class: center, middle, inverse, title-slide # Google Earth Engine
(GEE)
applications in hydrology
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Josh Erickson
###
USDA-Forest Service
--- ## About Me - Hydrologist (day job) - Remote Sensing Analyst (detail) - Geoscience and Math background - Focus is leveraging computing platforms (R, Python, GEE) for resource management work. .me-box[] --- ## Goals -- - Leave having an idea of what GEE is and what it can do <br> <img src="gee_talk_files/images/gee.png" height="50px" right: 25%/> <br> <br> - Most importantly, some applications in hydrology .water-box[] <br> <br> <br> <br> <br> <br> <br> <br> - What, how, apply. --- ## What is GEE? -- - free open source software .blue[(FOSS)] - Inherently parrallel; uses a .blue[petabyte] scale server ~ 1,000,000 GB - allows .blue[clients (users)] to ask for products (Image/ImageCollections) - And then will process those requests .blue[server-side] -- <img src="gee_talk_files/images/client_server.png" height="325px" /> --- ## Advantages -- - Extensive collections (e.g. imagery, geophysical, weather/climate models, etc.) - Reducing big ImageCollections - Fast, really really fast! - Lots of documentation, apps, tutorials, research, etc. -- .ferrari-box[ ] -- ## Disadvantages (IMO) -- - Can be 'coding' barrier entry - Can be abstract-ish, i.e. remote sensing - Research buzz... .problems-box[] --- ## Reduce Image (The how?) -- A big advantage of earth engine is to reduce large image collections fast. .bg-washed-green.b--dark-green.ba.bw2.br3.shadow-5.ph4.mt5[ For example, let's say we want the median PRISM monthly precipitation from 2010-present] <br> <br> <center> <img src="gee_talk_files/images/precip_intro.png" height="200px" align="bottom" /> </center> --- ## Reduce Image (The how?) <img src="gee_talk_files/images/client_server.png" height="100px" /> .pull-left[ <center> <img src="gee_talk_files/images/reducer.png" height="400px" /> </center> ] -- .pull-right[ <center> <img src="gee_talk_files/images/prism.png" height="200px" /> </center> ] --- ## Applying the Concept Reduce Regions is the key; points and polys. <br> Very similar to `extract` in ArcGIS .pull-left[ <img src="gee_talk_files/images/prism_zoom2.png" height="250px" /> ] -- .pull-right[ .rrhucs-box[] ] --- ## Applying the Concept Reduce Regions is the key; points and polys. <br> Very similar to `extract` in ArcGIS .pull-left[ <img src="gee_talk_files/images/prism_pts.png" height="225px" /> ] -- .pull-right[ .rrPts-box[] ] --- ## You can provide any geometry - For example, proposed land use activities. <img src="gee_talk_files/figure-html/unnamed-chunk-1-1.png" width="100%" style="display: block; margin: auto;" /> --- ## Layer units by images .units-box[] --- ## Now we have zonal stats for each unit! .unitsrr-box[] --- ## What about time series? Not going to get too crazy but you can. -- `\(\hat{Y}_t = a_0 + \sum_{n=1}^\infty (a_n\cos nx +b_n\sin nx)\)` .deep-box[] -- Just keep it simple <br> <img src="gee_talk_files/images/npp_ts.png" width="35%" style="display: block; margin: auto auto auto 0;" /> --- # Banding This is a way to keep a certain temporal feature, e.g. year, month, week, etc. .pull-left[ <img src="gee_talk_files/images/reducer.png" height="425px" /> ] -- .pull-right[ <img src="gee_talk_files/images/to_bands.png" height="300px" /> ] --- # Example with previous points .pull-left[ <img src="gee_talk_files/images/prism_pts.png" height="225px" /> ] -- .pull-right[ <img src="gee_talk_files/images/precip_time.png" width="100%" /> ] --- # Example with previous points <center> <img src="gee_talk_files/images/precip_month.png" height="500px" /> </center> --- # Animation with time series <center> <img src="gee_talk_files/images/prism_18_19.gif" height="500px" /> </center> --- # Animation with time series <center> <img src="gee_talk_files/images/ndvi_18_19.gif" height="500px" /> </center> --- # Animation with time series <center> <img src="gee_talk_files/images/drought.gif" height="500px" /> </center> --- # Animation with time series <center> <img src="gee_talk_files/images/jbratt.gif" height="500px" /> </center> --- # Into the future? <center> <img src="https://media.giphy.com/media/ZZkCo8zKWtt2ZgozfX/giphy.gif" height="500px" /> </center> --- # Into the future? There are available climate models in GEE. NASA Earth Exchange. <center> <img src="gee_talk_files/images/climate.png" height="500px" /> </center> --- # Into the future? What about the units we looked at? -- .pull-left[ <img src="gee_talk_files/images/units.png" height="300px" /> ] -- .pull-right[ <img src="gee_talk_files/images/future_temp_box.png" height="400px" /> ] --- # Wrapping Up -- - GEE is a way to .blue[reduce] big image collections .pull-right[ <center> <img src="gee_talk_files/images/prism.png" height="75px" /> </center> ] -- - You can do it from local to regional .blue[scale] .pull-right[ <center> <img src="gee_talk_files/images/units.png" height="75px" /> </center> ] -- - Climate projections into the .blue[future] .pull-right[ <center> <img src="gee_talk_files/images/climate.png" height="75px" /> </center> ] --- # Wrapping Up - slides available at https://hydroblog.org/slides/gee_talk/gee_talk.html - some apps from Justin Braaten; https://emaprlab.users.earthengine.app/view/lt-gee-time-series-animator, https://t.co/xqUN7W8KBa?amp=1, https://t.co/3fTl0wI8Gh?amp=1 <center> .end-box[] </center>