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A finite element model was used to examine the sensitivity of computed hydraulic head values to changes in the hydraulic conductivity of subsurface flow systems. Steady state saturated flow in nonuniform anisotropic cross sections was considered. From an examination of several hypothetical cross sections it was apparent that the sensitivity analysis procedure could be useful in locating those areas of the flow system that are most sensitive to changes in conductivity and in determining those components of conductivity that have the greatest effect on the hydraulic head distribution. Consequently, a sensitivity analysis could be very useful in designing efficient hydraulic conductivity measurement programs. One method that has frequently been used to determine conductivities is to adjust the conductivity components in a numerical model until the computed head values agree with field measurements. Information is presented that indicates that this procedure could lead to erroneous conclusions. By using the sensitivity analyses, a method was developed for determining the quantitative value of ratios of conductivity components from field measurements of hydraulic head. In principle, the number of head measurements must be equal to the number of unknown conductivity ratios. The accuracy of the results suggests that the method should be evaluated in a field situation.