evaluation of copula performance in groundwater quality zoning (case study: kerman and ravar regions)

this study presents a new method for interpolation by use of copula for groundwater quality zoning. in this regard, the data of the concentration of bicarbonate in 87 piezometric wells on the plains of kerman and ravar in september 2013 were examined. for this purpose, four archimedean copula including clayton, frank, gumbel and joe have been used. then, the obtained results were compared to the results obtained from conventional zoning methods to evaluate the performance of copulas. analysis of the results with respect to the root mean square error criterion in the zoning was obtained about 1.84 and 1.95 mg/l based on median and mean respectively, by use of copula which had a better performance compared to kriging method with an error of 2.21 meq/l, kriging method within box-cox transformation and error of 2.14 meq/l, kriging with logarithmic transformation of 1.98 meq/l and inverse distance weighting method with an error of 2.83 meq/l.