Calculation with tidal effect

Question

Hello, I created a model and included tidal conditions. But from my point of view, the result is not plausible. 
 The calculation starts with the maximum water level (elevation: 4,98 m) based on a Time-Elevation-Curve 
 
 Boundary Conditon Typ: Tidal 
 Tidal Gate: False 
 The correct water-level is shown during the calculation time-steps (?). 
 
 By using the Hydraulic Reviewer to check the Overflow Volume it gives me a total amount of about 10 m3. That is not plausible. Can someone assume where my mistake is?

Craig Calvin · Accepted Answer

Hello Michael, 
 The profile you provided is for scenario "Dynamisch &Uuml;berflutung r-15-30". When I open the model you provided this scenario doesn't have outfall O-1 set to use a tidal boundary condition type. Perhaps you didn't save the model before uploading it or you uploaded an older revision of the model? 
 From the image of the Cyclic Time-Elevation Curve you provided for outfall O-1, it appears that you are using the values from your spreadsheet's "Wasserstand Zustand 5 Faktor 2,5" column. 
 The image of the curve data you provided starts with time=1min, however the elevations start with values that correspond with time=0min (in the spreadsheet). 
 
 I recommend starting with time=0min and use the elevation values that correspond to these times in the spreadsheet. 
 
 Note that there is a difference between entering this data starting at 0min and 1 min. The following profile shows how this change will impact the results. 
 
 I am not seeing a total overflow volume of about 10 cu-m reported in the Hydraulic Reviewer for catchments or manholes in either of these configurations/scenarios. 
 Try correcting the values in the "Cyclic Time-Elevation Curve" to match the values in the spreadsheet. If that doesn't help, then please provide the updated model files and images of matching results that you believe are incorrect. Why do you believe the results you are seeing are not plausible? The results that I'm seeing appear to be reasonable for what is being modeled. Were you expecting the total overflow volume to be less or more than 10cu-m? 
 What software are you using? 
 Is this an existing system that you want to find out how much will overflow, or are you designing a system to avoid overflow? 
 Here are some related articles that might be helpful. 
 How to find volume (such as overflow volume) through specific elements 
 Troubleshooting unstable SewerGEMS and CivilStorm results using the implicit solver

Jesse Dringoli · Answer

One quick note to add along with Craig's answer: 
 The screenshot of the profile shows the result at time zero. The red lines indicate the maximum HGL at each node, and you can see that it is above the ground elevation for most of the network, which is likely the cause of the overflow volume, in the particular case that you were looking at (which may be different from the model that you sent, per Craig's reply). Be sure to move forward in time using the Time Browser, to see what happens later in the simulation. 
 If the overflow is unexpected, check your Continuity Error and general network stability, and adjust the advanced calculation options per the second article that Craig linked to.

Yashodhan Joshi · Answer

Hello Michael, 
 Michael Schäffer said: On your and my curves I see a negativ outflow. Is the reason the empty storm water network by t = 0? Do I have to define the water-level in the stormwater network for the calculation start? 
 What do you mean by negative outflow? Is the "Flow (Total Out)" field in the Outfall properties reporting negative outflow? 
 It would be helpful if you shared a snapshot of what you are seeing. 
 The flow in the storm-water conveyance system is generated from the runoff from your catchments.

Scott Kampa · Answer

Hello Michael, 
 The negative flows may be related to the hydraulic grade in the system. Since you are defining the elevation at the outfall, if the elevation is higher than the hydraulic grade further upstream, this may result in flow moving upstream into the network. 
 Regards, Scott