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Remote sensing of Waikato lakes

TR 2017/12

Report: TR 2017/12

Author: Mathew Allan (University of Waikato)

About this report

The Waikato Regional Council has statutory environmental monitoring requirements, including commitments arising from the National Policy Statement for Freshwater Management. The application of remote sensing obviates the large cost of monitoring all aquatic systems within a region, and although there are limitations in terms of accuracy, useful water quality metrics can still be derived, including timing of algal bloom/turbidity events, broadening the general understanding of aquatic hydrodynamics and ecology. There is also potential for “hindcasting” water quality metrics using historical image archives.

This study explored and utilised existing remote sensing technology and algorithms to determine total suspended sediments (TSS) in lakes at a regional scale, producing a dataset quantifying spatial and temporal variability of remotely sensed TSS (including an experimental algorithm for chlorophyll a concentrations). It is demonstrated that the remote estimation of TSS within Waikato lakes is feasible and provides TSS estimations within the ranges of measured in situ TSS concentrations within most of the Waikato lakes except a small number of lakes with higher than expected estimated TSS concentrations. The derived dataset maybe helpful to elucidate a better understanding of water quality variability and ultimately better understand implications for lake management.

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Remote sensing of Waikato lakes [PDF, 2.1 MB]


Table of Contents 7
List of figures 8
List of tables 9
Executive summary 10
Introduction 11
Objectives 12
Methods 14
Waikato lakes study site 14
Remote sensing 16
Satellite imagery, software and in situ data 16
Linear spectral unmixing 18
Watercolour 18
Results 20
Total suspended solids (TSS) 20
Chlorophyll a 27
Chromaticity analysis 29
Discussion 31
Conclusions 32
References 33
Appendix 35