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John Hammond

@hydrohammond.bsky.social
1.7K followers 2.9K following 118 posts

Research hydrologist and river photographer. www.riversfromabove.com

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Reposted by John Hammond
Shi En Kim @goesbykim.bsky.social · 21/04/2026
Over 150 definitions exist for the different manifestations of drought, and one of them is pretty gnarly to forecast. Can AI help predict the kind that grips waterways and staunches flow? Spoiler alert for my @azcentral.com piece: yes, AI improves on flow projections, but it's still a ways off.
azcentral.com
A new AI tool could help predict drought on Arizona rivers. Here's how
Climate change is drying out rivers across the country. A new AI forecasting tool can help managers, governments and water users plan.
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John Hammond @hydrohammond.bsky.social · 23/04/2026
Such a pleasure talking with you and thank you for spreading the word about the new tool!
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Reposted by John Hammond
KinarNicholas.bsky.social @kinarnicholas.bsky.social · 11/02/2026
Hydrology Paper of the Day @jpgannon.bsky.social @hydrochrista.bsky.social @domciruzzi.bsky.social on understanding the teaching of hydrology at the undergraduate level: course titles, assessments, and objectives; textbooks and grading; and the need for shared educational resources and objectives.
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John Hammond @hydrohammond.bsky.social · 06/02/2026
These changes in the timing and magnitude of streamflow, driven by different types of snow drought, require updated strategies to manage water for, amongst others, agriculture, hydropower, and ecological needs.
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John Hammond @hydrohammond.bsky.social · 06/02/2026
Water management implications: Warm snow droughts are expected to become more common, increasing risk for water supplies. Many reservoirs and operating rules weren’t designed for earlier, lower flows, and linking SWE to streamflow is critical for stronger drought earlywarning and forecasting systems
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John Hammond @hydrohammond.bsky.social · 06/02/2026
Snow drought impacts vary by type and region: Warm snow droughts boost cold-season flows but suppress warm-season runoff, while dry and warm-dry types reduce flows year-round, driving larger annual declines. Effects on flow magnitude and timing differ strongly across hydroclimates.
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John Hammond @hydrohammond.bsky.social · 06/02/2026
Snow drought impacts on rivers: Across cool-dry, warm-dry, and warm-wet types, annual streamflow and runoff ratios decline, peak flows shift earlier, and both highs and lows weaken. Back-to-back snow droughts amplify losses as subsurface storage is depleted.
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John Hammond @hydrohammond.bsky.social · 06/02/2026
While all snow droughts generally lower warm-season flow, warm snow droughts uniquely increase cold-season flow, whereas dry/warm-dry types reduce it.
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John Hammond @hydrohammond.bsky.social · 06/02/2026
Snow drought types (cool & dry, warm & dry, warm & wet) and regional hydroclimates control streamflow timing and magnitude, universally reducing annual, maximum, and minimum flows, with faster, earlier, and often lower runoff.
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John Hammond @hydrohammond.bsky.social · 06/02/2026
The combination of precipitation and temperature contributions to snow drought control the subsequent streamflow response we’ll see in the coming months. www.tandfonline.com/doi/full/10....
tandfonline.com
Streamflow timing and magnitude during snow drought depend on snow drought type and regional hydroclimate
Communities around the world rely on snowmelt to meet water demands, and periods of lower than normal snow accumulation, snow droughts, can decrease water supplies. Leveraging 172 minimally disturb...
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John Hammond @hydrohammond.bsky.social · 06/02/2026
Snow drought continues across much of the western U.S. For much of the region, below normal precipitation is partly to blame (OR, CO, UT, NM), while above normal temperatures have occurred across nearly the entire region.
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John Hammond @hydrohammond.bsky.social · 21/01/2026
New preprint led by Aaron Heldmyer and Roy Sando: Random forest + donor gages to predict daily streamflow drought across CONUS. Regional drivers differ—soil moisture, precip, SWE matter most. doi.org/10.5194/egus...
