Pathway to ephemeral channel widening algorithm improvement

Soil erosion is a problem across the globe and, quite often, is accelerated within agricultural settings. Splash, sheet, rill, and gully erosion govern soil loss by water, and these erosion mechanisms increase in complexity as the contributing area increases. For example, splash erosion occurs throughout the field during a rainfall event but is hyper localized (i.e., single drop impact) and sheet erosion occurs within the field but is connected to flow shear and a uniform depth of soil loss. With rill and gully erosion the processes are more complex and interactive, i.e., progressing incrementally from splash to gully erosion. Here, we focus on rill and gully channel widening mechanics influenced by a fixed bed. Experiments were conducted with three soils, three slopes, and three constant flow discharges. Soil textures ranged from sandy to clayey; slopes were 1, 5, and 11%; and flow discharges were 2.5, 6.7, and 10.8 cm2/sec. As bed slope and flow discharge increased, channel widening rate increased. As texture shifted from sandy to clayey, channel widening rate decreased. Initial experimentation and widening algorithm development was based upon the same experimental protocols with one soil only (sandy texture) and an empirical equation was defined in terms of slope and discharge. The current work builds upon the initial widening equation, investigates a Bayesian hierarchical structure, and strives to unite the previous algorithm development with the new experimental data.