed with saltwater
infiltration in their discharge zones. To quantify the effects of
saltwater concentration on the flow systems, seven scenarios with
different saltwater concentrations in the discharge zones are modeled.
It is found that the flow systems are most sensitive to the saltwater
concentration of the discharge zones when the concentration is between
2.23 and 4 g/L, and the threshold saltwater concentration that starts to
affect the flow systems is about 1.35 to 2.23 g/L for the specific
aquifer configuration selected for this study. The results also show
that the local flow systems retreat upward and the overall groundwater
velocity of the entire flow systems is decreased with the increase of
the saltwater concentration. This study may shed light on the control of
salinization, evolution of saline lake basins, and seawater intrusion
from a perspective of nested groundwater flow systems.