| Institution: | 1. Department of Engineering;2. IS-FOOD Institute (Innovation & Sustainable Development in Food Chain), Public University of Navarre, Campus de Arrosadia, Pamplona, Navarra, 31006 Spain;3. IS-FOOD Institute (Innovation & Sustainable Development in Food Chain), Public University of Navarre, Campus de Arrosadia, Pamplona, Navarra, 31006 Spain
Department of Agricultural and Biological Engineering, University of Florida, 101 Frazier Rogers Hall, Gainesville, FL, 32611-0570 USA;4. USDA-Agricultural Research Service National Sedimentation Laboratory, 598 McElroy Dr., Oxford, MS, 38655 USA;5. Department of Agronomy, Iowa State University, 2104 Agronomy Hall, Ames, IA, 50011 USA;6. Department of Geosciences, Middle Tennessee State University, Davis Science Building 239, Murfreesboro, TN, 37132 USA |
| Abstract: | Ephemeral gully (EG) erosion has an important impact on agricultural soil losses and increases field surface hydrology connectivity and transport of pollutants to nearby water bodies. Watershed models including an EG component are scarce and not yet properly evaluated. The objective of this study is to evaluate the capacity of one such tool, AnnAGNPS, to simulate the evolution of two EG formed in a conservation tillage system. The dataset for model testing included runoff measurements and EG morphological characteristics during 3 years. Model evaluation focused on EG evolution of volume, width, and length model outputs, and included calibration and testing phases and a global sensitivity analysis (GSA). While the model did not fully reproduce width and length, the model efficiency to simulate EG volume was satisfactory for both calibration and testing phases, supporting the watershed management objectives of the model. GSA revealed that the most sensitive factors were EG depth, critical shear stress, headcut detachment exponent coefficient b, and headcut detachment leading coefficient a. For EG outputs the model was additive, showing low sensitivity to interactions between the inputs. Prediction of EG spatial evolution on conservation tillage systems requires improved development of gully erosion components, since many of the processes were developed originally for traditional tillage practices or larger channel systems. Our results identify the need for future research when EG form within conservation tillage systems, in particular to study gully headcut, soil erodibility, and width functions specific to these practices. |
