Floods

Case Study 2 Week 3

https://www.nap.edu/read/1784/chapter/8

https://www.accuweather.com/en/weather-news/armero-colombia-tragedy-disaster-30-year-anniversary-lessons-learned-nevado-del-ruiz-volcano/53554025

https://www.unisdr.org/archive/46666

https://www.csmonitor.com/1985/1119/ocano.html

My favorite resource is also a case study of the Armero Tragedy. This resource is useful primarily because of the organized and obvious facts it presents. A lot of the information that I have learned in my various research so far on this tragedy parallels the details given in the case study. Not only that, but there is additional information given that I did not previously know. Ultimately, this resource presents useful and new facts in a “to the point” and efficient manner.

The Great Flood of 1993: Human Impact Resources

NOAA’s Natural Disaster Survey Report published February 1994 detailing “The Great Flood of 1993”

The USGS’s Upper Midwest Environmental Sciences Center published a report about the Ecological Status and Trends of the Upper Mississippi River System (UMRS). Chapter 15 of this report details the Great Flood of 1993.

“The 1993 Great Midwest Flood: Voices 10 Years Later.” A 10th-Anniversary Anthology of Stories of Hardship and Triumph collected by the U.S. Department of Homeland Security Federal Emergency Management Agency (FEMA).

Learning from the Mississippi Flood of 1993: Impacts, Management Issues, and Areas for Research.”

My favorite resource was NOAA’s Natural Disaster Survey Report from 1994. This report is full of information about the 1993 flood including general information, forecasting challenges, hydrological modeling capabilities, warning systems, preparedness, and major lessons learned. The abundance of information it has makes it long but overall I think it’s an all around great resource.

Stop Disasters! Flood

For the last part of Week 2’s assignment I played Stop Disaster! Flood and noticed several things. The first thing I noticed was that low-lying areas were inundated first. This meant that higher terraced areas free of water. Because of this, important buildings and utilities like hospitals, schools, and power stations do better on high ground where they have a lower risk of flooding. I also noticed that building material was an important part of flood mitigation. Wooden and brick buildings withstood flood damages worse than concrete houses which prompted me to build primarily with concrete. A key part of my learning experience with this game came from the small windows of information presented periodically throughout the game. These typically expanded upon actions I was doing and better explained how and why the actions were useful.

Case Study 2 Week 2

Something I learned from this week was that there actually was an evacuation issued for the surrounding towns of the Nevado del Ruiz volcano. Previously, I though the Colombian government was notified of the risk of eruption and mudslides, and they simply just brushed it under the rug. Actually, the government did contact Red Cross to notify an evacuation, but due to stormlike conditions mixed with the heavy ashfall from the eruptions, there was a power outage in that particular area. Regardless, the Red Cross could’ve sent units out there to spread the word once they realized their messages were not being received. This would’ve gave the residents at least three hours to get to higher ground before the series of lahars decimated Armero.

EOTW #7 The Great Flood of 1862

During December 1861 in California, it started raining and raining and raining and snowing in the mountains. After approximately two decades of drought, it rained for approximately four months, depositing so much water that massive regions in California flooded. Large portions of the Central Valley flooded, and approximately 66 inches of rain fell on typically arid Los Angeles. The result was huge losses of cattle from the ranch lands (1/4 of the total head in the state), houses and buildings due to widespread, and often very deep, flooding.  Sacramento, the state’s capital, was submerged in water. Flooding was extensive over several western states, including Oregon and Arizona. The phenomena responsible is called an “atmospheric river”.  Just this week, an atmospheric river delivered significant rain to the already vulnerable regions around Santa Barbara and Ventura, resulting in renewed called for evacuations due to possible mudflows in regions impacted by the Thomas fire. For this EOTW comment assignment, read the first two articles below. I include the USGS website as another tool you can use to learn more about the potential for future mega flooding in the state, as well as maps and assessments of vulnerable populations. Then, answer the following questions:

1) What are atmospheric rivers? About how often do megafloods impact the California and western states regions?

2) Approximately how extensive was the 1861-62 event in terms of geography? (ie which states and countries were impacted)?

3) How well do you think the public is aware of the mega flood hazard, compared with earthquake hazards, in California and other western states?

http://www.noaa.gov/stories/what-are-atmospheric-rivers

https://www.scientificamerican.com/article/atmospheric-rivers-california-megaflood-lessons-from-forgotten-catastrophe/

https://geography.wr.usgs.gov/science/mhdp/arkstorm.html

The Great Flood of 1993: Monitoring & Mitigation

Flood monitoring is done on different scales with the use of several different instruments. Local flooding is monitored through river streamflow gauges, depth sensors, and real-time observation. Large scale monitoring can be done through combining local measurements and remote sensing.

