The Leakage Calculator was developed by the "A Million Hectares for the Future" team for use in the Introduction to Salinity Workshop. The aim was to help farmers and their advisors quantify the amount of water leaking past the root zone of agricultural plants with a view to tailoring recharge minimising strategies for salinity management. It is assumed that other salinity management strategies are considered and employed, where appropriate.
The Leakage Calculator is a simple spreadsheet in which the calculation of runoff, evaporation, transpiration and deep drainage (leakage) have already been performed using the Department of Agriculture soil water balance model, AgET. There are seven versions of the Leakage Calculator, each representing an area of the south-west agricultural region. It was designed to be used by non-specialist presenters with little or no training.
Each Leakage Calculator consists of six worksheets, the first is a coversheet and the last is an information page detailing the soil types represented. There are four calculation worksheets, which the user steps through in turn.
The first two of these present the leakage results in volumetric terms, that is, in millimetres of water and as a percentage of mean annual rainfall. Leakage results displayed in both these worksheets are colour coded.
The third worksheet in each Leakage Calculator requires the user to enter the area of each Land Management Unit under each plant type. Areas may be input as per cent, hectares or acres and the areas of each Land Management Unit mapped in the region are supplied as a guide. There is also a calculator for converting the length and numbers of rows of trees in alley plantings to an area.
The final worksheet presents the volumes of leakage generated from each Land Management Unit - plant combination specified. The figures are colour coded in the same manner as the leakage rates shown in the first two worksheets. The user is required to enter the volume of an average farm dam; this is used to express the total leakage for the farm as a number of farm dams. The result is displayed in this way to highlight the volume of water involved and to encourage landholders to view it as a resource.
Contact Paul Raper at the Department of Agriculture, Bunbury.
Phone: 08 9780 6295
Fax: 08 9780 6136
Email: praper@agric.wa.gov.au
Page updated: 29 June 2005
Page amended : 8 March 2006
Content ID 4746