A Statistical Approach for the Assessment of Saturated Hydraulic Conductivity Values of Unsaturated Urban Soils Obtained by Field Infiltration Tests

Abstract

An evaluation and interpretation of the obtained results focusing the hydraulic conductivity of anthropogenic saturated soil, k, has been performed on an urban area vadose zone. Four methods have been used to quantify the hydraulic conductivity: the tube infiltrometer (TI), the double ring infiltrometer (DRI), the minidisk infiltrometer (MDI) and the inversed auger (IA). This study comprises (a) a comparative analysis of the results obtained by each method between several trials performed at the same location and at distinct locations within the plot, (b) a comparative analysis of the results of all methods, and (c) a statistical analysis regarding the correlation between k as a dependent variable and the infiltration area A as the main independent variable. To select the k values close or corresponding to the saturation state for TI and IA methods, a domain of validity was defined. A new parameter, k* = k/A, was introduced which represents the hydraulic conductivity corresponding to an infiltration surface unit (1 cm2). An increase in this ratio with the increase in the infiltration area, within the same method or between different methods, indicates the heterogeneity of the terrain but especially the fact that the infiltration area no longer represents the main independent variable on which the hydraulic conductivity depends for the saturated state.