Regional modelling of acidification in Wales; calibration of a spatially distributed model incorporating land use change

摘要

The Model of Acidification of Groundwater In Catchments(MAGIC) has been calibrated to 94 catchments in Wales, enabling the quantification ofregional response to reduced emissions under the second sulphur protocol and incorporatingthe potential impact of future changes in afforestation. To calibrate the model themethodology utilises, for each site, the best available data derived from databases whichare consistent across the whole region but which vary in spatial resolution. Thecalibrated model closely matches observed stream water chemistry across the region. Thepredicted future response is a reduction in acidity of surface waters in the region. Therecovery is less marked at forested catchments, and some forested sites undergo a furtherdecrease in acid neutralising capacity (ANC). The predictions from the multiple-sitemethod are statistically consistent with those produced by an alternative regionalmodelling method which is based upon Monte-Carlo procedures. The multiple-site method,however, has the advantage of providing future predictions which are also spatiallydistributed across the region.