Today’s canal map of South Florida is the third I’ve shared. These recently created maps are the work of SFWMD’s Z.(Ken) Chen, Ph.D., GISP, Supervisor, Geospatial Mapping Services Unit, and his very talented team: Lexie Hoffart, Nicole Miller, and Erica Moylan SFWMD’s GIS.
Exploring these maps of Dr Chen and Team, in particular, allows one to fly with out an airplane! I am always surprised by what I see and learn. You may be too! Through knowledge we shall achieve a clean water future.
Words of Dr Chen satellite map:
Current Satellite Imagery
The satellite images are from Landsat data that are the most recent cloud-free (e.g. <10% cloud coverage) images over our areas of interest. The sensor on Landsat is called TM or Thematic Mapper. Therefore these images are usually called Landsat data or TM data. Because these individual TM images (or scenes) are processed by USGS following a standard Landsat imagery processing process, and exported to a standard imagery format, therefore it was not very technically challenging when we mosaicked or stitched them together. But the mosaicking was a very time-consuming process because imagery processing always requires a lot of computer time (i.e. CPU and GPU intensive) partially due to the fact of large file size of images as well as the nature of imagery processing. During the mosaicking process, we cropped out the black edges of the individual scenes and applied a limited tonal balancing to minimized the tonal contrasts between the individual scenes.
Current Canal Network of SF w/Historic Imagery 1940-1953 Map (Simple Version), SFWMD, created by supervisor of Geospatial Mapping, Dr Ken Chen, and his team: Lexie Hoffart, Nicole Miller, and Erika Moylan.
~Today’s map has almost the same name as July 11, 2020’s shared map, but it is “simple,” as the 298 drainage districts are not marked. To best view this image go to South Florida Water Management District’s Featured Map Gallery, click on the image, and then export the PDF to your desktop. An easy way is to link here to the image entitled SFWMD Current Canal Network with 1940-1953 Historic Images Simple Version (2nd row, 3rd to right) then go to “File” and “Export as a PDF.”
Once downloaded to you desktop, you can zoom in and move up and down wherever you wish to go. North, south, east, west, central. What will you see? You will perceive the modern mapped canal network of South Florida atop hundreds of historic aerial photographs that have been stitched together. These maps are the first of their kind.
This image gives us a clear idea of what canals drain South Florida. I don’t think ever in one place has this information been so visually available.
I will use the east coast of Florida to zoom into with screen shots for examples, as this is my home. Later, hopefully, you can use your zoom feature as described at the beginning of this blog post to downloaded the map as a PDF for an even closer view. It will blow you away!
In the images below, from north to south, we see St Lucie; Martin; Palm Beach; Broward; and Miami-Dade Counties with in the footprint of the Central and South Florida Plan, now managed by the South Florida Water Management District. Mind you many of these canals in the map pre-date the SFWMD.
Oh my gosh! Look at all these canals! Look at the wetland images they rest upon. Most children grow up today not even knowing…
The canals are almost everywhere draining what was once of the largest wetlands in the world. Think of all the animals that once roamed and swam here. According to Mark Perry, CEO of Florida Oceanographic, through these canals approximately 1.7 million gallons of fresh water a day is drained to tide.
Kind of weird isn’t it. Like we are living on a squeezed out sponge. Looking at this map makes me want to rethink Florida. How about you?
CLICK ON EACH COUNTIES IMAGE TO ENLARGE AND SEE ALL OF THE CANALS OVER ONCE WETLANDS – as revealed in 1940-1953 aerials taken by the U.S. Dept of Agriculture.
To understand the creation and complexity of the maps I am including the following words of Dr Ken Chen Ph.D., GISP, Supervisor, Geospatial Mapping Services UnitInformation Technology Bureau, South Florida Water Management District. I had asked him to describe what was entailed with the historic imaging. Thank you to Dr Chen and Team whose talent, research, and time made these maps possible.
