Geography is our passion.
Posts tagged map
Wet or Dry, Rainfall Varies More Than You May Think
710 days
Every time I drive across the country I think about the vast differences in water availability that exist from one side of the country to the other. It’s especially noticeable when driving west on Interstates 10, 20 and 40. These routes begin in the well-watered Deep South, cutting through dense forests as they head west to the Mississippi River and into the plains states beyond.
Once Texas, Oklahoma, or Kansas are reached, the forest is quickly left behind. The pine trees change over to treeless plains in little over 50 miles. I-20 shows this the most dramatically in northeastern Texas where it emerges from the hilly Piney Woods into the tallgrass prairies just each of Dallas.
On the other side of the Dallas-Fort Worth area, another dramatic change occurs. The prairie quickly gives way to mesquite country – a landscape dominated by that thorny tree and littered with prickly pear cactus. Creeks become washes, and green becomes brown by the time you get to Abilene.
Average Annual Precipitation, 1971-2000
I created this map to better understand this transition that I have wondered about so many times before. It is clearly shown in the center of the map – rainfall averages plunge from the mid-50s in the lower Mississippi Valley to around 20 inches in central Texas. 20 inches seems to mark the start of the “dry country,” the West.
Through the process, I found that this east-west transition wasn’t actually the steepest change on the map. Both sides of the country have areas with widely varying rainfall rates within a few short miles of one another.
Notice the border area of Georgia and North Carolina. Rainfall increases from 40 inches in the Carolina Piedmont to almost 90 inches in the southern Blue Ridge Mountains, barely 50 miles away. Similar transitions occur in the New England Mountains of Vermont and New Hampshire.
Most dramatically, the West has the steepest variations between really wet and really dry areas to be found in the Lower 48.
Look at Southern California. Home to the driest desert areas in the country with around 3 inches (or less) per year, areas with around 40 inches of rainfall are found just a short 15 miles away. The Southwest has a lot of areas that illustrate the mountain lifting and rain shadow effects well.
The Pacific Northwest has the highest rainfall in the Lower 48 and also some of the most unbelievable transitions.
The Coast Ranges in Oregon, Washington, and California receive upwards of 190 inches in areas. The Cascades are similarly rainy. Move from Cannon Beach, Oregon to Portland to Baker City and the rainfall goes from the high 100s down to 43 at Portland, then up to the lower 100s around Mount Hood, and then it plunges to around 10 as you head east of the Cascades. All of this happens in 125 miles.
National Park Service Units Map
712 days
This map illustrates the National Park Service Inventory & Monitoring (I&M) networks and all park units in the NPS system. I created this map in response to frequent inquiries for maps showing the extent of the I&M programs.
This was a really fun map to create. It quickly became an often-requested product of the NPS Natural Resource GIS program office.
Design Features
The map shows each inventory & monitoring network with a shaded area colored to associate with the natural bio-region the network covers. For instance, North Coast & Cascades Network is shaded with a darker green to coincide with the predominant forests found in that region. On the other end, desert areas are represented with buff or terra-cotta colors to associate with the sandy and rocky landscapes.
All park units existing in 2006 are included on the map. Park units are colored green or gray to indicate if they are part of the I&M network programs (gray parks are excluded from the I&M program).
East coast park labels are grouped together off the shore by the city area they are found in. The labels for the cities point towards the location of the park unit grouping.
You may find a PDF version of the map here.
National Park Service Units Map
NPS Units Map (Southwest Detail)
A Map of Racial Segregation in the U.S.
715 days
I occasionally hear stories told about traveling across the country in the pre-Civil Rights Act years and the odd manifestations of racial segregation that would be encountered.
My family, always frequent travelers between our home bases in Iowa, Arizona, and Texas, has lots of these observations. Just recently, my uncle told me about his a trip through Texas as a kid. While stopping for a bathroom break at a gas station, he found the nearest restroom in an outbuilding, but missed the “colored only” sign at the entrance. Using the toilet before checking for toilet paper was a mistake. He went inside the building to ask for the paper, but was met with a chuckling clerk. “These restrooms over here are for you,” he informed as he pointed to the white-only men’s room which were found to have no shortage of toilet paper.
At Brown v Board of Education National Historic Site in Topeka Kansas, I found a map which showed racial segregation laws by state. It is a fascinating map, and I have re-created it below.
The map shows the states which had mandated segregation – mostly in the Deep South, as well as permissible segregation (Kansas, among several others).
Some states were progressive enough to have outlawed any segregation (northeast, Midwest, some western states), but many others had no laws addressing it at all.
Do you have any personal stories about encounters with racial segregation that you could share?
