Environmental Engineering Reference
In-Depth Information
catchment
catchment
Sub-catch
Sub-catch
pond
pond
pond
pond
pond
pond
unsewered
unsewered
unsewered
unsewered
sewered
sewered
sewered
sewered
pond
pond
pond
pond
pond
pond
pond
pond
pond
pond
pond
pond
Fig. 13.9
Overlaying ponds with 'sewered'
areas tofind 'unsewered' or 'undrained' ponds
and their contributing areas.
a
b
c
a
b
c
outlet
outlet
outlet
outlet
outlet
outlet
channel section) and bed roughness, extracted
fromtheDTM, are exported to themodel as inputs
for simulation.
system and rainfall-runoff (flooding) simulations
may then be carried out. The physical processes of
how these system components interact are de-
scribed in the next section.
Model output
A typical output from the model that was devel-
oped is shown in Figure 13.11. This identifies the
flow paths (blue) and the location of the ponds
(yellow). The surface water system is shown in
green, the combined sewer system is in red with
the node manholes as small black circles, and the
gullies are identified as dots by the kerb lines.
Once the surface flow model is created it can be
combined with the model of the subsurface
Integrated Surface/Subsurface Flow Model
As shown in Figure 13.4 the SIPSON model
(Djordjevic et al. 2005) was used to integrate the
surface overland flow model with the below-
ground drainage model. The surface and subsur-
face networks were physically linked at the man-
holes and road gullies, as shown in Figure 13.12.
Here there are two possible modes of operation.
Trapezoidal or
Arbitrary
Outputs
1 US/DS elevations
2 Average slope
3 Straighten length
4 Roughness
5 Calculated shape
Pond or
node
Pond or
node
DTM grid
DTM grid
6
5
Cross Section
1
1
4
1
2
3
4
3
2
2
2
3
3
1
Dist (m)
Pond or
node
Pond or
node
0
4
4
-5
-3
-1
1
3
5
Fig. 13.10
Estimation of pathways geometry. (a) A 3D digital terrain model (DTM) showing identified flow path (U/S
upstream, D/S downstream). (b) A number of cross-sectional lines drawn perpendicularly to the path. (c) The arbitrary
shapes of cross-sections plotted as found from the DTM. (d) Averaged output with two choices, trapezoidal or actual
shapes. (See colour version of this figure in Colour Plate section)
