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Dan Scott @geomorphdan.bsky.social · 04/05/2026

Everyone gets so obsessed with LARGE wood to form wood jams. Remember, y'all, it takes poorly sorted wood to form a jam that can actually do something. That means SMALL wood, too! It takes diversity (alternatively, poorly sorted/well graded size distribution)!

Photo of a wood jam with dozens of logs and sticks in a stream flowing through a forest

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Dan Scott @geomorphdan.bsky.social · 27/04/2026

Wood racking on a river channel split (bifurcation) can dramatically alter channel shape and how that split evolves (avulses). Here's a particularly extreme example from the Skykomish River, WA, USA. (flow bottom to top)

An aerial image showing a river channel split. Between the channels, a long linear wood jam controls how flow enters each channel.

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Dan Scott @geomorphdan.bsky.social · 24/04/2026

I just need to post some geomorphology for a second. Preferential erosion along a joint set formed a mini canyon-within-a-canyon. First picture shows the mini canyon, second looks back upstream at it. This is the kind of thing that got me into geomorphology.

Looking downstream along the length of a mini canyon of granite with an icy pool along its bottom. The background shows a forested hillside.

Looking upstream along a canyon with a dusting of snow. A small crack n the lower right side of the image is a canyon within a canyon.

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Dan Scott @geomorphdan.bsky.social · 12/01/2026

Studying avulsions. Time series below is 1953 (b/w), 1983 (false color), 2009, 2022. Here, avulsion = f(flow direction, curvature/migration, beaver, wood, erodibility, flow/time). Yeah, just that. That's all. Easy to predict how things will go, right? Also, notice that slope isn't in that list.

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Dan Scott @geomorphdan.bsky.social · 04/12/2025

Here's the inlet to this side channel, to give some sense of how big the Tolt is (200 ft wide at this location).

Photo showing a river with wood and a gravel bar.

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Dan Scott @geomorphdan.bsky.social · 04/12/2025

Beaver building up a wood jam in a side channel of the Tolt. Beaver like really big rivers, too! They just need them to be split into bite-sized chunks. Bonus, they're also felling pretty large trees here, too.

Beaver-chewed sticks laid by a beaver on top of an accumulation of logs in a side channel of the Tolt River.

A recently felled tree stump and log, with clear beaver tooth marks where it was cut.

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Dan Scott @geomorphdan.bsky.social · 21/11/2025

#River scientists, need some group opinion here: Do you define an avulsion as a sudden, complete change in the distribution of flow conveyance between channels (i.e., one channel captures all of another's flow) OR any change in flow conveyance between channels, sudden or gradual, full or partial.

An aerial image looking down on a river, flowing right to left, that has two side channels diverting from its mainstem. The two side channels are blocked with wood.

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Dan Scott @geomorphdan.bsky.social · 06/11/2025

#Drone folks - any considerations on a Mavic 3E vs 3M? I collect orthomosaics of rivers for ecogeomorphic mapping. I'm leaning towards 3M even though I'll rarely use the multispectral cams, since the cost is very similar to 3E, main cam is identical, and I can't see use case for the 3E zoom cam.

An oblique drone image of a river the was recently flattened and covered with large logs.

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Dan Scott @geomorphdan.bsky.social · 05/11/2025

For more context here, this is an image (from a few years ago) of what I mean by forest dispersing flow. The channel steepens just downstream of this forest (second image) - that looks to me like a headcut arrested simply by obstruction-forced widening upstream.

A river flowing through trees, grass, and logs in a floodplain forest.

A river flowing over steep cobbles and under logs.

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Dan Scott @geomorphdan.bsky.social · 05/11/2025

They do! Holy cow - never even occurred to me. Would take some absolutely beastly giant beaver to move these logs, though - I don't think even Casteroides ever got that strong, haha.

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Dan Scott @geomorphdan.bsky.social · 05/11/2025

Here's another one. Side channels in the floodplain have been there, and much shorter than the mainstem, for close to 30 years (inc. a 50-yr flood). Wood plays a big role here, but so does the vigorous floodplain forest, which disperses flow and inhibits headcuts that would otherwise drive avulsion.

A map view of a false-color aerial image of a river flowing towards the bottom of the image. The river has one main channel with 6 or more side channels flowing through floodplain forest.

