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Research Project: Computational Tools and Decision Support System Technologies for Agricultural Watershed Physical Processes, Water Quality and Ground Water Management

Location: Watershed Physical Processes Research

Title: Physically based numerical model for the landscape evolution of soil-mantled watersheds driven by rainfall and overland flow

Author
item JIA, YAFEI - UNIVERSITY OF MISSISSIPPI
item Wells, Robert - Rob
item MOMM, HENRIQUE - MIDDLE TENNESSEE STATE UNIVERSITY
item ZHANG, YAOXIN - UNIVERSITY OF MISSISSIPPI
item BENNETT, SEAN - UNIVERSITY AT BUFFALO

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/16/2023
Publication Date: 3/22/2023
Citation: Jia, Y., Wells, R.R., Momm, H.G., Zhang, Y., Bennett, S. 2023. Physically based numerical model for the landscape evolution of soil-mantled watersheds driven by rainfall and overland flow. Journal of Hydrology. 620 (2023) 129419. https://doi.org/10.1016/j.jhydrol.2023.129419.
DOI: https://doi.org/10.1016/j.jhydrol.2023.129419

Interpretive Summary: A two-dimensional computer simulation model was modified to simulate rainstorms and overland flow over small watersheds. Measured erosion data from both laboratory and field scales were used to calibrate and validate the simulation results. Measurements in the lab experiments included: 15-min runoff samples, overlapping surface imagery, total mass of solids passing the downstream terminus. Measurements in the field experiments included: overlapping surface imagery, radar hydrology. Computer simulations of the steady rainfall laboratory experiment reproduced sediment yield processes, as well as rill and gully erosion distributions and channel network patterns. Computer simulations of the unsteady rainfall field experiment provided reasonable results of topographic change, deposition patterns and micro-morphology of the land surface. The simulations represent an advancement as the technology is physically based and includes explicit processes for flow hydrodynamics, rain splash, soil erosion, and sediment transport. The research demonstrates how high resolution spatial and temporal topographic observations can be simulated and interrogated by computer simulation models producing accurate predictions of rill and gully erosion processes that cause soil and landscape degradation.

Technical Abstract: Soil and gully erosion is critical threat to sustainable agricultural lands and productivity. Soil erosion by rain splash, sheet runoff, and concentrated flow are complex problems conditioned by the combined interactions of soil physical properties, hydrology, human activity, landscape topography, and climate. Effective management of erosion processes driven by rainfall and surface runoff requires a combined effort of field observation, physical experimentation, and numerical simulation. A physically-based numerical model, CCHE2D, is constructed and applied to simulate landscape evolution processes as a result of raindrop impact and overland flow. CCHE2D solves a set of full hydrodynamic equations for depth-integrated flows. The numerical model simulates a thin layer of runoff and concentrated flow over complex terrains, and predicts sediment transport due to rain splash erosion and soil surface erosion due to shear flows. Soil erosion simulations due to rainfall are presented for an experimental landscape and a tilled agricultural field. Experiments in a laboratory flume created overland flow and soil erosion using simulated rainfall, in which the evolving topographic surface was captured by close-range photogrammetry. Numerical simulation results agreed well with the observed time-variations in surface topography, sediment yield, and drainage network development. Photogrammetric field data were collected using an unmanned aerial system (UAS) following planting and subsequent rainstorms. The simulated results of soil and gully erosion at this field location also agreed well with observations. This research successfully demonstrates how high resolution spatial and temporal topographic measurements in experimental and natural landscapes can be simulated and interrogated by physically-based hydrodynamic and morphodynamic models, and produce accurate predictions of rill and gully erosion processes that cause soil and landscape degradation.