Document Type

Conference Proceeding

Publication Date


Conference Title

Proc. WALIS Forum '99. Western Australian Land Information System. Perth March 31-April 1, 1999.

Place of Publication



Catchment management, eutrophication, after quality, targeting, decision support


Priorities for catchment management can be established based on either, an objective assessment of relative priorities throughout the catchment, or by simply responding to crises associated with particular land uses and their sectional interests. While the latter method can have advantages in terms of establishing community good will, team cohesion, and a sense of achievement for particular sectional interests, it may have shortcomings in terms of a more objective and rational assessment of the relative magnitude and hence priority of land management problems. Spatial modelling using GIS can form the basis for developing a catchment-wide understanding of the relative importance of land management problems. Spatial models have been successfully used to estimate water and pollution generation rates internationally, and to identify phosphorus-loss hot-spots in the Leschenault and Swan catchments locally. Land capability assessment, based on soil and landform information, has been well established as a basis for defining, together with an assessment of planning considerations such as demand, infrastructure and services, the suitability of the land for particular land uses. Land capability information can also be used to prioritise and target catchment management activities. Situations where land management practices need to be improved can be readily identified by combining current land use information, land capability information and the results of spatial models describing water, nutrient, sediment or salt generation using GIS. For example, an intersection between existing landuse, land capability and a nutrient generation model would flag annual horticulture as being inappropriate on leaching sands adjacent to fragile wetlands. Such an intersection would not flag this particular landuse where it had been established at a site with a higher land capability rating. These types of intersections can also help identify priority areas for rehabilitation or conservation of riparian corridors. An example of the use of these types of intersections in catchment management prioritisation is presented.