Predicting acid neutralizing capacity from landscape classification: application to Galloway, south-west Scotland

Regional estimates of acid neutralizing capacity (ANC) in stream waters are found using a regression model. The model has landscape classifications based on catchment characteristics as its main independent variables. It also includes continuously varying covariates. Landscape classifications and covariates are selected from a priori scientific understanding of acidification processes. Parameter estimates for the model are found using measurements of ANC in 50 streams in Galloway, south-west Scotland with a history of acidification. The parameterized model is then used to provide ANC simulations for streams throughout a subregion, assuming conservative mixing of ANC through the flow network. The stream water sampling survey is designed to reduce the variance of parameter estimates. A variance model is suggested for the concentrations, and this is used to simulate the variance of ANC concentrations throughout the subregion. Monte Carlo simulation is used to estimate the distribution of the length of river reach with ANC less than zero. (C) Crown Copyright 2004. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley Sons, Ltd.