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12. Stormwater and Flood Management
This section describes the Region’s hydrology, stormwater management and flood issues. The
information included in this section has been obtained from existing reports and management plans.
Studies conducted for the Department of Water, Land and Biodiversity Conservation (DWLBC, now
known as Department for Environment, Water and Natural Resources) have concluded that average
rainfall and runoff could decrease as a result of climate change. It has been suggested that a single unit
reduction in rainfall could lead to a two to three unit reduction in streamflow
33
(DWLBC, 2006,
There’s a
change on the way
–
An initial integrated assessment of projected climate change impacts and adaptation
options for Natural Resource Management in the Adelaide and Mt Loft Ranges Region
). However,
increases in the frequency of flood events can be expected (DWLBC,
2006
). In addition, global warming
could lead to significant increases in sea level due to rapid ice-melt at the poles and thermal expansion of
seawater (DWLBC,
2006)
, as discussed in Section 5.2.1. This scenario puts coastal regions at risk of
seawater inundation, particularly in conjunction with intense storm events.
The former Department of Water (now Department for Environment, Water and Natural Resources)
recently undertook an emergency risk assessment for the Patawalonga catchment. Other catchments in
the region have not yet been assessed.
A summary of each of the major catchments describes the sub-catchments, watercourses, Council areas
covered and key features is provided in
Table 12.1
and illustrated in
Figure
12.1
. Management
actions
a
nd further information are provided in the description of each catchment and provided in the following
text.
There is a variety of flood inundation modelling data available across the catchments of the Study Area.
The 100 ARI flood extent is the only level of flood modelling that is available across the entire Study Area
and this is mapped in
Figure 12.2
. More detailed modelling is available for selected catchments.
Climate change implications for catchment management are described at the end of each catchment
summary.
12.1. Port Adelaide
The Port Adelaide catchment consists of highly engineered urban catchments. The main sub-catchments
include North Arm, Torrens Road Drainage Authority, Port Road, West Lakes, Hindmarsh Enfield
Prospect, and South Road. The relevant councils for this catchment include the City of Port Adelaide
Enfield (PAE) and the City of Charles Sturt.
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It has been suggested that there could be a multiplier effect such that if there is 10% less rain, there could be 20-30% less
surface water flow (due to seepage, evaporation etc). It should be noted that the sentence is describing total volumes of rainfall
and streamflow, that is, it is not describing the relationship between rainfall and peak flows which will depend on intensity and
duration of rainfall and catchment characteristics amongst other factors
