Greenmount agricultural catchment study (Queensland) 1976-1990

This catchment study near Greenmount on the eastern Darling Downs 15km south of Toowoomba was established to examine the influence of soil surface conditions on runoff and soil erosion. The study was established in 1976 on a soil representative of one of the major soil types (Black Earth – Irving clay). Management at the paddock scale is likely to strongly influence water quality for the whole catchment, thus the basic unit of hydrology and erosion, a contour catchment was choosen as the focus for this study. This project examined the influence of rainfall depth and intensity, runoff rate and ground cover on suspended sediment moving through a flume at the exit from a contour bay and the effects of contour banks on sediment delivery to streams were evaluated.
Key findings included:
Surface cover was effective in reducing soil movement and runoff from contour bay catchments. Runoff and sediment concentration were both inversely related to surface cover and total soil movement was greatly reduced by surface cover.
Greater than 75% of the variance in soil movement from single events was explained by surface cover and peak runoff rate. F
ield observations were able to be reproduced within reasonable agreement using the Howleaky water balance model.