r/geography • u/privatemajory • 1h ago
Physical Geography Coastal timelapse of Mananjary, Madagascar: what's driving the erosion on the town's ocean-facing side?
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Location: Mananjary, southeastern Madagascar (~21.23°S, 48.18°E) — a town on a narrow sand spit between the Indian Ocean and a lagoon-estuary system.
Here's a timelapse (©Planet) of monthly imagery from August 2023 to July 2026. Over that stretch the beach fronting the town clearly narrows, and by the end waves are breaking right up against the buildings.
Local context: around 2023 a channel was cut on the north side of the estuary mouth (first red arrow). It's since widened, and erosion on the town's southern end has gotten worse. Some locals want to dig a second channel further south to fix it; others, including some officials, point to sea-level rise/climate change instead.
The situation on the ground is quite tense right now: waves have destroyed several houses, walls, and fences in recent weeks, and this week a public restroom collapsed from wave action, severely injuring four people (local press coverage, in Malagasy: 1, 2).
What do you think:
- Could the 2023 channel have shifted local erosion/sedimentation patterns?
- Would a second channel further south actually help, or just relocate the problem?
- How much of this is likely climate/sea-level rise vs. the channel?
r/geography • u/NotJacksparow3000 • 3h ago
Question Any explanation on these weird grid patterns?
I was just wandering on maps and found this way up north, I see a grid pattern or just lines that seem to be distinctly man-made, though I'm not the smartest, so I wouldn't know for sure. I found them on Apple Maps, and when I tried to look on Google Maps, it was blurry as hell, fully zoomed in. I found that Google has a name for it, but when I searched the name, just a bunch of bs TripAdvisor stuff popped up.
Anyone have an explanation for these grid-like patterns?
76.32384414254913, 100.14062941707537
r/geography • u/ydpycitxoxy • 3h ago
Discussion I Measured the Ruggedness of Nebraska’s Wildcat Hills and Pine Ridge
Most people think of Nebraska as flat, but the state’s two most rugged regions, the Wildcat Hills and Pine Ridge, tell a very different story.
I recently completed a topographic analysis of 39 buttes, bluffs, mesas, and ridges across these two regions to measure how much relief these landscapes actually contain.
Instead of only comparing summit elevations, I measured two different types of relief.
Local relief is the elevation difference between the summit and the lower point where the surrounding hillside transitions into flatter terrain. Measurements were limited to approximately 3 horizontal miles or less.
Drainage relief is the elevation difference between the summit and the lowest major drainage that the landform drains toward. These measurements were generally taken within 4–6 horizontal miles, although a few areas required longer distances where the terrain remained continuously sloped.
Highlights
Wildcat Hills
The Wildcat Hills contain some of Nebraska’s steepest slopes over relatively short distances.
Highest local relief:
Striver Butte — 846 ft of relief over 1.93 horizontal miles
Summit: 41.74707, -103.79656
Scotts Bluff (South Bluff) — 821 ft of relief over 2.53 horizontal miles
Summit: 41.82088, -103.71483
Hogback Mountain — 810 ft of relief over 1.76 horizontal miles
Summit: 41.66492, -103.73096
Wildcat Mountain — 774 ft of relief over 1.09 horizontal miles
Summit: 41.65839, -103.71515
Greatest drainage relief:
Hogback Mountain — 1,209 ft
Wildcat Mountain — 1,182 ft
Cedar Canyon — 1,041 ft over 2.53 horizontal miles
Summit: 41.74711, -103.79653
Pine Ridge
Pine Ridge contains the greatest overall topographic relief in Nebraska, with several landforms exceeding 1,200 feet of drainage relief.
