Sediment budgets for small salinized agricultural catchments in Southwest Australia and implications for phosphorus transport

Authors

Robert J. Wasson, James Cook University, AustraliaFollow
David Weaver, Department of Primary Industries and Regional Development, Western AustraliaFollow

Document Type

Article

Publication Date

12-13-2021

Journal Title

Water

ISSN

2690-0637

Keywords

sediment budget, dryland salinization, sediment delivery ratio, Western Australia, Kalgan River, phosphorus

Disciplines

Agriculture | Fresh Water Studies | Natural Resources Management and Policy | Soil Science | Water Resource Management

Abstract

Examples of sediment budgets are needed to document the range of budget types and their controls. Sediment budgets for three small agricultural catchments (7.6 to 15.6 km2) in southwestern Australia are dominated by channel and gully erosion, with sheet and rill erosion playing a subordinate role. Erosion was increased by clearing naturally swampy valley floors and hillslopes for agriculture and grazing, and episodic intense rainstorms. The proportion of sediment from channel and gully erosion in the sediment budget appears to be determined by the depth of alluvial fills. Dryland salinization caused by clearing native vegetation has connected hillslopes to channels across narrow floodplains, increasing the Sediment Delivery Ratio (SDR). Yield and SDR are found to be insensitive to major in-catchment changes of vegetation cover after initial clearing, the ratio of sheet and rill erosion/channel and gully erosion, and sediment storage masses. This supports the idea that yield alone is often a poor indicator of the impact of land use and land management change. Riparian vegetation would reduce sediment yield but not phosphorus yield. This study demonstrates the value of mixed methods where field observations and chemical analysis are combined with information from local people.

Recommended Citation

Wasson, R J, and Weaver, D. (2021), Sediment budgets for small salinized agricultural catchments in Southwest Australia and implications for phosphorus transport. Water, 13 (24), 3564.
https://library.dpird.wa.gov.au/nrm_research/17