Hello,
I'm a graduate student using the InVEST NDR model to estimate nutrient retention in riparian buffers. One of the model inputs is a DEM. The DEM doesn't capture agricultural canals and ditches that are a significant part of nutrient loading in the watershed I'm studying. I used the DEM Reconditioning tool in Arc Hydro to burn in canals. Disclaimer: I apologize in advance if I am blatantly ignorant about this subject; please correct me.
I wanted to get opinions on my methodology to see if I've made errors in my geoprocessing. My main concern is Z units. My understanding is that they are vertical units that are usually equal to the horizontal dimensions of whatever raster one is working with.
The DEM reconditioning tool prompts the user to choose the number of Z units that the elevation will be dropped to burn in the stream raster. Z units need to be integers greater than or equal to 1. My DEM was a 10x10 m raster, so if I chose a Z unit value of 1, that would equal a 10 m drop-- which is way too deep for an agricultural canal! Since I'm working with agricultural canals that aren't too deep (usually about 1 m), I needed my Z units to be able to reflect an accurate depth of these canals. As a work-around, I resampled both my DEM and my stream raster layer to 1 x1 m resolution. Then I choose a Z unit of 1 in my DEM Reconditioning tool (which hopefully is equal to 1 m).
I've attached photos of my DEM Reconditioning tool and an overall model of my work.
1. Is the above a viable approach for DEM reconditioning?
2. How can I check if the Z units of my 1x1 m raster are actually equal to 1 m?