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Title: Framework to parameterize and validate APEX to support deployment of the nutrient tracking tool

Author
item Moriasi, Daniel
item Teet, Stephen
item GUZMAN, JORGE - Waterborne Environmental
item King, Kevin
item Bosch, David - Dave
item Bjorneberg, David - Dave
item Williams, Mark

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/4/2016
Publication Date: 7/25/2016
Citation: Moriasi, D.N., Teet, S.B., Guzman, J.A., King, K.W., Bosch, D.D., Bjorneberg, D.L., Williams, M.R. 2016. Framework to parameterize and validate APEX to support deployment of the nutrient tracking tool. Agricultural Water Management. 177:146-164.

Interpretive Summary: Guidelines have been developed to parameterize and validate the Agricultural Policy Environmental eXtender (APEX) to support the Nutrient Tracking Tool (NTT). This follow-up paper presents a case study to illustrate how the developed guidelines are applied in a headwater watershed located in central Ohio. The developed guidelines were successfully applied in the study to determine the most sensitive parameters for water yield (wyld) or streamflow and the corresponding range of acceptable water yield output on a monthly and annual time steps. The most sensitive parameters were determined based on sensitivity analysis. Some of the most sensitive parameters exhibited some degree of interaction, which implies that the determined ranges of parameter values cannot be adjusted linearly but in combination with the values of other sensitive parameters. The range of simulated mean monthly wyld values was 40.3 mm to 43.4 mm, while simulated mean annual wyld values ranged from 489.5 mm to 521.8 mm. These values were within 5% of the mean observed wyld values. Overall, this case study example together with model parameterization guidelines developed previously are intended to serve as the framework to parameterize and validate APEX to support nation-wide deployment of NTT. This framework can be easily modified for additional APEX and other modeling studies.

Technical Abstract: Guidelines have been developed to parameterize and validate the Agricultural Policy Environmental eXtender (APEX) to support the Nutrient Tracking Tool (NTT). This follow-up paper presents 1) a case study to illustrate how the developed guidelines are applied in a headwater watershed located in central Ohio; 2) the calibration results for water yield (wyld); 3) the most sensitive wyld parameters for the study area and their corresponding value ranges; and 4) uncertainty and confidence intervals for simulated wyld from simulations that met preset model performance criteria. The developed guidelines were successfully applied in the central Ohio case study. Based on sensitivity analysis results, some of the most sensitive parameters exhibited some degree of interaction, which implies that the determined ranges of parameter values cannot be adjusted linearly but in combination with the values of other sensitive parameters. The 95% confidence interval for simulated mean monthly and annual wyld were 41.2 ± 0.2 mm and 506.6 ± 7.6 mm, respectively. The range of simulated mean monthly wyld values was 40.3 mm to 43.4 mm, while simulated mean annual wyld values ranged from 489.5 mm to 521.8 mm. These values were within 5% of the mean observed wyld values. Overall, this case study example together with model parameterization guidelines developed previously are intended to serve as the framework to parameterize and validate APEX to support nation-wide deployment of NTT. This framework can be easily modified for additional APEX and other modeling studies.