Create Level-12 Hydrological Unit Code (HUC) selection list

This script generates an XML file containing up or down stream Level-12 HUCs from a user specified HUC anywhere in the Contiguous United States (CONUS).

Briefly, the resultant XML file contains the following information:
[1] \"WhereStrings\" for selecting HUCs within the National Hydrography Dataset (NHD) using SQL in ArcMap or QTGIS.
[2] Location of stream outlets \"Intersection Points\" between Level-12 HUCs.
[3] A list of Closed Basins within the graph hierarchy.
[4] A list of NLDAS cell ids for forcing selection.
[5] Graph selection lists using DFS, BFS and undirected Dijkstra graphs. With distances to CONUS Level-12 HUCs.

INPUTS
\"-i\", \"--huc12id\" Level-12 HUC numerical identification i.e. 020502040102 for Slab Cabin Run
\"-r\", \"--reverse\" Reverse selection i.e. false (default) selects upstream, true indicates downstream
\"-o\", \"--ofolder\" Output folder location

Example usage
[Windows]: python.exe get_HUC_Graph.py -i 020502040102 -r false -o c:\
[Ubuntu]: python3 get_HUC_Graph.py -i 020502040102 -r false -o \tmp

Further information is available here:
http://ivi.sagepub.com/lookup/doi/10.1177/1473871616661868
https://doi.org/10.13140/RG.2.1.4397.0004