The Salt Front

The salt front is the point where a river becomes too salty to be safe for drinking water. The front moves upstream from the river’s mouth as less freshwater flows downstream to dilute it. I’d never heard of a salt front until I read about it in a recent article in the Philadelphia Inquirer. The region’s severe drought in November caused this front to move significantly further upstream than the median monthly location.

On the map above, via the Delaware River Basin Commission (cropped for ease of reading), the pink area is the median salt front location and the pink arrow shows the normal location of this front in November, near Wilmington, Delaware. The blue arrow shows the location as of November 18, 2024. 

The DRBC monitors freshwater flows to keep the salt front from migrating too far upstream. This protects drinking water and industrial water intakes. There are major drinking water intakes for both Philadelphia and New Jersey at the blue box on the map. One way to keep freshwater flowing is to release water from various upstream dams.

The worst droughts were in the mid 1960’s-this shot from one of their videos shows the most upstream movement of the front on November 20, 1964,

and here is a still map showing more specifically the salt front’s furthest upstream location during the “drought of record”

 

Finally, here is a screen shot from the hydrologic conditions dashboard, showing conditions on November 23, 2024.

 

Philadelphia Bookstore Map

Note: As September comes to a close so does Philadelphia month. There will be a couple more posts today and tomorrow before I return to my normal weekly schedule.

This one is personal. Several years ago I was working with a Philly-based computer programmer and an artist to create a map of bookstores in Philadelphia. We put together lists, artwork and I made a few mock up maps but we never got much interest from the store owners. Apparently someone else did because the Philadelphia Bookstore Map is now a reality. A creation of artist Henry Crane (I don't know him) and the booksellers (unlike us he got them to buy into the project), the map succeeds pretty well while incorporating some similar artwork to what we were going for-images of the stores and some local sites.

As a disclaimer, I have not yet seen the paper copy, only what is available on the web page and on Instagram. It looks like there is an inset map (not shown online) of the stores on South Street, a good way of the solving the density problem we also faced.

A few minor points of criticism. I would have muted the background map to make the points stand out more though he could have also done that using bolder point colors. I'm not a big fan of the overly Google-looking teardrop shapes but they work fine here. The colors for different categories of stores could also be more distinct. 

One of the best things about this is that in the online version there is a page to access sub-pages for each store by clicking on the bookstore drawings.

I chose this image of Bindlestiff Books because that is one of the stores we visited on our journey. One last nice detail - he used one of my favorite Rittenhouse Square statues from my childhood, Billy the goat on the cover.

via Instagram

 

Hidden Hydrology

In my day job I've mapped buried streams to give an indication of areas that are most likely to flood in major storms. It turns out that buried streams in older urban centers is common everywhere. Hidden Hydrology is a great resource for exploring disappeared waterways throughout the country. I stumbled across their extensive PhillyH2O page. Here are some maps, from the extensive Water History PHL site.

The map below shows just how few of the original streams (in blue) remain and shows the sewers that have replaced these streams in red.
 

An inset from the Lenapehoking Map, mentioned last week also does an artistic job of showing these same waterways.

Here is an 1895 map from the Water Department showing the proposed and existing sewers and how they head for and follow streams to take advantage of the gravity flow.

Here is an exaggerated topographic model of the city

Finally a diagram of Frankford Creek. The "A Snake That Will Be Straightened Out" says everything about the attitude of conquering nature that was prevalent at the time.

There's plenty more to read about Philadelphia's water system here and other cities here.

The Coaquannock Map

I will begin Philadelphia month at an early stage, just before European settlement.

via Historical Society of Pennsylvania

This 1934 map showing the homeland of the Lenape people when the first white settlers arrived in Philadelphia, was funded by the Works Progress Administration (WPA) . The full title is Philadelphia Region when known as Coaquannock "Grove of Tall Pines" and As First Seen by the White Men. 

 Here is a detail showing the villages of Coaquannock and Shackamaxon (still a street name having inpired this wonderful song), just north of center city. These are two of the four circular villages of the Turtle Clan, as described in this blog post.

The text on the map provides some place name translations such as Kingsessing (place of large shells) and Wingohocking (a favorite spot for planting) and, of course Manayunk (where we go to drink). There are also now buried creeks with name translations such as "where we were robbed".

This map is listed on the Temple University digital collections as "Map of Philadelphia at the time of the arrival of the first Swedes" and was originally published in the Philadelphia Bulletin, an evening newspaper that died in my youth. If you want to dig into the individual neighborhoods and see what remains, take a look at this post from Philly Trees. 

