Author: David  Kinsler,  Mr (Rhodes University)

Designation: 

Description:
Recent mass releases of the biological control agent, <em>Megamelus scutellaris</em>, by the Centre for Biological Control (CBC) of Rhodes University on Hartbeespoort Dam, South Africa and other nearby impoundments have seen significant declines in water hyacinth (<em>Pontederia crassipes</em>) populations. Monitoring and recording these events are important, but are challenging with in-field methods given the size and rate of change of the population. Therefore, Remote Sensing (RS) was used to measure and quantify the change in extent and relative health of the plants at a population-wide scale. With the cloud-computing resources of Google Earth Engine (GEE), hundreds of optical (Sentinel-2) and radar (Sentinel-1) satellite images were analysed for each dam, producing an accurate cover estimation time-series, at a high temporal frequency of 2-5 days, from 2016 to present. This quantified, for example, the collapse of water hyacinth on Hartbeespoort Dam over the 2019/20 summer period, where the extent dropped from >40% to <5%. The RS methods presented here are potentially scalable and present promising, collaborative opportunities to create a regional monitoring tool for invasive macrophyte species.

Category: Scientific Program Abstract > Special Sessions > CS02 Management and Conservation of Aquatic Systems