4.4: Bedload transport in large tropical rivers and its effect on dry-season pool habitat dynamics

Leader:

Andrew Brooks

Abstract

<p>The pools that remain in northern Australian rivers during the long dry season provide an important refuge for stream fauna and flora and are often culturally significant. There is a common perception, however, that many of these riverine waterholes are being filled by sands. Changes in land-use upstream and the effects of climate change have been suggested as causes for sand accumulation. This project will determine, whether there is evidence for sustained infilling of pools within two north Australian river catchments.</p>

Outcomes

Increased sediment accumulation in river systems is one of the risks associated with water resource development, intensified land-use in catchments and potentially, climate change. By clarifying the specific flow regimes required to maintain the balance of sediment movement and deposition, this research will allow water planners and natural resource managers to better calculate the risk that current and future water extraction and land-use may have on sediment accumulation (and thus loss of habitat) in pools. The effects of climate change on sediment movement and accumulation will be better appreciated.

By better understanding how sediment is moving through the river system and the sources of sediment land managers can better prioritise remediation works for erosion control.

For conservation planners, Indigenous land holders and recreational fishers, this research will clarify the nature and extent of the threat posed by sedimentation to waterhole dependent flora and fauna and their associated natural, cultural and social values.

Where is the research happening?

The research will focus on two catchments: the Mitchell River in Queensland and the Daly River in the Northern Territory. Dry season sampling of stream beds will kick off in the Daly catchment (2007) with the Mitchell to follow in 2008. Wet season sampling of bedload movement will happen as high-flow events and logistics dictate.

Who's involved

The project is being lead by scientists at the Australian Rivers Institute (ARI) at Griffith University in Brisbane. They will be working with other scientists from CSIRO Land and Water (in Canberra), the Natural Resources, Environment, the Arts and Sport agency (NRETAS) and Charles Darwin University in Darwin.