A statistical approach for the assessment of the saturated hydraulic conductivity applied to an Austrian region

• Published in: Journal of hydrology. Regional studies 2023-02, Vol.45, p.101310, Article 101310
• Main Authors: Flammini, A., Morbidelli, R., Corradini, C., Dari, J., Saltalippi, C., Goyal, A., Govindaraju, R.S.
• Format: Article
• Language: English
• Subjects: Areal infiltration; Saturated hydraulic conductivity; Soil; Statistical analysis; Uncertainty analysis
• ISSN: 2214-5818; 2214-5818
• DOI: 10.1016/j.ejrh.2022.101310

This study refers to the Hydrological Open Air Laboratory (HOAL) watershed, located in South-West Austria. The spatial variability of saturated hydraulic conductivity, Ks, is sometimes synthetized by geometric mean, K̃s, and coefficient of variation, while areal-average infiltration models rely upon the arithmetic mean, K¯sl, associated to log-transformed Ks, and relative coefficient of variation, CVal. Robust estimation of K¯sl and CVal, as well as of K̃s and associated coefficient of variation, CVg,would require a large number of Ks observations. The determination of the minimum number of Ks measurements, n*, for obtaining sufficiently accurate values of each aforementioned quantity over an area is an open issue addressed here. A statistical approach has been applied to Ks datasets on three grassy plots for an uncertainty analysis based on the non-parametric bootstrap method with replacement. The uncertainty of each quantity has been derived for different observation numbers and areas. Considering different sub-regions in the largest plot the uncertainty is almost invariant with increasing the sub-region area beyond a threshold. Furthermore, for a given n*, the uncertainty of K¯sl and CVal is much smaller than that of K̃s and CVg. Our approach defines a methodology for determining over an area the n* associated to a fixed uncertainty level in the joint estimation of the selected quantities. Guidelines for investigations over different plots are also proposed. [Display omitted] •The spatial variability of saturated hydraulic conductivity (Ks) is investigated.•The estimate of the mean and coefficient of variation of Ks are considered.•A minimum number of Ks observations is defined for any specified uncertainty level.•Insights for application in areal-average infiltration modeling are also provided.