IAH (NZ Chapter) Technical Meeting – Auckland
Members and non-members welcome to this free event!
5:00 pm networking, 6:00 pm technical talk
Wednesday 16 September 2026
Beca, 124 Halsey St, Wynyard Quarter, Auckland
(Please arrive before building locks at 5:30 pm. Late arrivals, please text James Botting: 021 036 8598)
Please RSVP to Natalia Jordan by 13 September for catering purposes.
Presenter: Stephen Collins (Beca Ltd.)
Refining the estimates of subsurface nitrate attenuation in New Zealand agricultural landscapes
Profile: Stephen is a hydrogeologist with Beca in Auckland. He has a PhD in Soil Science and an MSc in Earth Science, both from Massey University.
Abstract: At the same time intensive agriculture is feeding millions of people around the world, it is also having harmful effects on freshwater ecosystems. Nutrients, particularly nitrogen and phosphorus, can escape farm boundaries and be transported to freshwater environments where they may cause eutrophication and reduce water quality. Further challenges to freshwater management arise because nitrate, a soluble form of nitrogen, can be naturally reduced, or ‘attenuated’ in some subsurface environments before reaching rivers and streams, but not enough is known about where or how much this occurs.
Stephen’s research investigated the extent to which some agricultural landscapes in the Horizons region of New Zealand effectively attenuate nitrate. Using groundwater chemistry data, machine learning and field measurements, he developed a new way to map nitrate attenuation at landscape unit scale. His research showed that nitrate attenuation varies considerably across landscapes and demonstrates a practical approach for estimating nitrogen losses to support freshwater management and land use planning.
We look forward to seeing you at our first Auckland event in 2026!
Online Attendance
Those in Auckland are expected to join in person for drinks, nibbles and networking. For those outside Auckland who cannot attend in person:
Meeting ID: 423 134 104 162 176 | Passcode: RW6ih3SV
The New Zealand Chapter of IAH gratefully acknowledges Beca for hosting this event.