Environmental Engineering Reference
Surface temperature: The empirical approach of Parton
(2004) and the mechanistic
approach of Campbell (1985) based on the energy balance at the soil surface are
Transmission of heat in the profile: The Campbell
(1985) approach based on a
one-dimensional differential equation of heat transfer is available. The empirical
approach of SWAT (Neitsch et al. 2002) is being developed.
SoilReader: Accessing Soil Data at Initialization
The SoilReader component was developed by CRA and UNIMI. It has four
1. To load data (soil parameters, soil initial conditions, water table presence)
2. To estimate parameters which are either missing or which need to be estimated
using pedo-transfer functions
3. To create soil layering from soil horizon data
4. To create daily values of water table depth
The component uses the PedoTransferFunctions (PTF) component (Fig. 4.2 ) to make
estimates both of soil hydrological properties and of soil parameters needed by soil
water retention curve models from the available soil information. The PTF compo-
nent is implemented using the same design as other APES dynamic components.
SoilWater: Soil Water and Hydrologic Characteristics Dynamics
The Soil water component was developed by UNIMI (Acutis et al. 2007) . It allows
one dimensional water redistribution in the soil to be simulated, and the changes in
soil physical characteristic after a soil tillage operation. A soil profile is represented
as a series of superimposed horizontal layers. For each layer, hydrological properties
are provided by specifying the parameters of the appropriate hydraulic functions.
Alternatively, the HYPRESS pedotransfer functions (Wosten et al. 1999) can be
used to calculate hydrologic parameters from soil texture, bulk density, and SOM,
or the PTF component (see SoilReader) that includes a large collection of
Pedotransfer functions can be used to provide estimates. In addition, it is possible
to provide the soil water contents corresponding to field capacity and wilting point.
When, for numerical reasons (i.e. a finite difference approach for water dynamics
simulation), a finer soil layer definition is needed, a method is available to split
existing pedological horizons into thinner soil layers. The following processes are
simulated, allowing for selection of alternate approaches:
Soil water distribution: three approaches are available, an empirical cascading
model, a cascading model with travel time taken allowing for water contents
greater than field capacity but preserving the speed of calculation of the cascading
method itself, and a finite difference solution of the Richards' equation.
Water evaporation: two approaches, CropSyst (Stockle et al.
2003) and Ritchie
(1972) have been adopted.