Sediment dynamics in a partially cultivated catchment in new South Wales, Australia

Sediment transport from the 1.7 km 2, partially cultivated drainage basin of Maluna Creek, N.S.W., was measured over a three-year period. The sediment output of 49.8 t km -2 yr -1 was dominated by three runoff events, which together accounted for 79% of the total, though occupying only 0.6% of the study period time. These three events represented 10% of all episodes and accounted for 43% of the total runoff measured during the study period. In Maluna Creek, sediment concentrations usually reached a peak on the falling stage of the hydrograph, and mean concentration per event was positively related to discharge peakedness index, a measure of runoff intensity. Data from five erosion plots and water sampling within the catchment revealed cultivated vineyard soils as the major sediment source, compared with eucalypt forest and grassland, which made up 60 and 30% of the basin area, respectively. Caesium-137 concentration on stream-borne sediment delivered to the basin outlet was used to quantify sediment source. After certain assumptions were made, it was estimated that at least 93% of the sediment output was derived from vineyards, and the remaining 7% from forest and grazing land.