Open street map drains

[rosepearson]

We could add support for pulling drains down from open street map within a catchment area and incorporating them into a DEM. The assumption is they would be well aligned and pretty small. A uniform width would then be assumed and any areas where the drains go back up would be removed.

Tasks:

• [x] Use OSMPythonTools to download streams and drains within a catchment
• [ ] ~Keep waterways that aren't where other river / ocean bathymetry are~ See decision below - deferred
• [x] Convert drain centrelines into polygons
• [x] Sample along drain and transform into bathymetry estimate i. Figure out upriver direction ii. Take minimums then fit some sort of monotonically decreasing curve downriver
• [x] Save results so they can be incorporated into DEM generation process

Note that the first three tasks were initially explored in a Jupyter Notebook found here.

[rosepearson]

Notes on OSM tags

There are a variety of OSM tags relating to water that we may want to bring in.

The two images below show a stream/ditch and a series of lagoons with several culverts:

Some of these features, like culverts, are very small and we will want to take the minimum value, while others, like streams, are long and we will want to keep long sections and sample downstream.

[rosepearson]

Decision

Having looked at the rivers a bit more, I will initially focus only on streams, drains and culverts where there should be no overlap with the the estimated river bathymetries. We can worry about incorporating river networks not covered by the bathymetry estimation process but included in OSM at a later stage.