METHOD TO MONITOR AND QUANTIFY THE ENVIRONMENTAL IMPACT OF EUROPEAN AGRICULTURE
E.A. Addink
Department of Geo-Information Processing and Remote Sensing
Wageningen Agricultural University
Commission VII, Working Group 2
KEY WORDS: Monitoring, Agriculture, Environmental_Impact, Remote_Sensing, Crop_Growth_Models
ABSTRACT
Agriculture is a human adaptation of natural ecosystems in order to grow crops and to rear animals. Because of this adaptation
agriculture will always change the natural environment, though the degree can vary substantially. This degree, i.e. environmental
impact, is assumed to be strongly related to agricultural intensity. The latter is defined as all activities undertaken to raise the
production from a level where no fertilisers and irrigation are applied to the level of the actual yield. European policy is currently
aiming at reducing the environmental impact. To evaluate the effect of the measures, a European-wide method is needed which
provides standardised information for all countries.
A method has been developed which intends to determine where and to what extent the environmental impact of agriculture has
changed during a period of about five years. It consists of three subsequent procedures: change detection based on pattern
characteristics in NOAA-AVHRR images; determination of agricultural presence in the region by classification of the images; and
quantification of the impact by a combination of actual and potential yield figures obtained from statistics and crop growth models.
This paper presents the validation of the method in two study areas. In the Rhine Basin agricultural changes of the last decade are
primarily a result of the policy of the European Union, whereas the end of communism was the main driving force of changes in
Hungary. The validation has not been finished by now, but the first results look promising. The method seems to provide a fast and
cheap overview of those areas where the environmental impact of agriculture changed significantly.
1. INTRODUCTION
Agriculture is the purposive raising of livestock and crops for
human needs (Grigg, 1995). The including of ‘purposive’
distinguishes agriculture from the society of hunters and
gatherers, and implies an adaptation of the environment in
favour of agriculture. In Europe large areas have been changed
in favour of agriculture.
In natural ecosystems crops can grow within a range of
conditions; near the centre of the range they will grow
optimally, whereas closer to the boundaries conditions are
becoming more difficult (Jongman et al., 1987). In agriculture
humans try to adapt the environment such that it resembles the
optimal conditions as much as possible, which causes the actual
environmental impact.
Like all land use types, agriculture will result in a specific land
cover type. The aim of agriculture is to produce food and all
agricultural practices until harvest can be considered as an
attempt to reach a higher production level. The Common
Agricultural Policy (CAP) of the European Union (EU) aims to
raise production, to secure farmers’ incomes and to offer
products for reasonable prices to the consumers (Van der Bijl,
1997). Only recently negative side-effects of agricultura
intensification are acknowledged. ;
In 1992 the European Union signed the Treaty of Maastricht
which states that in all policies the environment should be taken
into account and it should be saved as much as possible.
Although the aim of the CAP has not been changed since,
several directives limiting the environmental impact of
agriculture have been defined (Van der Bijl, 1997).
To evaluate the measures environmental indicators are
established (OECD, 1997). They are either based on field
measurements or on statistics, both of which are labour-
intensive. For different countries they are often not directly
comparable. Future requirements for monitoring are amongst
others: monitoring at regional level and up-to-date information
(Brouwer, 1995).
The aim of this paper is to present an alternative method to
monitor the environmental impact of agriculture. Instead of
using information on the state of the environment as monitoring
input, remote sensing is used to detect changed regions. For
those regions where changes occurred environmental impact is
calculated using a yield index.
2. ALTERNATIVE INFORMATION SOURCES
It is not possible to obtain a complete up-to-date overview of
the state of the environment with the current indicators. They
are based on statistics or on field situations and before all
required information is collected at least several months, and
mostly even a year, will have passed. To fulfil the requirement
of up-to-date information alternative information sources must
be consulted.
2.1 Remote Sensing
Remote sensing images are available shortly after recording.
They show radiation characteristics of land cover, which is a
resultant of land use. Curran (Curran, 1988) showed the
possibilities of employing the variogram in remote sensing. The
variogram relates variance to distance and provides a concise
and unbiased description of the scale and pattern of spatial
variability (Journel and Huybregts, 1978). The variogram is
described by model type, and, mostly, three model parameters:
sill, range and nugget (figure 1). The sill indicates the level of
overall variance when no spatial dependency is
64 Intemational Archives of Photogrammetry and Remote Sensing. Vol. XXXII, Part 7, Budapest, 1998
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