South East Queensland
10.4 Recharge from surface water

This process occurs in the South East Queensland (SEQ) region, but the volume could not be quantified in a way that is complete, neutral and free from material error due to the lack of both data and a suitable quantification approach.

Both natural (passive) and artificial (active) recharge of groundwater from surface water occurs within the SEQ region. Suitable data were not available to quantify either of these components.

Natural recharge

When modelling the interaction between the surface water and groundwater within an area, typically only the net flow is able to be estimated. Due to the limited development of groundwater resources outside of the groundwater management areas described in line item 2.1 Water table aquifers, modelling of this flux has not been developed sufficiently to estimate the flow. The magnitude of this flow is currently unknown.

The rate of groundwater recharge and discharge to surface water varies across the SEQ region. In some areas the depth of water table determines if there is water in the streams, where as in other areas discharges from surface water storages are used to replenish groundwater supplies (Department of Environment and Resource Management 2009).

Artificial recharge

Artificial (active) recharge of groundwater occurs within the Central Lockyer and Cressbrook Creek water supply schemes (WSSs). Releases from Lake Clarendon and Lake Dyer (Bill Gunn Dam) within the Central Lockyer WSS, and Lake Cressbrook within the Cressbrook Creek WSS are made for multiple purposes that include recharging the groundwater. Groundwater licence holders within these areas extract the recharged water from the groundwater via their own bores. As this does not represent a traditional aquifer storage recovery (ASR) system, it has been included in this line item rather than a specific ASR line item.

When modelling the interaction between the surface water and groundwater within an area, typically only the net flow is able to be estimated. Due to the limited development of groundwater resources outside of the groundwater management areas described in line item 2.1 Water table aquifers; modelling of this flux has not been developed sufficiently to estimate the flow. The magnitude of this flow is currently unknown.

In general, groundwater levels higher than surface water levels indicate groundwater discharge into surface water and vice versa. Surface water groundwater interaction is vital for the health of rivers. In some areas high groundwater levels are important to maintain water in the streams either providing base flow to rivers or diminishing river leakage to groundwater. Whereas in other areas, discharges from surface water storages are used to replenish groundwater supplies (Department of Environment and Resource Management 2009). The rate of groundwater recharge and discharge to surface water varies across the SEQ region.

This flow is a significant proportion of the groundwater store inflows and would be considered material to the water balance for the groundwater store. Further information may be found in the Groundwater note.