This work evaluated the spatial variability and distribution of heterogeneous hydraulic conductivity (
K) in the Choushui River alluvial fan in Taiwan, using ordinary kriging (OK) and mean and individual sequential Gaussian simulations (SGS). A baseline flow model constructed by upscaling parameters was inversely calibrated to determine the pumping and recharge rates. Simulated heads using different
K realizations were then compared with historically measured heads. A global/local simulated error between simulated and measured heads was analysed to assess the different spatial variabilities of various estimated
K distributions. The results of a MODFLOW simulation indicate that the OK realization had the smallest sum of absolute mean simulation errors (SAMSE) and the SGS realizations preserved the spatial variability of the measured
K fields. Moreover, the SAMSE increases as the spatial variability of the
K field increases. The OK realization yields small local simulation errors in the measured
K field of moderate magnitude, whereas the SGS realizations have small local simulation errors in the measured
K fields, with high and low values. The OK realization of
K can be applied to perform a deterministic inverse calibration. The mean SGS method is suggested for constructing a
K field when the application focuses on extreme values of estimated parameters and small calibration errors, such as in a simulation of contaminant transport in heterogeneous aquifers. The individual SGS realization is useful in stochastically assessing the spatial uncertainty of highly heterogeneous aquifers. Copyright © 2004 John Wiley & Sons, Ltd.
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