170-11 Determination of the Tangential Model Soil Water Retention Curves for Various Soil Types.
See more from this Division: SSSA Division: Soil PhysicsSee more from this Session: Revisiting the Most Important Curve in Soil Physics: I
SWRCs available from the Unsaturated Soil Hydraulic Properties Database (UNSODA) were used. Tangential model curves were fit to 434 soils (139 Sand, 83 Sandy-loam, 53 Loamy-sand, 41 Sandy-clay-loam, 91 Silt-loam, 27 Silt-clay-loams) using a nonlinear regression method by minimizing the sum of the squared residuals.
For each soil type, the geometric means (GM), the medians (MD), and the arithmetic means (AM) of the coordinates of three points, E, M and F; and the arithmetic means of three slopes, ce, cm, and cf, were obtained to generate representative SWRCs. Mean errors, mean absolute errors, and root mean square errors were then calculated by comparing with observed water retention data.
For most soil types, AM resulted in the largest errors among three, while GM and MD performed similarly. Errors for sandy soils were, in general, larger than those for loamy soils. This study demonstrates that Tangential model curves constructed with mean coordinates represent well the observed curves for most soil types considered in this study.
See more from this Session: Revisiting the Most Important Curve in Soil Physics: I