Development and application of a catchment scale pesticide fate and transport model for use in drinking water risk assessment

S.P Pullan,M.J Whelan,J Rettino,K Filby,S Eyre,I.P Holman

doi:10.1016/j.scitotenv.2016.04.135

Abstract

This paper describes the development and application of IMPT (Integrated Model for Pesticide Transport), a parameter-efficient tool for predicting diffuse-source pesticide concentrations in surface waters used for drinking water supply. The model was applied to a small UK headwater catchment with high frequency (8h) pesticide monitoring data and to five larger catchments (479–1653km2) with sampling approximately every 14days. Model performance was good for predictions of both flow (Nash Sutcliffe Efficiency generally >0.59 and PBIAS <10%) and pesticide concentrations, although low sampling frequency in the larger catchments is likely to mask the true episodic nature of exposure. The computational efficiency of the model, along with the fact that most of its parameters can be derived from existing national soil property data mean that it can be used to rapidly predict pesticide exposure in multiple surface water resources to support operational and strategic risk assessments.

Highlights

Pesticides are widely used in modern conventional agriculture and contribute to increased yield and quality
This paper describes the development and application of IMPT (Integrated Model for Pesticide Transport), a parameter-efficient tool for predicting diffuse-source pesticide concentrations in surface waters used for drinking water supply
There is a clear need for catchment-scale modelling tools to predict pesticide exposure in surface waters, when used for drinking water abstraction

Summary

Introduction

Pesticides are widely used in modern conventional agriculture and contribute to increased yield and quality. In order to anticipate the levels of exposure which will be experienced at different drinking water abstraction points under current or future land use and meteorological scenarios, water companies are increasingly employing numerical models (Bloodworth et al, 2015) These models can help to assess DWD compliance risks and guide timing of sampling and the choice of analytical methods used on samples collected at water intakes. They can be used to explore the potential of different catchment management interventions for mitigating pesticide exposure (e.g. changing crop rotations, switching active ingredients, using different dose rates), as required by Article 7 of the Water Framework Directive (WFD; EC, 2000)

Results

Discussion

Conclusion