My Family's Exodus from Ukraine

A few weeks ago some of my family members had a Passover seder. Passover is an exodus story. With huge numbers trying to leave Ukraine right now our thoughts turned to my own family's exodus from there. Rising antisemitism, employment restrictions and forced military service drove my family to risk everything to escape from Khotyn, Ukraine (then part of Austria-Hungary) and come to the United States. My great grandfather was the first to leave, in 1905. He traveled by steamship from Hamburg, Germany to Philadelphia. How he got to Hamburg is less clear but the shipping companies arranged for passengers to travel there by train with minimal harassment. I made a map of the trip based on railroad maps of that era, making assumptions about the most likely route across Europe.

There was no railroad in Khotyn at the time so they would have needed to travel the 30 kilometers to Czernowicz (not Cherivsti), probably in secret. My great grandmother followed with several children two years later. It must have been very frightening to leave everything behind to go to a place where they didn't know the language or how safe they would be. I'm sure today's Ukrainians are going through similar or worse horrors. Here is a second, less interesting map I made to complete the journey.

There is a story about my great grandmother going grocery shopping on her first day and not recognizing the house on the way back because the houses in South Philadelphia all looked the same. She had to walk up and down the street a few times before a neighbor came and helped her. If you see a lost refugee, They might need your help!
 
 

Thirty Day Map Challenge - Part 1

 Several years ago Finnish cartographer Topi Tjukanov began the Thirty Day Map Challenge and it has run every November since. The idea is to create a map every day of November based on a theme he posts at the start. These maps are posted to Twitter using the hashtag #30DayMapChallenge. There have been some wonderfully inspiring maps created in this process. I had never participated before this year, correctly assuming it would take up a major part of my time and energy. 

As in other years, I had no plans to do this but on November 1st I suddenly found myself making a map and it took off from there. At the risk of being a self-indulgent show off here are the first 10 maps. As of right now I don't have an online portfolio so here is a place for me to post them. I'm hoping to continue on this challenge but time will tell if I make it to the 30-day mark.

Day 1 - Theme: Points

I'd been working on a general "where I've been" map and I got to thinking about places I've spent the night. I looked at a few states that either didn't seem interesting or had too many uncertainties when I settled on Ohio. I've been working on my weak artistic skills. This was drawn in watercolor pencils by hand while looking at a map of the state.

Day 2 - Theme: Lines

 I don't really like the song "Every Day is a Winding Road" by Sheryl Crow, but somehow it got stuck in my mind and I set out prove it. I used various mapping services such as Google, Bing, Apple and OpenStreetMap to illustrate examples of streets around the world named for the days of the week. One of the tricky parts was finding streets that are in fact "winding."

Day 3 - Theme: Polygons

Points, lines and polygons are the main building blocks of maps so each one gets a day. DC seemed like a good polygon city. I used Opendata DC to get my points. I removed some tiny triangles and it's possible I missed a few circles and squares. There are many rectangular parks that I didn't include because they don't have "square" in their name. I almost forgot about the Ellipse! 

This was a mixed media project. I made and printed a map using QGIS annotated it with pencils and put a little watercolor into the rivers.

Day 4 - Theme: Hexagons

Hexagons are a popular way to represent grids these days. Studies show that certain patterns are easier to detect with a hexagon grid than a square grid. They are particularly popular with election maps but I was looking to do something a little more creative. Not many things in nature are hexagonal. Bee hives use that shape but that kind of map has been done by many others.  While looking for inspiration, I discovered that some of Annie's Snack Crackers are hex shaped, including their saltines and cheddar crackers. I decided to use them as my hexagons.

    So where is a place that has both salt and cheese production? I settled on upstate New York, knowing where some of these places are located. The salt areas are mostly based on an old map I found showing salt deposits, mostly in the southwest. I also know of a couple of salt facilities from my travels so I put those in. I used the term "more likely" to cover the uncertainties but some of those hexagons in the southwest should probably be cheese. The cheese areas were determined by a combination of dairy farm maps and places I know that make cheese.

Day 5 - Theme: Data Challenge 1: OpenStreetMap

For the uninitiated, OpenStreetMap (OSM) is like Wikipedia meets Google Maps. Content is all user generated and it is freely available to use. Despite having contributed to OSM in the past, I don't have a lot of experience using the data so this was definitely a learning exercise. I knew that you can get things like businesses out of it so I tried a query on business names. For some reason, the first word that came to me was "monkey" so I grabbed all businesses with monkey in the name. After seeing an empty South America, I decided to add Spanish and then to make it a bit more objective I grabbed the other three of the world's top languages. In the process this became as much of a linguistic map as anything. 

