Tuesday, August 14, 2018

Tides?

I'm always obsessing about how things work. The river here has been one of those obsessions almost since I got here. Here's an annotated map of the river around Sevilla:
 This is the Guadalquivir River as it flows through the greater Sevilla area. It appears to split into two channels above Sevilla and merge back into a single channel below Sevilla. From there, it is navigable to the Atlantic Ocean. Because of this, Sevilla has been a significant naval and commercial port since the Romans established it in the 2nd century BC.

I say "it appear to split" because if you look closely at the top of the diagram, you see a land gap between the left and right channels. In fact, the right channel is really a spur that extends northward from the southern junction.

For being a long spur with no natural current, the water is surprisingly fresh, not stagnant. Though Palma once claimed that it was tidal, from my observations, the spur is not tidal. That said, the water level does change, but only by small amounts and only over a period of weeks (not a couple of times a day like a normal tide). This suggests that the water is some how engineered or managed. I can imagine that there are pipes underground at the north end that can be opened or closed. I know for a fact that there is a lock at the south end that controls flow and ships in and out of the Port of Sevilla (which is actually located on the spur).

According to Palma, Sevilla was subject to severe and regular flooding until the lock system was put in place. During high flow events, the lock prevents the water level in the spur from rising past flood stage. Meanwhile, the left-hand channel has built up dykes and flood walls to protect the city. From the wikipedia page, it looks like the river here has been an ongoing engineering concern almost since Sevilla was first settled by the Romans.

This morning it was cool and foggy. Here's a before and after photo of the river, last night (dry and sunny), this morning (damp and overcast):
It cleared pretty quickly this morning, but didn't get quite as hot.

Enough about the river. Tomorrow is the Roman Catholic holy day called "The Assumption of Mary". It's a big holidy here and everything is closed. We went to the supermarket today and made sure we had enough to get us through tomorrow (we have to do this for every Sunday too, so nothing new). Here's our goto market, about 1km from our flat:
Almost always get to see a dog in the foyer waiting:
This afternoon, I took a break from math and walked with Laura to her language school. I saw this other dog outside of a tapas bar, waiting:
On the way home, I spotted a sign with a cool contraction that I've been seeing in lots of places around town, but finally remembered to take a picture to share. In Spanish, there isn't really a possessive form with an apostrophe. Instead of  "Alice's car" you say "the car of Alice" or, in Spanish, "el coche de Alice". In this case, "de" means "of". It's such a common word that there's a symbolic contraction where the 'D' and 'E' a placed on top of each other. You can see an example of it in this sign:
It says "ASOCIACION SEVILLANA DE CARIDAD". Notice the 'D' and the 'E' atop one another. (It's amazing the stupid things I fixate on.)