1. General Model Information
Name: CATFLOW a new physically based, distributed model for the dynamics of
Main medium: terrestrial
Main subject: biogechemical, hydrology
Organization level: Landscape
Type of model: 3D
Keywords: catchment,drainage flow, runoff,erosion
Prof. Dr.-Ing. Dr.-Ing. E.h. E.J. Plate
Institute for Hydrology and Water Resources Planning (IHW)
University of Karlsruhe
Phone: +49 (0) 721 608 3814
Fax : +49 (0) 721 66 13 29
CATFLOW, a Physically Based Distributed Catchment Model
by Thomas Maurer
A new physically based, distributed model (named CATFLOW) for the dynamics of
water in a small rural catchment on the event and season time scale is presented.
Results are shown for the 3.5 sqkm research catchment
The model is based on the idea of subdividing the 3D-landscape
in patches of 2D-hillslopes of variable width (assuming water flowing normal to the
topographical contours) connected to a detailed (partly ephemeral) drainage network.
Though there have been developments based on this or similar ideas in the past a new
effort has been undertaken to improve concept and structure of this type of model.
With increasing size of a catchment the shape of a hydrograph is more and more
influenced by the properties of the drainage network rather then by overland flow;
the latter then mainly has to provide realistic estimates of event based runoff
coefficients. Increasing size is a relative measure. If we trace down the drainage
network into every single swale of the landscape these considerations are valid
for even very small catchments.
Thus we get a partial decoupling of runoff
production (at the hillslope) and runoff propagation (in the detailed drainage network),
achieving a reduction of the dimension of the problem.
Runoff coefficients are
determined by proper evaluation of infiltration and evapotranspiration, both at times
controlled by either soil or atmospheric conditions. CATFLOW spends considerable efforts
in a more precise description of these processes.
For infiltration these are:
For evapotranspiration these are:
- Consideration of macropores as introduced e.g. in the model
thus annulling the potential concept for the infiltration process.
of subsurface stormflow
- Consideration of interaction between the drainage networks
water level and the wetness condition at the lower end of a hillslope, strongly governing
the extension of the socalled contributing areas.
- Consideration of runoff
contribution from sealed surfaces.
Furthermore, special emphasis has been put on the following
- Relational data management for efficient and flexible input of driving
atmospheric and landuse boundary conditions.
- Rootzone water uptake is controlled
by a minimum resistance principle, i.e. water is always taken from that depth within
the rootzone, where total potential difference to the surface is minimal.
Dynamic development of plant parameters in the growing season is accounted for by
use of plant development curves which are modulated by a quality measure for the
- Pre- and postprocessing is supported by ARC/INFO based
developments to comfortably assists in spatial analysis of the catchments geometry
- Hillslope geometry is described by use of orthogonal, curvilinear
coordinates to (a) flexible model the irregular boundaries and (b) to more easily
conduct numerical solution of Richards equation for matrix flow on a mathematical
- Potential based solution of Richards equation using Picard
iteration and Taylorseries expansion of the moisture content with respect to the
- Soil hydraulic properties are provided in tables, thus flexible
to different data sources. The model allows to account for anisotrophy.
- Channelflow within the drainage network is calculated based on St. Venant
equations or Muskingum-Cunge method.
- Each hillslope has its individual time
step control, thus reducing overall CPU time consumption.
- Development of
similarity criterions for hillslope behaviour are under examination, thus further
reduction of CPU time consumption might be possible.
Source of the abstract:
II. Technical Information
III. Mathematical Information
V. Further information in the World-Wide-Web
VI. Additional remarks
Last review of this document by: T. Gabele: Oct 7 1998
Status of the document: -
last modified by
Tobias Gabele Wed Aug 21 21:44:40 CEST 2002