USE OF SOIL TEXTURE, BULK-DENSITY, AND SLOPE OF THE WATER-RETENTION CURVE TO PREDICT SATURATED HYDRAULIC CONDUCTIVITY

With advances in computer software and hardware, mathematical subsurfa ce flow models are routinely being used for many field applications. T he application of the subsurface models depends on the availability of accurate input parameters describing the hydraulic properties of the soil, especially the soil matrix saturated hydraulic conductivity. Sat urated hydraulic conductivity can be measured directly which is very c ostly and time consuming, or estimated indirectly from more easily mea sured data such as soil texture, the most readily available soil prope rty in the United States. This study grouped more than 900 saturated h ydraulic conductivities far the soil matrix according to the USDA soil texture classes and two porosity classes. The geometric mean and a va riability measure are reported. Comparing these values with previously published values indicates that the new data yield higher values for the heavy textured (clay) soils. Also, values for the fine sand classe s which were not previously available are reported A redefined version of the Kozeny-Carman saturated hydraulic conductivity equation based on effective porosity and the slope of the water retention curve is pr esented for estimating the saturated hydraulic conductivity for the so il matrix.