Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2003
Publication Date: September 30, 2003
Citation: Wells, R.R., Dicarlo, D.A., Steenhuis, T.S., Parlange, J., Romkens, M.J., Prasad, S.N. 2003. Infiltration and surface geometry features of a swelling soil following successive simulated rainstorms. Soil Science Society of America Journal. 67:1344-1351.
Interpretive Summary: Heavy clay soils like those found in the Mississippi Delta (among other places) undergo large shrink/swell cycles with water content. The cracking that takes place on drying will determine the amount of infiltration from the subsequent rainstorms, and the amount of runoff and soil erosion. We subjected a Sharkey clay soil to many rainstorm/drying cycles and studied the crack pattern with a laser to measure surface elevations and a cone penetrometer to measure water infiltration. Our results show that the cracks often appear in an alternating pattern from rainstorm to rainstorm, with implications for retarded downward water movement, and more flow uniformity.
The theory of water movement in high shrink/swell soils has experienced consistent revision since Haines first presented the topic in 1923. Several aspects of the infiltration process in cracking soils have proven to be difficult to measure; seal/crust formation and properties, crack network patterns, preferential flow zones and contributions, and soil moisture determinations within the profile (near crack and near center of prismatic column) to name a few. Here, we used simulated rainstorms, laser measurements of surface elevation, needle-penetrometer measurements, and mass measurements of infiltrating water over a 206 and 145 day period to examine water movement and cracking patterns in a large sample box filled with a swelling clay soil. Water movement was restricted to the neighborhood of the crack zone, since the formation of a surface seal/crust prohibited infiltration into the surface of the prismatic columns of soil between cracks. Also, the location of cracks was observed to alternate between rainstorms. The alternating crack pattern led to more uniform wetting with depth as time increased and the number of rainstorms increased, thereby reducing the extent of preferential flow.