Bed-material grain size data for the Ngarradj catchment between 1998 and 2003

Department of the Environment and Heritage, 2003

Internal Report 392
Saynor MJ, Smith BL, Erskine WD & Evans KG
Supervising Scientist Division

About the report

Erskine et al (2001) proposed that eriss should adopt a sediment budget framework to assess the physical impacts, if any, of the Jabiluka mine on the Ngarradj catchment. Thirteen projects were outlined by Erskine et al (2001) to form the basis of this assessment including the systematic sampling of channel and floodplain sediments on the mine site channels and Ngarradj.

The purpose of this Internal Report is twofold, namely to:

  • document the extensive particle size data collected by eriss for the bed material at each of the 56 permanently marked cross sections discussed by Saynor et al (2002a, 20004a, b) as well as for discrete sediment storages in the Ngarradj channel network; and
  • present the particle size distribution data collected for the six years (1998 to 2003 inclusive) of the project.

The first sediment samples were collected before streamflow commenced for the 1998/1999 wet season and hence represent baseline data before any sediment had been eroded from the Jabiluka mine and supplied to the channel network.

Saynor et al (2001) outline all the geomorphic field monitoring that is being conducted by eriss in the Ngarradj catchment. Saynor et al (2002a; 2004a, b) discuss channel changes at the 56 cross sections that were used in this report to sample the bed material during the dry seasons between 1998 and 2003 inclusive. Saynor et al (2002b; 2004a, b) present the results of scour and fill for the wet seasons of 1998/99 to 2002/2003 at selected cross sections. Saynor et al (2003) detail the results of erosion pin measurements between 1998 and 2001 which were undertaken at the same cross sections as the scour chains. Erskine et al (2003) describe the bed-material and floodplain sediments in the Ngarradj catchment and outline the vertical variations in texture and other sediment characteristics. This report complements but significantly expands upon the data in Erskine et al (2003).