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Spatial variations in water quality between the studied rivers in wet season. Spatial variations in water quality between the studied rivers in wet and dry seasons were studied to evaluate the spatial patterns in the water quality of rivers. Three major rivers of South Florida were the grouping (dependent) variable, while the observed parameters in each season constituted the independent variables. Both standard and stepwise modes of DA were applied. First, the spatial variations in water quality between the studied rivers in the wet season were evaluated. As shown in Table 5, the values of Wilks' lambda and the chi-square for each DF varied from 0.217 to 0.804 and from 35.635 to 133.646. P-values were all less than 0.01, indicating that the spatial DA was credible and effective. In the stepwise DA, only five variables (TKN, TP, ammonia-N, magnesium, and sodium) were selected as the most important discriminating variables. The two DFs explained 78.7 and 44.3% of the group differences, respectively. The first DF separated Miami Canal from Kissimmee River and Caloosahatchee River (Figure 3), and was significantly and negatively correlated with total phosphate and TP (Table 6). The second DF established some separation between Kissimmee River and Caloosahatchee River, and was significantly correlated with chl-a. The CFs and CMs obtained from the two modes are shown in Tables 7 and 8. In the standard mode, all 12 variables were included and the constructed CFs produced 80.2% accuracy in assigning cases. However, in the stepwise mode, DA produced 79.2% correct assignment using only five discriminating variables.
Table 5

Wilks' lambda and chi-square test for the spatial DA of water quality variations across three studied rivers in wet season

ModeDFsCanonical correlation (R)EigenvalueWilks' lambdaChi-squarep-level (Sig.)
Standard mode 0.821 2.065 0.217 133.646 0.000 
0.578 0.503 0.665 35.635 0.000 
Stepwise mode 0.787 1.625 0.306 107.666 0.000 
0.443 0.243 0.804 19.830 0.000 
ModeDFsCanonical correlation (R)EigenvalueWilks' lambdaChi-squarep-level (Sig.)
Standard mode 0.821 2.065 0.217 133.646 0.000 
0.578 0.503 0.665 35.635 0.000 
Stepwise mode 0.787 1.625 0.306 107.666 0.000 
0.443 0.243 0.804 19.830 0.000 
Table 6

Structure matrix for the spatial DA of water quality variations across three studied rivers in wet season

Standard mode
Stepwise mode
ParametersFunction 1Function 2ParametersFunction 1Function 2
Total phosphate −0.404 −0.070 Total phosphate −0.451 −0.194 
TP −0.405 −0.038 TP −0.453 −0.117 
Sodium −0.095 −0.206 Sodium −0.098 −0.317 
Chloride −0.136 −0.125 Chloride −0.200 −0.092 
Magnesium −0.081 0.070 Magnesium −0.094 0.082 
Ammonia-N 0.185 −0.038 Ammonia-N 0.210 −0.012 
Dissolved oxygen −0.139 0.333 Dissolved oxygen −0.135 −0.009 
Chl-a −0.186 0.186 Chl-a 0.038 0.319 
TKN 0.059 0.014 TKN 0.066 0.034 
Turbidity −0.227 −0.168 Turbidity −0.125 0.119 
TSS −0.102 −0.142 TSS 0.133 0.070 
WT −0.094 0.256 WT −0.051 0.218 
Standard mode
Stepwise mode
ParametersFunction 1Function 2ParametersFunction 1Function 2
Total phosphate −0.404 −0.070 Total phosphate −0.451 −0.194 
TP −0.405 −0.038 TP −0.453 −0.117 
Sodium −0.095 −0.206 Sodium −0.098 −0.317 
Chloride −0.136 −0.125 Chloride −0.200 −0.092 
Magnesium −0.081 0.070 Magnesium −0.094 0.082 
Ammonia-N 0.185 −0.038 Ammonia-N 0.210 −0.012 
Dissolved oxygen −0.139 0.333 Dissolved oxygen −0.135 −0.009 
Chl-a −0.186 0.186 Chl-a 0.038 0.319 
TKN 0.059 0.014 TKN 0.066 0.034 
Turbidity −0.227 −0.168 Turbidity −0.125 0.119 
TSS −0.102 −0.142 TSS 0.133 0.070 
WT −0.094 0.256 WT −0.051 0.218 
Table 7

CFs coefficients for the spatial DA of water quality variations across three studied rivers in wet season

 Standard mode
Stepwise mode
ParameterKissimmee coef.aCaloosahatchee coef.aMiami coef.aKissimmee coef.aCaloosahatchee coef.aMiami coef.a
Chl-a −1.401 −1.467 −1.549    
Dissolved oxygen 9.940 10.897 11.142    
TKN 58.595 65.589 75.088 41.668 44.773 51.713 
TP 5.466 −21.418 −26.290 −18.42 −8.456 −72.102 
Total phosphate −158.888 −116.608 −186.954    
Ammonia-N 81.958 88.992 114.317 32.908 36.687 52.102 
WT 17.873 18.044 18.041    
TSS −0.773 −0.792 −1.006    
Turbidity 1.577 1.242 1.518    
Magnesium −0.059 0.061 −0.049 0.182 0.26 0.197 
Chloride 0.032 0.028 0.040    
Sodium −0.033 −0.073 −0.047 −0.077 −0.108 −0.067 
(Constant) −297.426 −314.877 −323.796 −28.07 −33.348 −39.89 
 Standard mode
Stepwise mode
ParameterKissimmee coef.aCaloosahatchee coef.aMiami coef.aKissimmee coef.aCaloosahatchee coef.aMiami coef.a
Chl-a −1.401 −1.467 −1.549    
Dissolved oxygen 9.940 10.897 11.142    
TKN 58.595 65.589 75.088 41.668 44.773 51.713 
TP 5.466 −21.418 −26.290 −18.42 −8.456 −72.102 
Total phosphate −158.888 −116.608 −186.954    
Ammonia-N 81.958 88.992 114.317 32.908 36.687 52.102 
WT 17.873 18.044 18.041    
TSS −0.773 −0.792 −1.006    
Turbidity 1.577 1.242 1.518    
Magnesium −0.059 0.061 −0.049 0.182 0.26 0.197 
Chloride 0.032 0.028 0.040    
Sodium −0.033 −0.073 −0.047 −0.077 −0.108 −0.067 
(Constant) −297.426 −314.877 −323.796 −28.07 −33.348 −39.89 

aFisher's linear DFs coefficients for three groups of sites correspond to wij as defined in Equation (1).

Table 8

CMs for the spatial DA of water quality variations across three studied rivers in wet season

Rivers assigned by DA
Monitoring rivers% correctKissimmeeCaloosahatcheeMiami
Standard mode 
 Kissimmee 80.0 24 
 Caloosahatchee 76.7 23 
 Miami 83.3 30 
 Total 80.2 31 32 33 
Stepwise mode 
 Kissimmee 70.0 21 
 Caloosahatchee 70.0 21 
 Miami 94.4 34 
 Total 79.2 29 30 37 
Rivers assigned by DA
Monitoring rivers% correctKissimmeeCaloosahatcheeMiami
Standard mode 
 Kissimmee 80.0 24 
 Caloosahatchee 76.7 23 
 Miami 83.3 30 
 Total 80.2 31 32 33 
Stepwise mode 
 Kissimmee 70.0 21 
 Caloosahatchee 70.0 21 
 Miami 94.4 34 
 Total 79.2 29 30 37 
Figure 3

Scatter plot for the spatial DA of water quality variations across three studied rivers in wet season (stepwise mode).

Figure 3

Scatter plot for the spatial DA of water quality variations across three studied rivers in wet season (stepwise mode).

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