Hi all,

Over the past few years I've built up a set of Google Earth Engine scripts for my water-resources work. I finally cleaned them up so they run as-is in the Code Editor with public datasets.

What's included:

1. Wetland water mapping with Random Forest: Landsat 5/7/8/9, eight water indices, hold-out accuracy and kappa, and a water-area time series back to 1985.

https://github.com/RisaRezaei/gee-wetland-water-rf

1. Air-quality toolkit: monthly Sentinel-5P NO2, SO2, CO, O3, HCHO and MODIS AOD for a region and its stations, exported as one CSV.

https://github.com/RisaRezaei/gee-air-quality-toolkit

1. Lake chlorophyll-a: Sentinel-2 NDCI with Cloud Score+ masking, plus a MODIS-Aqua comparison.

https://github.com/RisaRezaei/gee-lake-chlorophyll

1. Basin hydroclimate: monthly precipitation, ET, temperature and GRACE storage averaged over any HydroBASINS basin.

https://github.com/RisaRezaei/gee-basin-hydroclimate

1. A six-lesson course for hydrology students: water frequency, epoch maps, SMAP downscaling with RF, Sen's slope and Mann-Kendall.

https://github.com/RisaRezaei/gee-water-resources-course

To use one on your own area, change the region and dates at the top of the script. There's a step-by-step walkthrough of the code for each tool here: https://risarezaei.github.io/#code

Everything is MIT-licensed and archived on Zenodo.

I'd really appreciate feedback, especially on the Random Forest water classification (training samples, index choice) and on anything that breaks for your region.

I've found a few papers that attempt to put embeddings on the surface of the earth, to describe different classes of climate/terrain/use:

• https://arxiv.org/pdf/2311.17179
• https://arxiv.org/pdf/2607.03949
• https://deepmind.google/blog/alphaearth-foundations-helps-map-our-planet-in-unprecedented-detail/

The papers are interesting, and of course the authors cite the wide variety of tasks that they could be used for, but has anyone actually used them for anything? It feels interesting from an academic point of view, but I'm curious if there's any real-world workflows where they've been helpful as they seem a bit abstract

Our college mandates completion of one project in 5th sem, and we need to publish a research paper too for the project.

I am currently facing an issue - a specific part of my project needs crop mapping - like finding brinjal field locations through remote sensing. But for that I need a dataset - at least locations. There is nothing like that... Now what do I do.

Can someone please let me know what can be done? I am stuck. And not really in a position to move around and create a dataset myself.

What do you think I should do?

How do you handle such issues?

Read on Reddit about the massive wildfire in the Mongolia-China border (it’s barely made any headlines on this side of the world), so I had to check for myself: over 500,000 hectares of steppe burnt according to Mongolia, 80% of the Nömrög Protected Area.

Sentinel-2 true colour, 18 days apart, 10 to 40m.

From what I see, quality control on commercial satellite imagery mostly happens on the provider side, through their calibration, validation and metadata. On the user side, it seems to come down to manual spot checks on the vendor imagery.

I’m curious how others usually handle it. Do you check things like gaps, geolocation accuracy or cloud masks yourself, or mostly trust what the provider delivers?

NASA’s feature, Autumn Paints Poland’s Bieszczady Mountains, offers a beautiful example of how Earth observation can capture seasonal changes across a landscape.

Autumn colors are more than a visual spectacle. Satellite imagery can help researchers observe patterns in vegetation and study how landscapes change over time.

Earth observation is often discussed in the context of urban development, infrastructure, agriculture, or disaster response, but monitoring seasonal changes in natural environments is another important application.

For those working with satellite imagery: how do you use Earth-observation data to monitor vegetation or seasonal changes? Do you typically compare imagery captured at different times of the year, or combine satellite data with other sources?

