WATER CORPORATION — DRAINAGE INFRASTRUCTURE —
ELLEKER
980. Hon JAMES HAYWARD to the minister representing the
Minister for Water:
I refer to flooding issues in Elleker.
(1) When was the design of the drainage system in
Elleker last reviewed, and will the minister table the report?
(2) Will the
minister direct the Water Corporation to upgrade the drainage system in Elleker
to reduce future flooding risk?
(3) If no to (2), why not?
(4) Considering
that extreme weather events are predicted to become more common due to climate
change, what programs has the Water Corporation initiated to review the ability
of drainage systems across WA to cope with more frequent extreme weather
events?
Hon
ALANNAH MacTIERNAN replied:
I thank the member for the
question. The Minister for Water has provided the following information.
(1) The Elleker
drainage system has performed as intended since its construction and therefore
a significant design review has not been required.
(2) As was the case during the period of the former
Liberal–National government, the Water Corporation's rural
drainage networks are designed to be consistent with the rural drainage
standards manual specified under the Water Corporation's operating
licence. Under the rural drainage standards manual, Water Corporation rural
drainage networks are designed to eliminate or reduce the risk of flooding from
more or less frequently occurring events. Prior to the events of July
this year, the last time the Elleker community experienced flooding as a result
of rain events exceeding the capacity of Water Corporation's rural
drainage network was 1991. As described by
the rural drainage standards manual, it is not possible for practical and
economic reasons to design any
drainage system to convey the peak flow from the maximum run-off that could
ever occur.
(3) Refer to the answer to question
(2).
(4) The Water
Corporation reviews the capacity of its drainage networks on a regular basis,
using the latest modelling techniques,
ground-truthed by monitoring. After major storm events, the Water Corporation
reviews modelling assumptions and updates them based on the lessons
learnt. Engineers Australia's Australian rainfall and run-off standards
are regularly updated and take into account the impacts of climate change, such
as more frequent intense storm events.