Being Dutch and a history-buff, I have one mayor gripe with historical maps, that sees land as 'moving lines' on a fixed map. When I look at a historical maps (also in books), I often see the Netherlands represented in it's current form, i.e. containing land that is not even 50 years old, being prestent hundreds or even thousands of years. I get that it is an intricate history, and maybe too much effort in some cases, but please at least remove flevoland. https://en.wikipedia.org/wiki/Flevoland
It's true, and it is not just a Dutch problem. Basically all major river systems change throughout the centuries: meandering arms evolve and others get cut off; river deltas grow and change shape and of course human activity shapes the landscape (canals, irrigation, drainage of swamps and floodplains etc.). The ancient city of Eridu for example was a coastal city around 5000BC and today lies hundreds of km inland.
I've recently been thinking about this with regards to borders. There are plenty of borders around the world that rely on rivers as a boundary, but river's aren't static, and meanders shift all the time.
Of particular interest to me was the England/Scotland border, as I was visiting the area, and noticing that it doesn't always follow the path of the river Tweed.
When a river is a border, that is by nature always changing, how do countries decide which bit of land/islands are sovereign?
It seems like this is adding some vectors on a gridded base map. But OSM has every object in a vector form, also coastlines etc. So I don't think there is a technical reason why coastlines would have to be fixed for a historical map. On the timescale of ages and millennia, rivers in delta planes are also usually not very static.
Well... coastlines are handled in a deep, dark, arcane part of OSM planet and data processing, but you're right. Rivers, on the other hand should be straightforward to change. We'll have some cleaned up examples in the near future.
Not only deltas, any river meandering over any plain will change its course pretty "quickly" (which creates problems if such a river is defined as the border between two countries BTW)
I live in the Fens in England and noticed the same thing. You can set it back 1000 years and not only is the Fens still drained, there are artificial drainage channels that weren't dug out for another 600 years. It seems an assumption has been made that rivers and coastlines don't change over time but it's so far from true! For me it's one of the most interesting, and scary, things when looking at old maps. Does the data model support changing natural features like rivers and coastlines?
Yes any feature as far as I'm aware can have a start date and end date so can show the changes over time. As can be seen in London (https://www.openhistoricalmap.org/#map=16/51.5108/-0.1086&la...) where the shape of the river changed when the Embankment was built in 1869. As far as I'm aware there is no reason why changing coastlines couldn't be mapped, though it is a lot of work to draw in a long length of coastline.
I personally also find https://hisgis.nl/ an interesting resource, especially if you want to know about the 1832 kadaster maps, which are far more detailed that the maps that topotijdreis shows of that period. I do not know if this is available for the whole of the Netherlands, but the maps of Overijssel are available.
