Rivers nutrient loads and transport assessment
Agricultural and urban disturbance within a catchment leads to increases in nutrient exported to the river systems. These increased nutrient loads affect river ecosystems, usually in undesirable ways. Assessing changes in nutrient loadings is therefore an important aspect for assessing river condition, and one that highlights the linkages between a river and its catchment.
Assessing river nutrient load is complex, either using measured data or by modelling, because of the complex processes involved in nutrient sourcing and transport, and the high temporal variability of river flow. Process modelling is usually carried out in conjunction with detailed daily hydrology modelling. However, this is not required for broad-scale assessments of changes, and in any case sufficient data are often not available.
A model of river nutrient transport (Annual Network Nutrient Export or ANNEX?see next section) was developed to predict current and pre-disturbance nutrient loads in Australian rivers
Annual Network Nutrient Export (ANNEX)
Sums nutrient sources delivered to each link of a river network, and accumulates the consequent loads to determine average annual exports.
Combines soil nutrient concentrations from Australian Soil Resources Information System with estimates of average annual sediment loads from SEDNET modelling to estimate the average annual nutrient loads to rivers associated with water erosion.
Combines estimates of average annual nutrient loads for surface run-off from BIOS modelling with point source data from the National Pollutant Inventory (www.environment.gov.au/epg/npi/database/database.html) to estimate the average annual loads of dissolved nutrient to rivers.
Annual Network Nutrient Export considers the following nutrient source terms at each network link:
sediment-attached nutrients from hillslope erosion (from SEDNET)
sediment-attached nutrients from gully erosion (from SEDNET)
sediment-attached nutrients from river channel bank erosion (from SEDNET)
dissolved nutrients in surface run-off and sub-surface drainage (from BIOS)
point source nutrient discharges (from National Pollutant Inventory database)
Nutrients are transported in both dissolved and sediment-attached forms. The model assumes that the:
sediment-attached nutrient load is associated with the clay fraction of the sediment being transported entirely in suspension; and
capacity for transport of nutrients both in dissolved forms and associated with suspended sediments is unlimited.
Rivers nutrients in Western Australia
|River basin name||
Total nitrogen exported (t/yr)
Total Phosphorus exported (t/yr)
Nitrogen delivered to estuaries (%)
Phosphorus delivered to estuaries (%)
|Ashburton River||909||155||No Data||No Data|
|Cape Leveque Coast||1,277||256||No Data||No Data|
|De Grey River||668||126||No Data||No Data|
|Drysdale River||1,406||249||No Data||No Data|
|Fitzroy River (WA)||961||173||No Data||No Data|
|Fortescue River||1,184||195||No Data||No Data|
|Gascoyne River||650||120||No Data||No Data|
|Isdell River||2,045||314||No Data||No Data|
|Keep River||1,431||245||No Data||No Data|
|King Edward River||2,537||363||No Data||No Data|
|Lennard River||1,601||266||No Data||No Data|
|Lyndon-Minilya Rivers||792||131||No Data||No Data|
|Mackay||706||143||No Data||No Data|
|Murray River (WA)||7,426||1,095||65||47|
|Nullarbor||1,363||207||No Data||No Data|
|Onslow Coast||969||158||No Data||No Data|
|Ord River||1,158||201||No Data||No Data|
|Pentecost River||807||164||No Data||No Data|
|Port Hedland Coast||828||138||No Data||No Data|
|Prince Regent River||2,431||348||No Data||No Data|
|Salt Lake||1,748||273||No Data||No Data|
|Sandy Desert||438||104||No Data||No Data|
|Warburton||856||160||No Data||No Data|
|Wooramel River||1,196||200||No Data||No Data|
|Yarra Yarra Lakes||1,871||310||37||37|
Click on the river basin name or map below to view a report on the nutrient - sediment - landscape budget terms.
- View the Australian Agriculture Assessment 2001 report.
- View the river nutrient loads and transport chapter of the Australian Agriculture Assessment 2001 (theme) report.
- Technical reports have been prepared by CSIRO division of Land and Water in the development of this work on river nutrient loads and transport:
- View or download a technical report on " Modelling nutrient loads in large-scale river networks " by W.J. Young, I.P. Prosser, and A.O. Hughes (PDF 0.6 MB)
- a technical report on the " Regionalisations of flow variables used in modelling riverine material transport " by W.J. Young, P. Rustomji, A. O. Hughes, D. Wilkins (PDF 896 KB)
- Link to the Map Maker to make a map using this information.
- Link to the Australian Natural Resources Data Library
Links to an another web site
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