RECENT flooding hasn't helped when the hand of the region's water authority is forced due to high rainfall and storages reaching capacity.
Lake Buffalo is a gated storage but is a relatively small catchment (23,504ML) compared to others in the region such as Dartmouth (4,000,000ML).
However, when water is released the outflow from Lake Buffalo, which connects to the Buffalo and Ovens rivers, can create some issues for property owners downstream.
Goulburn–Murray Water (GMW) emergency controller Shayne Lowe explained that their water storages are not designed for flood mitigation purposes, although they do reduce peak flows downstream where possible.
With gated storages where they can manage water releases GMW take in elements such as current storage capacity and Bureau of Meteorology rainfall forecasts.
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"We are able to manage our gated storages by pre–releasing water to make room for further inflows," Mr Lowe said.
"We determine whether releases are needed and the rate of any potential releases by assessing catchment conditions, storage levels, and the Bureau of Meteorology rainfall forecasts.
"During significant rainfall events, Lake Buffalo's gates are fully opened, allowing all inflows to pass.
"This is because Lake Buffalo is a relatively small storage, and without the gates open, Lake Buffalo would soon reach capacity and begin to spill.
"The downstream impacts would be largely the same, but the potential damage to infrastructure would be more substantial."
Mr Lowe said most of their storages are fixed crest spillways and they have limited ability to manage water levels at these storages, instead, they simply reach capacity and then begin spilling.
At the moment, all GMW storages are releasing water over uncontrolled spillways or releasing via gated (controlled) spillways.
They are making room for further inflows from future rain events in order to mitigate downstream flooding as much as possible.
All releases are communicated to the relevant authorities so they can be used in modelling and flood warnings and advice.
GMW aims to have the storages at 100 per cent at the conclusion of flood events to maximise water availability for future use by its customers.
The level of flood mitigation that a water storage can provide depends on the operating rules of the storage, the size of the flood event, the level of water in the storage at the beginning of the event, the capacity of the storage and the capacity of the spillway.
Water storages may provide significant mitigation for small floods and may significantly reduce downstream flooding.
The storage's ability to mitigate downstream flows so they remain below flood thresholds reduces as floods become larger.
Floods are natural events occurring on a regular basis in Victoria.
As a storage manager, GMW must be prepared to manage these events to minimise their negative and maximise their positive impacts as far as is possible within its control.
GMW storages take regard of the Australian National Committee on Large Dams (ANCOLD) and Victorian State Guidelines in their management, with regular inspections and works undertaken on them to maintain their integrity.
Each has a Flood Incident Management Plan that guides operators in how the storage is managed during flood events, and these plans have been activated.
The current level of inflows are well within the design parameters for all GMW's storages.
