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As shown in Table 9, the values of Wilks' lambda and the chi-square for each DF varied from 0.168 to 0.638 and from 40.419 to 156.314. All p-values were less than 0.01, indicating that the spatial DA was credible and effective. In the stepwise DA, seven variables (chl-a, DO, TKN, TP, ammonia-N, magnesium, and chloride) were selected as the most important discriminating variables. The two DFs explained 82 and 60.1% of the group differences, respectively. Likewise, in the wet season, the first DF separated the Miami Canal from the Kissimmee River and the Caloosahatchee River (Figure 5), and was significantly correlated with TP, DO, and TKN (Table 10). The second DF established some separation between the Kissimmee River and the Caloosahatchee River, and was correlated with chl-a and magnesium. The CFs and CMs obtained from the two modes are shown in Tables 11 and 12. In the standard mode, all 12 variables were included and the constructed CFs produced 79.2% accuracy in assigning cases. However, in the stepwise mode, DA produced 81.3% correct assignment using only seven discriminating variables.
Table 9

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

ModeDFsCanonical correlation (R)EigenvalueWilks' lambdaChi-squarep-level (Sig.)
Standard mode 0.837 2.348 0.168 156.314 0.000 
0.663 0.783 0.561 50.578 0.000 
Stepwise mode 0.820 2.057 0.209 140.995 0.000 
0.601 0.567 0.638 40.419 0.000 
ModeDFsCanonical correlation (R)EigenvalueWilks' lambdaChi-squarep-level (Sig.)
Standard mode 0.837 2.348 0.168 156.314 0.000 
0.663 0.783 0.561 50.578 0.000 
Stepwise mode 0.820 2.057 0.209 140.995 0.000 
0.601 0.567 0.638 40.419 0.000 
Table 10

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

Standard mode
Stepwise mode
ParametersFunction 1Function 2ParametersFunction 1Function 2
Total phosphate −0.297 −0.080 Total phosphate −0.278 0.006 
TP −0.306 −0.033 TP −0.327 −0.074 
Sodium −0.129 −0.052 Sodium −0.211 0.004 
Chloride −0.158 −0.124 Chloride −0.176 −0.129 
Magnesium −0.126 0.197 Magnesium −0.135 0.226 
Ammonia-N 0.210 −0.132 Ammonia-N 0.228 −0.157 
Dissolved oxygen −0.262 0.084 Dissolved oxygen −0.285 0.107 
Chl-a −0.083 −0.250 Chl-a −0.095 −0.274 
TKN 0.450 0.000 TKN 0.493 −0.023 
Turbidity −0.147 0.008 Turbidity −0.025 0.054 
TSS 0.016 −0.003 TSS −0.211 0.058 
WT 0.134 0.311 WT 0.238 −0.001 
Standard mode
Stepwise mode
ParametersFunction 1Function 2ParametersFunction 1Function 2
Total phosphate −0.297 −0.080 Total phosphate −0.278 0.006 
TP −0.306 −0.033 TP −0.327 −0.074 
Sodium −0.129 −0.052 Sodium −0.211 0.004 
Chloride −0.158 −0.124 Chloride −0.176 −0.129 
Magnesium −0.126 0.197 Magnesium −0.135 0.226 
Ammonia-N 0.210 −0.132 Ammonia-N 0.228 −0.157 
Dissolved oxygen −0.262 0.084 Dissolved oxygen −0.285 0.107 
Chl-a −0.083 −0.250 Chl-a −0.095 −0.274 
TKN 0.450 0.000 TKN 0.493 −0.023 
Turbidity −0.147 0.008 Turbidity −0.025 0.054 
TSS 0.016 −0.003 TSS −0.211 0.058 
WT 0.134 0.311 WT 0.238 −0.001 
Table 11

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

 Standard mode
Stepwise mode
ParameterKissimmee coef.aCaloosahatchee coef.aMiami coef.aKissimmee coef.aCaloosahatchee coef.aMiami coef.a
Chl-a −0.722 −1.022 −0.738 −0.148 −0.368 −0.17 
Dissolved oxygen 16.053 17.204 15.654 7.805 8.413 7.292 
TKN 47.975 52.815 69.377 59.089 63.939 77.278 
TP −145.526 −194.743 −217.95 −76.051 −59.214 −114.523 
Total phosphate −45.610 28.722 −10.294    
Ammonia-N 124.317 140.425 165.566 113.794 128.452 156.259 
WT 6.786 7.158 6.704    
TSS 0.194 0.191 0.338    
Turbidity −0.298 −0.335 −0.620    
Magnesium 0.176 0.297 0.278 0.239 0.326 0.32 
Chloride 0.033 0.018 0.021 −0.008 −0.023 −0.019 
Sodium 0.007 −0.003 0.001    
(Constant) −146.359 −166.618 −168.765 −61.155 −70.314 −80.84 
 Standard mode
Stepwise mode
ParameterKissimmee coef.aCaloosahatchee coef.aMiami coef.aKissimmee coef.aCaloosahatchee coef.aMiami coef.a
Chl-a −0.722 −1.022 −0.738 −0.148 −0.368 −0.17 
Dissolved oxygen 16.053 17.204 15.654 7.805 8.413 7.292 
TKN 47.975 52.815 69.377 59.089 63.939 77.278 
TP −145.526 −194.743 −217.95 −76.051 −59.214 −114.523 
Total phosphate −45.610 28.722 −10.294    
Ammonia-N 124.317 140.425 165.566 113.794 128.452 156.259 
WT 6.786 7.158 6.704    
TSS 0.194 0.191 0.338    
Turbidity −0.298 −0.335 −0.620    
Magnesium 0.176 0.297 0.278 0.239 0.326 0.32 
Chloride 0.033 0.018 0.021 −0.008 −0.023 −0.019 
Sodium 0.007 −0.003 0.001    
(Constant) −146.359 −166.618 −168.765 −61.155 −70.314 −80.84 

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

Table 12

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

Rivers assigned by DA
Monitoring rivers% correctKissimmeeCaloosahatcheeMiami
Standard mode 
 Kissimmee 83.3 25 
 Caloosahatchee 76.7 23 
 Miami 77.8 28 
 Total 79.2 34 30 32 
Stepwise mode 
 Kissimmee 80.0 24 
 Caloosahatchee 80.0 24 
 Miami 83.3 30 
 Total 81.3 31 32 33 
Rivers assigned by DA
Monitoring rivers% correctKissimmeeCaloosahatcheeMiami
Standard mode 
 Kissimmee 83.3 25 
 Caloosahatchee 76.7 23 
 Miami 77.8 28 
 Total 79.2 34 30 32 
Stepwise mode 
 Kissimmee 80.0 24 
 Caloosahatchee 80.0 24 
 Miami 83.3 30 
 Total 81.3 31 32 33 
Figure 5

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

Figure 5

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

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