Find selected research, consulting and student projects on this page
Brief description of recent and ongoing research projects. Please contact me for further information and to discuss collaborations.
Detecting cyanobacteria from space - Eye on Lakes
Cyanobacteria blooms can produce toxins that seriously impair water supplies, biodiversity and ecosystem services derived from lakes. These blooms are increasing nationally as a result of nutrient enrichment and climate warming and are underestimated nationally due to the high cost of sampling and bio volume estimation.
We are using field surveys, culture experiments and machine learning techniques to develop improved methods for the detection of cyanobacteria by satellites.
New Zealand lakes bio-optical survey
I have been leading a team of students and colleagues in a campaign to collect in situ measurements from over 100 lakes since 2017. We gain unique knowledge across an extreme diversity of lakes which is used for ecological studies and to validate satellite observations. Watch a movie from our trip to Lake Hauroko.
The cornerstone of the measurements are water colour observations (hyperspectral reflectance spectra). Read a Xerra blog post about it.
This data set has been shared internationally and collaborations include Atmospheric Correction Inter-comparison Exercise and algorithm development (see co-authored papers by Balasubramanian et al. 2020 and Pahlevan et al. 2020) .
NASA PACE Early Adopter
PACE is a NASA satellite mission to be launched in November 2022 which will carry a hyperspectral imager. It will allow us to determine the extent and duration of harmful algal blooms in Aotearoa’s coastal waters and large lakes in ways that have previously not been possible. As an early adopter I am actively engaged with an international community to develop end user applications.
Rotorua lakes satellite sensing
The Rotorua or Te Arawa Lakes are a diverse group of lakes with a long history of water quality monitoring. They represent a natural lab for satellite algorithm development. My research is aimed at uncovering ecosystem change through time series and spatial analysis. This helps stakeholders manage and restore these treasured lakes.
Our time series analysis of water clarity using Landsat satellites shows trends towards improving water quality in several lakes (Lehmann et al. 2019).
Currently I am developing an improved method for algae monitoring using the Sentinel-2 satellite.
Selected consulting projects
Consulting is an essential progression of science and research. It is about solving applied problems with rigour in an efficient and result-oriented way.
I have worked on an amazing range of projects from protecting shellfish aquaculture all around the coast of Nova Scotia, Canada, to predicting the outcome of lake restoration activities in shallow lakes in the Waikato, New Zealand.
Satellite lake water quality monitoring: Manawatū-Whanganui
Detailed study that revealed that satellite monitoring can be used to monitor over 50 lakes in the region at better-than-monthly frequency. This monitoring can support state of environment reporting requirements under the National Policy Statement – Freshwater Management
Lake Forsyth cyanobacteria monitoring by satellite
I conducted an exploratory study to demonstrate the potential of using satellites to monitor chlorophyll a and cyanobacteria in Lake Forsyth, Canterbury
Waikato shallow lakes restoration modelling
I managed a team to develop hydrodynamic and water quality models for four deteriorated lakes to predict the effectiveness of restoration initiatives. The challenging one-year timeline required extremely close supervision of student and post-doc team members and client liaison. Report link.
Environmental effects assessment for diversion wall in Lake Rotoiti
I carried out an analysis to detect the long-term effectiveness of the diversion wall in Lake Rotoiti. This project involved presentations and hui with council and stakeholders.
Feasibility of remote sensing of water quality
I led an end-to-end project to provided quantitative arguments for the efficiency, accuracy and cost of regional water quality monitoring of lakes, rivers and estuaries in the Waikato region. Report link.
Marine water quality monitoring for shellfish aquaculture in Atlantic Canada
Project manager for Environment Canada contracts to collect, analyse and report over 15,000 water samples in rivers and coastal waters of Nova Scotia for the Canadian Shellfish Sanitation Program.
Sedimentation and erosion control programme
Military training exercises often lead to erosion and sedimentation of nearby watercourses. As project manager and lead investigator, I used statistical modeling to quantify trends in suspended-sediment load for improvements caused by mitigation activities.
Sediment transfer study for the Maritime Link
Project manager and chief investigator for a study commissioned by Emera Newfoundland & Labrador, Canada. The project identified, modeled and described dynamic features of the sediment in the Cabot Strait to facilitate the routing of a subsea power transmission cable.
My experience in aquatic science, Earth observation, and access to diverse satellite data leads to frequent requests for me to join postgraduate supervisory committees and to assist with student projects.
Developing estuarine health indicators based on multispectral remote sensing. University of Waikato.
Machine learning for lake cyaobacteria and other water quality attributes. University of Auckland.
Super resolution of optical imagery. University of Waikato.
Developing Estuarine Health Indicators based on Chromaticity Analysis on Sentinel-2 Imagery of Tauranga Harbour
Using satellite imagery to map Total Suspended Sediments in Tauranga Harbour
Carbon dioxide and methane emissions from the Te Arawa lakes of Rotorua, New Zealand