08 Nov Tim Malthus
Research Group Leader – Coastal Sensing and Modelling Group
Integrating Citizen Science, Low Cost Optical Sensors And Satellite Data For Observations Of Water Quality And Algal Blooms
Passive optical remote sensing approaches are a key tool for improving the current understanding and monitoring of inland water quality. We describe here a method which integrates in situ observations and satellite observations into a complementary tool for the observation of water quality issues such as algal blooms in rivers and lakes. Our method incorporates:
- a smartphone-based tool for use by citizen scientists to collect observations of water colour of water to assist in the parametrization of the satellite derived data. We adapted the Eye on Water application (www.eyeonwater.org) for Australian conditions; in this app a photograph of the water surface is taken and the colour matched to the 21 colour Forel-Ule colour scale by the citizen scientist. The colour and accompanying metadata are uploaded to an Australian-based server which assists us to find the linkage between the water colour (and Forel-Ule number) with the optical characteristics of the water body and to trophic state. The aim of the analysis includes comparing the spatio-temporal characteristics of colour indicators in the citizen science data with satellite derived Forel-Ule data.
- a low-cost spectrometer to reliably measure spectral reflectance across the visible spectrum from inland water bodies for the continuous detection and early warning of algal blooms. This approach relies on the fundamental physically-based principle that the spectral reflectance signal from algal dominated inland waters contains information which can be related to quantitative descriptions of algal amount, such as chlorophyll and the detection of accessory pigments (e.g. phycocyanin). We have evaluated the spectral performance of a prototype sensor in ~15 Australian waterbodies and further demonstrated continuous monitoring using a deployable version of the sensor in remote locations with wireless data upload. Preliminary results show the capacity to independently measure TSS, CDOM, and chlorophyll, with accuracies similar to that of much more expensive research instruments.
- Satellite-based (Landsat 8, Sentinel 2A) observations of water quality and algal bloom issues. The recent emergence of ‘Open Data Cube’ concepts (www.opendatacube.org/) offers a solution to overcome perceived “barriers to entry” to the adoption of satellite data as a complement in water quality monitoring programmes. Satellite sensors offer the potential of a free, high resolution, wide-scale and timely source of information.
The presentation will outline these three approaches and emphasise the use of an integrated approach to provide high density match up data for validation of satellite observations, as well as some of the key building blocks needed to develop an algal bloom forecasting tool.