Q: Did anyone else generate a number of streams in this week’s skill check that was NOT the “30+ ” bolded answer? I kept getting 28 streams, and after repeating steps from Flow Direction to Stream to Feature, and then loading in the data again, still managed to get 28. I am trying to understand where I went wrong before I move on with the “hydrologic analysis” part of the lab.
A: The output of the Set Null operation (Streams_step1) had 3,678 cells with value of 1. Did you find the same number? One other thing to check – are you using the “revised” flow direction raster (FlowDirection_step2) in your calculations? This was the flow direction raster you computed after the sinks were filled.
Also remember the difference between the Coordinate System of a dataset and the Coordinate System of the Map Pane. As long as your data uses the WA State Plane South (NAD83, m) projection you should be good. You can always change the Coordinate System of the Map Pane in the Map Pane Properties interface (right-click Map Pane name from the Contents window > Properties).
The contributing areas of the 50-m and 250-m pour point locations is almost the same (and in the neighborhood of the 9,000 number you report above).