Let's say, for the sake of simplicity, we have the following Y Shape water pipe network:

S1 and S2 are the reservoirs ( input source), Sout is the water demand where water is drawn out for commercial use or whatever use. We know the height of the reservoirs at S1 and S2 relative to the ground and we also know the height of the Sout.

All S1, S2 and Sout are inm^3/s.

For the pipe, we know for each pipe their corresponding diameter d, length L, roughness coefficient C.

My question is, given the above information, is there anyway we can uniquely compute S1 and S2 for the Y shape network above? From what I know, we have one equation but two unknowns ( the conservation of source):


But this is not sufficient for us to uniquely determine S1 and S2 unless we have other equations here. I think the height of the nodes are also playing a role in the solution, but I just don't know how it can be done. Any ideas?

On a side note, if our water pipe network is a loop, we can use the hazen william formula and hardy cross method to compute the head loss. This means that whatever that is required to be known about the pipe is already known, as long as they are used in hazen william formula and hardy cross method.

  • Appears to be a math question and not related to GIS. – Hornbydd Jun 20 '18 at 7:39
  • @Hornbydd, I don't think this is a "math" question ( for it certainly involves geophysics) – Graviton Jun 20 '18 at 7:40
  • What are these drains? Are they pixels in a raster? You have told us nothing about the dataset, an image would be nice, hence my thought that you had abstract it away to a math question. – Hornbydd Jun 20 '18 at 7:45
  • @Hornbydd, The flow of the drain shall be determined by Manning Formula. There is no raster or advanced dataset involved. – Graviton Jun 20 '18 at 7:52
  • Which tool are you using to do the flow-direction map? the r.watershed has the flag -s to cope with it: SFD: single flow direction, MFD: multiple flow direction – Marco Jun 20 '18 at 8:01

This is a classic hydraulic problem. It varies a lot if it is a pressurized system or not. I would hardly tag it as hydrology, it has almost nothing to do with it, but I consider it a relevant GIS topic.

For pressurized complex network systems there the EPANET, an "Application for Modeling Drinking Water Distribution Systems" link

In case of free flow systems, there is SWMM, an "application that helps predict the quantity and quality of runoff within urban areas" link

For both software there are some links to GIS, but that is another very wide question.

  • Marco, is it possible to show the corresponding SWMM or EPANET section that directly answers my question? – Graviton Jun 20 '18 at 8:41
  • The EPANET User's manual has everything link but I thing it is not a good starting point to study hydraulics – Marco Jun 20 '18 at 8:48
  • Marco, you said that you would hardly tag it as hydrology, do you have a more appropriate tag? – Graviton Jun 29 '18 at 8:38
  • I would tag it as hydraulic or pipe network – Marco Jul 2 '18 at 6:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.