Document Type

Conference Proceeding

Publication Date

2001

Conference Title

In proceedings of the Third Australian Stream Management Conference, eds Rutherfurd, I., Sheldon, E., Brierley, G. and Kenyon, C. August 27 - 29, 2001, Brisbane, pp 427 - 433

Place of Publication

Brisbane

Keywords

Nutrient, riparian, phosphorus, sediment, eutrophication

Abstract

Riparian vegetation can trap sediment and nutrients coming from hillslopes and reduce stream bank erosion. This study presents results from a 10 year stream monitoring program in a small agricultural catchment near Albany, Western Australia. In 1996, a 1.6 km stream reach was fenced, planted with eucalyptus species and managed separately from the adjacent paddocks. Stream flow, nutrient and sediment concentration data were collected at the downstream end of the fenced riparian area between 1991 and 2000, so there are data for the “before” and “after” riparian management periods. Suspended sediment concentrations fell dramatically following riparian management; the average event mean concentration (EMC) dropped from 254 mg/l to 15.8 mg/l. Maximum suspended sediment concentrations dropped by an order of magnitude. As a result, sediment exports from the catchment reduced noticeably following riparian management, mainly due to reduced stream bank erosion. In contrast, riparian management had limited impact on nutrient exports. There was no detectable change in total phosphorus EMC, a 67% increase in filterable reactive phosphorus average EMC and a 37% decrease in average total nitrogen EMC between the before and after periods. This study demonstrates the benefits of riparian management in reducing stream bank erosion, and suggests that in this environment, with sandy soils with low phosphorus retention, there are limitations on the effectiveness of riparian management for reducing nutrient exports.