The RDII or Rainfall Dependent Infiltration Inflow method in InfoSewer is similar to the RDII or RTK method in SWMM5, InfoSWMM and InfoWorks ICM but with some differences. The RTK data for triangles 1, 2 and 3 are defined in the Unit Hydrograph but instead of individual R values, the overall R is set and the Percent R1, R2 and R3 are defined based on the total R. R3 is calculated internally as 100 – R1 – R2. Each loading manhole with RDII flow has a total area, a hyetograph and a Unit Hydrograph. The hyetograph has to be set at multiples of the unit hydrograph, so you can define the time or X columns with integers and then use the Block Edit command to change X to minutes by multiplying by the Unit Hydrograph time (Figure 1). You can use only one component if you set R1 or R2 to 100 percent or R3 to 100 percent by setting R1 and R2 to 0 percent (Figure 2). The overall area of the Unit Hydrograph is divided amongst the loading manhole using the Subbasin Area (Figure 3). The storm flows generated can be viewed using a Group Graph (Figure 4) and the area of the loading manholes has a relationship to the total area of the defined unit hydrograph (Figure 5).

The unit hydrographs could be of any duration (e.g., 15-minute, 1-hr), but the duration must be the same for the entire unit hydrographs involved in modeling of the watershed. For example, Figure’5 and 6 shows the hyetograph for the example Storm event, it is in increments of 30 minutes which is the duration of the unit hydrograph. Figure 8 shows the resultant RDII storm event flow at 15 minute intervals.

There is an Update post on RDII Analyst in Innovyze SWMM “One of the most powerful InfoSWMM and H2OMAP SWMM Application Tools from Innovyze is RDII Analyst. RDII Analyst will separate out the Groundwater base flow, Dry Weather Flow (DWF), DWF Patterns, estimate the Wet Weather flow component or RDII Rainfall -Derived Infiltration Inflow (I&I) and use a Genetic Algorithm to find the best fit 12 RTK parameters for RDII modeling. This powerful tool can be used for RTK flow in InfoSWMM, H2OMAP SWMM, InfoSewer, SWMM 5 and InfoWorks ICM. Figure 1 shows one of the end results of RDII Analyst – a correlation plot of Observed versus Calibrated RDII Volume for the simulated events.” See more on this newer blog post http://blog.innovyze.com/2016/02/01/innovyze-rdii-analyst-for-the-analysis-and-calibration-of-rdii-dwf-dwf-patterns-and-gwi-in-sewer-collection-systems/

Figure 1. Hyetograph Curve for the RDII Unit Hydrograph

Figure 2. The Unit Hydrograph is defined for various values of R, R1, R2, T1, T2, T3, K1, K2 and K3. The longest time base of the Tri-Triangle hydrograph is T3*K3 or 9 hours.

Figure 3. The-Unit-Hydrograph-and-Hyetograph-are-tied-to-a-particular-loading-manhole-using-a-Subbasin-Area

Figure 4. The Unit Hydrographs that are generated can be viewed using a Group loading Manhole Graph. The R1, R2 and R3 have only one triangle

Figure 5 How the Loading Manhole UH Area relates to the UH Area for the Defined Hydrograph.

Figure 6. The Unit Hydrograph is defined for various values of R, R1, R2, T1, T2, T3, K1, K2 and K3. The longest time base of the Tri-Triangle hydrograph is T3*K3 or 24 hours. This applies to the following two graphs.

Figure 7. How to define the combination of the hyetograph, duration in minutes for the unit hydrograph and the unit hydrograph shape. The rainfall lasts for 150 minutes.

Figure 8. The stormflow hydrograph from the combination of the storm hyetograph and hydrograph. The flow last for 24 hours which is based on the time base of the longest RDII UH or T3*K3 of 24 hours.

## About Robert Dickinson

Robert Dickinson is a Product Sector Leader with Innovyze in the USA for InfoSewer, InfoSWMM and H2OMAP SWMM. He has over 42+ years experience in modeling the key hydrologic, water quality and hydraulic processes involved in urban and surburban drainage design and analysis. He has been very lucky to work with many talented engineers and scientists in his professional life at the University of Florida, XP Software, CDMSmith, the US EPA and at Innovyze Inc which allows him to offer worldwide support, training and sales/adaptation help for the Innovyze Products InfoSWMM, InfoSewer, InfoSWMM 2D, H20Map SWMM, SWMMLive and SWMM features in ICM and ICM SE.
Short Time History:
Product Sector Leader with @Innovyze for InfoSWMM / InfoSewer, 46+ years w/ SWMM3/4/5 11+ Years w/ @Innovyze! 8+ years @CDMSmith 9 years w/ XPSWMM 17 years @UF
Very long bio -
https://www.linkedin.com/pulse/my-history-various-versions-swmm-swmm3-swmm4-swmm5-robert-dickinson?trk=prof-post