title: Data worth and prediction uncertainty for pesticide transport and fate models in Nebraska and Maryland, United States.
abstract: BACKGROUND
  Complex environmental models are frequently extrapolated to overcome data limitations in space and time, but quantifying data worth to such models is rarely attempted. The authors determined which field observations most informed the parameters of agricultural system models applied to field sites in Nebraska (NE) and Maryland (MD), and identified parameters and observations that most influenced prediction uncertainty.
  
  
  RESULTS
  The standard error of regression of the calibrated models was about the same at both NE (0.59) and MD (0.58), and overall reductions in prediction uncertainties of metolachlor and metolachlor ethane sulfonic acid concentrations were 98.0 and 98.6% respectively. Observation data groups reduced the prediction uncertainty by 55-90% at NE and by 28-96% at MD. Soil hydraulic parameters were well informed by the observed data at both sites, but pesticide and macropore properties had comparatively larger contributions after model calibration.
  
  
  CONCLUSIONS
  Although the observed data were sparse, they substantially reduced prediction uncertainty in unsampled regions of pesticide breakthrough curves. Nitrate evidently functioned as a surrogate for soil hydraulic data in well-drained loam soils conducive to conservative transport of nitrogen. Pesticide properties and macropore parameters could most benefit from improved characterization further to reduce model misfit and prediction uncertainty.
authors.affiliation: US Geological Survey, Reston, VA, USA.
authors.forename: Bernard T
authors.initials: BT
authors.lastname: Nolan
authors.affiliation: US Department of Agriculture, Ames, IA, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Malone
authors.affiliation: Watermark Numerical Computing, Corinda, Australia.|National Centre for Groundwater Research and Training, Flinders University, Australia.
authors.forename: John E
authors.initials: JE
authors.lastname: Doherty
authors.affiliation: US Geological Survey, Tacoma, WA, USA.
authors.forename: Jack E
authors.initials: JE
authors.lastname: Barbash
authors.affiliation: US Department of Agriculture, Fort Collins, CO, USA.
authors.forename: Liwang
authors.initials: L
authors.lastname: Ma
authors.affiliation: US Department of Agriculture, Fort Collins, CO, USA.
authors.forename: Dale L
authors.initials: DL
authors.lastname: Shaner
mesh_terms: D000081:Acetamides / Q000737:chemistry; D002138:Calibration; D006540:Herbicides / Q000737:chemistry*; D008396:Maryland; D008962:Models, Theoretical; D009329:Nebraska; D010573:Pesticide Residues / Q000737:chemistry; D016062:Porosity; D012987:Soil / Q000737:chemistry*; D035501:Uncertainty; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D000081:Acetamides; D006540:Herbicides; D010573:Pesticide Residues; D012987:Soil; D014874:Water Pollutants, Chemical; C051786:metolachlor
keywords: RZWQM; degradates; metolachlor; parameter estimation; prediction uncertainty