C 
solute concentration (M/L^{3}) 
c and c_{s} 
specific heat capacities of the groundwater and rock, respectively (ML^{2}/(T^{2}Θ)) 
C_{0} 
initial concentration of the groundwater (M/L^{3}) 
C_{i} 
concentration species i (M/L^{3}) 
C_{i,0} 
reference concentration of species i (M/L^{3}) 
c_{P} 
volumetric heat capacity (M/(LT^{2}Θ)) 
C_{ss} 
concentration associated with a source (M/L^{3}) 
D 
diffusion coefficient (L^{2}/T); for solutes, D=D_{C} the molecular diffusion coefficient; for heat, D=D_{T} the thermal diffusion coefficient 

solute dispersion tensor (L^{2}/T) which includes the effect of both molecular diffusion and mechanical dispersion 
D_{C} 
solute diffusion coefficient in the bulk medium which is decreased from the diffusion coefficient in open water by the factors of connected porosity (n) and tortuosity (τ) (L^{2}/T) 
ΔC 
concentration difference (M/L^{3}) 
Δρ 
density difference (M/L^{3}) 
∆T 
temperature difference (Θ) 
D_{T} 
thermal diffusivity (L^{2}/T) 

dispersion tensor which includes the combined effects of thermal conduction and mechanical dispersion (L^{2}/T) 
g 
gravitational acceleration (L/T^{2}) 

gravitational acceleration vector (L/T^{2}) 
H 
thickness of the layer (L) 
h_{p} 
pressure head (L) 
h_{p,i} 
pressure head for a piezometer at location i containing a fluid column with density ρ_{i} (L) 

solute mass flux (M/(L^{2}T)) 

heat flux (M/T^{3}) 
k 
intrinsic permeability (L^{2}) 
K_{d} 
distribution coefficient (L^{3}/M) 
k_{T} 
thermal conductivity (ML/(T^{3}Θ)) 
μ 
dynamic viscosity (M/(LT)) 
n 
porosity (dimensionless) 
∇ 
gradient operator which represents the rate of change of a variable per unit of distance in the x, y and z direction 
NS 
total number of solutes that contribute to the fluid density 
p 
pressure (M/(LT^{2})) 
p_{0} 
initial fluid pressure (M/(LT^{2})) 

slope of the densityconcentration relationship for species i 

specific discharge (L/T) 
Q_{h} 
heat flow across the source boundary (M/T^{3}) 
Q_{m} 
mass flux across the source boundary (M/(TL^{2})) 
q_{ss} 
discharge rate per unit of volume of water source, or sink (1/T) 
ρ 
groundwater density (M/L^{3}) 
ρ_{0} 
density of the fluid at initial concentration, temperature and pressure (M/L^{3}) 
ρ_{b} 
dry bulk density of the rock (M/L^{3}) 
ρ_{r} 
density of the rock (M/L^{3}) 
ρ_{ss} 
density of water source, or sink (M/L^{3}) 
t 
time (T) 
T 
temperature (Θ) 
T_{0} 
initial temperature of the groundwater (Θ) 
T_{s}_{s} 
temperature associated with a source (Θ) 
z 
elevation relative to a datum (L) 