Latest Contributions by DeanDjokic

The *_FS tables are the "flow split" tables (for drainage line and catchment feature classes).  They contain the HydroID of a downstream feature if there is more than one downstream feature at a given feature (HydroID of the first downstream feature will be stored in the field NextDownID of the feature itself, while the _FS table will have the additional values).  In the _FS table, "FEATUREID" field contains the HydroID of the feature that has a flow split, while "NEXTDOWNID" field contains the HydroID of the downstream feature. The only time there will be an entry in those tables is if you have braided streams in your system (there are flow splits).  If you are using dendritic terrains and you do not provide streams with braids as inputs into the process (as in your case where streams are unknown), these tables will always be empty.   ... View more

Arc Hydro for Pro 3.1 is compatible with Pro 3.2.  You can use Arc Hydro install 3.1.45 for now or any later build.  We will be adding a Pro 3.2 link to the Arc Hydro download site shortly, but it will be pointing to 3.1 installs for now.  Dedicated 3.2 install might be developed later on. ... View more

The key difference is that Arc Hydro fill allows you to specify "deranged" polygons as input.  These areas will NOT be filled.  So it is a different option than standard fill that can limit the fill by depth.  Document that Dan pointed you to goes into details on how to identify and manage sinks if you choose to have them.  Note that if you are going to do full terrain preprocessing (so you can use AH tools for watershed delineation etc.), you need to tweak the flow direction in sinks (described in that document as well).   And finally, if you are using Pro 3.0 and up, there are tools that allow you to do flow direction and accumulation without filling sinks.  In general, it provides better results than using the fill approach.  ... View more

Randal, We have updated the code for the Trace by AH Attributes to make it more Arc Hydro-ish with respect to how it is called from python.  Please install AH version 3.0.58 (of course, uninstall the previous version first). Your updated code should then look something like (you can type this on the python command line and replace with proper pointers to your data – if it works, then move to your code): import arcpy import hydroconfig import tracebyahattributes in_flags = "D:\\10Data\\Raindrop2022\\AH2022.gdb\\Trace_by_AH_Attributes_Input_Start_Points_Points_3" in_barriers = None in_streams = "DrainageLine" trace_direction = 'Upstream'  #or 'Downstream', 'Both' search_distance = 50 max_next_lines = 0    #0=all, 1, 2, 3, =first, first 2, first 3 line(s) when there are splits exclude_start_elements = False  #..start elements would be included in the results (elements a flag hits) p = tracebyahattributes.TraceByAHAttributes() p.DebugLevel = 1 t_returns = p.executeAH(in_flags, in_streams, trace_direction, search_distance, max_next_lines, in_barriers, exclude_start_elements) if(t_returns[0] == hydroconfig.C_OK):     print(t_returns) else:     print(t_returns[0])   -------- to try on the python command line after successful trace run print(t_returns) ('OK', '36,31,32,25,26,27,30,21,22,18,19,23,24,16,17,14,15,3,4,11,13,1,2,12,20,9,10,5,6,7,8', 'ts_results', 'ts_start_points', '36', None) Several things to note: t_returns – this is the “result” that the function returns.  It consists of several elements. Fist element (index 0) is whether the function completed successfully.  If it is “OK” then it finished correctly and the following elements in the list are individual results. Second element is a string containing a comma delimited list of ArcIDs that are the trace results.  This can be useful if you are running the script “headless” – e.g. outside of Pro (pure python). Third element is feature set of returned lines ( -- I think you are looking for this --) Fourth element is feature set of input flags (starting points) Fifth element is the count of returned trace lines ( -- I think you are looking for this --) Sixth element is feature set of barriers if any were used. This should return a selected set if you are running your code from within Pro. Using this function makes sense if you have simple “network” and want basic upstream/downstream trace analysis.  You should use trace network if the trace system is more complex (e.g. multiple layers, complex edges, …).  We use TN for stormwater analysis within Arc Hydro. Let me know if this works for you. Also, please review document "Arc Hydro - Calling Arc Hydro Tools in Python.pdf" (https://community.esri.com/t5/water-resources-documents/arc-hydro-calling-arc-hydro-tools-in-python-pdf/ta-p/920821).  It goes into more detail on accessing AH functions through python script. ... View more