NASA’s article: https://science.nasa.gov/earth/earth-observatory/autumn-paints-polands-bieszczady-mountains/

LandEye app: https://app.landeye.com/dashboard

LandEye: https://landeye.com

Hello, I am pretty new to InSAR techniques and I have run into a problem with my unwrapped imagery. I have no clue why but my output has incorrect borders such as in the attached image. I have no clue what is causing this so any ideas would be greatly appreciated :)

Every time I need something useful for analysis, I end up bouncing between 10 different sites: Copernicus, EarthExplorer, a commercial portal or two, plus whatever cloud catalog has the right collection. And each one has its own way of defining your AOI (draw a box, upload a shapefile, paste GeoJSON, pick a tile ID) and its own cloud cover filter if you're after spectral data. Half the time goes into learning each portal's quirks instead of doing the actual analysis. Does anybody else feel like decentralization is one of the biggest bottlenecks?

Upfront disclosure: I work at Picterra, and we built this.

We wanted to show what you can get from stacking public datasets rather than just talk about it, so we put this together and made it free with no sign-up, because gating it would have defeated the point.

Pick anywhere, zoom in, and it returns erosion risk, fire and flood history, land cover, climate projections to the 2040s, land conversion emissions, and forest change since 2020. Sources include Dynamic World, MODIS burned area, Copernicus DEM, JRC Global Surface Water, and the Google forest typology layer. All of them are listed in the app.

One thing worth knowing before you try it: it frames the analysis area by zoom level rather than detecting parcel boundaries, so the numbers describe the frame you are looking at rather than a specific plot. That was a deliberate scope decision, not an oversight, but it changes how you should read the output.

Happy to answer anything on methodology or sources.

lens.picterra.ai

When assessing the impact of a flood, knowing what the area looked like before the event is just as important as seeing the damage afterward.

For this case study, we compared satellite imagery of Prachin Buri, Thailand, from October 7, 2025, with imagery from October 2, 2026, showing flood conditions along the Bang Pakong River.

The comparison highlights an important principle in geospatial analysis: you can't reliably understand change without a reference.

Historical imagery can help analysts:

• Establish baseline land conditions
• Identify changes in flooded areas
• Assess potential impacts on agricultural land and infrastructure
• Support future disaster risk assessments

One important consideration is timing. A historical image provides context, but it doesn't automatically establish the exact conditions immediately before a disaster.

For those working in GIS, remote sensing, or disaster management: how do you typically establish a baseline when assessing flood impacts? Do you rely on historical optical imagery, radar data, or a combination of both?

Hi! I need to do a classification of forest species for an area. Unluckily, I don't have enough polygons to train a model to do it, but I have 2 classifications done in the two neighbouring regions (one very big in the north, one of the same dimension of my target area in the south). I don't have the training polygons of these two neighbouring areas.

Since both existing maps should carry enough information to classify my area (same forest types, same morphological conditions etc), I was considering using them as predictors, together with other bands. I should have then some hundred points in my area to validate the obtained map.

Since my main field is not RS, I want to ask you if it something acceptable from the methodological point of view, and most of all if there is a way to account for the native uncertainties of the maps I use for the training together with new uncertainties derived from my model.

Thank you! If it is something no remotesensing expert would ever do, pls don't insult me

bye!

https://github.com/sekaikx/lifeline

🚨 NEW RESEARCH 🔥
We mapped the 2025 Palisades Fire to explore how wildfire burn severity intersected with the demographic characteristics of the affected communities.
JPG

Spatiotemporal Patterns of Wildfire Severity and Demographic Characteristics in the 2025 Palisades Fire, Los Angeles, California https://www.mdpi.com/4123346 #mdpigeohazards via @GeohazardsM

Hey everyone,

I've been playing around with satellite imagery and ended up building this little project to look at possible changes in forest cover around Koh Phangan, Thailand.

It compares satellite images from 2019 and 2026 to flag areas that might be worth checking on the ground, specially by rangers and authorities. I've added the terrain altitud to get a better idea of where water might flow and how that lines up with the waterways on the map. I'm now wondering if there's something useful I could do with this for flood monitoring or drainage, although I'm still figuring out what might actually be possible.

https://koh-phangan-forest-watch.vercel.app/

I'd love to do some humanitarian work and NGOs, so this has been a way to learn by building something practical I guess.

