Full text: Resource and environmental monitoring

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 
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