Ga. Harrington et al., A compartmental mixing-cell approach for the quantitative assessment of groundwater dynamics in the Otway Basin, South Australia, J HYDROL, 214(1-4), 1999, pp. 49-63
Transient groundwater fluxes, as calculated by a groundwater flow model (MO
DFLOW) are used as input into a compartmental mixing-cell (CMC) model to si
mulate the transport of hydrochemical and isotopic species in regional grou
ndwater systems. Good agreement between modeled and measured concentrations
of solutes in groundwater provides greater confidence in estimating aquife
r parameters for the flow model. The CMC model is currently developed fur m
ulti-layered groundwater systems and allows for both recharge to the upperm
ost aquifer and upward or downward leakage between individual aquifers. The
combination of the CMC approach and MODFLOW allows chemical and hydraulic
data to be analysed simultaneously to allow for improved conceptualization
of the groundwater system. The use of transient fluxes reflects the tempora
l scale and variability of the chemical tracers as well as the temporal var
iability of hydraulic conditions. The model is applied to a transect in the
Gambler Embayment of the Otway Basin in South Australia to quantify mixing
between two main aquifer systems. This groundwater system is hydraulically
connected to the ocean in the west and as a result would have been affecte
d by sea level changes over the last 30000 yr. Radiocarbon simulations help
ed to quantify a major zone of downward leakage to the confined aquifer, wi
th modeled rates of leakage ranging 2-9 mm/yr. (C) 1999 Elsevier Science B.
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