Effects of alpine ash logging on stream sediment levels in the East Kiewa River catchment. I. First progress report.  C. J. Leitch.  December 1979.  19 pp. (unpubl.)

SUMMARY

This is the first report on a catchment study being undertaken on two adjacent tributaries of the East Kiewa River in north-eastern Victoria. The aim is to monitor natural levels of sediment in these streams, Slippery Rock Creek and Springs Creek, and subsequently determined whether clearfelling of alpine ash (Eucalyptus delegatensis) on one of the catchments affects sediment levels in the stream. Stream water from the East Kiewa River is used by the State Electricity Commission for power generation, and high sediment levels cause siltation of hydro dams and reduce the life of turbines. Approximately 1000 ha of alpine ash forest within the East Kiewa River catchment is suitable for logging and the future use of this land is under review by the Land Conservation Council of Victoria.

The experimental catchments occupy areas of 165 ha (Slippery Rock) and 220 ha (Springs), and have slopes ranging from 35% to 70%, which are typical of the locality. Measurement stations were established on the streams early in 1978 to enable continuous recording of rainfall and streamflow. Stream water samples have been collected every four hours by automatic samplers since May 1978. These are analysed for sediment concentration, and sediment yields are then computed for each catchment.

After a suitable calibration period one catchment is to be roaded and then logged during the following two seasons. Two coupes of approximately 20 ha each will be clearfelled each season. The other catchment is to be maintained as a control. A model describing the sedimentation behaviour of each stream will then be developed to determine any changes in sediment yield of the treated catchment.