Screen Scraping GIS Tax Ditch Lines Substandard

Better to get the GIS data someone else has already digitized than to try to digitize from a screenshot. That is what I tried a few months back before I found better source data recently delineating where stormwater drainage goes.

The idea that ditches are taxable, or tax exempt, is still mysterious to me, but we have them in Maryland.

https://geodata.md.gov/imap/rest/services/Agriculture/MD_NutrientManagementSetbacksFromWaterways/MapServer/5

"Description: This is a 35 foot buffer area along PDA ditches where fertilizer applications are restricted on croplands."

A PDA is a "Public Ditch Association." Essentially we've already done the environmental damage cutting down the forests and then terraforming the soil for industrial crop harvests. The ditches stretch for miles in some Eastern Shore counties. Taxes pay for the maintenance, as roadside ditches will fill in with dirt and trash otherwise. 

Initially I found maps showing the ditches, and the surrounding service area, as online maps.

And a map of fire coverage.

One good starting point for "ditches" is https://data.imap.maryland.gov/search?collection=dataset&q=ditch. I followed QGis tutorial lessons [https://docs.qgis.org/3.34/en/docs/training_manual/forestry/stands_digitizing.html], digitizing the above into 2 layers, one for the boundaries and one for the lines. Not very good resolution when you zoom in.

I found, after searching with different criteria, similar tax ditch geo-data in the Maryland State site, and the Eastern Shore collective site. So instead of trying to redo the digitizing effort I could skip that part. 

https://data-maryland.opendata.arcgis.com/datasets/1ad8de34212c4a1cbc41c2d989ba0582/explore?location=39.059721%2C-75.779000%2C12.34

https://esrgc.org/data/taxditch

https://salisburyu.maps.arcgis.com/apps/webappviewer/index.html?id=6da9e776a0eb492c8b70b43d44a49c53

When I downloaded the shape files, they looked good. But when I tried to pull them into a PostgreSQL database, the points flew somewhere else. I am unsure what was missed. I made a second attempt by downloading a KML file instead of a set of shape files. These lines and areas worked, after a fashion. My PostGIS skills are still pretty fresh, like only this year did I run a local database. 

I experimented with arrows for directions, as this helps visualize the land slope, even if miniscule. There is a great example here: https://docs.qgis.org/3.34/en/docs/training_manual/vector_analysis/network_analysis.html. The "loop" above is an oddity from the ditch crossing the highway intersection. Changing the scale and map view sometimes triggers taffy-pull looking connection lines.

This page has more about rules: https://plugins.qgis.org/planet/tag/thematics/.

Next step for me is altering the labels so that roads are distinct from ditches, because there is both a Chicken Bridge Road and a Chicken Bridge drainage area/network.