Critical Step 1.2.2: Ground-truthing new remote sensing technologies

Project team: 

Lead: Moritz Lehmann

Uyen Nguyen, Brendan Hicks


Project description:

Recent work has proven that retrieval of water-quality parameters by satellite remote sensing in New Zealand lakes provides regional-scale synoptic assessments of variables such as chlorophyll or suspended sediment. New satellites, such as Sentinel-2 and 3, allow resolution of a new suite of water-quality measurements from individual lake to national scales. Additionally, hyperspectral sensors mounted on airborne or hand-held platforms provide capacity for rapid water quality surveys at a regional scale. A key task of this critical step will be ground-truthing and regional adaptation of algorithms to convert sensor measurements to water quality variables.


Links to other critical steps:

These activities are linked to CS1.2.1, in which the necessary in situ measurements will be available for validation, and to CS1.1.2 to assist with more advanced time series and spatial data for model calibration.


Action partnerships:

  • Waikato Regional Council: Field support, providing data, and commissioning of a technical report

  • Bay of Plenty Regional Council: Field support and providing data

  • Horizon's Regional Council: Field support and providing data

  • Southland Regional Council: Field support and providing data


Current work:

  • We are currently downloading and processing of 18-year archive of Landsat imagery of New Zealand. Concurrently, a field campaign is underway to obtain water quality samples from lakes at the time of satellite overpasses and, importantly, obtain ground truthing measurements of spectral upwelling radiance reflectance.


Key sites:

All NZ lakes


Outputs:

Journal Publications

  • Lehmann MK, Nguyen U, Allan M, van der Woerd H-J. (Submitted). Colour classification of 1,486 lakes across a wide range of optical water types. Remote Sensing, 10.

Commissioned Reports

  • Allan M, 2017. Remote Sensing of Waikato Lakes. ERI Report No. 93. Client report for the Waikato Regional Council. Environmental Research Institute, The University of Waikato, Hamilton, New Zealand.

  • Lehmann MK, Schallenberg LA, Allan M. 2016. Feasibility of Aquatic Environmental Monitoring by Remote Sensing for the Waikato Region. ERI Report No. 87.  Client report prepared for Waikato Regional Council.  Environmental Research Institute, Faculty of Science and Engineering, The University of Waikato, Hamilton, New Zealand.

Conference Presentations

  • Lehmann MK. 2018. Remote sensing for automated lake monitoring. Oral presentation, 2nd What on Earth Colloquium, Te Papa, Wellington, New Zealand. 6-7 March 2018.

  • Lehmann MK, Nguyen U, Allan M. 2017. Watercolour trends over 18 years in all New Zealand lakes from Landsat observations. Oral presentation, 5th Biennial Symposium of the International Society for River Science: Integrating Multiple Aquatic Values. Hamilton, New Zealand. 19-24 November 2017.

  • Nguyen TNU, Hamilton D, Lehmann M, Hartland A. 2017. The relationship between watercolour, CDOM absorption and remotely sensed reflectance spectra of New Zealand lakes. Oral presentation, 5th Biennial Symposium of the International Society for River Science: Integrating Multiple Aquatic Values. Hamilton, New Zealand. 19-24 November 2017.

  • Lehmann MK, Nguyen U, Allan MG. 2017. New Zealand-wide lake colour statistics from spaceborne sensors. Oral presentation, Association for Sciences of Limnology and Oceanography Conference (ASLO), Honolulu, Hawai'i. 26 February - 3 March 2017.

  • Lehmann MK, Nguyen U, Allan MG. 2017. Colour and observation frequency of all New Zealand lakes from Landsat 8. Poster presentation, 3rd International Ocean Colour Science (IOCS) Meeting,  Lisbon, Portugal. 15 - 18 May 2017.

  • Lehmann MK, Nguyen U, Allan MG, King J. 2016. New Zealand-wide lake colour and visibility statistics from spaceborne sensors. Poster presented at the New Zealand Freshwater Sciences Society Annual Meeting, Invercargill, 5-8 December 2016.