The salinity model was easier to calibrate and verify in the traditional sense because salinity and level data has been recorded in the lake for many years. The level record wasn't very useful as large wind sieches cause rapid fluctuations of lake level unrelated to those flows like, the river, rain and evaporation, which substantially change the salinity.
The rule based model is in a sense self-calibrating and verifying. The rule base model is essentially the written declaration of experts on how particular fauna and flora respond to salinity. Thus calibration and verification merely consists of checking that the output of the rules is consistent with the expert's expectations.
There are several global level checks that one can apply to the rule based model. For example :- It is expected that the ecosystem response must in some sense, display the Remane curve. The Remane curve of graphs the salinity vs number of estuarine species present for a healthy ecosystem. The graph shows two peaks, the first for freshwater species and the second for marine. There are far fewer brackish and brine water species.