A. Avila et al., CLIMATE-CHANGE IMPLICATIONS FOR STREAMFLOW AND STREAMWATER CHEMISTRY IN A MEDITERRANEAN CATCHMENT, Journal of hydrology, 177(1-2), 1996, pp. 99-116
MAGIC, a hydrochemical model of catchment acidification has been linke
d to a model, PROFILE, which estimates catchment weathering rates, in
an application to a small forested catchment in the Montseny mountains
of Catalonia (northeast Spain), to assess the effects of climate chan
ge on streamwater chemistry for a montane-Mediterranean region. Two sc
enarios of climate change are considered: a 4 degrees C temperature in
crease combined with 10% precipitation increase and a 4 degrees C temp
erature increase combined with 10% precipitation decrease. The modelle
d effect of a 10% precipitation increase on the water partition betwee
n runoff and evapotranspiration is a slight dilution of the streamwate
r chemistry, Correspondingly, the modelled effect of a 10% precipitati
on decrease is a sharp concentration increase in streamwater chemistry
. Weathering rates increase with increased temperature and increased p
recipitation but are almost unaffected by increased temperature and de
creased precipitation. Therefore, changes in streamwater concentration
s, linked to the effect of weathering changes, appear only in the scen
ario with a warmer and wetter climate. The approach has also been used
to assess the effects of changing air mass patterns caused by climate
change as an increase in alkaline-rich rains associated with Sahelo-S
aharan dust may well result. This study indicates that the main chemic
al changes following climate change will be associated with weathering
rate changes rather than with changes in the atmospheric supply of ba
se cations and alkalinity, The case for considering the effects of tem
perature and moisture availability in climate change models of soil an
d streamwater quality is shown to be overwhelming as rates of weatheri
ng are strongly influenced by these factors.