The Water Quality Index is an attempt to represent overall quality of water collected from pond/lake/river/storage/effluent channel etc.First samples are tested for desired parameters.
Then the purpose of finding WQI is determined.The weightage is given to the parameters according to purpose where most influential/representative parameter for the purpose is given higher weightage than the less important one.The weighted average of the parameter will give the WQI of that sample for the desired purpose.The purpose will also select the choice of the parameters.
How to apply WQI ?
Say,for example,if the suitability of lake water for drinking is the purpose,important parameters like colliform, pH or acidity, hardness, Iron, Cadmium, Biological Oxygen Demand, Total Suspended Solids, Total Suspended Solid etc. which represent suitability of the collected water for drinking is first determined from literature review or standard reports if available.
Samples are then tested for the selected parameters.The next step will be to select a standard for maximum and minimum permissible limit.Once the results from the sampling is available the weighted average of the values of the parameters are calculated.As mentioned earlier the influential parameter for drinking water is given higher weightage than the other less influential ones.
How to interpret WQI ?
Generally from literature reviews it can be seen that 0-20% represents least quality,21-50% represent a quality better than the least but worse than the WQI of 51 and above.51-70% denotes good quality of water along with 71-90 and 91-100% where latter represents the best quality of the water for the desired purpose(say drinking).WQI may vary with respect to purpose and standards selected.
Double Click on Water Quality Index Calculator V2.
A Trial Alert will be generated.
The Calculator window will open automatically.
How to import dataset ?
If you have the data in an excel file then rename the column name according to the field name showing in the calculator.First column must be same as the first field.Save the excel as comma separated value.Go to File,then select Import and select the csv file.Click OK.Then the Final WQI field of the calculator will show the WQI of your entire dataset.
How to export the dataset with calculated WQI ?
Go to file and select Export.Your entire data along with the calculated WQI will be exported to a csv document.
What is WQI1 ?
It is the field which will store the WQI of the parameter you just entered into the calculator.
What is WQI2 ?
WQI2 will show the WQI of the earlier dataset.
What is Final WQI ?
This field will show the actual WQI of the dataset which must be used in your research works.
W A T E R Q U A L I T Y I N D E X C A L C U L A T O R V2