AllanP wrote: ↑
Fri Aug 01, 2008 10:29 pm
In looking through the Poor Wizard's Almanac AC 1012
I saw in the table of 'Average Seasonal Temperatures on page 172 that Specularum's altitude is given as 150 feet (above sea level), and it is noted "River may flood in spring"
AllanP wrote: ↑
Thu Aug 07, 2008 10:05 am
One aspect I'm looking at is the vertical elevation - the the top of the mound on which the castle sits is 15 foot above Bricktop Road and I estimate that by the time you've got down to the dock ara near the High Tower you will have descended another 45 foot vertically if we assume a 5% gradient between the various points. So the castle mound (top) is 60 feet above the level of the dockside. (I shall have to sketch this out to make it clearer). Which then makesme ask: what's the distance from the dock side level down to the water level of Mirror Bay?Also Specularum is up river from the sea (looking at the GAZ1 Karameikos map the city is in the second hex up from the coast, so it's could be between 8 and 16 miles from the sea) Will the river continue to fall as it malesit way to the sea? I'm asking this because the PWA
entry says Specularum is 150 feet abiove sea level - and on the above measurements the mound is (say) 75 feet above Mirror Bay which means the river has to descend another 75 feet before it reaches sea level...
Ok, this part is interesting.
By river, Specularum is not more than two hexes from the Sea of Dread... around 9.25 miles. If it meanders it could be as much as 15 miles. It is a navigable river at least as far as Specularum, so that means it is not too fast flowing, but relatively placid. A very strong current would make upstream navigation impractical.
You seem to be using 75 ft as the elevation of Mirror Bay, but I don't see how that can be practical. It is hard to find specific data on practical river gradient online, but I did find this:
Due to its significant drop in this area – 82 ft over 7.5 mi – the river has many rapids. The Chambly Canal consists of nine locks and a length of nearly 12 mi, allowing boats to navigate past the rapids.
So a similar real life river, with a similar slope to what you are proposing, required a canal with nine locks to allow navigation past the rapids. And that is for barges not seagoing ships.
For comparison, Portland Oregon is about 110 miles from the ocean by a river navigable to oceangoing ships. Portland has a stated elevation of 50 ft, but the Portland waterfront has an elevation of 20 ft. Having walked along the waterfront, I know that the ground level is at least 10 ft above the water level. So a fair estimate of water level is about 10 ft, at a distance of 110 miles from the ocean. Also for comparison: Astoria, located at the mouth of the Columbia where the river is at sea level, has an official elevation of 23 ft. Longview, about 50 miles inland, has a stated elevation of 20 ft. So clearly the river follows a very level course, and the port towns along it are at least 20 feet above the water.
Interestingly, Vancouver on the opposite bank of the river from Portland, has an official elevation of 171 feet... approx 160 feet above the river surface. Vancouver is also a port city receiving oceangoing ships and does not appear hilly, although the ground does slope up away from the river.
Portland and Vancouver were very vulnerable to flooding prior to the dams; the river is known to have risen 15-33 feet during flood season, completely inundating low lying areas, creating a "lake" miles across. This image shows Vancouver with a clearly visible floodplain, and the slope up to the actual town level behind it:
As you can see the slope is noticeable but not extreme; this does not feel like hilly country, though there are some slopes here and there. That is what I think Specularum is probably like.
I am going to suggest that the elevation of the Volaga river at Specularum should close to sea level... maybe 10 ft at most, probably more like 2-5 ft. I would guess the river is slow and placid and deep up to Specularum, which is the highest place reachable to seagoing vessels; and still placid but shallower and somewhat swifter up to Kelvin, suitable for riverboats. Beyond that the river alternates navigable and rapid sections, and in some places boats might have to be towed upstream by mules due to swift currents.
The land around Specularum is generally level around 150 ft elevation. There are occasional streams and very gentle slopes, and an occasional hill. The Volaga flows through a broad, well-defined valley. The river valley generally slopes gently, but at Specularum the hills are fairly steep and approach close to the river. This provides both a good place for fortifications, and also high ground on which to build a port city safe from floods. The presence of mirror bay is an additional fortuitous feature. Mirror Bay was originally part of a river oxbow that stretched in a long arc through the foreign quarter, and down along the wall between the nest and the church district. It had become a separate oxbow lake long before humans settled here, as the river shifted course and the lands to the north and south filled in. The Stronghold and Church districts are low hills, which long ago were islands in the Volaga. They rise maybe 40 ft, enough to escape floodwaters but not reaching the level of the surrounding land.
When the city was built, it was first build in the Old Quarter on high ground nearly 150 ft above the water. A canal was dug (by Nithians?) between Mirror Lake and the River, creating a sheltered port. The King's hill was taller and more defensible, but too steep and rocky for a village with gardens. As the settlement expanded, the soggy Nest (once home to marsh-loving birds) was filled in and built up.
Most of the town is not really built on hills, so much as shoulders of the river valley that are separated by gentle ravines. The tops of the hills are generally all the same level as the surrounding land, but provide nice views of the river and valley. While significant parts of the city are in the ravines, the western half of the city, particularly the Old Quarter and South End, is built at this 150 ft elevation level ground, and that is generally taken as the elevation of the town. The one true "hill" that rises above the surrounding land is of course The Hill, crowned by the ducal palace. The hill rises maybe 50 feet above the surrounding land, enough to be noticeable, and the palace is built at the highest point