Mapping the regional benefits and costs of strategies for controlling dryland salinity

Hydrologists predict that salinity in the agricultural region of Western Australia will eventually affect an average of 30 percent of the landscape if nothing is done to reduce current levels of recharge. The scale of tree planting and other works thought to be required for controlling salinity represent a radical departure from the traditional agricultural system practised in WA. The objective of the research presented in this paper was to assess whether a large investment in salinity control is warranted at a regional level and, if so, who are the winners and losers. A geographic information system (GIS), together with maps of predicted salinity, were used to facilitate the economic analysis. The GIS served as a systematic way of identifying and quantifying the areas of agricultural land and off-farm public assets that are at risk from salinity. Area statistics from the GIS were coupled to a spreadsheet model that simulated costs and benefits over a 20 year period. Net present values were then passed back to the GIS for mapping. The procedure described in this paper is a useful way to gain an initial appraisal of the relative size and spatial distribution of economic impacts associated with a particular control program.