SWAT development continues, and the model is
widely recognized as an integrated tool for multidisciplinary
studies at the regional scale in different
physiographic and climatic conditions. It is now one
of the most widely applied river basin-scale models
worldwide. The SWAT model is currently undergoing
Water resources assessment with SWAT 779
Downloaded by [124.120.171.215] at 03:22 08 December 2015
a major revision, which is expected to be released in
the summer of 2015. The internal structure of SWAT
is being revised to better utilize modern FORTRAN
structures, object-oriented concepts and data structures.
The input file structure for SWAT is also
being condensed to be more robust, computationally
efficient, and easier to edit with common spreadsheet
and database tools. Once the new version is released,
development efforts should be shifted to this version.
Existing versions of both the executable and interfaces
will still be maintained and supported, but
further enhancement is unlikely as available
resources shift to the new versions.
Central to the new code revisions is the modularization
of the core data structures. In previous
versions of SWAT, state variables (variables which
describe the current condition of each model process
that changes daily, e.g. soil water content or plant leaf
area) are stored in massive arrays which are accessible
to nearly every subroutine. These arrays are being
condensed into more logical data storage structures
(analogous to an object), in which a related group of
state variables can be nested. This approach has a
number of advantages, the most important of which
is better definition of both processes and data into
physically meaningful modules.