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UID:pretalx-foss4g-2022-PGD3HM@talks.staging.osgeo.org
DTSTART;TZID=CET:20220826T093000
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DESCRIPTION:Forest disturbance can have a significant impact on the hydrolo
 gic regime and health of watersheds\, aquatic habitats\, and their overall
  ecological functions. Although these impacts can vary as a result of phys
 ical and hydroclimatic conditions in watersheds\, over the past decades a 
 simple metric known as equivalent clearcut area (ECA) has emerged to quant
 ify the cumulative disturbance at any point in time in a watershed\, accou
 nting for the temporal dynamics\, including recovery\, of historical distu
 rbance. \nECA is widely used as an indicator to quantify forest disturbanc
 es as it not only covers all disturbance types but also considers the subs
 equent recovery of these disturbed areas through space and time. An ECA co
 efficient of 100% means there is no hydrological recovery due to planting 
 trees\, on the other hand\, an ECA of 0% means 100% of the disturbed area 
 has reached its maximum potential in recovery. \nThe prime objective of th
 is project was to generate an annual time series of ECA for every watershe
 d within the area covered by the Nadina Natural Resource District in Briti
 sh Columbia\, Canada. The disturbance types identified in this project wer
 e forest fire\, timber harvest\, pest infestation\, and permanent infrastr
 ucture development. The time and location of these disturbances were integ
 rated with the BC Freshwater Atlas\, in order to provide quantitative esti
 mates of ECA for the watershed associated with stream reaches in the study
  area. \nDue to the cumulative nature of ECA over space and time\, all typ
 es of forest disturbances have to be combined and recovery factors must be
  applied to account for vegetation and hydrological recovery over time. Pr
 evious field research was used to find the relationship between the tree s
 tand height and the age following logging. \nIn order to apply the methodo
 logy\, open source data and tools were used. We used two publicly availabl
 e global satellite image derived raster products of forest change for our 
 initial disturbance data source. We updated the forest change raster produ
 cts using GDAL with local public geospatial datasets to assign change type
 s for each year from 1985-2020\, creating a unified multiband raster of ch
 ange. The multiband raster was processed within Python\, using GDAL and Nu
 mPy libraries\, and recovery factors were applied to each pixel dynamicall
 y based on the year and type of change. The result of this processing was 
 a collection of time series for watersheds broken down by year and type of
  change present. \nThe ECA results for the study area were loaded into Pos
 tGreSQL for delivery to a web application that allows a user to compare a 
 location’s ECA with the forest disturbance input. The application relies
  on Mapbox GL to interact with a web map and the spatial data display of t
 he forest disturbance locations. D3 and Crossfilter JS libraries were used
  to interact with the disturbance data\, allowing a user to filter histogr
 ams based on a variety of attributes\, which are reflected in the histogra
 ms and web map in real time. ECA time series data is displayed in interact
 ive histograms and line charts.
DTSTAMP:20260412T013603Z
LOCATION:General online
SUMMARY:If a tree falls in the forest\, does the river notice?: Creating an
 d Visualizing Equivalent Clearcut Area using Satellite Imagery\, Python an
 d Crossfilters - Christopher Webb
URL:https://talks.staging.osgeo.org/foss4g-2022/talk/PGD3HM/
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