Historical aerials (1940 – 1953)
“Sources of historical aerials, especially 1940s and 1950s, are very scarce, especially for such a large area in South Florida. Therefore our focus was to get whatever we could find online regardless cloud cover or quality of images. As you know, all of those old images were recorded in an analog format (i.e. film or paper), instead of digital. Some (maybe all) of those films/paper images were later scanned and saved to a digital format and made available online. Scanning usually results in loss of imagery quality. For this canal map project, we were fortunately able to locate aerial index images (I would call them aerials index panels), after weeks of online research including data download and review. Each index panel displays a group of aerials in sequence over a specific area. For instance, say 200 images from #1 to #200 over an entire county. These index panels are usually used for aerial imagery management and archival purposes, just like a library index card for images. There is no information at all regarding how those index panels were created, but they are seemingly made via camera shooting or scanning of a group of stacked paper images or positive films. The index panels are simple graphics or pictures without any geospatial information, such as projection, coordinate system etc. The first step to process these index panels, prior to mosaicking, was to geo-rectify and inject geospatial information into the images. To do so staff needed to identify ground control points. It’s very challenging to identify those points in those very old images due to lack of apparent landmarks, e.g. road intersections. This is particularly difficult in the middle of nowhere across the vast wetlands in 1940s-1950s. So staff tried to use a very few of the intersections between rivers, canals and a few major roads to geo-rectify the panels and assigned appropriate geospatial information into them to make them georeferenced images. Then staff clipped each panel image to trim out the white or black edges before stitching all of them together for the majority of south Florida.
The original aerials were collected by the U.S. Dept of Agriculture. The aerials index panels were obtained from the Univ. of Florida’s Imagery Library. One thing to note – it’s very evident that there are strong image vignetting effects in the old aerials – bright in the center and getting darker toward the edges. That is an inherent optical artifact in the analog images and can not be corrected during the post processing.
This may be more than you asked for. I’m not sure if I have explained this clearly. To summarize it, this process can be simply illustrated in the following format:
Online search of available sources of data -> data download and review to accept or reject -> identify ground control points (GCP) in prep for image processing -> Using GCPs to georectify the index panels -> inject geospatial information into the panel pictures to make them georeferenced images -> remove the white/black edges -> Mosaick all georectified index panel images -> clip the mosaic to the district’s boundaries before use in the maps.
I forgot to mention the number of historical aerials we used to create the historical mosaic. We used totally 84 aerial index panels. Each panel consists of roughly 50+ to 200+ individual aerials, depending upon the geographic area each panel covers. I can’t get the exact number of aerials, my best guess the number would be ~7,000+-12,000.”
Phy·to·ge·og·ra·phy: the branch of botany that deals with the geographical distribution of plants.
It started with a request, an idea, and over many months materialized with the guidance of Tia Barnett, Governing Board and Executive Services, and Dr. Ken Chen, Supervisor, Geospatial Mapping Services Unit, Information Technology Bureau, SFMWD.
The request: “Could we create an educational map blending pre-drainage natural features such as water flow, plants, and forests with the modern sixteen county map we use for today’s SFWMD’s “Facilities and Infrastructure”?
Dr. Chen excitedly assigned two young modern-day cartographers/geographers to the task: Ms. Lexie Hoffart and Ms. Nicole Miller.
Their research began with an overlay of the famous 1913 Phytogeographic Mapof the Original Florida Everglades by John Harshberger. Then they “moved north” to research the Kissimmee River and Lake Okeechobee using the 1882 Communications Steamboat Map by W.G. Williamson and Q.A. Gilmore of the USACE.
Modern publications were studied as well: a 2017 article by Michael A. Volk, UF, entitled “Florida Land Use and Land Cover Changes in the Past 100 Years:” alsoLandscapes and Hydrology of the Predrainage Everglades, 2011 by Christopher W. McVoy. All this and more was taken into account as an overlay on a modern SFWMD map of present-day facilities and infrastructure including modern estimates of populations.
Wow! What does the old adage say? “The only constant is change!” May understanding the past help us to be better stewards of the future…
The outcome, a document rich in revelation past and present. Thank you, Lexie and Nichole!