Fluid flow and elevation vs pressure

Hey guys! does anyone have a graph of the relationship between elevation change and pressure loss in pipes? I currently have experimental data of a negative gradient graph. know it's theoretically correct however, I just need supporting research for this - have tried finding everywhere but can't find it

Welcome to PF.

There are many interpretations of your question. I wonder what you mean.
Are you referring to hydrostatic pressure reduction, or a head loss due to flow restriction?

Please describe the hydraulic system, and attach the "negative gradient graph" to your next post.

Hi, a change in pipe elevation. My setup is currently; horizontal pipe into vertical pipe and from the vertical pipe into another horizontal pipe. The last pipe is in partial flow and so im assuming the pressure is atmospheric pressure. I am then backtracking to find P1 (original pressure) - and finding the change in pressure due to the elevation. Attached is my graph - would really appreciate your help, thank you

That appears to be hydrostatic pressure. The equation is here.
https://en.wikipedia.org/wiki/Vertical_pressure_variation

Your coefficient 9961.4 should be close to g * density.
For g = 9.8 m/s² the liquid is water, with a density of 1016 kg/m³.

What "supporting research" do you require for something so fundamental ?