NbS: Assess historical deforestation

Modified on Mon, 27 Mar 2023 at 11:58 AM

Summary Description


This template project looks at historical forest loss to assess forest loss across Cambodia, and within the defined project areas. This template will enable you to determine whether your project area has experienced deforestation at any point in the past 20 years.



TABLE OF CONTENTS


Demonstration Video





What should I use this template for?


You should use this template project to look at historical deforestation and forest loss for a given location. This could either be a large area (as in this example, where we are looking at Cambodia) or in one or more project sites (here we are looking at 5 different project sites). You can look at forest loss between the years 2001 and 2021.



What data has been used?


The data used in this template is the Hansen Global Forest Change v1.8 dataset. This dataset shows annually updated global-scale forest loss, derived using Landsat time-series imagery from 2000-present. The data are provided by the Global Land Analysis and Discovery (GLAD) laboratory at the University of Maryland, in partnership with Global Forest Watch (GFW) and represent a relative indicator of spatiotemporal trends in forest loss dynamics globally. Users should beware of potential inconsistencies in these data due to differences in data density, processing and instrumentation over the 20+ year time period. 2012 in particular had reduced coverage due to only one satellite in operation that year.


This dataset is updated on an annual basis, with the 2022 forest loss data predicted to be available sometime in mid-2023. It takes many months for the dataset providers to produce the update because they are processing raw satellite imagery for a whole year across the whole globe.



What do the outputs show me?


Map Outputs


This template project has only one map output layer. This shows the extent of forest loss in Cambodia between 2001 and 2021. The legend on the left-hand side tells us that the colour scheme relates to the year in which deforestation occurred. Yellow is 2001 and Red is 2021, with different shades of orange representing the intervening years.




Dashboard Outputs


If we look at the dashboard tab, you will see that we have one chart and two tables. The chart shows the area of forest loss for the whole of Cambodia on an annual basis from 2001 to 2021. This chart can be downloaded as an image using the download button at the bottom-left of the chart. You will have the choice of downloading it as an image, or the underlying data as a CSV spreadsheet. This is true of all charts created with Earth Blox.

 

The table called Cambodia Forest Loss (ha) shows this same data as the chart, except in tabular form. This data can also be downloaded as a CSV spreadsheet using the download button at the bottom-left of the table. This is true of all tables created with Earth Blox.


The table called Project Forest Loss (ha) shows the area of forest loss for each of the project sites on an annual basis from 2001-2021. This data can also be downloaded as a CSV spreadsheet using the download button at the bottom-left of the table.



What are the blocks used in the workflow?

Here we will go into more technical detail about what the workflow is doing.


  • The Use this Dataset block has selected the input data which (as described above) is the Hansen Global Forest Change.
  • The Select Area of Interest block selects the primary area of interest for visualising and analysing the data.
  • The Select Time Period" block selects the time period for our analysis.
  • The Aggregate Images block simply tells the system how to handle all the images that are pulled through. This is set up so that we can see forest loss for all years at the same time.
  • The Add Map Layer block controls how data is visualised on the map, and how it looks. The data we have selected is "lossyear" which shows us the year in which forest loss occurred at a given location. The default colour scheme relates the year in which the deforestation occurred to a particular colour. Yellow is 2001 and Red is 2021, with different shades of orange representing the intervening years.
  • The two Add Table blocks create the tables and charts for us.
  • The table called Cambodia Forest Loss (ha) shows the area of forest loss for the whole of Cambodia on an annual basis from 2001 to 2021. In the table settings, we can see that we are calculating the forest loss coverage in hectares and that we are grouping this information by the year in which the loss occurred (from the image band "lossyear"). This will be applied to our main Area of Interest, as selected on the block above. You will see that we have also chosen to include a chart of this data.
  • The table called Project Forest Loss (ha) shows the area of forest loss for each of the project sites on an annual basis from 2001-2021. In the table settings, we can see that we are calculating the forest loss coverage in hectares, that we are grouping this information by the year in which the loss occurred (from the image band "lossyear"), and that we also want to group this by the different projects we have loaded into the map.











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