Model prediction capacity of ephemeral gully evolution in conservation tillage systems

Authors: LUGUIN, EDUARDO - Public University Of Navarra; CAMPO-BESCÓS, MIGUEL - Public University Of Navarra; MUÑOZ-CARPE, RAFAEL - Public University Of Navarra; Bingner, Ronald - Ron; CRUSE, RICHARD - Iowa State University; MOMM, HENRIQUE - Middle Tennessee State University; Wells, Robert - Rob; CASALÍ, JAVIER - Public University Of Navarra

Submitted to: Earth Surface Processes and Landforms
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2021
Publication Date: 8/17/2021
Citation: Luguin, E., Campo-Bescós, M.A., Muñoz-Carpe, R., Bingner, R.L., Cruse, R.M., Momm, H.G., Wells, R.R., Casalí, J. 2021. Model prediction capacity of ephemeral gully evolution in conservation tillage systems. Earth Surface Processes and Landforms. p. 1-17. https://doi.org/10.1002/esp.5134.
DOI: https://doi.org/10.1002/esp.5134

Interpretive Summary: Ephemeral gully erosion produces serious water quality and economic problems in Midwest watersheds of the United States. A critical barrier to effective gully soil conservation practice development is information needed to describe the evolution of gullies in agricultural fields. There is also limited technology available to describe the relationship between the implementation of conservation practices and the potential erosion from ephemeral gullies. This research study evaluated the corresponding parameters of an ephemeral gully erosion model to estimate soil loss in an Iowa field. The most sensitive ephemeral gully parameters found in existing gully erosion technology were gully depth, critical shear stress, and headcut migration erodibility. The study showed that improved ephemeral gully erosion components are needed to evaluate the evolution of gullies on conservation tillage systems, since many of the components describing gully processes were developed for tilled agricultural conditions or larger channel systems. Future research is needed to study gully headcut, soil erodibility and width functions that will be different on conservation tillage systems compared to tilled fields in order to develop effective conservation management planning tools for use by agencies such as NRCS.

Technical Abstract: Ephemeral gully (EG) erosion has an important impact on agricultural soil losses and increases field surface hydrology connectivity, transporting pollutants to nearby water bodies. Watershed models including an EG component are scarce and not yet properly evaluated. The objective of the study was to evaluate the capability of AnnAGNPS watershed planning tool to simulate the temporal evolution of two EG formed after gullies were filled in conservation tillage systems. The current dataset for model testing included runoff measurements and EG morphological characteristics during an extended experimental period. Model evaluation focused on EG morphological characteristics (volume, width and length) and included calibration and testing phases and a Global Sensitivity Analysis (GSA) using the Sobol Method. The model was classified as additive, showing low sensitivity to input factor interactions. According to results from GSA, the most sensitive factors were depth, critical shear stress, headcut detachment exponent coefficient “b” and headcut detachment leading coefficient “a”. Model efficiency was classified as satisfactory for both calibration and testing phases. The model was capable of simulating EG volume evolution properly supporting the long-term evaluation objectives of the model. EG evolution on conservation tillage systems requires improved development of gully erosion components, since many of the processes were developed for tilled agricultural conditions or larger channel systems. Future research is needed to study gully headcut, soil erodibility and width functions that will be different on conservation tillage systems compared to tilled fields.