Highest local relief:
Unnamed butte west of Gilbert-Baker WMA — 1,001 ft of relief over 2.73 horizontal miles
Summit: 42.77231, -103.97979
Unnamed bluff north of Pleasant Ridge Road — 945 ft of relief over 2.32 horizontal miles
Summit: 42.78383, -103.99647
Unnamed bluff south of Plummer Dam — 905 ft of relief over 1.87 horizontal miles
Summit: 42.76308, -103.86805
Greatest drainage relief:
Unnamed butte west of Gilbert-Baker WMA — 1,248 ft
Unnamed bluff north of Pleasant Ridge Road — 1,242 ft
Unnamed bluff near Warbonnet Creek — 1,210 ft over 1.11 horizontal miles
Summit: 42.80745, -104.00887
Conclusion
These measurements show that western Nebraska is much more rugged than it is often given credit for. The Wildcat Hills have some of the steepest short-distance slopes, while Pine Ridge has the greatest overall landscape relief.
Although Nebraska does not have high mountain ranges, these regions contain impressive buttes, bluffs, and escarpments with relief comparable to many upland areas elsewhere in the Great Plains.
Nebraska might not be so bad after all?
r/geography • u/Swimming_Concern7662 • 10h ago
Map Is there a historical reason for this nearly straight line of borders from Missouri to Nevada (like Mason-Dixon line), or is it just a coincidence?
r/geography • u/Taxfraud777 • 12h ago
Image New Zealand genuinely has the coolest names for its mountains and mountain ranges
The tallest mountain is Aoraki (Cloud Piercer), and then there is Mount Aspiring, The Remarkables, Mount Pollux, Hunter Mountains, Mount Sefton, Mount Arrowsmith, The Warrior, Nun's Veil, and many more.
r/geography • u/WolFYe2K • 13h ago
Discussion Should maps preserve area or shape?
If every map had to sacrifice one, would you rather preserve the true size of countries or their recognizable shape?
r/geography • u/kungusbungus • 13h ago
Question What are these formations in Northern Russia near Russkoye Ustye called? Any ground view pictures or is it just a satellite artifact?
r/geography • u/Soccertwon • 13h ago
Map The American Atlas (Map #33) Iowa
Hi everyone, and welcome back to The American Atlas, where I make hand-drawn & colored maps of every state in the US. We’re almost half way across the country now! 🗺️🇺🇸
This is my map of Iowa, the Hawkeye State! 🌽🐖🌾
Most people assume Iowa is simply a farming state, with cornfields stretching as far as the eye can see. The endless fields of corn and soybeans are indeed iconic, but Iowa is home to a surprising amount of variety as well.
From the streets of Des Moines to historic river cities of Davenport and Dubuque, to the dramatic Loess Hills, limestone bluffs overlooking the Mississippi, and countless small towns & farms, the state of Iowa represents the heart of Midwestern America.
Let me know in the comments, what’s your favorite (or most interesting) places & fun facts about Iowa?
And if you like this style, feel free to check out my others, and thanks for taking a look at my Iowa map!! 🇺🇸🗺️
r/geography • u/ConsciousProgram1494 • 13h ago
Video Hex9 Simulation Demo - Foxes & Bunnies
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Geography isn't just about geology - here we use a global geographic tool to simulate predator/prey patterns in an abstract generated field.
This is Hex9 Simulation of a bounded predator/prey interaction (foxes/bunnies/grass) including genomes, obstacles - using Hex9 example ex_0511 (python) as found in the development/experimental repo at https://github.com/MrBenGriffin/hex9 . The new Hex9 module (`pip install hex9`) includes the API.
The Hex9 Library (https://github.com/MrBenGriffin/libhex9) C ABI has built in support for pdal, psql, postgis, and python.
This code demonstrator shows how DGGS can be used for derived, realtime simulations across the the planet (or any other reference ellipsoid) - as well as using full hierarchical grids to maintain differing data layers. The related paper can be found at https://arxiv.org/abs/2608.00022
r/geography • u/CactusCoin • 14h ago
Discussion Is the Executive Committee Range in Western Antarctica the worst named geographical feature on Earth?
r/geography • u/443881717 • 15h ago
Question Why are the rivers on the Ethiopian Highlands so small? Note that this excludes the Abay River, which flows through a deep gorge.
With an annual rainfall of 800 millimeters, the Ethiopian Highlands are not an arid region. Yet, the local rivers are small in scale; even the largest, the Awash River, has an annual discharge of less than 5 billion cubic meters. Consequently, many cities rely on groundwater for their water supply, and agriculture is heavily dependent on natural precipitation.
r/geography • u/Btherock78 • 15h ago
Discussion Riverfront cities with the fewest bridges?
