Stormwater management is one of the most significant seasonal issues facing Barron Catchment Care and is the focus of major projects in the Upper and Middle Zones of the catchment, to manage and mitigate localised flooding and erosion.
Like all catchments in the Wet Tropics, the Barron River receives high rainfall in the summer monsoon, and lighter falls throughout the remainder of the year. Annual rainfall varies from over 2500m in the upper catchment (or higher in the Lamb Range), through 900 mm in drier parts of the middle catchment, to 2000 mm on the coastal plain.
A feature of the catchment is the dense, fine network of small streams, which flow over a highly modified landscape. The intense summer storms can dump huge volumes of water into the catchment in a short time. The stormwater moves in sheets across the landscape, and channels into streams as hi-energy flows, causing local flooding and erosion at various ‘hotspots’ identified in the catchment.
The dirt on Griffin Road
The sediment detention ponds at Griffin Road, Tolga, proved their worth in the downpours of early 2011, trapping tonnes of mud from the stormwater.
In May 2011, the Tablelands Regional Council cleared 1000 tonnes of red mud from the three basins – sediment that would have made it into the Barron River and out to the Great Barrier Reef without the ponds.
The TRC and Barron Catchment Care built the three descending detention ponds in 2009 to slow the stormwater flow and trap sediment from muddy run-off from the area above Tolga. It seems that the innovative structure is working as planned.