1D - 2D
Fully two-dimensional (2D) models have been widely used for modeling river and coastal hydraulics and recently
have become a viable practical option for modeling urban oods. As a stormwater management tool 2D models
are more accurate and produce results that are far more readily accepted and understood by managers, decision
makers and other stakeholders.
modeling package is based on the TUFLOW program developed by WBM Oceanics Australia and the
University of Queensland.
has incorporated the TUFLOW engine into a user-friendly graphical interface
which walks the user through preprocessing of input data and the calculation of the model. All of
familiar tools for generating tables, graphs, and animations are available for reviewing, analyzing and presenting
model results. New 2D animation and 2D Scenario Management tools make it easy to present results to
managers and decision makers. Multiple sets of 2D results can be loaded, animated and compared.
A powerful feature of
is its ability to dynamically link to any 1D (quasi-2D) model in an integrated fashion.
The user sets up a combination of 1D network domains linked to 2D domains in a single model. An add-on
module allows multiple 2D domains that can have
dierent grid sizes and orientation. Multiple 2D
domains can be linked with 2D/2D Interface lines.
2 Dimensional Flow
Stormwater ows overland until it enters the
underground network. Surcharges may exit the
network and resume overland ow after being
subjected to inlet or 2D inow capture rules.
1D elements may be integrated into a 2D ow
area to accurately model 1D ow. Cells
underlying natural channels that are modeled in
1D are made inactive to avoid double calculation
of conveyance and volume.
The 2D active area is divided into cells with user deﬁned dimensions and
orientation. Multiple non-contiguous active areas may be deﬁned.
At each time step, depths are calculated at the cell center and corners
and velocities are calculated on each edge. This 9-point calculation
produces highly accurate model results.
Polygons can be imported or digitized within the program to simulate varying initial water surface elevations for
ponds, lakes and other storage facilities. Sets of polygons and polylines called Elevation Shapes can be used to
alter the grid derived from the DTM such as building ﬁnished oor, road crowns, ood walls and other features
that would alter the overland ow. Dynamic Elevation Shapes can be used with triggers to simulate levee
breach, dam failure, collapsing fences and other real time phenomena.
Polygons assigning rainfall directly to cells allow distributed
hydrology in 2D. The cells can be further described by 2D Landuse
with associated 2D Soil Types. The inﬁltration can be assigned to the
cells with user deﬁned parameters or USDA Soil Type using Green-
Ampt or Initial and Continuing loss models. In the 2D rain on grid
models no catchment delineation is necessary.
2D Rain on