I am calibrating a system, the distribution network which has two inlets (feeder mains) on which I have flow and pressure measurement data. After simulation it is observed that one of my reservoir more push water in non supply hours and it goes to another reservoir in same supply hours through distribution network. Resulting in positive and negative flow from both the reservoirs. The hydraulic grade pattern has been given to both the reservoirs using pressure recorded. The reservoir which pushed water in non supply hours has GL 2.3 m and the other reservoir has 1.86 m GL. The difference between two reservoir GL is approx. 0.4 m. I tried to balance flow by changing GL of both the reservoir but could not succeeded. Am I doing in wrong way or anything i am missing? Please help me out from this issue. The system also has one more complexity that the network also supplied by one more inlet through Tube Well. So there is mix type of supply.
Reservoir R1 GL: 1.86 m, Flow : 2.04 MLD
Reservoir R2 GL: 2.30 m, Flow : 1.89 MLD
Hello Naresh,
Are you modeling a connection to an existing system? If so, you will need to be careful with the assumptions, as you can have issues where more than one source. In addition, you typically would use a pump to help general the flow and head. The link above has more information on that.
Otherwise, we may need more information and a copy of the model files.
Regards,
Scott
Hi Scott. I have uploaded the model files "dma 15" for your reference.
I am not modeling a connection. In model u can see that the two reservoirs are the inlet points of the DMA existing distribution network. Reservoirs are placed on feeder main at entry point of DMA. Network on u/s of reservoir is deactivated for time being. The calibration is done from this entry point of DMA using measurement data at this point i.e. inflow and HGL. The scenario 'Base' is calibrated scenario. First of all I would like to know from you Scott am I modelling or building in proper way? There is Tube Well present in the network supplying at the same time. The reservoir, pump are given with some values. I would like to know more about pump definition, Pump Curve and System head Curve.
The flow from the reservoirs will be enough to balance the hydraulic grade and satisfy demands in the system. So with the elevations, headlosses, and demands in the system, the flow from the reservoirs are likely accurate.
Including a flow control valve would allow you to control the flow coming out of the reservoir. However, it may introduce further headlosses in the system and cause even more negative pressures that what is there currently.
It is usually best to model what is in the system. This would include anything that might control the flow. Currently, the elevations at R-1 and R-2 are the same as or lower than the elevations of the nearby junctions. For instance, R-1 as an elevation of 2.05 meters (and a hydraulic grade even lower based on the pattern you have included) and the elevation of junction J-234 is 2.3 meters. This means that for a larger power of the model run, the pressure is negative.
Is the correct setup? Are these the actual sources and the actual elevations? If not, what do the reservoirs actually represent? You mention pumps as well. If there should be pumps, that will help with the negative pressures and may help with the flows as well.
You can find information on pumps and pump selection here: General Pump Selection Process. There is a link to another wiki related to system head curves there as well. You would need to start with a pump definition that will roughly be what you expect as you use the other tools to hone the pump definition.