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Research article2007Peer reviewed

Accounting for uncertainty in pedotransfer functions in vulnerability assessments of pesticide leaching to groundwater

Stenemo F, Jarvis N

Abstract

A simulation tool for site-specific vulnerability assessments of pesticide leaching to groundwater was developed, based on the pesticide fate and transport model MACRO, parameterized using pedotransfer functions and reasonable worst-case parameter values. The effects of uncertainty in the pedotransfer functions on simulation results were examined for 48 combinations of soils, pesticides and application timings, by sampling pedotransfer function regression errors and propagating them through the simulation model in a Monte Carlo analysis. An uncertainty factor, f(u), was derived, defined as the ratio between the concentration simulated with no errors, C-sim and the 80th percentile concentration for the scenario. The pedotransfer function errors caused a large variation in simulation results, with f(u) ranging from 1.14 to 1440, with a median of 2.8. A non-linear relationship was found between f(u), and c(sim), which can be used to account for parameter uncertainty by correcting the simulated concentration, c(sim), to an estimated 80th percentile value. For fine-textured soils, the predictions were most sensitive to errors in the pedotransfer functions for two parameters regulating macropore flow (the saturated matrix hydraulic conductivity, K-b, and the effective diffusion pathlength, d) and two water retention function parameters (van Genuchten's N and alpha parameters). For coarse-textured soils, the model was also sensitive to errors in the exponent in the degradation water response function and the dispersivity, in addition to K-b, but showed little sensitivity to d. To reduce uncertainty in model predictions, improved pedotransfer functions for K-b, d, N and alpha would therefore be most useful. (C) 2007 Society of Chemical Industry

Keywords

pesticide leaching; vulnerability assessment; MACRO model; uncertainty; pedotransfer functions

Published in

Pest Management Science
2007, Volume: 63, number: 9, pages: 867-875
Publisher: JOHN WILEY & SONS LTD

      SLU Authors

    • Stenemo, Fredrik

      • Department of Soil Sciences, Swedish University of Agricultural Sciences
      • Jarvis, Nicholas

        • Department of Soil Sciences, Swedish University of Agricultural Sciences

      UKÄ Subject classification

      Fish and Aquacultural Science
      Agricultural Science
      Environmental Sciences related to Agriculture and Land-use

      Publication identifier

      DOI: https://doi.org/10.1002/ps.1415

      Permanent link to this page (URI)

      https://res.slu.se/id/publ/14825