Map by Jacob Morgan
Enterprise GIS Support for Georgia Power Company
728 days
Power Service Territories of Georgia, by Jacob Morgan
The Southern Company is one of the largest electric power utilities in the United States. Based in Atlanta, Georgia, the company consists of five separate power companies – Alabama Power, Georgia Power, Gulf Power, Mississippi Power, and Savannah Power & Light, in addition to numerous subsidiaries involved in related industries.
Southern GIS is an enterprise geospatial services group within the Southern Company and is tasked with providing geospatial assistance to all departments in the company. From 1999 through late 2000, I had the pleasure of working with this talented group on a variety of projects.
One such project was the creation of a Power Service Territories layer for the state of Georgia. Georgia’s cities and counties are served by numerous municipal and rural electric cooperatives in addition to the extensive coverage provided by Georgia Power. The state’s Public Service Commission approved these service areas and maintained the maps that laid them out.
These maps had been mylar-based up until 1999. With the increase in deregulated services provided in addition to the core business of electric power distribution, the need for easy access to the maps became critical. Georgia Power planned for the conversion of all of the mylar maps to a digital dataset.
The project involved scanning and digitizing information from around 159 individual maps (one for each of Georgia’s counties).
Most of the mylar maps were larger than 30 inches wide and required a wide-body scanner to be handled. My University of Georgia friend, Jay Sellars, assisted with the scanning phase of this project. He handled most of the scanning and quality control for that part of the project.
Once scanned, all of the digital images had to be geographically registered. This involved comparing the images to vector road layers and selection of coincident points to setup the “warp,” or image transformation.
After registration was complete, features had to be captured from each of the images. I did most of the digitizing in this phase, heads-up drawing polygons from each of the images into a statewide coverage (this was way before geodatabases).
Finally, all polygons were cleaned and checked for errors before being made available to other company employees.
This layer became one of the most requested datasets both inside and outside the company. It found interest amongst most of the electric power industry in the state once completed.
Fly-map Video Image of Transmission Structure
I eventually moved to a GIS Specialist position with the Georgia Power transmission department. I found myself planted into a huge project being undertaken at the time – the creation of a multimedia digital layer for the 16,000 mile transmission system in Georgia.
The project to collect data had been completed already. Helicopters had flown all transmission lines and had captured video and GPS coordinates for all structures (i.e. towers, switches, substations, etc.). (Georgia Transmission Line Mapping 2004-05 White Paper). The output of the data was essentially a lump of files that needed to be assembled into a database and connected to geographic features.
Working through this project required lots of database manipulations, ID matching, video review (for finding structure numbers), and reconciliation of incorrect attributes. It was very time consuming and frustrating at times, but was an opportunity to learn more about power transmission than I had ever wanted to know.
It also presented great opportunities for field work to verify data and to correct errors.
Read an article from the Atlanta Journal-Constitution on the Georgia Power transmission system control room – the bunker inside their giant black box headquarters in downtown Atlanta where the state’s power system is controlled.
Georgia Power’s Transmission Control Room, courtesy Christie Co.
Mississippi River – Flood Diagram/Map
732 days
Mississippi River Project Design Flood Diagram
The Flood of 2011 on the Lower Mississippi this spring has fascinated me to no end. I’ve been reading lots of news and blogs on the subject as well as digging into other websites of the US Army Corps of Engineers to learn more about this complicated, engineered river system.
Through this I came upon a diagram of the river that is really informative. It visually describes how floodwaters move through the lower Mississippi basin by depicting the river and its tributaries as a tree – with branches sized in scale with the amount of flood flow they are able to carry.
Here are some of the things I find surprising:
- The flood flow of the Mississippi above Cairo, Illinois is TINY. Most of the flow comes from the Ohio River. Even the Tennessee River carries more flood flow than the middle Mississippi.
- The bulk of the capacity of the river is in the middle section between Helena, Arkansas and Vicksburg, Miss rather than at the bottom of the system.
- The river sheds half of its water into the Atchafalaya River Basin through the Old River and Morganza Spillways leaving a much smaller amount of water to continue past Baton Rouge and New Orleans.
Colorado Cycling Maps – Cycling Fort Collins, Greeley & Loveland
736 days
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Cycling Fort Collins, Greeley & Loveland – a map and guide for road and touring routes in Northern Colorado.$12 - Available soon. |
Air Routes over the U.S.
739 days
While working on a GIS project for Backpacker Magazine I had the opportunity to construct a schematic map of airline routes to and from U.S. airports. The result is a very fascinating map which dramatically shows how busy our skies are, especially across the eastern and southern sections of our country. What other patterns do you see?
Airline routes over the continental U.S. in January 2011
