Abstract:

Many hydrochemical variables were required to test in tradition methods in order to assess groundwater pollution, the cost was higher. More importantly, these methods could not consider the effect of interval water quality target limit on synthesis assessment. A new method was introduced in this paper: first the variable fuzzy set theory was employed to assess groundwater pollution; and then application of fuzzy rough set to evacuate critical variable, the min-decision rules were used to forecast groundwater pollution synthesis index, which was yield by fuzzy-rough set. This method was applied in Luoyang basin to evaluate its validity, the result indicated: there were five hydrochemical variables (As, Hg, Se, I, NH₃-N) played a controlled role in groundwater pollution classification. In testing data, 7 groups of samples' relative error was 0.104 0-0.172 5; the surplus 15 groups samples’ relative error was 0.001 5-0.093 7. Therefore, the groundwater pollution synthesis index could be predicted by variable fuzzy sets and fuzzy-rough set theory according to the above five hydrochemical variables, which could make the monitoring cost decrease and provide reliable data source for groundwater pollution control and remediation.

Key words: groundwater, hydrochemical variable, pollution, fuzzy, errors