Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 97
ITEM
REVIEW OBSERVATIONS
COMMENTS/
RECOMMENDATIONS
culverts are located along main waterways and have significant
influence on results. Field measurement of culverts should be
obtained and 1D culverts should be included in the model.
There are multiple culverts layers separated by geographical
location. It is recommended to combine all culverts into a single
layer which will be easier to update when modelling different
blockage scenarios.
Blockage
Design blockage is applied to culverts (not stormwater
pipes)
No pit blockage applied to trunk drainage
Design blockage is based on ARR 2016 (according to comment in
ecf). Blockage looks reasonable however this differs from the Flood
Study (i.e., no blockage applied to structure in the flood study).
Design blockage also does not vary with AEP (ie. The same level of
blockage is applied to all events) and ranges from 0% to 50%
blockage.
No blockage has been applied to 2D structures (such as bridges)
LINKAGES BETWEEN 1D AND 2D DOMAINS
1D/2D
Connections
SX points used for small width 1d elements and SX lines
used for wider elements to connect to multiple cells.
1D/2D connections are appropriate. However, several larger size 1D
culverts are found to be connected to SX points which may be
under-representing inlet and outlet capacity of the culvert. SX lines
are required to connect 1D culverts to the 2D domain if the culvert
