Subsurface processes in braided rivers: leakage to groundwater
MBIE Endeavour
2019-2024
Team
Dr Leanne Morgan, Dr Eddie Banks (Flinders University, Adelaide), Dr David Dempsey, Alice Sai Louie, Linda Robb, Christy Songola, Scott Wilson (Lincoln Agritech)
The problem
Braided rivers are continuously changing environments comprising meandering channels and bars, and dynamic surface water – groundwater interaction. They are a major source of recharge to aquifers in New Zealand, but little is understood about this process. Consequently, regional councils currently set water limits and identify management plans without knowing how much water is lost as rivers traverse their alluvial plans.
Research approach
Waterways researchers are using standard field monitoring techniques at high resolution in combination with innovative tracer methods such as heat and radon, to assess surface water-groundwater interaction from braided rivers. For example, horizontal direction drilling was used to construct two ~ 100 m drill holes at depth of about 5 m below and perpendicular to the bed of the Waikirikiri-Selwyn river. Within the drill holes, fibre optic cables and a copper heating cable were installed and are now being used to quantify the velocity and quantity of water leaving the river under different river flow regimes. Active distributed temperature sensing experiments of this nature have not been carried out beneath the bed of a river previously.
Project Partners:
Lincoln Agritech
NIWA
Outputs:
Sai Loui A, Morgan LK, Banks E, Dempsey D, Wilson S (2023) Quantifying braided river loss to groundwater using Active Distributed Temperature Sensing (Conference presentation) Vienna: EGU General Assembly, 23 - 28 Apr 2023 Session HS10.8 (copernicus.org)
Wilson S, Di Ciacca A, Hoyle J, Measures R, Woehling T, Banks E, Morgan LK (2023) Conceptualisation of groundwater recharge from braided rivers (Conference presentation) Vienna: EGU General Assembly, 23 - 28 Apr 2023 Session HS10.8 (copernicus.org)
Banks EW, Morgan LK, Sai Louie A, Dempsey D, Wilson S (2022) Active distributed temperature sensing to assess surface water–groundwater interaction and river loss in braided river systems, Journal of Hydrology 615 Part A https://doi.org/10.1016/j.jhydrol.2022.128667
Songola C (2022) Characterising Surface Water and Groundwater Interactions in Braided Rivers Using Hydraulics and Environmental Tracers: The Waikirikiri Selwyn River, Master’s thesis, Lincoln University
Robb L (2021) Characterising groundwater-surface water exchange in the Waikirikiri Selwyn River, using radon, Master’s thesis, University of Canterbury
