How much of that eFlow success was due to effective water management?

How do we use held environmental water?

In Australia’s southern states, a proportion (usually a legislated volume topped up by opportunistic buy backs of entitlements) of the water held in storages is put aside as water for the environment. These environmental water holdings are released according to strategic watering plans. The watering plans contain environmental watering objectives, which specify the timing and quantity of water that should be delivered to support plant and animal populations, along with ecological conditions and processes.

With the right seasonal conditions an environmental watering requirement could be met with natural and managed river flows. However, the more common scenario is for releases from environmental water holdings to supplement, or piggyback on, natural and managed river flows.  In fact, it is exceedingly rare for an environmental watering requirement to be achieved solely by the managed release of environmental water holding.

For example, in the Murray Darling Basin about 23% of water entitlements are allocated to the environment. This water is often released in conjunction with water orders from irrigators or in conjunction with natural river flows to achieve environmental watering requirements.

Even though it is common practice to use environmental water releases from holdings to supplement river flows to achieve environmental watering requirements, there is no consistent way to account for the contribution of those releases meeting objectives and requirements.

Instead, we pat ourselves on the back in wet years because we met all the environmental watering requirements and blame El Nino in dry years!

How do we account for the contribution of managed environmental releases?

Truii has created eFlow Projector a data-driven web application that accounts for the flow contribution from held environmental water that contributes to achieving environmental watering objectives.

eFlow Projector reports on the proportion of the environmental water requirement’s success that was achieved due to the release of managed environmental water.

The approach used by eFlow Projector is to proportion the magnitude of water delivered during an environmental watering event into managed water and other flows (natural or irrigator releases). The overall environmental water management performance is therefore a reflection of the proportion of the magnitude of successful environmental watering that was provided by a managed environmental water release.

Using this functionality in eFlow Projector requires connecting an environmental release time series to a flow rule (plus a lag time between the release location and performance reporting location).

eFlow Projector uses an event opportunity approach to determine the event days to target in its calculation. Then if the environmental release time series is provided, it calculates a daily score (%) of how much the release contributed to meeting a flow requirement’s magnitude for the targeted event days.