2019

Past Events in Christchurch

Tuesday 12 February 2019

Technical meeting presented by Dr Eva Sutter from Cook Costello at the new Turanga Library. This event was kindly sponsored by Cook Costello who arranged the venue, provided the drinks and an amazing platter for the event.

Dr Eva Sutter has a range of work experience including a voluntary role with Groundwater Relief.  Further details can be obtained here: https://groundwater-relief.org/

Hydrogeophysics – An introduction to complimentary tools for hydrological studies

Abstract

From the total 3 % of freshwater on Earth (97 % is saltwater), almost one third of the worldwide available freshwater resources are stored underground in aquifers, making up by far the largest source of liquid freshwater. Although better protected than surface water, aquifers are still vulnerable to contamination from natural and anthropogenic processes, especially the shallow, unconfined aquifer types. Increasing research attention is directed towards understanding groundwater related processes and ways of ensuring their protection in recent years. Governments have started realizing the importance of protecting groundwater resources from anthropogenic contamination and are putting measures in place for industry to monitor their impact on this important resource.

In order to gain a deeper understanding of groundwater resources, hydrology traditionally relies on the availability of point measurements such as precipitation records, groundwater levels and chemistry or soil moisture content. This builds a necessary and solid base of information, but often is far from being complete. Hydrological models provide a way of extrapolating this point information to a larger area. However, they suffer from non-uniqueness and the fact that the variability of the subsurface geology, structure and hydraulic properties are often poorly understood. In order to overcome these short comings extra information is needed. Hydrogeophysical methods can provide such information.

Although around for several decades, hydrogeophysics is still rather unknown or rarely used in the hydrological community. Often geophysical measurements are completely detached from hydrological measurements and only in recent years have efforts been made to focus on combining the two fields of expertise. This talk focuses on giving an introduction to what hydrogeophysics is, which methods can be used to answer specific hydrological questions, and will showcase some field studies I have been directly involved with in the past years. It is aimed to start (or continue) a discussion between professionals from both disciplines, geophysics and hydro(geo)logy, in order to generate an understanding of where the current needs are and how these can be addressed by using geophysics as complementary tools.

 

 


Past Events in Auckland

Tuesday 18 June 2019

Jon Williamson and Hangjian Zhao of Williamson Water & Land Advisory (WWA) presented their recent research at the Auckland meeting. This event was kindly sponsored by Jacobs NZ Ltd who provided the venue and the drinks for the event.

Ruahuwai Decision Support Tool and its implication for the Plan Change 1 of the Waikato Regional Plan.

The Ruahuwai Decision Support Tool is a sophisticated catchment calculator designed by WWA for Wairakei Estate. It combines a series of coupled models that collectively predict hydrology and water quality outcomes throughout the Ruahuwai Sub-Catchment (an area that covers the upper portion of the Waikato River basin).

It is part of an adaptive management framework to model and predict changes in biophysical properties, climatic and natural capacity of the landscape to attenuate contaminant losses. For example, it has been used to assess relative changes in nitrogen losses into the groundwater within the catchment as shown on the figure, which shows nitrogen vulnerability (<0.1% is shown in red and >99% is shown in blue).

Further information can be obtained from the Wairakei Estate website: https://www.wairakeiestate.nz/sustainability/ruahuwai-decision-support-tool-rdst/

 

 

Tuesday 5th March 2019

Technical meeting presented by Anthony Kirk and Zoë Pattinson from GHD. This event was kindly sponsored by GHD who provided the venue and the drinks for the event.

Groundwater and Nutrients – a tropical island experience

Synopsis: This popular tourist stop has in recent years seen extensive seaweed growth and degradation in water quality. A broad range of potential causes have been suggested, including changes to lagoon hydrodynamics, historical agriculture, commercial development and on‐site wastewater disposal.
As part of the Mei Te Vai Ki Te Vai (MTVKTV) project, GHD was involved in a detailed catchment and lagoon environmental investigation to identify the primary causes for lagoon degradation.