Thresholds and grades go hand in hand. When you set a threshold for a parameter, the scores feed into the grading scheme that you create under the Grades tab. You can set thresholds for as many parameters as you would like and they will respond to the universal grades that you created. If you create thresholds for more than one parameter, your map output will display an average of all thresholds in the final score.
Create a new Thresholds
- Score. Enter a whole number. Flow will assign this score to any value that meets the conditions of this threshold. The grades will use this score to assign a grade to the value.
- Parameter. Choose which parameter refers to.
- Station Category. If your scoring system differentiates between station types, make that description here. The column title that you’ll add to your template is station_category. Two common examples are “tidal” and “non-tidal”. At this time, you can only include one station category in your template so only one parameter’s thresholds can have a station category.
- Parameter modifier Does the selected parameter have special scoring conditions? If so, enter the appropriate text from your source data. A good example is salinity regime. In tidal contexts, some parameters (e.g. nitrogen and phosphorus) require salinity regime data in order to obtain correct scores. Salinity modifiers would then be any of “tidal_fresh”, “oligohaline”, “mesohaline”, and “polyhaline”. If you are unsure how to use categories and modifiers, get in touch as email@example.com.
- Scoring Conditions. Use these controls to set boundaries for this threshold. Flow will use the outputs from these instructions to generate grades for this parameter’s thresholds.
- Threshold type. Which option best describes this threshold’s logic? If it should compare reading values to a single number, choose Boundary. Otherwise, select Range.
If your parameter has a threshold that is based on one value, such as enterococci is "safe" below 104 cfu, then you will want to use the Boundary logic. You will create an additional threshold of "unsafe" for enterococci above 104 cfu separately.
If your parameter has a threshold, like pH, that is "normal" between 6.5 and 8.5, then you can add in the range that meets that criteria here. You will create additional thresholds for pH below 6.5 and above 8.5 separately.
Finishing up your thresholds
Most likely, you're going to spend a bit of time building your thresholds. Each parameter that has thresholds will need to be added to your list here, with a separate input for each category of values. So, for the most part, if a parameter has thresholds then the minimum number of inputs you'll need to create will be two.
It's important to note that if you create error ranges in your thresholds, your data source file will not upload or display correctly.