Thursday, October 21, 2010

Flooding of the Tiber: Notes

Hey guys! It's Consul Lisa! I went to the lecture on the Flooding of the Tiber tonight on behalf of all of us at Classics Club! These are the notes I took : )

- floods and civilization go hand in hand
- civilizations arose on flood plains, near rivers
- easy to build on, good for irrigation, fertile, good for farming
- attractive but dangerous (Katrina, 19th/20th century floods in China wiped out a lot of the population in just 3 floods)
- Rome along Tiber River, right below Tiber island
- natural place for trade
- between hills: low valleys and plains
- before: valleys were marshes and swamps
- Rome was at the most flood prone stretch of the Tiber River (awesome...)
- Rome continuously occupied 3700 years
- flood marker plaques on the walls (showed the heights of the different floods)
- earliest plaque in 1277
- hydrometer next to a church near Tiber River, record of floods from 1495 on
- before 1200 there were no plaques to record flood heights, but there were literary records and geological evidence
- 44 accounts of 33 floods, 18 famous names (Cicero, Cassius...etc.)
- Tiber River: 400 km from Apennines all the way to Ostia where it empties out
- Tiber riverbed changed very little (now it still looks like it did in antiquity)

Characteristics of Floods in Rome
- Fall/Spring rainy seasons + snowfall from Apennines (75% of floods take place in these months)
- Major Flood: 7-9 days
- Minor Flood: 3-5 days
- above is true for all floods (modern and ancient)
* 1789: Pantheon flooded!
Tiber Classification:
- Ordinary level: 5-7 m above sea level
- Elevated level: 7-10 m above sea level
- Ordinary flood: 10-13 m above sea level
- Minor flood: 1 every 5 years
- Major flood: 1 every 19 years
- all ancient romans would experience 2 or 3 major floods in their lifetime

How far did they reach?
- ground levels in rome much higher now than in antiquity
- Campus Martius, Forum Boarium, Emporium, Transtiberium, Valley of the Circus, Forum Romanum: would have been affected by flood (in major flood, the 7 hills would become like islands)

Floods and different types of buildings
Roman Forum
- political heart
- squarely in the flood plain (would be completely flooded)
Forum Boarium
- early economic heart
- in flood plain (would flood all the way halfway up the columns)
- would have been very first place to be flooded
Coliseum, Flavian Amphitheater, Circus Maximus
- all in flood zone
- did they just not care?

- every building seems to have been built without considering flooding
- except for bathhouses (all were moved to just out of the flood zone, except for the first 2 that were built)
- bathhouses have more vulnerabilities to floods than other buildings
- wealthiest romans could afford private homes (the domus)
- 790 domus
- 1400 apartments
- wealthy could choose where they wanted to live
- most of them (85%) were on hilltops (out of flood zone)
- this wasn't all because of floods, but it was a nice bonus to be out of danger of flooding

Anti-flood strategies
- not one single strategy
Fill: Raise the ground levels
- putting tons of dirt down to raise the ground level to make it higher so water doesn't come in (Forum Romanum)
- Campus Martius
- "The Great Drain" (Cloaca Maxima)
- built before they built the city (to drain the marsh)
- storm drain (quickly carries away flood water)
Divert: Canal Schemes
- cut off tributaries
- early empire: in the end they decided not to cut off the tributaries and do nothing
- because to cut off the tributaries would be to "lessen the majesty of Father Tiber" (Tiber River was considered a god)
Contain: Embankments
- most common way
- if they had, city would have been safe
- some were built, but not continuous or high up enough (only for unloading boats)
- 1870 flood: finally decided to build embankments (18 m above sea level)

Why didn't the Romans do more to prevent floods?
- they had the technology
- study of vulnerability to flooding
- they were either very resistant to floods, or got rid of them really quickly
- hilly and flat
- no matter where you were, you were near higher ground (low mortality rate during floods, different from other places)
Construction Methods:
- horizontal pressure from flood against walls (ancient walls were super thick, could resist this pressure)
- today this would be a problem, walls are super thin
- floods undermine foundation
- roman foundation=hole with concrete, resisted floods
- in all accounts of floods, not one record of important buildings being damaged
Elite Housing Distribution:
- lived on hills (only poor lived near the river)
- the floods would get rid of poor bad housing, make room for more wealthy housing
Food Storage:
- down by river (could be bad for grain: mold...etc)
- but no sources of famine (only after major floods not minor)
- built really resistant warehouses
- only one door, tiny windows, thick thick walls
- kept thieves out, kept water out too, grain was kept dry
Water Supply System:
- after a flood, people need to be supplied with fresh water (could be a big problem)
- aqueducts! (solution, get water from far away: above the start of the flood)

- Roman temples built on podiums (height of podium was according to height that floods could reach)
- libraries too
- this way all the valuable items were safe


1 comment:

  1. Great job!
    I love the part about why the Romans never got around to fixing the problem of the flooding! I guess "if it ain't broke, don't fix it!"
    I like the fact that the libraries were elevated up high (just like JPL Library!) because they were so valuable.