Drought is an environmental disturbance of aquatic ecosystems which negatively impacts aquatic life and overall river health. As such, flow events in arid and semi-arid zone streams and rivers are highly unpredictable and these environments are considered to have a boom-bust ecology. Therefore, between routine extreme episodic flow events, aquatic communities are restricted to small permanent aquatic habitats called refugia pools. Mapping the spatial extent and temporal changes of these pools using high resolution satellite imagery can help better understand and manage our water resources and identify, protect and manage potential biodiversity that resides within them.
Baseline refugia pools were extracted from SPOT 6/7 satellite imagery in Barwon river obtained in July 2019, coinciding with the long drought. Water-sensitive remotely sensed indices were used for this purpose. This was then validated against Planet labs imagery. Thereafter, the spatial and temporal persistence of these pools was investigated by mapping them using Landsat and Sentinel imagery from 2016-2021. Other ancillary datasets used included rainfall data from BOM and river flow data.
Based on preliminary results from the analysis of SPOT 6/7 satellite imagery from July 2019, refugia pools are mainly located where the river meanders. Further multi-temporal analysis of change in the spatial extent of these refugia pools is underway.
Mapping the locations of refugia pools is an important first step in rehabilitating and preventing degradation of river ecosystems. Depending on the long-term persistence of these pools, protection zones may be established to ensure long-term sustainability of Barwon river.