Interpolation river depth

MelissaVanderheyden

I'm analyzing habitat suitability using river depth data. However, my data are pretty basic: point data of the water levels at measuring stations. First, I'm trying to interpolate these data to the river sections between the stations, but I'm not sure which methods to use. I also have to simplify my river polygon very much to make the interpolation with barriers work in the first place. So I'm wondering whether interpolation makes sense in the first place, and whether simplifying the polygon this much would do any harm. Hope someone here knows the answers 😁 Thanks!! 

jcarlson

Do you mean that the depths are at single points along the river, as opposed to along transects?

If that's the case, you could still get a basic interpolation of depth using a TIN, but the resulting surface will be V-shaped, and likely not accurate. Still, it could give you a good sense of depth along the river, if not across. To get a more accurate shape to the bottom, you'd need more points added.

The other thing to keep in mind is the shape of the river. A TIN probably won't generate correctly around a bend if the river is quite sinuous, unless you've got points at fairly frequent intervals in those spots.

 

HEC-RAS, while it is made to work with transect data, has the ability to interpolate depth across a transect and along the river. Its particular advantage here is that it treats the river or transect as being a one-dimensional linear object for interpolation, and the results of that are "projected" onto the two-dimensional shape. But you have to ask, to quote someone I know from Florida, "Is the juice worth the squeeze?" Learning how to use the USACE's hydro-modelling software for data so sparse may not be.

In my opinion, you probably ought to see if there are ways to augment the data you've got. What area are you working in? You might check if there are any bare-earth (not hydro-flattened) DEM or LiDAR datasets available to try and fill in some missing data points.

And if there aren't other sources of data for the river's shape, what level of approximation would be acceptable to your project and the integrity of the results?