It's still a work in progress, and the results aren't verified forest loss. I'd be curious to hear what people think, could something like this be useful in conservation or environmental work? Any feedback is welcome.

Hi everyone,

I’m an undergraduate civil engineering student working on a research project involving multi-temporal landslide mapping along Nepal’s Mid-Hill Highway.

My goal is to develop a reliable landslide inventory covering approximately 2010–2023, identifying landslide locations, mapping their boundaries, and determining when they first appeared or reactivated based on historical satellite imagery.

I’ve been exploring Google Earth Engine (GEE), QGIS, Sentinel-2, and Landsat imagery, but I’m struggling to determine the most efficient and reliable workflow for mapping landslides across such a large area and multiple years.

I would appreciate advice on the following:

1. Mapping methodology: What is the most practical approach for creating a multi-temporal landslide inventory over a long highway corridor? Is manual digitization, semi-automated detection, or a combination of both preferable?
2. Historical imagery: What datasets or platforms would you recommend for identifying landslides from 2010 onward? In particular, are there suitable alternatives to Sentinel-2 for the pre-2015 period?
3. Change detection: Are there reliable methods for identifying newly formed landslide scars by comparing satellite images from different dates?
4. Existing inventories: Does anyone know of publicly available landslide inventories covering Nepal’s Mid-Hill Highway or nearby regions, particularly those containing temporal information?
5. Practical workflow: If you have worked on a similar project, what workflow would you recommend for mapping landslide polygons and estimating their occurrence periods without manually inspecting every image?

I’m particularly interested in approaches that are feasible for a student research project with limited computational resources.

I’m not expecting a fully automated solution. My aim is to develop a scientifically defensible inventory using satellite-based candidate detection and manual verification wherever necessary.

Any advice, relevant publications, open datasets, scripts, or examples of similar projects would be extremely helpful. I’d also appreciate hearing from researchers who have worked on landslide inventories in Nepal or the Himalayas.

Thank you!

Hey everyone,

I've been playing around with satellite imagery and ended up building this little project to look at possible changes in forest cover around Koh Phangan, Thailand.

It compares satellite images from 2019 and 2026 to flag areas that might be worth checking on the ground, specially by rangers and authorities. I've added the terrain altitud to get a better idea of where water might flow and how that lines up with the waterways on the map. I'm now wondering if there's something useful I could do with this for flood monitoring or drainage, although I'm still figuring out what might actually be possible.

https://koh-phangan-forest-watch.vercel.app/

I'd love to do some humanitarian work and NGOs, so this has been a way to learn by building something practical I guess.

It's still a work in progress, and the results aren't verified forest loss. I'd be curious to hear what people think, could something like this be useful in conservation or environmental work? Any feedback is welcome.

Hey everyone,

For those who process Orthophotos from aerial imageries at work, what tools/softwares do you use? Proprietary or free software? Is there any tool(s) in the Python ecosystem?

I have got hands-on with some aerial imagery and am looking for software options for deriving orthophotos from it.

Thanks!

Hello everyone, can someone help explain this concept to me and provide some examples of active and passive sensors? Thanks so much!

Hi everyone,

I’ve been working on a live cohort-based course called Anefelo (Pixel to Alpha) focused on Earth Observation and machine learning.

I built this because I kept seeing standard ML practices failing in spatial contexts—specifically, people using random pixel splits that cause massive data leakage, leading to 95% accuracy scores on models that completely fail when you actually look at the map.

The course focuses heavily on honest model evaluation: using spatial blocks instead of random splits, and calculating class areas with 95% confidence intervals using proper probability sampling (stratified estimation).

I have a live cohort coming up on Nov 3-12, and before we kick off, I’d love to get some brutally honest feedback from the professionals in this sub.

Does the curriculum on the landing page make sense to you?

Are there any major blind spots or topics you feel are missing when it comes to defending classification maps?

Is the messaging on the page clear?

You can check out the page here: anefelo.com

I really appreciate any thoughts or critiques you have. Thanks!