Hi,

It depends on your goal, it can be a 4 dimensional question or just a 2 dimensional.

For 4 dimensional, you can use multidimensional function of degree n (it can be linear or non-linear) which from mathematical point of view; it is easy but from computer science point of view you can have a 3+1 dimension (you can not view 4D at the moment)!

As you are interested in relation between water quality based on elevation information.

1. You can consider a 2 dimensional matrices including your water quality values and elevation information.

2. Interpolation using any statistical or mathematical model shows relationship between your water quality values and elevation information.

You have f(x,y) where x is water quality values and y is elevation information.

Regards,

Ali

You can check Matlab as well where they offer 4D interpolation.

https://www.mathworks.com/help/matlab/ref/interpn.html

For example you have f(x,y,z,t)=t.*exp(-x.^2 - y.^2 - z.^2)

where x,y,z are your coordinates and t is your water quality value.

You can create your own linear or non-linear function with four independent variables of x, y, z and t.

Dear Sir,

I guess you can distribute your parameter of interest including elevation (possibly from DEM) using universal kriging or regression kriging or even you can go for random forest and evaluate these methods.