Comparison of Geostatistical Methods for Estimating Transmissivity Using Data on Transmissivity and Specific Capacity

For regional aquifer modeling it is often necessary to produce maps of the distribution of the transmissivity in the aquifer, for example, as initial input for the calibration phase of the model, either by automatic or by trial and error procedures. Such estimations must be based on all possible information available in the field; in many instances, direct transmissivity measurements from pumping tests are scarce, whereas indirect estimations based on specific capacity data are more numerous. It is, however, possible to use jointly both types of data when a geostatistical estimation technique is used. Four such methods will be compared here: (1) kriging combined with linear regression, (2) cokriging, (3) kriging with an external drift, and (4) kriging with a guess field. This comparison is made both on a set of real field data and on a theoretical case, where the "true" solution is known.