Short Virtual Presentation & Digital Poster 10th Australian Stream Management Conference 2021

Remapping the distribution of Common Reed along the Wimmera River using satellite imagery.  Why has the distribution and abundance changed in the last 15 years? (#53)

Jamie Kaye 1 , Greg Fletcher 2 , Ewen Silvester 3
  1. Water Technology, Wangaratta, VIC, Australia
  2. Wimmera Catchment Management Authority, Horsham, VIC, Australia
  3. Centre for Freshwater Ecosystems , La Trobe University, Wodonga, VIC, Australia

Common Reed (Phragmites australis) was mapped and its distribution quantified along the Wimmera River between Horsham and Lake Hindmarsh in 2004 using aerial photography and video imagery.  The Wimmera Catchment Management Authority (WCMA) was interested in understanding if that abundance and distribution had changed in the following 15 years.  Spectral analysis of multi wavelength 2019 satellite imagery was used to map and quantify Common Reed abundance, and comparisons were then made with the 2004 data.  Nutrient analysis of Common Reed root and shoot material was also undertaken in 2004 and repeated in 2021.  The chemical analysis of plant material also provided insights into the mode of spread and contraction of Common Reed patches over the 15 year assessment period.  This work successfully used satellite imagery to identify, map and quantify a specific aquatic plant within a river system.  The chemical analysis of plant material also helped to inform the reasons behind expansion and contraction of the species.  This remote sensing approach has application for other plants of interest to quantify distribution and abundance, particularly over large areas or within remote, difficult to access areas.  

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