Assessment of the Optimal Sampling Arrangement Based on Cokriging Estimation Variance Reduction Approach

Existing monitoring networks of hydrochemical parameters in groundwater can be used in order to achieve information on water quality . Parameters estimation based on sampled data strongly influences managerial choices. A methodology based on cokriging estimation variance (CEV) evaluation is presented, useful to minimize the samples in an existing monitoring network keeping the CEV below a desired threshold. The spatial behavior of the considered chemical parameter is assumed persistent in time so that the variogram parameters are evaluated using data from previous sampling campaigns. A sequential elimination procedure has been used in order to assess the optimal sampling arrangement for estimating concentrations in particular critical sites. The methodology has been applied to monitoring network of the aquifer of the Lucca Plain, Central Italy.