Figure 6 . The dependence of export pattern, or C-Q slopeb , on the ratio of shallow water versus deep water concentrations
(Cratio = Csw / Cdw).
The gray line is an ensemble of 500 gray circles from 500 Monte-Carlo
simulations under different land use conditions. Each gray circle
represents one simulation with a calculated slope b from
simulated C and Q values and Cratio from an annual
average of simulated Csw and Cdw (see
Figure S8). The triangles and stars are from individual watersheds: some
are based on measured stream discharge, chemistry, and soil and
groundwater concentrations Cratio (triangles), and
others are based on high-frequency stream data (stars). The error bars
are for one standard deviation. The black line represents the fitting
equation\(b=\frac{\delta_{b}\ C_{\text{ratio}}}{C_{\text{ratio},\ 1/2}\ +\text{\ C}_{\text{ratio}}\ }+b_{\min}\),
which describes the black line and the dependence of b on
Cratio. Here \(\delta_{b}\)is the difference between maximumb (\(b_{\max}\)) and minimum b (\(b_{\min}\)), and\(C_{\text{ratio},\ 1/2}\) is the concentration ratio when b = ½
(\(b_{\max}+b_{\min}\)). Here \(b_{\max}=0.73\) and\(b_{\min}=-0.93\), \(\delta_{b}=1.66\), and\(C_{\text{ratio},\ 1/2}=0.80\). The agricultural and mixed lands
cluster toward high b and Cratio values, indicating
flushing as the predominant export pattern. The urban watersheds lean
toward chemostasis (near zero b ) and dilution (negative b )
patterns. The undeveloped watersheds cover a wide range with more
flushing than dilution patterns.