Long-duration high-volume dam releases are unique anthropogenic events with no naturally occurring equivalents. The impact from such dam releases on a downstream Quaternary alluvial aquifer in New South Wales, Australia, is assessed. It is observed that long-duration (>26 days), high-volume dam releases (>8,000 ML/day average) result in significant variations in river–aquifer interactions. These variations include a flux from the river to the aquifer up to 6.3 m3/day per metre of bank (at distances of up to 330 m from the river bank), increased extent and volume of recharge/bank storage, and a long-term (>100 days) reversal of river–aquifer fluxes. In contrast, during lower-volume events (<2,000 ML/day average) the flux was directed from the aquifer to the river at rates of up to 1.6 m3/day per metre of bank. A groundwater-head prediction model was constructed and river–aquifer fluxes were calculated; however, predicted fluxes from this method showed poor correlation to fluxes calculated using actual groundwater heads. Long-duration high-volume dam releases have the potential to skew estimates of long-term aquifer resources and detrimentally alter the chemical and physical properties of phreatic aquifers flanking the river. The findings have ramifications for improved integrated management of dam systems and downstream aquifers.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: HA, AB, MM, MS and IA were supported by the National Centre for Groundwater Research and Training (NCGRT), an Australian Government initiative, funded by the Australian Research Council and the National Water Commission. PG was supported by the NCGRT and New South Wales Science Leveraging Fund (NSW SLF). Infrastructure was funded by the NSW SLF and the Groundwater Education Investment Fund. Water level and climate data used in the research are available at http://groundwater.anu.edu.au
ASJC Scopus subject areas
- Earth and Planetary Sciences (miscellaneous)
- Water Science and Technology