Strahler Classification

Discussion created by yuri.veneziani on Jul 21, 2011
Hello everyone!

I'm having problems to do a Strahler classification in a complex basin. From a topo vector I did a DEM using 3DAnalystTools>TopotoRaster put topo, stream and elevation point vectors into the process, defining 15 as a output cell size. Then, using its product I tried get a flow direction raster through hydrology tools in Spatial Analyst, but It's not working well. When the direction raster is created it's not able to define with precision way flows, and when I put the overlay stream raster (with the drainage basin) crossing with the flow direction derived from the DEM, the Strahler classification it isn't made. Many streams are not classified correctly, because in the middle of them the model change the order, 1 to 2 for exemplo, desconsidering the net drainage, coincident points between streams, etc. I looked for sinks in DEM using sink and fill tools, but I didn't found. Aparently all atribute tables are ok, and the net streams of the hydro vector is ok, too. What can be happenig?! Is there a right way to do a DEM to flow direction raster?!
Please, if one could help, I'll appreciate!
Thanks a lot!