Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: January 5, 2001
Publication Date: N/A
Technical Abstract: Frozen soil can impede drainage and thereby accentuate runoff and erosion in cold regions. Indeed, erosion during spring thaw can constitute more than half of the soil loss occurring annually in the northern Corn Belt. This study describes a laboratory technique to assess erosion from a variably saturated, partially frozen soil. Simulated rain was applied to a loam soil contained within a 0.3-m wide, 0.4-m long, and 0.3-m deep box (erosion box). The box was equipped with access ports for applying suction or to assess vertical drainage and lateral subsurface flow. The erosion box was designed for installation of Time Domain Reflectometry (TDR) probes and thermocouples to assess soil liquid water content and temperature throughout the 0.3-m profile. Depth of frozen soil and surface thaw was monitored using frost tubes and by inserting a pointed rod into the soil. Insulation (0.2 m of styrofoam) was placed on all sides of the box, except the top, to simulate one-dimensional freezing and thawing. The box was placed in a freezer to achieve a uniform temperature of -10 deg C throughout the soil profile. The box was then moved to a raindrop tower (30-m height) and positioned at a 6% slope. Rain was applied for 1800 s at an intensity of 64 mm h**-1 after the soil had thawed to a specified depth (20, 50, 100, and 200 mm). Runoff, soil loss, splash erosion, drainage, and subsurface flow were measured during the rainfall event. Our results indicate that erosion diminished with an increase in thaw depth. The non-linear relation between erosion and thaw depth suggests that soil is most susceptible to erosion at the commencement of soil thaw. Therefore, to curtail erosion during spring thaw, management practices are sought that expedite thawing and drying of the soil in the spring.