Modelling catchment management impact on in-stream phosphorus loads in northern Victoria
Date
2012
Authors
Vigiak, O
Rattray, D.
McInnes, J.
Newham, Lachlan
Roberts, A M
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Publisher
Environment Institute of Australia and New Zealand
Abstract
Phosphorus pollution severely impairs the water quality of rivers in Australia and worldwide. Conceptual models have proved useful to assess management impact on phosphorus loads, particularly in data-sparse environments. This paper develops and evaluates the coupling of a point-scale model (HowLeaky2008) to a catchment scale model (CatchMODS) to enhance modelling of farm management impacts on in-stream phosphorus loads. The model was tested in two adjacent catchments in northern Victoria (Avon-Richardson and Avoca), Australia. After calibration of the in-stream attenuation parameter against measurements at gauging stations, the model simulated specific annual phosphorus loads across the catchments well (Nash-Sutcliffe model efficiency of 0.52 in the Avon-Richardson and 0.83 for the Avoca catchment). Phosphorus loads at both catchment outlets under current conditions were estimated at 7 t y-1 and were dominated by field exports. Changes to farm management practices, i.e. the use of perennial pastures in grazing systems and zero-tillage in cropping systems were estimated to reduce phosphorus load by 31% in the Avon-Richardson catchment and 19% in the Avoca catchment, relative to current practices (annual pasture and minimum tillage). The model afforded a major improvement in conceptual modelling by explicit simulation of the impacts of soil and climatic conditions on field-scale exports and by placing them in the context of landscape processes.
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Keywords
Keywords: phosphorus; basin management; catchment; conceptual framework; cropping practice; grazing management; phosphorus; streamwater; suspended load; zero tillage; article; Australia; catchment; cropping system; environmental impact; environmental management; po CatchMODS; Howleaky; In-stream attenuation; Phosphorus model; South-east Australia
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Source
Australasian Journal of Environmental Management
Type
Journal article
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2037-12-31