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John Hammond @hydrohammond.bsky.social · 15/01/2026
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John Hammond @hydrohammond.bsky.social · 15/01/2026
🔥💧 New paper out in Environmental Research: Water led by Brian Ebel! Synthesis shows how wildfires fundamentally shift hydrologic processes and streamflow generation—from infiltration and runoff to baseflow and flood response — post wildfire. iopscience.iop.org/article/10.1...
iopscience.iop.org
A review and synthesis of post-wildfire shifts in hydrologic processes and streamflow generation mechanisms
A review and synthesis of post-wildfire shifts in hydrologic processes and streamflow generation mechanisms, Ebel, Brian A, Hammond, John C, Walvoord, Michelle A, Partridge, Trevor F, Rey, David M, Murphy, Sheila F
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Reposted by John Hammond
Sarah H. Ledford @sledford.bsky.social · 12/01/2026
If you know an undergraduate looking for a geosciences REU program, our applications are due in one month! Focus this year on community, air, and water projects! sites.google.com/view/csaw-re...
sites.google.com
CSAW REU
Overview
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Reposted by John Hammond
Hilary McMillan @mcmillanhydro.bsky.social · 07/01/2026
I wrote a commentary discussing Daniele's huge new global synthesis of controls on hydrological processes in forested catchments: read it here: rdcu.be/eXTrq . Some surprising findings on the importance of overland flow, soils and antecedent conditions.
rdcu.be
Forest streamflow driven by soils, topography and previous rains
Nature Water - Forests cover almost a third of earth’s land and supply high-quality streamflow and groundwater. A global synthesis of forested catchments provides surprising insights into the...
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Reposted by John Hammond
Anne Jefferson @annejefferson.bsky.social · 07/01/2026
New paper! Real-time flood inundation mapping (FIM) services are an incredibly valuable tool for emergency management and affected communities. But do their visualizations help users quickly and accurately interpret information to make decisions? onlinelibrary.wiley.com/doi/10.1002/...
onlinelibrary.wiley.com
Comparing Flood Inundation Map Features and Diagnosing Decision Support Design Challenges
Using visualisation typologies, we developed a diagnostic evaluation method for eight user-controlled ensemble FIM visualisations. Key design challenges include unclear messaging, non-accessible and ...
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Reposted by John Hammond
Daniele Penna @danielepenna.bsky.social · 07/01/2026
How do #climate, #antecedent #moisture, #soils, #topography, #geology, and #vegetation control #runoff #processes in #forested #catchments worldwide? Find this out here rdcu.be/eXTtd! @natwater.nature.com Thanks a lot @mcmillanhydro.bsky.social for this commentary www.nature.com/articles/s44...!
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John Hammond @hydrohammond.bsky.social · 01/01/2026
Thank you Anne!
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John Hammond @hydrohammond.bsky.social · 01/01/2026
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John Hammond @hydrohammond.bsky.social · 01/01/2026
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John Hammond @hydrohammond.bsky.social · 01/01/2026
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John Hammond @hydrohammond.bsky.social · 01/01/2026
I’ve always been more of a photographer than anything else when it comes to art. Still trying sketching sometimes, but also enjoying creating vector art versions of my #riversfromabove photos, and some other travel photos. I feel like style is “you love/hate it” without much in the middle. Thoughts?
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John Hammond @hydrohammond.bsky.social · 01/01/2026
Such a fantastic body of work!
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Reposted by John Hammond
Giulia Bruno @gbrunohydro.bsky.social · 03/12/2025
A piece that felt particularly relevant to write
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Reposted by John Hammond
Ryoko Araki @rarakihydro.bsky.social · 29/12/2025
Check out the end-of-the-year blogpost about model design by Jonathan Frame! deepgroundwater.com/blog/what-do...
deepgroundwater.com
What does your model do? - Deep Groundwater
A collection of open-source blog posts and articles
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Reposted by John Hammond
Ryan Webb @webbhydrology.bsky.social · 29/12/2025
New paper in WRR: Snow Sublimation Significantly Decreases Following Stand-Replacing Fire With Minor Water Balance Impacts From Forest Thinning in a Water Limited Forest. find it here: doi.org/10.1029/2025...
doi.org
Snow Sublimation Significantly Decreases Following Stand‐Replacing Fire With Minor Water Balance Impacts From Forest Thinning in a Water Limited Forest
Snow sublimation is significantly reduced following a wildfire A thinning prescription that targeted ladder fuels and white fir had minimal impacts on sublimation and the overall water balance
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Reposted by John Hammond
KinarNicholas.bsky.social @kinarnicholas.bsky.social · 27/12/2025
Hydrology Paper of the Day @andy-baker.bsky.social on quantifying the drip of water underground as part of rainfall recharge: groundwater monitoring near the water table in Australia; why mines, tunnels and caves are essential monitoring locations; and relating rock aquifer response to rainfall.
