Groundwater evolution with mixing

[rudolff16]

Dear all,

I have three hydrochemical fancies in my study area:

group 1 (Recharge area, low TDS)    initial solution 1
units ppm
temp  21.8
pH  7.9
Ca  47.41
Mg  25.28
Na  40.8
K   1.8
S(6) 31.33
Cl  70.92
C(4) 149.48
N(5) 31.25 as NO3

group 2 (transition zone, moderate TDS)    initial solution 2

units ppm
temp  25.1
pH   7.91
Ca  59.59
Mg  32.63
Na  62
K   1.8
S(6) 56.9
Cl 114.01 
C(4) 257.75
N(5) 90.88 as NO3

group 3 (discharge area, high TDS value)  end-member water

units ppm
temp  23.4
ph  8.17
Ca  107.515
Mg  41.89
Na  138.1
K   7
S(6) 350.65 
Cl  136.88
C(4) 176.9
N(5) 24.3474 as NO3

as you see above, the groundwater salinity increases gradually from the recharge to the discharge area and along the groundwater flow path.
the question is; how to find the ratio of the groups 1 and 2 to form the group 3 considering gypsum, halite dissolution, ion exchange (CaX2) and calcite precipitation

I would appreciate your help,
thanks

[dlparkhurst]

Look at INVERSE_MODELING in the manual, and examples 16, 17, and 18.

You could also look at the NETPATH manual for additional examples of inverse modeling.