Modelling long-term hydrochemical response at ENCORE catchments in the UK and Norway

Abstract

MAGIC, a catchment-scale model of soil and water acidification, is applied to 10 ENCORE catchments in the UK and Norway and used to examine the dynamic response to several scenarios of future land-use. The model is evaluated against catchment manipulation studies involving acid addition, acid exclusion, terrestrial liming and upland afforestation. Critical loads for sulphur are calculated. At all sites MAGIC successfully simulates present-day observed stream and soil chemistry. The predicted response of soils and surface waters to the two standard future deposition scenarios is similar at all catchments. All catchments continue to acidify under worst-case scenario(business as usual) and all catchments recover (or begin recovery) under best-case scenario. Exceptions are related to situations with concurrent land-use, or in the case of nitrogen saturation. The success of MAGIC illustrates its robustness and indicates that major processes included in the model are correctly identified as the major mechanisms controlling catchment chemical response to acidic input.