User-defined rainfall data in InfoDrainage

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When you are working in a region that is not covered by one of the standard rainfall theories provided within the program,

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you can define your own rainfall.

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But to do so, you must be able to enter two pieces of information:

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the IDF curve or curves,

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and the dimensionless shape curve.

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If you have data tables that reflect these, then you can build your own rainfall definition.

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Open the Rainfall Manager, and in the toolbar, click New to create a new rainfall event.

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For this example, name it “Test 1”, and then click Save.

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Under Rainfall Manager Items, expand the IDF node to access the IDF library.

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If you had a single IDF curve, you would choose Single RP IDF.

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But for this example, a series of curves is available in the spreadsheet,

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so click Table IDF to create a table of events.

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To review the data, open the sheet.

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In this example, there are data for the IDF curves for three storm durations,

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and temporal patterns for the dimensionless curve data.

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Start with the IDF data.

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Back in the Rainfall Manager, with Table IDF selected, click Add.

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First ensure that Rainfall Intensity is enabled to specify that you are entering rainfall intensity values.

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Next, since the Duration already has a column,

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you only need to create columns for each of the three return periods.

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In the table tools, click Add (+).

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In the Add Return Period popup, add in one of the return periods.

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In the Return Period (years) field, enter 2, for the 2-year return period, and then click OK.

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Repeat this process to add in the 30-year and then the 100-year return periods.

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Back in the table in the Rainfall Manager,

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you do not need the 1-year return period for this exercise,

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so select the column header and then click Delete (-) to remove it.

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Once the column headers are set,

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return to the spreadsheet and copy out the data.

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Ensure that you copy only the actual data, not the headers.

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Back in the program, click the first cell under Duration,

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and then paste the data.

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With the three different return periods entered,

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best practice is to rename the table.

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Under the Items list, highlight the child Table IDF item,

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and then type “Test 1” to rename it to match the project name.

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Next, you need to enter the temporal pattern data,

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which again is the dimensionless relationship data that defines the curve.

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In the Rainfall Manager Items list, click Temporal Pattern.

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Then in the toolbar, click Add (+).

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Under Temporal Pattern, next to Label, enter a name, such as “Test 2” for this exercise.

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Expand the Profile Type drop-down and select Custom – Dimensionless.

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For the Editable Column drop-down, keep Cumulative selected.

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Back in the spreadsheet, copy the percentage time values, and again, do not include the header.

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Be aware that for these, you cannot start from a percentage time of 0.

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Copy from a non-zero value, such as 5, as shown here, through 100,

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then place them into the table in the Rainfall Manager under Time (%).

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Repeat this process with the Cumulative column.

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From the spreadsheet, copy the data under Percentage depth,

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then return to the program to paste it under Cumulative (%).

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Now that you have the two essential elements—the IDF curve and the shape of the event—you need to bring them together

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to create a series of user-defined rainfall events.

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Expand the Design Storms node,

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then select User Defined Rainfall.

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Click Add (+).

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Next to Label, rename it “User Defined Rainfall 1”.

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Click OK to close the Rainfall Manager.

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Note that for the library to update with the new information you just entered,

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the Rainfall Manager first needs to close.

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Now, when you re-open it, the User Defined Rainfall 1 Design Storm is still active,

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and on the Storms tab, notice that the Create From IDF tool is available.

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Click Create From IDF, and in the User Defined Rainfall From IDF popup,

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select From Library, and then expand the drop-down.

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The Test 1 IDF curve you created now appears in the library.

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Select Test 1.

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The return period information appears.

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Expand the Return Period drop-down and select 30-years.

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Click OK.

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To identify it more clearly, change the Label to “30 years”, and then press ENTER.

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Next, in the table, under Temporal Pattern, expand each drop-down and select the Test 2 pattern you created.

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Ensure that you apply it to each one.

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Also, enable Use for all the rows,

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as it is not active by default.

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This means you will now use these nine rainfall events

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with the Temporal Pattern set to Test 2.

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Click the Temporal Pattern tab, where you can double-check that it displays the data you entered.

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Click the Increase Rainfall tab.

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If you wanted to add in an aspect of climate change, you could do that here.

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Click Save to save your rainfall definition,

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then click OK to close the Rainfall Manager.

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Be aware that you can reuse this same rainfall later, if needed.

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Now, you can run an analysis using your data.

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On the ribbon, Analysis tab, Criteria panel, click Analysis Criteria.

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In the Analysis Criteria dialog,

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your User Defined Rainfall 30 years set of curves is now available.

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And crucially, you can see that there are nine rainfall events matching the nine that you chose to use.

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Click OK.

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It is always good practice to run a validation,

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so in the ribbon, click Validate.

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In the Validate dialog, if it shows as OK, click OK to close it.

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In the ribbon, click Go.

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A Progress dialog appears.

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This network model is small, with only 40 manholes and 40 pipes, and only 9 storms.

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This does not take long to process, but a larger model may take longer.

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Once the simulation is finished, the Stormwater Controls Summary appears,

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but you can look at the results in several different ways.

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Click Close.

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For example, on the ribbon, click the Results tab,

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and in the Item Results, expand the Inflows drop-down and select S29-DA.

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In the graph, you can look at the flows entering or leaving an inflow area, or entering a manhole.

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You can also choose which rainfall events you want to review.

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In the Event Selection panel, expand the Select Event drop-down

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and choose a different rainfall event, such as 240.

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Back in the graph, if you switch off the inflow, you can see only the rainfall.

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In this case, because it is a 1-in-30-years storm, 240-minute event,

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the maximum intensity is a little more than 26 millimeters per hour.

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As you can see, creating your own rainfall data for determining temporal patterns is easy

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if you have the IDF curve and shape curve data for your area of interest.