Saturday, 15 July 2006
116-47

Effective Soil Hydraulic Properties at the Landscape Scale and beyond.

Jianting Zhu1, Binayak Mohanty2, and Narendra Das2. (1) Desert Research Institute, 755 E Flamingo Road, Las Vegas, NV 89119, (2) Texas A&M Univ, Dept of Biological & Agricultural Engineering, College Station, TX 77843-2117

Soil hydraulic properties at a spatial resolution typically larger than one square km are a key input for land-atmosphere feedback schemes in Soil-Vegetation-Atmosphere Transfer (SVAT) models. Previous studies investigated the significance of first- and second-order moments (mean and variance) of soil hydraulic parameters on defining “effective” parameter for heterogeneous soils at the landscape or remote-sensing footprint/pixel scale. In this study, we examined the impact of the skewness (third-order moment) of hydraulic parameter distributions on “effective” soil hydraulic parameter averaging schemes for heterogeneous soils in a flat landscape. The effective soil hydraulic parameter of the heterogeneous soil formation is obtained by conceptualizing the soil as an equivalent homogeneous medium. The averaging scheme requires that the effective homogeneous soil will discharge the same ensemble moisture flux across the land-atmosphere boundary. Numerical/field experimental results show that distribution skewness is also important in determining the upscaled effective parameters in addition to the mean and variance.

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