Modelling the effects of acid deposition: refinements, adjustments and inclusion of nitrogen dynamics in the MAGIC model
- 1Department of Environmental Sciences, University of Virginia, Charlottesville, VA22901 USA
- 2Macaulay Institute, Craigiebuckler, Aberdeen AB9 2QJ, UK
- 3Centre for Ecology and Hydrology, Wallingford, Oxon OX10 8BB, UK
- 4Norwegian Institute for Water Research, Box 173 Kjelsas, N-0411 Oslo, Norway
- Email for corresponding author: B.J.Cosby@virginia.edu
Abstract. The MAGIC model of the responses of catchments to acidic deposition has been applied and tested extensively over a 15 year period at many sites and in many regions around the world. Overall, the model has proven to be robust, reliable and useful in a variety of scientific and managerial activities. Over the years, several refinements and additions to MAGIC have been proposed and/or implemented for particular applications. These adjustments to the model structure have all been included in a new version of the model (MAGIC7). The log aluminium – pH relationship now does not have to be fixed to aluminium trihydroxide solubility. Buffering by organic acids using a triprotic analog is now included. Dynamics of nitrogen retention and loss in catchments can now be linked to soil nitrogen and carbon pools. Simulation of short-term episodic response by mixing fractions of different water types is also possible. This paper presents a review of the conceptual structure of MAGIC7 relating to long-term simulation of acidification and recovery, describes the conceptual basis of the new nitrogen dynamics and provides a comprehensive update of the equations, variables, parameters and inputs for the model.
Keywords: process-based model, acid deposition, recovery