Down in the tropical reaches of South Florida, a stone's throw from the vast Everglades and the Keys, is a sparkling city set like a sapphire on the crest of the land and facing the Atlantic Ocean with pure adoration. The clear blue water is so beautiful that it's almost unbearable to look at, and Miami runs up to the edge as if to claim the entirety of the sea, and be entirely claimed by it. No height is too high, no closeness to close, as Miami towers precariously over the delicious sea.
On The Water
Florida is both framed by water and saturated in it, with much of the low-lying terrain being made up of porous limestone. The spongelike quality increases as the peninsula continues south, and with it the presence of marshlands and mandrake fields where little can be built, and which contribute greatly to the health of ecosystems and help filter the water inland. Miami is situated just east of the huge marshland of the Everglades, and just north of the low-lying Florida Keys flung like pebbles into the Straits of Florida. This is an area geographically defined by its relationship with water, and where regular flooding is a natural part of the ecosystem. It extends away from the rest of the continental US like a foot dangling in a stream, leaving it protruding so vulnerably that it's almost as though it wants to be hit by hurricanes and tropical storms. For populous and popular cities like Miami that line the edges of Florida and practically throw themselves into the sea, occasional major flood events should be understood to be inevitable. A map of the Miami area is on the right (Click to enlarge).
Dealing with water is among the most important factors to consider in the design of the built environment, from architecture to infrastructure. Water intrusion and stagnation can cause deterioration of building materials and the spread of harmful mold and even insects. Shallow-rooted trees like palms can tip over easily when the soil is saturated. Large amounts of water rushing in to an area can cause incredible damage, and if the area stays flooded for a while it can create health risks and leave people stranded. So while major storm events are inevitable, it's important that cities which are environmentally vulnerable are infrastructurally prepared for evacuation and water management. In a series of map layers, we'll compare human element of Miami with its vulnerability to rising waters, while visualizing the incredibly sharp wealth disparities in this shining tropical metropolis. Click below to enlarge.
This flood map shows the places in Miami in which flooding is most likely to happen, according to data from FEMA. Notice that these are not only the shores of the ocean and the bay, and areas adjacent to other bodies of water inland; many areas are simply very low in elevation, so they are likely to collect the water rising from below, falling from above, and flowing in from nearby areas, during a flood event.
Consider the legend on the left. You can refer back to it for the rest of the map layers. The flood zones break down into two categories: in less saturated blue, the regions with a 0.2% chance of flooding in a given year; in brighter blue, the 100-year flood zone, or the areas with a 1% chance. In solid blue are the water bodies in and around the Miami area. By comparing the map with and without the flood layers we can get a visual idea of how water encroaches during major storms, which Miami experiences not infrequently. You can find FEMA's detailed definitions of various flood zone types here.
The majority of the indicated flood hazard zones belong to the 1% hazard category. It can be expected that in the event of the 0.2% hazard area being flooded, the areas with more significant risk are likely to be flooding too. Flood hazard zones affect almost every part of the Miami area, with some areas virtually encompassed in the 1% zone not only on the islands in Biscayne Bay and along the beaches, but far inland as well, especially along the artificial waterways toward the north and bisecting the city diagonally. As you can see in the map, a flood event could affect entire city blocks and neighborhoods and significant portions of infrastructure.
Underwater
With this information alone, it's apparent that the city of Miami is situated with considerable vulnerability to flooding. Even outside of the flood zones, districts can be negatively impacted by high speed winds, heavy rains, loss of power, and blocked roadways. Knowing that floods can create a wide range of threats to health, life, and property, it's clearly important that the city be prepared to protect citizens in advance of oncoming storms, to fortify infrastructure to withstand them, and to recover from inevitable damage after they pass by. But what does the human element of this situation look like? In the next map layer we'll see where the people are, compared to where the water rises. Click to enlarge.
On a regular day in Miami, within a short distance you can go to the ocean. During a major storm, the ocean comes to you. This map layer illustrates total population using a yellow tint, with larger populations in more saturated yellow, broken down by census tract according to the most recent data from the American Community Survey. Referring again to the legend, you can see that the population ranges from fewer than 500 in the least populous areas, to over 10,000 in the most populous. The two major gaps inland are airports, where nobody lives but many people go. In addition to being one of the most populous cities in the United States, Miami is also extremely attractive to tourists and seasonal residents. By overlaying the consolidated flood hazard zones on this demographic information, we can begin to visualize how extensively major flooding could affect people.
