English Abstract This report presents the simulation standard SiShell.
This standard is aimed at developing modular simulation programs in
FORTRAN-77. Sishell simulation programs have the following features: - All
modules in a program are independent units. Opening files, reading model
parameters and initialisation are carried out within the module. - The
modules can be placed in a hierarchical system. On the highest level are so
called model modules. These modules in fact are complete simulations
programs, but timing is controlled by the calling program. On a lower level
are modules that describe a number of processes. Modules that have the same
functionality can be inter changed. - The only function of the main program
in a SiShell program is calling a number of model modules, reading the
vertical discretisation and timers. Emphasis is on modelling transport and
behaviour of water and solutes in the unsaturated soil. The report also
describes the subroutine library SiShell which is meant as a tool in
developing SiShell programs.