Season and erosion pavement influence on saturated soil hydraulic conductivity

Soil infiltration controls the partitioning of rainfall into surface runoff, groundwater recharge, and soil moisture. Understanding seasonal variability and the influence of soil erosion pavement on infiltration is critical to increasing our ability to predict runoff. Our objective was to evaluate seasonal variability in infiltration and the importance of erosion pavement. A tension disc permeameter was used to measure infiltration seasonally for 3 years with soil erosion pavement in place and for up to 1 year after the pavement was removed. Seasonal and erosion pavement effects were evaluated using saturated hydraulic conductivity, flow-weighted characteristic pore size, and macropore capillary length data. There was a significant season-by-year interaction for conductivity with the erosion pavement in place. Conductivity was substantially lower in the fall season, whereas the rates were similar for the other seasons. Differences in years within seasons were also observed. The calculated soil pore structural components of size and length could not account for the seasonal changes in conductivity. The pore size and length remained comparatively constant for the seasons and years. To account for the low fall hydraulic conductivity, it was concluded that raindrop impact from the high intensity summer thunderstorms closed some pores or interconnections. Freeze-thaw cycles from late fall through spring apparently opened the pores, resulting in increases in conductivity. Soil erosion pavement removal caused an immediate significant decrease in hydraulic conductivity and pore size and an increase in pore length that lasted longer than a year. Results indicate that soil erosion pavement is important in maintaining soil surface structural integrity to maintain the higher conductivity. Disc permeameter measurements were clearly able to show seasonal and erosion pavement influences on soil conductivity and that soil erosion pavement must be incorporated into hydraulic runoff models to improve predictions.