There are many translation issues here. French and Spanish have different masculine and feminine words and the Spanish words (mona, mono) are contained within many other words and names. My Hindi translation must have been especially off since all my results came from outside of India. Anyway I did what I could here.

Day 6 - Theme: Red

Getting personal here. This is a map of the town where I was born. I was nervously waiting my turn to perform some music on Zoom and parlayed that energy into drawing. Like #1 I tried this completely freehand, while looking at Apple Maps. I've only been through Red Bank as an adult on a train so I don't know the place at all. Someday I hope to visit. The river west of downtown is very wrong and there are other mistakes. Also the map monster and train station were poorly done.

Day 7 - Theme: Green 

Staying in the realm of the personal, Rittenhouse Square is around the corner from my grandmother's former building. As a child I enjoyed playing here, especially with the goat statue. I also lived in the area briefly as an adult. I'd been thinking about how the same places look in different map services so I made an animation of the square using Apple, Google, Bing, Mapbox, Carto, Esri, Stamen, Mapquest, OSM and the philly.gov web site.

Day 8 - Theme: Blue

I started out trying to get a list of blueberry names using the Day 5 OSM theme but the results were not great. Next, I tried using the Google Maps API but also had issues with that. Finally, I found an embedded Google Map from travel-mi.com. I wasn't planning on a Michigan focus but because the data set was there I went with it. I already had a blueberry symbol from my What They Drop on New Years Eve map so I was good to go!

Day 9 - Theme: Monochrome

I thought one of those solar potential maps would look good in monochrome but I'm not sure it works. I also thought that light should be more sun but usually darker means more so this ends up being a bit counterintuitive. I also was not really able to get the subtle gradations of grays with a watercolor pencil. I probably should have tried charcoal instead. I don't trust my drawing abilities to do a complicated outline like this freehand. I traced it right off the computer screen. The rest was done freehand, making it "charmingly inaccurate". 
 

Day 10 - Theme: Raster

I made a very low resolution version of a satellite image of Australia. Then I made a fuzzy version. I couldn't decide which I liked better so I made an animation: blocky vs fuzzy

Though this challenge has taken up way too much of my time and thinking process, it has also been a creative inspiration and a great learning experience so far. I'm looking forward to some of the upcoming challenges with a touch of dread but also excited to take them on.

Mapping the Dream

For many years I had a recurring dream where I am exploring a non-existent neighborhood in Philadelphia. Despite its non-existence, it had very clear geographic parameters within West Philadelphia's University City area. I would take the subway westbound to approximately 33rd Street, walk through the area passing all the interesting urban things (coffee shops, clothing, book and record stores) that mostly don't exist there and get back on somewhere in the 40-something streets to go home. The picture in my head is clear enough that I decided to draw it.

I left the street names off of the drawing because they were not in the dream. The area breaks free of the grid pattern in interesting ways, revealing my anti-grid bias. Also in the dream I'm taking an underground subway whereas in reality it comes out of the ground and becomes a surface streetcar. This is what the area really looks like via a SEPTA map. The Baltimore Avenue trolley line is the closest thing to this subway. 

Using some photo manipulation I altered the map to the dream reality. I moved Baltimore Avenue northwards because I pictured the subway line as a direct continuation from 33rd Street.

Here is an animated comparison of reality vs. dream

Keep on dreaming!

A Critique of the New SEPTA Map

A recent article in Bloomberg discusses how SEPTA, Philadelphia's transit authority is trying to improve wayfinding including creating a new map with new nomenclature. While most of you probably don't care about SEPTA, I navigate this system almost every time I visit my Mom so this is personal.

The system is very difficult to map, complicated by subways, both elevated and underground, commuter trains, buses and various types or trolleys, some running along streets, others with their own dedicated rights of way. Additional complications come from the many different agencies that run lines through the area such as Amtrak, PATCO and New Jersey Transit. While trying not to go full negadelphia on here, the more I look at this map the less I like it. 

 

My first big complaint is this triple line representation. It creates a lot of unneeded visual clutter to just show local and express routes separately. The current map. does just fine with one line.

I'm also not impressed with the new nomenclature. Naming lines based on the county they serve M1, D1, etc seems arbitrary, especially given how county lines cut across otherwise uniform suburban areas. Then using "T" for trolley lines, but giving the Girard Avenue trolley a separate letter and color? I could go on a rant about the "L" for what used to be the "MFL" too but I'll spare you. Also, there's an "L" bus line to add to the confusion. Why doesn't PATCO get a letter designation? Finally, is it really necessary to have G1, L1 if there is only one line? I would remove the "1" to keep it simpler.

