Environmental Engineering Reference
In-Depth Information
data are available. Infiltration of water in soil is simulated using either Smith and
Parlange (1978) equation or Green and Ampt
(1914)
equation. Peak runoff is
estimated with an empirical equation from EPIC (Williams et al.
1989)
, or is
intrinsic in the Kinematic Wave approach.
Erosion is estimated using the MUSLE (Modified Universal Soil Loss Equation,
•
Williams and Berndt 1977) which is suitable for single rain events. The EUROSEM
(Morgan et al.
1998)
and Kineros (Woolhiser et al. 1990) models use a differen-
tial dynamic balance between splash erosion, shear stress of runoff water, carry-
ing capacity of runoff water and deposition. RUSLE (Revised Universal Soil
Loss Equation) using the adaptation of Cooley
(1980)
for single storm events
is currently being developed for SoilErosion.
The SoilErosion component can also be used to simulate small hydrological basins
because each simulation unit can accept as input runoff from an adjacent unit of
simulation and can be either a plane or a channel.
SoilNitrogen: Soil Nitrogen Dynamics
This component was developed by UNIMI and is an implementation of SOILN
(Johnsson et al.
1987)
, simulates the transformation of organic carbon and of organic
and inorganic nitrogen in the soil. The model uses three pools to represent organic
C and N: one is slow cycling (humus), and two are labile (litter and manure). Dead
roots and incorporated crop residues are added to the litter pool, while animal faeces
are added to the manure pool. Each input of organic matter is characterised by a
specific N:C ratio and humification and ammonification coefficients, and is assigned
to a “litter” or “manure” category. Inorganic N is represented by two pools,
ammonium and nitrate. All transformations of C and N (except denitrification) are
simulated with first-order kinetics, using environmental controls (soil temperature
and water content) to modify decomposition rate constants. Denitrification is
simulated with a zero-order kinetic. Potential decomposition of organic matter is
simulated by calculating C flows from litter and manure to humus and from all pools
to CO
2
. Soil microbial biomass is implicitly represented as part of the two labile
pools, which therefore represent the association of added organic materials with
their decomposers. The following sources and sinks of ammonium and nitrate are
simulated by the component: urea hydrolysis, nitrification, denitrification,
atmospheric deposition, nitrate leaching, crop uptake, and ammonia volatilisation.
Although denitrification and ammonia volatilization are implemented following the
strategy pattern, there are no alternative approaches currently available.
SoilTemperature: Simulation of Temperature in the Soil Profile
The soil temperature component was developed by UNIMI. It allows soil temperature
to be simulated down a one dimensional profile. The following processes are
simulated:
