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United States Department of Agriculture

Agricultural Research Service

Research Project: INTEGRATED ASSESSMENT AND ANALYSIS OF PHYSICAL LANDSCAPE PROCESSES THAT IMPACT THE QUALITY AND MANAGEMENT OF AGRICULTURAL WATERSHEDS

Location: Watershed Physical Processes Research Unit

Title: Evaluation of runoff, peak flow and sediment yield for events simulated by the AnnAGNPS model in a Belgian agricultural watershed

Authors
item Zema, D.A. -
item Bingner, Ronald
item Denisi, P. -
item Govers, G. -
item Licciardello, F. -
item Zimbone, S.M. -

Submitted to: Land Degradation and Development
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 6, 2010
Publication Date: May 1, 2012
Repository URL: http://handle.nal.usda.gov/10113/54482
Citation: Zema, D., Bingner, R.L., Denisi, P., Govers, G., Licciardello, F., Zimbone, S.M. 2012. Evaluation of runoff, peak flow and sediment yield for events simulated by the AnnAGNPS model in a Belgian agricultural watershed. Land Degradation and Development. 23:205-215. doi: 1068.

Interpretive Summary: A watershed scale assessment of the effect of conservation practices on controlling erosion is critical when recommending conservation management practices to agricultural producers. Pollutant loading allocations established with comprehensive studies of sediment sources from many locations around the world will result in the appropriate placement of conservation practices to those locations that have the most effective impact on reducing watershed sediment loads. The US Department of Agriculture AnnAGNPS watershed model was implemented in a small agricultural watershed located in central Belgium, to assess the prediction capacity of runoff, peak flow and sediment yield in humid temperate conditions. Model performance was evaluated for individual storm events using a database reporting hydrological, geomorphologic and land use data collected during a two year period. Seventeen events were simulated and compared with the corresponding observations at the watershed outlet. Results indicated the model produced satisfactory results when predicting the largest runoff volumes. Predictions of peak flow and sediment yield did not produce satisfactory results that can have several causes: the internal model deficiencies may be due to the incomplete representation all of the complex watershed processes, while external problems may be related to the conditions within the modeled watershed and the quality of recorded data. On the whole the model may be considered as being suitable to simulate the significant runoff events in the experimental watershed. However, the model may be seen as better suited for comparative assessments of alternative management and policy scenarios and for gross estimation of nutrient loads rather than the precise prediction of a single event for watersheds in these conditions, consequently helping in the prediction of land degradation problems in the experimented conditions.

Technical Abstract: The AnnAGNPS model, widely utilised as a practical tool in approaching erosion problems and land use planning, was implemented in a small agricultural watershed located in central Belgium, to assess its prediction capacity of runoff, peak flow and sediment yield in humid temperate conditions. Model performance was evaluated at the event scale by using a database reporting hydrological, geomorphologic and land use data collected during a two year period. Seventeen events were modeled and compared with the corresponding observations at the watershed outlet. The model performed well in predicting the largest runoff volumes, as shown by the high values achieved by the coefficients of efficiency (E = 0.89) and determination (r2 = 0.92). However some events resulted in zero runoff simulation. The prediction capability for peak flow and sediment yield was poor (E = 0.35 and 0.16 respectively). This inaccuracy can have several causes: the internal model deficiencies may be due to the incomplete representation of watershed complex processes, while external problems may be related to the conditions within the modeled watershed and the quality of recorded data. On the whole the AnnAGNPS model may be considered as being suitable to simulate the significant runoff events in the experimental watershed. However, the model may be seen as better suited for comparative assessments of alternative management and policy scenarios and for gross estimation of nutrient loads rather than the precise prediction of a single event, consequently helping in the prediction of land degradation problems in the experimented conditions.

Last Modified: 9/23/2014
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