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Reposted by John Hammond
Thiago Nascimento @thiagovnascimento.bsky.social · 19/12/2025
Working with large-sample hydrology datasets and curious about how maps with varying levels of detail influence the identification of geology–streamflow relationships? Check out our latest preprint at HESS! #Hydrology #CatchmentHydrology #LargeSampleHydrology #Eawag #hightlightpaper #HESS
doi.org
How do geological map details influence the identification of geology-streamflow relationships in large-sample hydrology studies?
Abstract. Large-sample hydrology datasets have advanced hydrological research, yet the impact of landscape map details on identifying dominant streamflow generation processes remains underexplored. Th...
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John Hammond @hydrohammond.bsky.social · 18/12/2025
Make sure to check out the supplement for individual signature maps, attribute distributions, and model performance info.
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John Hammond @hydrohammond.bsky.social · 18/12/2025
Process maps derived from signatures highlight strong climate controls in the West, soils/topography in the East, and a scalable path to link process understanding to ungauged basins. Big implications for large-scale hydrologic modeling & change detection. #Hydrology #Streamflow #Hydroclimate #EGU
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John Hammond @hydrohammond.bsky.social · 18/12/2025
@rarakihydro.bsky.social leads an exiting new preprint that maps dominant hydrologic processes across >14k US watersheds using streamflow signatures + ML. It’s been such fun following Ryoko and Hilary’s leadership alongside Admin, Anne and Gemma. egusphere.copernicus.org/preprints/20...
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Reposted by John Hammond
Frederik Kratzert @kratzert.bsky.social · 18/12/2025
Excited to unveil Caravan-Qual! 🌊 We've expanded the Caravan framework to bridge the gap between water quantity and quality. This new open dataset features: 🔹 ~70M observations 🔹137k stations 🔹 100 constituents 🔹 Linked streamflow, forcing & attributes Links in 🧵
A world map with red and blue dots. Each dot denotes a water quality measurement station that is included in Caravan-Qual. Red dots are stations with additional streamflow observations. Blue dots are stations without streamflow observations.
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Margaret Zimmer @margaretzimmer.bsky.social · 18/12/2025
Happening this morning! Run don’t walk to room 228-230 to hear @zhaozhechen.bsky.social talk hydroclimate-ET synchrony!! @agu.org
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Reposted by John Hammond
Daniel Swain @weatherwest.bsky.social · 17/12/2025
In case you missed it live, a full recording of my rapid-response livestream regarding news surrounding the proposed imminent and sudden dismantling of the National Center for Atmospheric Research (NCAR) is now available.
youtu.be
Special rapid response stream re: proposed dismantling of National Center for Atmospheric Research
The latest in a recurring series of live, virtual, & interactive "office hours" hosted by Dr. Daniel Swain on various topics related to extreme #weather and #climate. 12/17/2025 topic: This will be a special emergency livestream to discuss the context and broader implications of breaking news last n
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Eric Booth @egbooth.bsky.social · 17/12/2025
Another example - from just today - of excellent and essential climate and weather research from @ncar-ucar.bsky.social with clear impacts on flood-prone communities doi.org/10.1038/s432... #NCAR
doi.org
Moisture from US Corn Belt fuels more intense convective storms - Communications Earth & Environment
The groundwater-crop-irrigation interactions across the US Corn Belt amplify convective storm frequency, extend storm lifetime, and accelerate storm movement, based on a high-resolution regional clima...
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Reposted by John Hammond
Daniel Swain @weatherwest.bsky.social · 17/12/2025
I 'll have a special rapid-response livestream for 8:30am PT today to discuss dire implications of this proposal to dismantle NCAR. Due to extreme fire weather in Boulder today (and associated pre-emptive power outages/NCAR closure), I am going live ASAP. www.youtube.com/live/FTKW68R...
