Landform Parameters Correlated to Soil Drainage

Quantitative means of describing land surfaces were developed in this study and related to soil drainage. Hundreds of elevations were determined on each of 40 plots representing 6 soil series. The 3‐dimensional equations developed to approximate these elevations assume radial symmetry and a parabolic relationship between elevation and distance from the symmetry axis. An electronic computer was used to solve and test equations for several positions in each plot. Areas that crossed soil boundaries were excluded. The equations of 75% of the remaining positions closely approximated the data and were used in this study. Parameters representing slope, rate of change of slope, and radius of curvature were obtained from the equations. These parameters were used to classify the shapes of the land surfaces both qualitatively and quantitatively. Three‐dimensional plots of these parameters correctly predicted the drainage class of 90% of the positions with usable equations. Surfaces having equivalent drainage at all points were defined by equations in terms of radius, slope, and rate of change of slope.