If you are running a large InfoSWMM, H2OMap SWMM or SWMM 5 model is it often hard to see all of the details for the Runoff Hydrology at one glance. A few quick checks on the overall balance sometimes help speed up the model greatly for new runs:
1. Check the Overall Runoff Balance (Bullet 1 in Figure 1)
2. Check the overall Hydraulic Balance (Bullet 2 in Figure 1)
3. Check the average time step (Bullet 3 in Figure 1). If the average time step is much less than the Maximum time step the Maximum time step should be reduced in the next run.
4. Do have pervious infiltration in every Subcatchment? (Bullet 4 in Figure 1)
5. The Min, Mean and Max Infiltration Rate can be found with the DB Statistics Tool.
6. A Scatter Plot of Runoff Coefficient versus Infiltration for all the Subcatchments to show any outlying Subcatchments - this can show an improper setup for the Infiltration in InfoSWMM DB Table (Figure 2).
1. Check the Overall Runoff Balance (Bullet 1 in Figure 1)
2. Check the overall Hydraulic Balance (Bullet 2 in Figure 1)
3. Check the average time step (Bullet 3 in Figure 1). If the average time step is much less than the Maximum time step the Maximum time step should be reduced in the next run.
4. Do have pervious infiltration in every Subcatchment? (Bullet 4 in Figure 1)
5. The Min, Mean and Max Infiltration Rate can be found with the DB Statistics Tool.
6. A Scatter Plot of Runoff Coefficient versus Infiltration for all the Subcatchments to show any outlying Subcatchments - this can show an improper setup for the Infiltration in InfoSWMM DB Table (Figure 2).
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| Figure 1. Mass Balance Items to Check in the InfoSWMM or H2OMap SWMM Output Run Manager |
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| Figure 2. A Scatter Plot of Runoff Coefficient versus Infiltration can also Show Outlying Subcatchments |
