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Parliamentary Questions


Question Without Notice No. 980 asked in the Legislative Council on 16 November 2021 by Hon James Hayward

Parliament: 41 Session: 1

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.