The most populous census regions in Miami are Downtown, portions of Coral Gables (near the University of Miami), Dadeland, Coral Terrace, and Alameda and Doral near the Miami Airport. In the northern part of the map, other populous areas in Miami-Dade County are Hialeah, Opa-Locka, and North Miami. On the islands, at Miami Beach and Key Biscayne, there is a moderate resident population which is supplemented by high tourism. With the exception of Coral Gables, near the center of the map, all of these highly populated places would be significantly affected during a flood event.
Follow the Money
To the world, Miami is a shining, sparkling place full of color and culture, unique architecture and incredible food. It attracts visits from everywhere, and it's a favorite second home to wealthy people with a house or condo overlooking the deep turquoise water. But Miami is a city of sharp contrast as well, and just as real as the luminous and photogenic beachside metropolis is the face of deep poverty and struggle. There is a wide gulf between the poorest and the richest, although they might live within just a couple of miles from one another. Let's look at one more map layer comparing the flood zones to the distribution of wealth in the Miami area, and think about what a flood event can mean for people with or without means. Click to enlarge.
This map layer visualizes the average income in each census tract in the Miami area, according to the most recent data from the American Community Survey. The FEMA flood zones are again overlaid. Areas highlighted in pink are below the median income, and green is above. Referring again to the legend, you'll see that the areas in brightest color are at the extremes: the brightest pink being areas where the average annual income is below $20,000, and brightest green being above $200,000. Note the correlation between proximity to the beach and relatively high wealth, as well as the relative poverty in the center of the city.
When I lived in Miami, I found that one of the most remarkable things about its urban fabric is how incredibly rapidly you can go from high-end, well kept, popular areas, to neighborhoods lacking in maintenance and funding and abundant in vacancies and dilapidation. The shift is most dramatic at the edge of downtown, where you can stand in one of several poor, low-built neighborhoods and see lofty cultural centers and skyscrapers literally a couple blocks away. Almost as incredible is how the towering and relatively new architecture overlooking the sea and the bay tend to be built as physically close to the water as possible, so that you hope they were built to last and withstand inevitable storms.
During a flood event, people on both financial extremes can face different problems. Take a look at the brightest pink areas, in the central part of Miami. In Overtown, Little Havana, Little Haiti, Shenandoah, Allapattah, Brownsville, and Liberty Square, poverty is deepest. All of them, as well as the areas where income is more intermediately low, are directly affected during flood events. Damage to property will be more personally devastating where people may struggle to acquire the means to repair or replace it. If power goes out, it might stay out longer than in primary urban areas. People experiencing the health problems and mobility limitations that are more prevalent in poorer populations, will struggle more if streets remain flooded and blocked for a while after the storm event has passed. People living in these areas should be provided by the city with extra resources to prepare or evacuate, and to receive information, to protect the personal wellbeing and livelihood of lower-income families.
Rising Waters
It's also important to recognize the impact a major storm can have on the richer side of a city as metropolitan and tourism-heavy as Miami. There's a certain idealistic shine that makes the city feel impervious, where most days are sunny and floral, and the sea stops where it should. But once the storm is here and the full ferocity of the sea is sending the tides up to the doorsteps of luxury hotels, its fragility and vulnerability is far too visible. Looking at the way the FEMA flood hazard zones overlap with the entire coastline and almost completely eclipse the islands, we can imagine how serious a major flood event would be for people in higher-income areas where property values tend to be higher. These places are more expensive to repair, more dangerous if they experience structural failure, and their financial viability is dependent on their being safe and available for use by tourists or wealthier residents.
For any area, regardless of the relative wealth of its residents, to be totally submerged for any period of time is extremely dangerous. Miami's recreational and cultural centers are highly vulnerable in the event of a severe storm, and as the entire city is geographically situated such that major storms are an eventuality, it's necessary for the city to have a thorough action plan in place. Fortunately, the city appears to take it seriously, and has resources available on the County website here, in and out of hurricane season.
Based on the map layers we've discussed, we can identify the exact areas where extra help and resources are most likely to be needed during a major storm, and visualize Miami's vulnerability in multiple ways. You can find a similar study focused on Jacksonville, FL in this post, an earlier part of Hovertown's Rising Waters series.
This map was produced with data from the American Community Survey and from FEMA, powered by ArcGIS Maps for Adobe.
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