ABSTRACT - DELIVERABLE 110
Report on the application of PEARLS to Bjerkriem
Climate change will potentially influence surface water quality in river basins. Regional scale estimates of these impacts are required to assess the possible extent of future ecological pressures. These can be derived from spatio−temporal models of the propagation of water and its chemical constituents through the river network. The PEARLS model was developed to estimate regional−scale surface water acidification with uncertainty estimation and has the potential for being extended for use in simulating the effects of climate change. It describes the partial process of flow and transport through the surface water network, excluding within−soil processes. The model, originally conceived as steady state, is extended to allow flow routing. This accounts for long residence times, particularly in river basins with large lakes. The model is also extended, through the use of non−linear weighted regression, to allow the statistical estimation of concentrations constrained to be positive. The extended model is applied to the Bjerkreim catchment, Norway, using time series of stream water concentration measurements from 1993 to 1995 at a frequency of once every two weeks. Monthly simulations showing the spatial and temporal variability in acid neutralising capacity and nitrate concentrations are presented. The usefulness of the model is assessed in relation to other modelling system applications in the same catchment.
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