Spatial variability of infiltration rate in soils on a swell-swale landscape
Abstract
Infiltration rate in natural soils varies spatially, and the variability may differ at various scales of measurement. An accurate prediction of the infiltration process requires adequate quantification of this spatial variability. This experimental study, which is based on fundamentals of soil taxonomy and geomorphology, was designed to evaluate spatial variability of steady-state infiltration rate at three adjacent scales, plot, hillslope and landscape using geostatistical technology. A straight transect was established on a swell-swale (s-s) landscape of the Wisconsinan till plain. Soil survey and infiltration measurements were made along or near the transect. Optimal infiltrometer size was studied in five plots by using six nested square infiltrometers. Three-dimensional variation of steady-state infiltration rate in a 1 x 1 m area was measured using small rings on three horizons for each of three soils. One-dimensional spatial variation of steady-state infiltration rate along a landscape transect and a hillslope transect nested within the landscape transect were characterized using three nested square infiltrometers. Steady-state infiltration rates were measured every 2 m on a 90 m transect for the hillslope-scale study and every 10 m on a 710 m transect for landscape-scale study. It was found that the s-s landscape had a hole effect on spatial variability of depth of surface horizon and organic matter content. An optimal infiltrometer size (60 x 60 cm with buffer) was determined for most of the soils studied. Influence of measurement scale on steady-state infiltration rate at the plot scale was soil dependent. Preliminary semivariance analyses showed that in most cases steady-state infiltration rate varied randomly within a small plot. Spatial structures of steady-state infiltration rate at both hillslope and landscape scales were present, and were affected by measurement scale, soil series and cyclic variation of the landscape. The dominant control factors for the observed spatial variability at the plot, hillslope, and landscape scales are, respectively, soil structure and macroporosity, soil series, and landscape units. The spatial relationship is found to coincide with basic concepts of the soil pedon, soil polypedons and geomorphology.
Degree
Ph.D.
Advisors
Kladivko, Purdue University.
Subject Area
Agronomy|Geology|Geography|Hydrology
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