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Dan Scott @geomorphdan.bsky.social · 05/11/2025

It's a buckle down, turn on some Chappell Roan, and measure some rivers kind of morning. This looks like a normal meander cutoff, right? Wrong! The channel that lost flow (left side of image) is expanding again, just a few years after what I thought was a full avulsion. What's the culprit? Wood?

A map view of a false-color aerial image of a river flowing towards the bottom of the image. The river is split into two channels, one of which is jammed up with lots of logs.

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Dan Scott @geomorphdan.bsky.social · 30/09/2025

Is anyone aware of a private river science and/or consulting company that is organized as a worker-owned cooperative or worker self-directed non-profit? Is anyone else in my field prefiguring an alternative to capitalism?

A photo of a human-constructed wood jam with many logs and driving vertical pilings in a river. Flow is cresting over the jam and into the floodplain, which is covered by tall willows.

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Dan Scott @geomorphdan.bsky.social · 14/06/2025

Longmont, CO showed up today to say "NO KINGS!" loud and clear!

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Dan Scott @geomorphdan.bsky.social · 06/05/2025

Ever been surprised by a river in a bad way, like a flood? I help folks understand rivers and not get surprised so they don't get hurt or lose stuff. NOAA, USDA, and NSF fund the work I do. If those agencies stop working, people become endangered.

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Dan Scott @geomorphdan.bsky.social · 14/04/2025

I'm not really *that kind* of geologist but this one really captivated me. Basal basalt, then sandstone/conglomerate, then basalt, more sandstone (the bright red/white), then more basalt! And then tuff to mantle it all! What a cool spot - Frijoles Canyon, NM.

A cliff wall with striking striated rocks.

Black basalt cliffs with beige tuff mantling it on the side of a hillslope.

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Dan Scott @geomorphdan.bsky.social · 21/02/2025

#timelapse camera folks, got any good recommendations for a timelapse camera that will last for a year unattended at a 15-60min day/night interval (15 preferred)? Been using Bushnell for years, but build quality has declined recently and I'm looking for something new.

A man very derpily staring into a timelapse camera's field of view to check if it's working. Frame background shows a river with logs and some trees.

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Dan Scott @geomorphdan.bsky.social · 16/01/2025

Been severely overworked for about 10 months now, and my recent writing (my primary output) is clearly worse than my past work. My writing's hurried, more focused on "what" than "why," less concise. This sucks. I feel like this river (more work than I can keep up with).

A river that recently received a sediment pulse that it will eventually need to work through. The channel is broad and flat, with no vegetation and braided flowpaths.

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Dan Scott @geomorphdan.bsky.social · 20/11/2024

Big snow avalanches deliver tons of wood to streams. How much of it sticks around? How do these huge wood pulses affect the wood regime? Or, do they? Are they mostly just mulched trees, with very few large logs? We're working on it. Images show the same 300m-long slide deposit in 2019 and 2024.

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Dan Scott @geomorphdan.bsky.social · 14/11/2024

What makes beaver dams so effective? They're outstandingly effective structures. Is it how they're built? Materials? Where they're located? No. It's care. Careful attention, day in and day out, by beavers. Stewardship. So why do we think process-based restoration is a one-and-done sort of thing?

A picture looking downstream at a beaver dam with grass and willow growing in the wetland around it.

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Dan Scott @geomorphdan.bsky.social · 01/12/2023

Straight-up Stranger-Things level stuff going on with this burned tree.

A thoroughly charred root network of a large tree on a steep, burned hillside with leaves on the ground.

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Dan Scott @geomorphdan.bsky.social · 08/11/2023

Looking for writing mentoring suggestions. I've taught technical communication, but mentoring junior scientists/engineers one-on-one is another ball-game. Tips on guiding someone towards clearer technical communication would be much appreciated!

A DALLE-3 image showing a desk with a notebook and laptop, scientific equipment, and mountains in the background.

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Dan Scott @geomorphdan.bsky.social · 01/11/2023

Unvegetated sand dunes can deliver tons of sediment to adjacent streams. E.g., North Sand Creek, CO, where sand pulses on the order of 10k m^3 (4 olympic swimming pools!) can move downstream annually. Log jams attenuate these pulses, but a downstream diversion ditch is still getting well-buried.

people standing around a large wood jam storing a huge sand in its backwater

sand stratigraphy in an exposed bank, with layers of different colors of sand and a small orange pen for scale

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