Here is a simulation with two choices of order:
cp = ContourPlot[
Cos[x/10000] + Sin[y/10000], {x, -50000, 50000}, {y, 0, 10000},
ContourShading -> None, ImageSize -> Large, Contours -> 10,
ContourLabels -> True,
FrameLabel -> {{HoldForm[y[m]], None}, {HoldForm[x[m]],
None}}]; pl =
Plot[3000/(1 + (x/5000)^4), {x, -50000, 50000}, PlotRange -> All,
PlotStyle -> Black, ImageSize -> Large, AxesOrigin -> {-50000, 0},
Filling -> {Axis}, FillingStyle -> {Opacity[1], Gray}];
Show[cp, pl]
Show[pl, cp]
Neither is what you need?
