Environmental Engineering Reference
In-Depth Information
The operational use of APES will highlight data gaps that need to be filled if it is
to be used throughout the EU (both in absolute terms and in specific areas/countries).
Such an analysis can be considered a side-product of the APES development action,
but of specific importance. For instance, the formalization of agro-management
using a common framework for current agricultural practices is a need which goes
beyond its use in APES.
Current APES inputs can be grouped in six file types (the detail is provided in
the documentation):
•
Site data (e.g. latitude, elevation, …)
•
Daily weather
•
Soil data (e.g. clay, silt, and organic carbon percentages, horizon thickness) by
soil horizon; slope, field length - unique values
Soil initialization data (initial conditions for state variables; if missing, default
•
values are used)
Soil water table (if missing, the assumption is that no water table affects the
•
root zone)
Planned agro-management (see AgroManagement component)
•
Site and weather data are loaded at run-time from the WeatherReader component,
which allows missing data to be estimated using CLIMA. Soil data are loaded
at run time from the SoilReader component, which allows missing data and
hydraulic parameters to be estimated using the PedoTransferFunctions
component. Agro-management has proved to be the most challenging problem,
because the lack of a common formalism to store information beyond its use in
agricultural statistics (i.e. a static, summary description) makes it difficult
to develop rules to simulate the dynamic part of farmers' decision making
processes based on bio-physical drivers. APES development, and specifically the
AgroManagement component has, however, provided a framework to formalize
such data, making them of use for simulation of current and alternative agricultural
management at field level.
Parameters
Parameters are defined as quantities that do not change value during either the whole
simulation or parts of it. For example, crop parameters change when a crop is
changed during the simulation, but their values do not change during the time a given
crop is simulated. A simulation system which allows the use of more than one modelling
approach cannot define a constant set of parameters for two reasons. First, some
simulation approaches may need to model a parameter which then becomes a
variable. For instance, a simulation system which does not model impact of
tillage on soil physical properties will probably consider soil bulk density as a
parameter; whereas bulk density will be modelled as a variable if the goal of simula-
tion is to estimate the impact of tillage on soil hydrological characteristics. Secondly,