youtube.com
Special rapid response stream re: proposed dismantling of National Center for Atmospheric Research
YouTube video by Weather West
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UK Centre for Ecology & Hydrology (UKCEH) @ukceh.bsky.social · 17/12/2025
The latest UK Hydrological Summary has been published 🌧️ November was UK's wettest month so far in 2025 & many areas have shifted from drought concerns to flood risk. Groundwater levels notably low and reservoir levels still below average in parts. Winter rainfall amount will be crucial. 🧪 1/
Maps of UK indicating river flows in November 2025 and in September 2025 to November 2025
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John Hammond @hydrohammond.bsky.social · 15/12/2025
We had a small amount of freezing rain before getting ~10 cm of snow
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John Hammond @hydrohammond.bsky.social · 15/12/2025
Photos from the Patapsco River in Maryland yesterday. Lucky to have the snow stick to the trees despite the high winds! #riversfromabove
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Daniel Swain @weatherwest.bsky.social · 12/12/2025
The fact that parts of Washington are seeing record-breaking flooding this week is not surprising given that 1) many locations saw record 24hr precipitation (well above 100yr ARI) & 2) near-record temperatures *simultaneously* (no snow in mtns, so all precip became runoff). #WAwx
Map showing locations where recent 24 hour precipitation exceeded estimated 100yr recurrence interval thresholds. There are many such locations east of Puget Sound in Washington. Via Russ Schumacher's Precipitation Systems Research Group website (https://schumacher.atmos.colostate.edu/precip_monitor/precip_monitor.php?atlas=atlas14&dataset=stage4&ari=1000y&duration=48h).
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The Associated Press @apnews.com · 11/12/2025
A powerful atmospheric river has drenched Washington state with nearly 5 trillion gallons of rain over the past week. The deluge is linked to warm water and air, along with unusual weather conditions tracing back to tropical cyclone flooding in Indonesia.
bit.ly
Blend of unusual weather conditions brings trillions of gallons in persistent rain to the Northwest
A powerful atmospheric river has drenched Washington state with nearly 5 trillion gallons of rain over the past week.
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John Hammond @hydrohammond.bsky.social · 11/12/2025
Sand bag deployment and flood as seen from USGS High Vis camera in Everson, WA apps.usgs.gov/hivis/camera...
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Anthony Edwards @edwardsanthonyb.bsky.social · 10/12/2025
Officials warned of “locally catastrophic” river flooding in Washington state Wednesday amid a major atmospheric river storm that was poised to drop 20 inches of rain in the Cascade Range. Two rivers north of Seattle, the Snohomish and Skagit rivers, were predicted to crest at record levels.
sfchronicle.com
Atmospheric river dumping 20 inches of rain on West Coast mountain range
Dozens of rivers were forecast to spill their banks across the Pacific Northwest, as Washington state braced for its worst flooding in at least 16 years.
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Steve Herman @newsguy.bsky.social · 10/12/2025
Washington Gov. Bob Ferguson declares a statewide emergency in response to flooding occurring throughout the Pacific Northwest. www.king5.com/article/weather...
king5.com
Statewide emergency declared in Washington as major flooding occurs
Gov. Ferguson is asking the federal government to approve an expedited emergency declaration for the 'extremely serious' situation.
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Ross Woods @rosswoodskiwi.bsky.social · 10/12/2025
Bettina Schaefli and I warmly invite you to submit abstracts to a new EGU session HS2.2.5 New Developments in Hydrological Synthesis Abstract submission: www.egu26.eu/session/55911 1/6
egu26.eu
Session HS2.2.5
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Daniel Swain @weatherwest.bsky.social · 10/12/2025
On Wednesday, widespread heavy rain & very high snow levels (7,000-9,000 feet) will cause enormous runoff into already swollen rivers. Widespread moderate to major flood is likely, with some rivers expected to experience *record* flooding (esp. Skagit & Snohomish). #WAwx [2/3]
Snapshot from NOAA National Water Center website depicting all river forecast points in Washington expected to experience flooding. There are numerous purple squares visible, denoting "major flooding."
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John Hammond @hydrohammond.bsky.social · 07/12/2025
Been focused on photos of rivers from above for a few years, but starting to try my hand at rivers from below. Wish I could be snorkeling every day! sites.google.com/view/riversf...
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Ross Woods @rosswoodskiwi.bsky.social · 05/12/2025
New paper alert: "Diverging Impacts of Snow Fraction and Soil Drainage on Seasonal and Annual Water Balances Across Snow-Influenced Catchments" Led by Zeqiang Wang. A synthesis of some controls on spatial variations in snow-influenced hydrology across the USA. doi.org/10.1029/2025...
Diagram to illustrate synthesis of between-region and within-region water balance differences and their drivers across the snow-influenced US.
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