Also, notice the mess created at 69th St Station by separating local and express lines.

The complete lack of visual prominence of the heavily used regional rail lines is also not good. I get how they create a lot of clutter on the current map but they went too far the other way. I'm OK with making the more frequent rail lines more prominent but one of the problems here is that the less prominent lines are almost indistinguishable from the seemingly random* occasional street. See how the width changes at Penn Medicine** below and then compare the thin line below it with Spruce Street.

Getting back to the multiple line representation, take a look at how it makes the green subway-surface lines way more prominent. I don't know what the ridership data shows but I usually think of the blue line as being the most used/important line here.

A few more complaints before I finish. The wheelchair accessible symbols are almost invisibly small. They want to show accommodations for disabilities while making it hard on those with vision issues. Does the "express sports special service" really need a separate line given how infrequently it runs? I also don't like how tiny the dots are on the non-transfer subway stops.

I'm all for changing the map and even the line names where it makes sense but so far this new map is not an improvement. I hope they can get to something better.

* I understand why they chose the streets they did to include but by only having a couple of non-transit streets, it gives those decisions a random feel.

** I could really go on a rant about corporate station names but that is a decision SEPTA made without consulting me. Jefferson Station is particularly bad as the name says little about its location to anyone not very familiar with that part of town. This is also one of the busiest and most tourist-y. stations in the city. Also, if you're visiting from out of town and want to see your sports team (most likely) beat us, you're just supposed to know to head to "nrg"

What Can We Learn From Orientation

This week's popular distraction on the geo-webs is an app that draws every street in a city (or other location) colored by orientation. Here is one of my favorite personal places, Philadelphia.

While seemingly just a meaningless distraction the colors do tell you something about settlement patterns. Settled on a part of the Delaware River that runs due south and then west, the major part of the city is along an almost north-south (red) grid. However most of the river flows at about a 45 degree angle and much of southeastern Pennsylvania is on a grid shaped by the river's direction (the purple and blue lines). In the outer parts of the city these grids collide creating some of the more interesting urban spaces in the city (IMHO). Here is the southeastern part of Pennsylvania. I expected to see more purple but there is still quite a bit in the northern regions of the metro area where I grew up.

Note that the app allows you to change the background color. For most of these images I set it to black because the roads show up more clearly. 

For a more meta view here is all of Pennsylvania.

I do not recommend loading an entire state as it takes a while and may overwhelm your computer (and their server).

Points of interest include the colorful twists and turns of the central valleys and ridges, the separately unique Lake Erie grid, and the holes in the northern forests where no roads run. As a different type of city Pittsburgh, one of the toughest cities in the country to navigate, is quite colorful. There are still many grid neighborhoods but they run at all kinds of angles, often at the whims of the rivers.

Pittsburgh-taste the rainbow!

For a suburban view, here is the area around my childhood home in Levittown, PA. The blue lines in the upper left corner are from a shopping mall parking lot.

Many cities in the western half of the United States strictly follow the township and range grid of the public land survey system. Often the downtown areas run at an angle either to follow a railroad or to accommodate an older grid system. Here is Denver. 

Denver-embrace the yellow!

As a proof of concept here are four other cities with a similar pattern.

I could go on about this for way too long but I'll end with an artistic mashup of some of the more interesting and colorful places I've explored in Philadelphia. You can explore you favorite places here.
 

Clockwise from top left - the art museum area, the effect of the Schuylkill River bends, roads curving around the airport runways, the way Roosevelt Boulevard breaks up the northeast grid, some curvy suburban colors, and a difficult to see Logan Circle.

Sea Level Rise-Coming to a City Near You

Conspiracy of Cartographers has a series of maps showing what will be underwater in various cities after 215 feet (66 meters) of sea level rise. Keep in mind that this is "end point" sea level rise and not anything we would see in our lifetimes. A recent page highlights new maps of Philadelphia,

and Washington, DC.

Both maps show similar patterns with the central cities completely flooded and the land being mostly peninsulas in the hilly north and western suburbs. There are also some nice puns.

In Philadelphia, Hunting Park becomes Fishing Park, University City becomes Irreversibly Pity, Wayne Junction, Drain Junction, and Northern Liberties is now Northern Fisheries.

Other maps have been done for cities in the U.S., Australia and England as well as a few larger regions. Here are Cascadia,

 The Palm Springs-Coachella area of California,

an almost completely waterlogged Brisbane,

and Los Angeles, featuring one of my favorite puns- the Ex-LAX airport.