1D/1D dual-drainage simulation
NETWORK SIMPLIFICATION
DEMs and Urban Flood Modelling
Dual-drainage concept (1D/1D and 1D/2D)
Sewer system (manholes and pipes)
Overland system (depressions and flow paths)
Overland system
1D overland flow modelling
Overland system consists of nodes (ponds)
and links (flow paths), generated using
DEM.
2D overland flow modelling
Surface divided into small elements
(squares or irregular triangles), the flow
equations (St. Venant) are based on
terrain characteristics derived from the
DEM.
Network simplification strategies
• Pruning: <10m; <300mm
• Merging: similar hydraulic capacity - difference in
dimension of consecutive links <100mm
• First strategy
– Simplifications are applied to the sewer network and the
overland network simultaneously (1D/1D model)
• Second strategy
– Simplifications are applied first to the sewer network and
then to the 1D/1D model network, i.e. including the
overland flow network
Second Strategy
First Strategy
Preliminary results: network simplification
Complete
(1D/1D)
1D/1D
model
Sewer system pruned and merged and
complete overland model (1Dpm/1D)
1D/1D model pruned
together ((1D/1D)pm)
and
merged
Sewer system pruned and merged and
overland model pruned and merged
separately (1Dpm/1Dpm)
Preliminary results: simulation results and time reduction
Type of network
1D1D
(1D1D) pm
1Dpm1D
1Dpm1Dpm
Simulation time
for rainfall A
780 min
Reduction of the
simulation time
193 s
-
122 s
71s (-37%)
89 s
104s (-54%)
44 s
149s (-72%)