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Lab 10: Impact of Sea Level Rise on Coastal Communities

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There are two parts of this lab. In the first, you will look at recent trends in sea level from tidal gauge data going back to about 1940. This will allow you to determine the places where sea level is rising the fastest. In the second part of the lab, you will be looking at future sea level rise projections for certain areas. The first part of the lab is in Google Earth; the second part is in a web browser (the Google Earth files for this type of analysis don’t work well yet).

Video: Instructions (8:27)

Click here for a transcript of the Lab 10 Instructions video.

Hi students. So, today we're going to be talking about the sea-level lab, and how to manipulate files and get the data you need. In the first part of this lab, you're going to be looking at tide gauge data to look at recent sea-level rise, since about 1940 or so. And this is a KMZ file that you will load into Google Earth. And what I recommend you do, is you load it, and then basically it's very, very straightforward. What you're going to want to do is zoom in. So, I've loaded it, and now you can see my dots appear on my map. This is just the U.S.; the data are global, though. And you can see the dots appear on the map. The different colors are the time intervals. So, the last reported year is, in green, is 2016. Generally, we don't tend to use the older sites which stop recording in 1998, etc. So, we're gonna be looking mostly at these green dots, and I'm gonna give you the name of a station in this state. So, you're gonna have to cruise around a little bit to look for them. So, let me just pull up one of these records that look at the east coast of Florida. Let's zoom in a little bit. Let's say we're gonna look at the east coast of Florida, and I'm gonna click on this guy here. You can see that there are two dots that show up. It doesn't really matter which one you choose. I always tend to choose the one that's in the ocean. If you see two dots that have different colors, you're gonna want to choose the most recent one. So, generally choose the green one. If there's like a yellow one and a green one, choose the green one and click on it. And then, it says Trident Pier, Port Canaveral. And I'm gonna click on the PS MSL ID number, and it's gonna open like a little web window here in Google Earth for you, and you're gonna see down here. This curve is what you want to be looking at. It's the monthly data in millimeters. Okay, these are millimeters, so seven thousand millimeters, seventy-two fifty millimeters. This is a 250 millimeter difference. Which 250 millimeters is 25 centimeters. Okay, so you can see 25 centimeter difference from here to here. And you're gonna be looking at trends. So, in this case, you can see that the sea level is rising. It's kind of slow. You're gonna want to be looking at the middle of this these annual variations, which are to do with tides and all sorts of other phenomena. Alright. So, you're gonna want to look at the averages, and you can see that it's averaging rising from about 7,000 here in 1995, which is the beginning of your time series. And up here, it's averaging somewhere in the middle maybe, up here, just about 7200 or so. So, sea level is going up, as shown by this tide gauge data. So, you can be looking at a bunch of stations from different places and answering questions about what the trends are. Is sea level going up or down? Remember, this is relative sea level, so it is sea level relative to the coastline. And, in some cases, just to tell you, the sea level (relative sea level) is actually going down, which means the land surface is rising up. So, this is kind of a cool lab because you're gonna be looking at very powerful data set, the tide gauge data. All right, so, that's that. It's pretty straightforward. So, I'm gonna get out of Google Earth. I'm gonna quit Google Earth. And now, I'm gonna keep looking at the sea-level rise data set, which is a really cool data set because it shows you flooding maps for what happens when we raise sea level. And the first thing I want to do is I want to change feet to meters. Unfortunately, it's underneath my recording button, so I'm not sure I can actually do that. But you're gonna want to change it to meters. This is a foot scale and if you click down here on the bottom, you'll see that it allows you to click on the knob, which I can't do, and change it to meters. Okay, so you will be working in meters. There are several things you can do. You can change that, you can raise sea level 2 feet, 3 feet, 4 feet. It doesn't show a whole lot till you move close. So, let's let's look at Houston, Texas. I'm going to zoom in on Houston. It’s a pretty low-lying area. It's not one of the ones we deal with though. Look at the coastline in Houston and you can see it's a really nice Google Earth Map. You can actually go up here and you can look at base map Street View. So, in some cases, I'm having you look at Street View, in some cases I'm having you look at satellite view. So, it's kind of cool. If you live in a coastal area, you can see the street you live on. And now, you can see what happens when I start raising sea level 5 feet, 6 feet. You'll see that not much is happening over here. But if we move up here, you can see there's a lot of flooding right in this part of Houston. You can see if I if I go back to one foot, two foot, three foot, four foot, you can see the progressive flooding. So, that's one thing that you're gonna want to look at in this lab. The other thing that's really cool in this lab, and I'm gonna go back to Street, and I want to move out. Let's move over here. This should be my…Why is it not letting me move out? There should be a scale over here. I'm not quite sure why it's not letting me move out. That should stay here, okay. So, actually, you know what I can do? I can enter an address. So. this is a cool thing. I actually have you do this. So, Miami, Florida. Actually let’s not go to Miami because that scenario you're gonna be dealing with. Let's go to another coastal city. Let's look at a flat coastal. Let’s go to Mobile Alabama. Mobile, Alabama and now it’s going to take me there. Okay, so here we are, Mobile. Obviously very low-lying and there's five foot of sea level rise in Mobile. Go back down again, three foot, you can see the water goes out, but, boy, it's flooded this area pretty well. I'm gonna go back out to satellite view. And what you can look at on the left side here, is you can look at flood frequency, which would give you an area in red. Very similar to that other map showing you how frequently that area floods. But you'll also notice areas around these creeks are flooding a lot as well in red. So, that's the flood frequency. And the other thing we have you look at is this vulnerability map, which I find really interesting. And you look at the vulnerability map, and it tells you a lot. So, there's not a lot of construction here, so that's why that's not that vulnerable. But if you look at Mobile, most vulnerable is in red and least vulnerable is in pink. And you can tell differences between different areas in terms of their vulnerability. What it means is the vulnerability is not just the susceptibility of an area to sea level rise, but it's also how vulnerable the population is. So, for example, if you're looking at the inner city where there's a lot of poor people who can't adapt to sea level because they don't have the resources, that's going to be an area that's more vulnerable to sea level rise, than if you're looking at downtown Manhattan where everybody's millionaires. Okay, and so that's just an example. This is sort of a sociological side of sea level change that I find so interesting, and I hope you will too. So, you're going to be looking at a combination of the sea level rise view, you're going to be looking at the flood frequency view, and you're also going to be looking at this vulnerability view. And to move around from area to area because… Oh yeah, here it is. Look at this, there it is. I just lost it. I'm thinking I'm in Google Earth, but here it is, down here. Just enter these addresses where you want a tool around to. So, enjoy yourselves. I think it's a lot of fun. It's a really interesting lab, and you can tell I'm really enthusiastic about it. So, I will talk to you later on.