One example of large scale flood monitoring is the Global Flood Monitoring System (GFMS). This system is a “NASA-funded experimental system using real-time TRMM Multi-satellite Precipitation Analysis (TMPA) precipitation information as input to a quasi-global (50°N – 50°S) hydrological runoff and routing model”. This system monitors precipitation and produces flood vectors that can be uploaded into GIS to models flood intensity. The National Weather Service offers flood watches and warnings for large-scale gradual river floods. A flood watch is issued when local weather conditions generate conditions that may produce flooding.

During the Great Flood of 1993, the Weather Surveillance Radar 88 Dopplar (WSR-88D) systems were used to document rainfall and monitor flashflood conditions in large cities like Chicago and Kansas City.  Additionally, The Long Term Resource Monitoring Program (LTRMP), whose goal was to “support decision makers with the information and understanding needed to maintain the Upper Mississippi River System”, had field stations positioned around the Mississippi floodplain. These stations allowed for continual observation of the flood.

Global Flood Monitoring System (GFMS) 

Long Term Resource Monitoring Program

 

Flooding Hazards Game / Landslides Ideas

My second case study is focused on the Armero Tragedy – the deadliest lahar in recorded history. Seeing as the volcano mitigation game focuses primarily on the actual eruptive aspect of a volcano and not the landslide/lahar aspect, I decided it was best to play around with the flood game as well as come up with a few ideas for a landslide game.

The most useful thing about the flooding game was the little bits of information and advice they would periodically bestow on you as you progressed through the game. The more the game advised me, the more comfortable I was with making decisions regarding the safety of the town.

Something that got annoying to me was the time it took to preform upgrades on buildings. Realistically, if a town had to put up new buildings in preparation for a known destructive event, one would think that the proper “upgrades” would be included with the building originally. It would make the experience more worthwhile if there was an option that included the appropriate upgrades upon each time you built something, for more time could be focused on protecting and developing other areas.

In my eyes, a fun and engaging landslide mitigation game would follow nearly the exact format as the various mitigation games: as time went on, the towns risk of a landslide would increase ever so slightly. One would be assigned a budget and a number of people in need of protection and/or displacement due to their location in relation to an area likely to give way or act as a channel for a landslide. The budget would be used to build new homes for people to move out of landslide prone areas, as well as things like walls to catch sliding debris or chain-link meshes encasing slopes or anchors driven into rock faces. As one would progress through the game, they would be given hints that might help them in their future decision making upon their timing and strategy as far as when and where to conduct certain upgrades. Eventually, the landslide would ensue and the player would a receive a report card of sorts including information on casualty rate and number of homes destroyed.

The Great U.S.A Flood of 1993

The “Great USA flood” occurred along the Mississippi and Missouri rivers from May – September 1993. The event took place in the American Midwest, caused $15 billion dollars of damages, and resulted in 50 deaths.

The Midwest is located in the interior United States, north of the Ohio River between the Appalachian and Rocky mountains. This region consists mainly of flat geographic features like plains, plateaus, river valleys and lakes. Due to its location, far from the moderating effects of the ocean, the Midwest region experiences extreme temperature and precipitation that is responsible for hazards like severe thunderstorms, drought, heat waves, regional flooding, and winter storms.

The 1993 flood was an overbank river flood that occurred along the Mississippi and Missouri Rivers following record summer rainfall in the early months of 1993. The influx of water from persistent heavy rainfall and from melting snowpack after the previous winter caused the river to exceed its capacity and overflow the channel.

The most interesting thing I’ve learned so far about this flood is that of the 3 largest floods in the U.S.A. (The Great floods of 1844, 1951, and 1993) the 1993 flood had the highest waters and the lowest discharge rates.

Case Study 2 Week 1

On November 13, 1985 the Nevado del Ruiz volcano in Colombia erupted and triggered the deadliest lahar in recorded history. The presence of the volcano is due to the convergent margin formed by the Nazca plate subducting beneath the South American plate. Again, the eruption wasn’t the deadly factor, but the lahar that the eruption generated is responsible for burying 25,000 people. The most interesting thing that I have learned thus far is that the Colombian government was actually warned about an eruption here and chose not to evacuate. This evacuation without a doubt would have saved thousands of lives, so it is still a mystery to me why it wasn’t executed.

Mitigation of Landslides

The methods that are used for mitigation are often building restrictions. The building of roads requires additional slope stabilization and drainage efforts. Roads may be closed during high snow seasons or preventative avalanches may be caused to control the areas of the slide.  Some common mitigations you see on the west coast is metal mesh netting placed over loose or unstable rocky areas above the roadway.  The used of tiered slopes is also common when heavy grading has been done leaving largely exposed slopes

 

Tiered slopes reinforcing areas of heavy grading.

Rockfall protection along highways.

Gravel wire mesh bank revetment erosion control - Stock Image

Slope support and drainage.

Avalanche protection over highway section prone to avalanches.

 

Cannon used to fire explosive charges to cause a controlled avalanche.