Modeling the mechanical effects of incorporated residue on rill erosion

Thomas George Franti, Purdue University

Abstract

Rill erosion by water involves the processes of soil detachment,transport, and deposition. These processes can be significantly affected by the presence of incorporated crop residue or other stable nonerodible material within the soil profile. A model was developed to predict soil erosion rates when incorporated residue acts as a stable grade control in a rill. The model assumed a quasi-steady sediment delivery rate, with the transport capacity of the flow much greater than the sediment load and the soil detachment rate equal to the detachment capacity. For the purposes of computing the flow hydraulics and erosion processes, the length of rill between two stable residue sections was considered an independent control volume. The independent control volumes were linked in series to compute the total sediment load rate from the rill. The model was verified using data collected from laboratory rill erosion experiments. Sediment load rates and rill geometry were measured in sixteen rills, each with a different combination of four discharge rates and four residue spacings. The model will simulate the sediment load rates, changes in rill geometry, and final rill geometry with various residue spacings and buried depths. The simulated results compared well to measured sediment load rates, changes in rill width over time, and final rill slope. The simulated results underpredicted the total eroded sediment volume and average rill width, and overpredicted the rate of change in rill slope over time. The simulated sediment load rates were most sensitive to changes in the soil critical shear and rill erodibility parameters.

Degree

Ph.D.

Advisors

Monke, Purdue University.

Subject Area

Agricultural engineering

COinS