Files to Download

PSMSL Tide gauge file

Practice Questions

Part 1.

In this part of the lab, you will look at tide gauge data showing relative sea level rise data back to about 1940. The goal will be to determine trends from rather noisy data, determine places where relative sea level is rising faster than others, and the reason for the rapid rise. In the practice lab, we will focus on the West Coast of the US.

Load the PSMSL Tide gauge file in Google Earth. The file shows tide gauge data from around the world which will allow you to explore the rates of sea level rise. The dots show stations organized by the last reported year. Click on stations, and you will see a PSMSL ID number; click on that, and you will get tidal gauge data in mm (for several locations several dots appear; make sure you click on one of the dark green dots).

  1. Go to Crescent city in Northern California. Is relative sea level rising or falling over time?

    A. Rising

    B. Falling

  2. Roughly how much has relative sea level changed since the beginning of the record at Cresent City?

    A. Over a meter

    B. Over 0.25 m

    C. Under 0.25 m

  3. Now go to Neah Bay in Washington State in the tip of the Olympic Peninsula. Is relative sea level rising or falling over time?

    A. Rising

    B. Falling

  4. Roughly how much has relative sea level changed since the beginning of the record at Neah Bay?

    A. About 0.5 m

    B. About 0.3 m

    C. About 0.1 m

  5. Based on just these two records, what is the dominant process controlling relative sea level change in these locations?

    A. Isostatic rebound (removal of ice)

    B. Subsidence

    C. Uplift due to tectonic activity

Part 2.

Prediction of the extent of flooding that results from sea level rise is much simpler than predicting the absolute amount of sea level rise that will occur over coming decades. Flooding predictions are based on digital elevation maps that have great accuracy and resolution. The NOAA sea level rise and coastal flooding tool allows you to look at areas in detail and make predictions about the future under higher seas. At the top, you can enter an address to look closely at an area. For the practice, we will look at Tampa, FL, so enter this in the search window. Note: it can take a while for a clear image to come into view. Remember 1000 mm is a meter.

Go to NOAA Sea Level Rise Viewer and click on Get Started. You will see a map focused on the US which is where we will be working. On the bottom left, please make sure the elevation scale is in meters, not feet. We will look at three different views: (1) sea level rise which allows you to see how the area floods as you move the slider up. (2) Flood frequency which shows the areas that currently flood frequently; and (3) vulnerability, which is a comprehensive assessment on how vulnerable certain regions are to sea level rise (based on elevation as well as population density and demographics such as the percentage of people living under the poverty line).

Using these three maps answer the following questions:

  1. At what sea level rise in meters does Davis Island begin to flood? (Give your answer as a number.)
  2. At what sea level does St. Pete Beach begin to flood? (Give your answer as a number.)
  3. Look at De Soto Park (southeast of downtown). Why is this area vulnerable to sea level rise?

    A. Low elevation

    B. Demographic factors

  4. Look at Ybor City (northeast of downtown). Why is this area vulnerable to sea level rise?

    A. Low elevation

    B. Demographic factors (poorer residents)

    Now go back out to St Petersburg. Compare downtown St. Petersburg with St. Pete Beach.

  5. Which has higher flood frequency?

    A. Downtown St. Petersburg

    B. St. Pete Beach

  6. Which has higher vulnerability?

    A. Downtown St Petersburg

    B. St. Pete Beach

  7. Why is the vulnerability of St. Pete beach generally low?

    A. Because it is close to sea level

    B. Because of demographic factors (wealthy residents)