A SENSITIVITY ANALYSIS OF THE PROFILE MODEL IN RELATION TO THE CALCULATION OF SOIL WEATHERING RATES

Recently there has been growing interest in, and use of, the PROFILE m odel, principally through the role of weathering rates in determining critical loads. In many cases the accuracy of the data used to run the model is not quoted, A simple sensitivity analysis of the model has b een carried out by varying the input data one at a time in a systemati c fashion. The variation in weathering rate that this generates for mo nomineralic soil profiles and for a soil profile from an acid sensitiv e forested catchment in Scotland has been recorded. Variations in weat hering rates of over 100% can be generated using ranges of input param eters measured in held studies. The model broadly predicts the relativ e ease of weathering of the different minerals. Minerals which are par ticularly sensitive to input variations have been identified, e.g. K-f eldspar. Some input parameters exert a larger influence on the weather ing rate as calculated by the model than others. The most sensitive in put data are soil temperature, moisture content and exposed mineral su rface area. The least sensitive input data are cation load and precipi tation rate. Copyright (C) 1996 Elsevier Science Ltd.