The stepwise DA identified five variables (chl-a, DO, TKN, TP and WT) as the most important discriminating variables. Table 2 shows that the first function in the stepwise DA was perfectly correlated with temperature (coefficient = 1.000), and then mostly correlated with DO (coefficient = 0.613). Classification functions (CFs) and the classification matrices (CMs) obtained from standard and stepwise modes of DA are shown in Tables 3 and 4. In the standard mode, all 12 variables were included to construct CFs which correctly classified 95.3% of the original grouped cases. In the stepwise mode, the DA correctly assigned 93.2% of the cases using only five discriminating variables. Therefore, the temporal DA results of the stepwise mode suggested that chl-a, DO, TKN, pH, and WT were the most significant parameters for discriminating differences between the wet season and dry season, and could be used to explain most of the expected temporal variations in water quality.

Table 2

Structure matrix for the temporal DA of water quality variations across two wet and dry seasons

Standard mode
Stepwise mode
ParametersFunction 1ParametersFunction 1
WT 0.940 WT 1.000 
Dissolved oxygen −0.321 Dissolved oxygen 0.613 
TKN 0.195 TKN −0.300 
Chl-a 0.164 Chl-a −0.337 
Ammonia-N 0.091 Ammonia-N −0.234 
Total phosphate 0.092 TP −0.179 
TP 0.088 Total phosphate −0.157 
Magnesium −0.047 Magnesium 0.094 
Sodium −0.037 Sodium −0.016 
Chloride −0.019 Chloride −0.017 
Turbidity 0.014 Turbidity 0.016 
TSS 0.012 TSS −0.046 
Standard mode
Stepwise mode
ParametersFunction 1ParametersFunction 1
WT 0.940 WT 1.000 
Dissolved oxygen −0.321 Dissolved oxygen 0.613 
TKN 0.195 TKN −0.300 
Chl-a 0.164 Chl-a −0.337 
Ammonia-N 0.091 Ammonia-N −0.234 
Total phosphate 0.092 TP −0.179 
TP 0.088 Total phosphate −0.157 
Magnesium −0.047 Magnesium 0.094 
Sodium −0.037 Sodium −0.016 
Chloride −0.019 Chloride −0.017 
Turbidity 0.014 Turbidity 0.016 
TSS 0.012 TSS −0.046 
Table 3

CFs coefficients for the temporal DA of water quality variations in wet and dry seasons

 Standard mode
Stepwise mode
ParameterDry coef.aWet coef.aDry coef.aWet coef.a
Chl-a −0.586 −0.532 −0.116 0.046 
Dissolved oxygen 9.121 8.514 3.338 1.985 
TKN 27.702 25.936 24.694 27.791 
TP 41.686 78.262 5.835 11.915 
Total phosphate −126.870 −168.289   
Ammonia-N 43.744 45.375   
WT 7.452 9.299 5.541 7.319 
TSS −0.107 −0.180   
Turbidity 0.307 0.568   
Magnesium −0.082 −0.141   
Chloride 0.017 0.020   
Sodium 0.039 0.048   
(Constant) −123.968 −165.618 −60.360 −104.781 
 Standard mode
Stepwise mode
ParameterDry coef.aWet coef.aDry coef.aWet coef.a
Chl-a −0.586 −0.532 −0.116 0.046 
Dissolved oxygen 9.121 8.514 3.338 1.985 
TKN 27.702 25.936 24.694 27.791 
TP 41.686 78.262 5.835 11.915 
Total phosphate −126.870 −168.289   
Ammonia-N 43.744 45.375   
WT 7.452 9.299 5.541 7.319 
TSS −0.107 −0.180   
Turbidity 0.307 0.568   
Magnesium −0.082 −0.141   
Chloride 0.017 0.020   
Sodium 0.039 0.048   
(Constant) −123.968 −165.618 −60.360 −104.781 

aFisher's linear discriminant functions coefficients for wet and dry seasons correspond to wij as defined in Equation (1).

Table 4

CMs for the temporal DA of water quality variations in wet and dry seasons

Season assigned by DA
Monitoring season% correctDry seasonWet season
Standard mode 
 Dry season 89.6 88 
 Wet season 97.9 95 
 Total 95.3 89 103 
Stepwise mode 
 Dry season 87.5 84 12 
 Wet season 99.0 95 
 Total 93.2 85 107 
Season assigned by DA
Monitoring season% correctDry seasonWet season
Standard mode 
 Dry season 89.6 88 
 Wet season 97.9 95 
 Total 95.3 89 103 
Stepwise mode 
 Dry season 87.5 84 12 
 Wet season 99.0 95 
 Total 93.2 85 107 

Close Modal

or Create an Account

Close Modal
Close Modal