Retrospective analyses and future predictions of snowmelt-induced acidification: example from a heavily impacted...

We have combined a long-term hydrochemistry model (MAGIC) with a model that predicts short-term transient changes in hydrochemistry (pBDM) during hydrological events in order to improve the temporal resolution of retrospective analyses and future predictions of streamwater acidification. The model has been applied to a heavily impacted catchment in the Czech Republic. Spring flood acid-neutralizing capacity (ANC), pH, and inorganic monomeric aluminum (Ali(n+)) were simulated for the years of 1860, 1900, 1930, 1950, 1965, and 1985, measured in 1999, and predicted for 2030 using two different emission control scenarios. If the emission reduction according to the current legislation scenario is implemented, the model predicts that the spring flood pH, ANC, and Ali(n+) will recover close to the level of the 1950s by 2030. This will occur despite the annual average chemistry being farfrom having recovered to that level. The results suggest that the recovery of spring flood events is faster then the recovery of annual average chemistry and that much of what is won by further emission reduction will not be fully realized on an annual time scale.