Environmental Engineering Reference
In-Depth Information
Fig. 13.11
Ponds andflowpaths derived fromthe digital elevationmodel (DEM). Flowpaths in blue; locationof ponds in
yellow; surface water system in green; combined sewer system in red; node manholes as small black circles; gullies
identified as dots by the kerb lines. (See colour version of this figure in Colour Plate section)
Firstly, water from the pond or the preferential
flowpath may enter the sewer via the manhole, or
conversely, the flow in the sewer system may
become surcharged and flows may exit from the
manhole onto the catchment surface or into a
pond. After the storm the flood waters re-enter
the drainage system through manholes. The in-
teraction is dynamic and occurs over the complete
duration of an event. The interactions between
surface and subsurface networks are enabled by
virtual weirs or orifices or combinations (termed
'equivalent inlets'), which connect the surface
network nodes (ponds, street junctions, point-type
junctions) with subsurface network nodes (man-
holes). Fuller details may be found in Leandro
et al. (2007).
Exit
direction
Exit
direction
Exit point
(x,y,z)
Exit point
(x,y,z)
Terrain
Terrain
Manhole
Manhole
Lowest
point (x,y,z)
Lowest
point (x,y,z)
Fig. 13.12
The interaction between
manholes and a surface pond.
