The prediction error of a relatively simple soil acidification model (SMART2) was assessed before and after calibration, focussing on the aluminium and nitrate concentrations on a block scale. Although SMART2 is especially developed for application ona national to European scale, it still runs at a point support. A 5 x 5 kmr grid was used for application on the European scale. Block characteristic values were obtained simply by taking the median value of the point support values within the corresponding grid cell. In order to increase confidence in model predictions on large spatial scales, the model was calibrated and validated for the Netherlands, using a resolution that is feasible for Europe as a whole. Because observations are available only atthe point support, it was necessary to transfer them to the block support of the model results. For this purpose, about 250 point observations of soil solution concentrations in forest soils were upscaled to a 5 x 5 kmr grid map, using multiple linear regression analysis combined with block kriging. The resulting map with upscaled observations was used for both validation and calibration. A comparison of the map with model predictions using nominal parameter values and the map with the upscaled observations showed that the model overestimated the predicted aluminium and nitrate concentrations. The nominal model results were still in the 95% confidence interval of the upscaled observations, but calibration improved the model predictions and strongly reduced the model error. However, the model error after calibration remains rather large.
|Journal||Stochastic environmental research and risk assessment|
|Publication status||Published - 2002|
Kros, J., Mol-Dijkstra, J. P., & Pebesma, E. J. (2002). Assessment of the prediction error in a large-scale application of a dynamic soil acidification model. Stochastic environmental research and risk assessment, 16(4), 279-306. https://doi.org/10.1007/s00477-002-0098-0