The effects of antecedent moisture conditions on the relationship of hydrology to hydrochemistry in a small forested watershed

✍ Scribed by Pascale M. Biron; André G. Roy; François Courschesne; William H. Hendershot; Benoît Côté; Jim Fyles

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 237 KB
• Volume: 13
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(19990815)13:11<1541::aid-hyp832>3.0.co;2-j

✦ Synopsis

The relationship between stream discharge and the concentration of dierent solutes re¯ects the hydrological processes occurring in a catchment, but is also strongly aected by antecedent moisture conditions. In this study, the eects of antecedent conditions were examined for a small forested watershed near Montre al (Que bec) by comparing data from sequences of fall events for two years of contrasting antecedent moisture conditions. The relationship between discharge and stream water chemistry was also quanti®ed using crosscorrelation analysis. Results show that concentrations of dissolved organic carbon, nitrate and calcium increased during storm events with dry antecedent conditions but that the relationships were weaker under wet conditions. For both years, concentrations of sulfate, silicon and sodium and the pH were negatively correlated with discharge (cross-correlations from À0 . 20 to À0 . 53). With dry antecedent conditions, there was a general decrease in the concentration of all solutes with time, whereas concentrations remained at about the same level under wet conditions. The concentration±discharge relationships for sulfate shifted frequently from higher concentrations during the rising limb to higher concentrations during the falling limb from one event to another as a result of changing antecedent conditions. Although the contrast in antecedent moisture conditions between the two years was moderate in comparison with that reported in other studies (25% dryer than average in 1995 and 12% wetter than average in 1996), the hydrochemistry of the stream was markedly dierent.