Agriculture, Ecosystems and Environment 80 2000 191–204
Pollution of surface waters with pesticides in Germany: modeling non-point source inputs
A. Huber, M. Bach
∗
, H.G. Frede
Department of Natural Resources Management, University of Giessen, Senckenbergstrasse 3, D-35390 Giessen, Germany Received 7 May 1999; received in revised form 6 December 1999; accepted 12 January 2000
Abstract
Pesticide pollution of surface waters represents a considerable hazard for the aquatic environment. However, the mean amount of pesticides reaching the water resources varies considerably between regions and depends highly upon application
rates, chemical characteristics of pesticides and natural conditions during application. In this study a model was developed which estimates loss of 42 active ingredients applied to 11 field crops, vineyards and orchards along each non-point source
path of entry subsurface drains, runoff and spray drift. A spatially and temporally differentiated data set of application rates and periods was compiled for each active ingredient and target culture to enable the modeling of pesticide transport.
The model results are provided in digital raster format 100 m×100 m within a geographic information system GIS. The calculated pesticide loads in surface waters were compared with measured loads from different catchments in Germany.
Both data sets agreed as to the order of magnitude, nevertheless due to the scale of the study the estimated loads cannot be interpreted as absolute values and only differences between active ingredients, regions and application periods should be
assessed. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Pesticides; Surface water; GIS; Models; National scale; Non-point sources
1. Introduction
Pesticide contamination of surface water resources is a major water quality issue in western Europe.
Nowadays there is not only a growing concern about hazardous effects on aquatic ecosystems but also
about a possible degradation of an important source of drinking water. To reduce water pollution from
agrichemicals it is important to know the mechanisms of pesticide transport and the extent of pesticide loss
on a specific pathway. The latter was the subject
∗
Corresponding author. Tel.: +49-641-99-37375; fax: +49-641-99-37389.
E-mail address: martin.bachagrar.uni-giessen.de M. Bach
of detailed reviews like those of Wauchope 1978 and Burgoa and Wauchope 1995 on losses through
surface runoff, or the report of Flury 1996 about experimental data on pesticide leaching and losses
through tile drains. However, results obtained in plot studies may not always be applied to the situation in
an entire catchment. In most cases the factors that fa- vor pesticide migration along different pathways such
as tile drains, surface runoff or spray drift, are subject to spatial variability and thus the relative importance
of a single path of entry to surface water varies within the catchment. To overcome this limitation several au-
thors focused on pesticide migration to surface waters on the catchment scale Frank et al., 1982; Wu et al.,
1983; Squillace and Thurman, 1992; Ng and Glegg,
0167-880900 – see front matter © 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 7 - 8 8 0 9 0 0 0 0 1 4 5 - 6
192 A. Huber et al. Agriculture, Ecosystems and Environment 80 2000 191–204
1997; Fenelon and Moore, 1998; Frede et al., 1998. Nevertheless it is evident that experimental findings
cannot be easily extrapolated to unmonitored sites with different soils, climate or application practices.
In the past few years an increasing number of studies dealt with the creation of regional scale maps of pesti-
cide migration risk, mostly leaching potential Petach et al., 1991; Loague et al., 1996; Tiktak et al., 1996;
Zhang et al., 1996; Diaz-Diaz et al., 1998; Soutter and Musy, 1998. Regional scale pesticide loss via surface
runoff has been studied to a lesser extent than leach- ing, e.g. Mizgalewicz and Maidment 1996 estimate
the atrazine transport in Iowa-Cedar River basin us- ing discharge concentrations regressions. At present,
no reports about regional scale assessment of pesti- cide input via spray drift are known to the authors of
this paper.
In this study an approach was developed to estimate regional importance of tile drains, surface runoff and
spray drift to total non-point source pollution of sur- face waters with pesticides in Germany. Pesticide loss
on each pathway was estimated separately for the en- tire country based on models which account for spatial
variability of governing factors for pesticide transport to surface water. The study does not deal with risk as-
sessments by basing model assumptions on the worst possible case of pollution but aims to depict the actual
situation instead.
2. Materials and methods
