Cartographers will often exaggerate the natural scale of a mapped feature to help it communicate something of its nature. Some examples are vertical exaggeration of terrain or the very existence of point symbols (cities aren’t actually that big). We embellish for effect. Making a river a bit wider at its mouth, where it meets the sea or a lake, is an echo of a general phenomena of river deltas. But we are usually working with line features when it comes to rivers in a GIS. How can we imbue a bit of riverine character and a sense of flow direction into river lines in ArcGIS Pro?
We’ll use the global tapered polygon effect! Here’s how, in two minutes…
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0:00 Intro illustration
0:19 Tapered polygon effect
0:43 Giving the new (tapered) river polygons a fill
0:58 How to reverse those backwards rivers
And, because the full riches of the ArcGIS Geoprocessing library is unknowable, I wasn’t even aware of the glorious flip line tool (which lets you select all the backwards lines and reverse their node order in one fell swoop) until Tommy Fauvell let me know moments after publishing this video. Cheers to geoprocessing, and to friends! Relatedly, here’s Craig Williams showing me how to taper rivers.
Happy mapping! John
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