Statistical Analysis of Trends in the Red River Over a 45 Year Period

Figure 3.1: Mean monthly streamflow (1960-2007) at each monitoring station in
order to define hydrologic seasons
drological periods. Hydrologic seasons generally do not define periods of similarity
in conditions, like “summer” or “winter” do for climate, but rather directional tendencies
(Glozier, et al., 2004). The yearly streamflow patterns were similar within
the three stations with all sites exhibiting peak discharge between March and June.
Based on these patterns Table 3.1 represents the seasons defined for the analysis of
seasonality. Clearly these time periods are dissimilar in length but represent periods
which are distinct hydrologically.
In order to get a graphical representation of the data for each constituent we
can examine boxplots of the concentrations. A boxplot is a five-number summary
of the data depicting the minimum and maximum values of the data, the first and
third quartiles and the median, or middle number of the data.
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