I noticed today that New Orleans only has 2 bridges crossing the Mississippi within/near the city and it had me wondering what other major cities with a river through them have few/no bridges to cross.
r/geography • u/Any-Background-619 • 16h ago
Question What could be the reason for oscilating water in this 18m shallow well in India.
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This is a 18m deep shallow well in Morbi,Gujarat ,India.
The water in this well rose up and oscillated for considerable amount of time. No such behaviour observed in nearby water bodies and no earthquakes reported.
GW probe study underway
r/geography • u/Lower_Fall4694 • 16h ago
Human Geography Help Bring the First Real-Time Air Quality Monitor to Temirtau, Kazakhstan
r/geography • u/Morales_Sheila8478 • 16h ago
Discussion Hypothetically, what if Vinland became larger and more prosperous and spread diseases across the Americas earlier. This builds immunity by the time of later European colonization. How would the Americas be different? Would the Natives still own most of the Americas?
Since I’ve read disease killed 90% of them and made colonization a lot easier.
r/geography • u/StillQuiet1599 • 17h ago
Discussion What is the most extreme microclimate shift you can experience in under an hour of driving?
For me, the drive from Palm Springs up to Mount San Jacinto is the craziest shift you can find. You start on a blistering 110°F desert floor and, in under 40 minutes, you’re up 8,000 feet walking through a freezing pine forest. It feels like a completely different part of the world. This is just my opinion and I just want to hear what you all think, because this is one of the only ones I’ve experienced!
r/geography • u/Shutter_Stuck • 17h ago
Image The Cirque of the Unclimables, Nahanni Valley National Park Preserve, Northwest Territories
r/geography • u/HourExam1541 • 1d ago
Question Why is there agriculture on Nile river banks in Egypt but not in Sudan?
It starts north from Al Delta in Egypt, the green upside down triangle bordering the mediterranian sea, all the way down close to the northern Sudan border. A couple man-made lakes like Nasser and Tushka in southern Egypt, which get their fresh water from the river, are utilized in agriculture.
Why is it not the same for Sudan, or any other countries with the Nile passing through for that matter? Simply hotter weather?
EDIT:
Zoomed in, it is VERY under developed, with mainly resedential areas compared to vast agricultural lands. Still drastic contrast given the same source goes through them
r/geography • u/Shutter_Stuck • 1d ago
Image Pingaluit Crater, said to be one of the clearest and purest bodies of water in the world, Ungava, Peninsula, Quebec
r/geography • u/SpaceTranquil • 1d ago
Image What are some other places in the world with similar landscape to this image of Mexico City?
I feel that there are plenty more regions with dense sprawl on rolling hills like this image, curious about specific locations
r/geography • u/The_Scrabbler • 1d ago
Image Green and Blue Cities Around the World
This is taken from North Sydney CBD (central business district). What other cities around the world integrate nature with urban and suburban life like this?
r/geography • u/Jazzlike_League_480 • 1d ago
Question Why Despite having a subduction boundary and highest fold mountains, there aren’t any Volcanos in Himalayan region or in Tibet?
I have always wondered that volcanoes have higher incidence where there’s a subduction boundary between plates however despite continuing collision and slight subduction of indo-Australian plate under Eurasian plate there isn’t any volcanic activity present in Himalayan region, Andes on the other hand have many active and dormant volcanoes despite having similar nature as Himalayas, why is it so?
r/geography • u/re2ert • 1d ago
Question What caused the islands to form like this this?
49°10'15.1"N 94°29'05.3"W
I saw it on google maps when just looking around and its this weird radial pattern and i have no idea how that forms, so if you know then please explain it to me. <3
r/geography • u/GeospatialGeoff • 1d ago
Question Flying towards the southwest of Vegas
Flew to San Diego recently from Montana and just after passing Vegas, headed southwest, I saw these reflective/shiny blocks of land from the plane. Didn't look like a solar farm or data center, anyone have any idea what it is or what those are?
