# Is there a way to compute an average gradient over an area, using several data points?

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01-04-2021 03:09 AM
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ArcMap desktop 10.8.1

I have an idea, and I'm wondering if there's a way to implement it in ArcMap.

In hydrogeology, using 3 water elevation data points, we can determine the hydraulic gradient (direction of groundwater flow) by turning the scenario into a 'three-point problem'. You take the high and low points and connect them with a line. Then, you determine where the intermediate point fits into the range of values between the high point and low point and draw a line from the intermediate point to the point on the line connecting the high and low point, at the point equal in magnitude to the intermediate point. You then have an area with a defined slope that represents the hydraulic gradient.

For my research, I'm looking at a large dataset of hydraulic head (water level) measurements. The data is not very consistent because of different levels of confinement (pressure) impacting the hydraulic head. What I'm hoping to do is turn the umpteen dozen water level measurements I have into a flat surface that represents the average water level gradient across the area, using all the data points. This will help me determine the direction of groundwater flow. As it stands, I have peaks and valleys, which makes it difficult to determine the general flow trend.

Imagine you're looking at a map and there are data points scattered about, and you place a sheet of paper above the map. The sheet of paper represents the average water table elevation. I want to use the water level at each data point to determine the orientation of the paper.

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