Image above: PlanetScope image of research study site of Hilo Bay, Hawai’i taken February 17, 2019. © 2019, Planet Labs PBC. All Rights Reserved.
The turbidity of water can be characterized by its relative cloudiness or haziness caused by light scattering through the water column. Often generated by loads of small particles in the water, this can look similar to smoke in the air. Scientists use turbidity as a key indicator of shallow water quality, and it provides useful context to studying the well-being of organisms that rely on underwater light like phytoplankton and seasgrasses. However, water quality monitoring programs that measure turbidity have historically been time and resource intensive with on-the-ground field sampling techniques. To help scale this important coastal ecosystem research, scientists are conducting water turbidity monitoring from satellites, allowing them to sample a greater spatial extent with higher temporal frequency. Due to our Dove satellites’ daily revisit capabilities, researchers from Arizona State University and Stanford University are using our PlanetScope data to track water turbidity dynamics. The research group has developed a new shallow coastal water turbidity estimation algorithm, accounting for bottom reflectance in their turbidity values. The algorithm was tested with 235 PlanetScope images of five shallow water ecosystems from Hawai’i, American Samoa, and Puerto Rico. The algorithm was validated with 75 days of field-measured data from the same five sites, and results show that the algorithm using PlanetScope data accurately detects turbidity in nearshore environments. “Dove satellite-derived turbidity information is expected to contribute to multiple types of coastal ecosystem studies, such as tracing the transport of terrestrial sediments from land to ocean, analyzing the effects of storm events on Suspended Particulate Matter dynamics, identifying priority spaces for land-sea conservation, monitoring pollution discharge from land to coral reefs and exploring landcover and land-use change effects on coral reef health,” said the authors.
The full study can be found in Remote Sensing in Ecology and Conservation.