ArcHydro and HEC-GeoHMS: Calculating Basin/River Slopes

[MichaelHross]

I have been using ArcHydro and HEC-GeoHMS to analyze a watershed, and everything has been running rather well until I started trying to calculate slopes. Both ArcHydro and HEC-GeoHMS give me the error "The dataset does not have spatial reference. Please specify a valid spatial reference!".

All of my layers are in GCS_WGS_1984 so I do not understand why it is saying this.

[MichaelHross]

I have been trying to get it to work and now the following is happening: I went into the prj file to set the units and the Z-unit to METERS and 1, respectively. I tried to calculate slope again and it gave me the same result; however, now after trying to find the slope the spatial reference changes to <Undefined>. I changed the spatial reference back, fixed the prj file (since it undid what I had changed) and then tried calculating slope again. The error still occurred and then it reverted the spatial reference back to <Undefined>.

In case it may matter, the original raster data I have been using is from CGIAR-CSI SRTM 30m DEM.

[PeterWilson]

Hi Michael

ArcHydro and HEC-GeoHMS require that your datasets are stored in a projected coordinate system. The DEM fro CGIAR-CSI are stored in a geographic coordinate system. You need to project the DEM tiles before you can use them to perform any calcs using ArcHydro or HEC-GeoHMS.

Regards

[NimiDan-Jumbo]

Please how do you go the prj File to set in meters.


Please I need an urgent assistance with Using HEC GEO HMS.

I have had success running the model, but I'm stock having error message  with the River Slope generation. I am using a USGS DEM. I have also projected the DEM  to a National Grid coordinate system (unit in meters).
The DEM raster I am using works when I calculate basin slope using Arc Hydro but give error message when trying to generate the River slope.

Its say "spatial reference does not have z unit. Assuming Z-unit  is the same as unit linear unit and z factor =1

How can I eliminate this error
Many thanks

[ISHAG_ABBASHERABDELKREEM_HASSA]

Hi dear

> R-click on PreFillDEM layer and go to properties > source copy file data source for example (E:\ISHAG\SDI\HY\ArcHydroAnalysis\Raster\Layers\)  and go to open any folder past in track after that you will fine folder of layer into yo will find prj.adf R-click open with notepad (uncheck Always open...) Zunits to  100

Regards