Poster Presentation Australian Society for Limnology Congress 2013

Ecological resilience in a water supply stream as a result of significant habitat and geomorphic shift from several major storm events up to approximately a 1:100 year ARI event (#211)

Joshua P Cox 1 , Phil Taylor 1 , Norm Mueller 1
  1. GHD, Canberra, ACT, Australia

Burra Creek is a fourth order ephemeral stream in a major ACT Water supply catchment that was impacted by major storm events in late 2010 resulting in large scale geomorphological change within the stream. This event scoured large sediment deposits and macrophyte beds, in many places down to bedrock, which had been aggregating since the last significant storm events in 1995, approximately 15 years previously, and prior to that 1988-89.
This study assesses the ecosystems ability to rapidly recover and adapt to significant structural geomorphological and habitat changes brought on by a naturally occurring environmental disturbance.
The health of streams is generally measured through macroinvertebrate assessment of riffle and edge samples undertaken biannually in spring and autumn with taxa identified to family level. Assessment was completed with taxa identified to genus level and supplemented with water quality, riverine vegetation, habitat, and detailed geomorphological data for broader impact detection.
The analysis uses multiple metrics investigating macroinvertebrates at the genus level with further analysis of supporting data for comparison and determination of impact from an environmental disturbance.
This detailed data has been analysed and compared to pre-storm data to assess potential change and recovery to the freshwater ecology of Burra Creek using a before-after design. Response of the system and mechanisms of resilience to major storm events are identified.