Intermittency on soil movement: The role of landscape macro/microtopography

Authors: Papanicolaou, Athanasios - Thanos; Wacha, Kenneth - Ken

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 9/21/2022
Publication Date: 12/14/2022
Citation: Papanicolaou, A.N., Wacha, K.M. 2022. Intermittency on soil movement: The role of landscape macro/microtopography [abstract]. American Geophysical Union.

Interpretive Summary:

Technical Abstract: Landscape macro/microtopography strongly influences the physical and biological processes that transform surface soil and its constituents. Through the natural coevolution of geomorphic and hydrologic processes in the landscape, or by punctual changes in these processes as a result of weather events, dynamic landscapes establish characteristic hierarchies of geomorphic controls on soil erosion and ultimately on organic matter stability and reactivity. Few studies, however, have attempted to develop a comprehensive understanding of upland watershed mechanistic controls on soil movement and associated chemical alterations to the material exported from watershed to the rivers. A combination of simulated rainfall experiments and analytical approaches were used to assess the mechanisms of soil dynamics for event-based hill-slope processes. As a first step this study shows that mobilization of sediment remains unsteady especially as the early stages of a storm with constant rainfall intensity. The selective and intermittent movement of soil that occurs along pathways redistributes particles of different sizes unevenly, creating a dynamic mosaic of land surface maps that are characterized by different size fractions along the upslope and downslope sections of a hill-slope. Measurements and analytical calculations suggested that rain splash and head-cut retreat were the dominant drivers of geomorphic evolution during the unsteady timescale, collectively accounting for 82% of total sediment mobilization, while flow entrainment was the dominant entrainment mechanism during the pseudo-steady timescale, accounting for 60% of total sediment mobilization, where the drainage network was incised and mature.